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  1. #1
    Senior Member markm109's Avatar
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    Why would Alum feel better than Steel?

    My wife and I test road 4 tandems yesterday, two traditional and two recumbents. I'll discuss recumbents in that forum. So we rode the 2004 Santana Arriva SE and the 2004 Trek T2000. The Santana felt like we were fishtailing constantly, while the Trek felt smooth and didn't have that issue, therefore we liked the Trek ride better, which was the opposite that the store owner predicted and what I have read on these forums.

    So here are my questions. The Trek is made of that new Klien designed ZR9000 aluminum - perhaps it is good stuff? The weight of my wife and I combined is almost 500lbs (it was over 500 until we started biking) and it will be less by the end of summer (it is our goal to get fit and healthy). Perhaps the high weight is causing the aluminum to feel smooth and the cromo to bend excessively?

    Another idea I'm considering is we are new to tandems and only I ride a road bike on a regular basis where my wife rides the occasional mtb. The first ride was the Santana and I was riding as I do on my road bike and I have no idea what my wife was doing but we went out and back flopping around. I mentioned the feeling of the bike to the store owner before we took out the Trek and he said you have to work together - give into the feel of the bike all the time unless you booth together crank up a hill, etc. So on the Trek we road together and it was much more pleasant and didn't have any floppyness. So perhaps this is the reason - must learn to ride as a team. If we were both trying to ride as we normally do but not necessarily at the same time doing the same thing, would that cause the wobbles? By wobbles, I felt constantly trying to correct for the weight of the bike being shifted from one side to the other, like the back end was flopping left then right - and we were going straight.

    The test rides were only 2 miles and it was our fist time on a tandem this year. We test rode a few last fall. We will test those two bikes again for a longer ride, like 10 miles each and see how it goes, but right now we both liked the Trek. We intend to ride a Cannondale tandem when it shows up as well since it seems to have a decent setup for just over $2k while the Trek and Santana were $3k each.

    We looked for used but only found ones that were over 12 and 20 years old - nothing within a few hours drive that was only a few years old.

    Any suggestions why we expierienced the floppies on the Santana that should have ridden like a cadilac would be helpful.

    Mark & Laura

  2. #2
    SDS
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    "the opposite that the store owner predicted and what I have read on these forums."

    I would have agreed alright. The Santana should have 1.85" of trail and the Trek should have 2.00" (I think). So the livelier (less stable) handling of the Trek should have increased the likelihood of fishtailing.

    "Perhaps the high weight is causing the aluminum to feel smooth and the cromo to bend excessively?"

    I think that is exactly right. You are fishtailing in part because the frame is flexing. It is also quite likely that if you had reversed the test order the Santana would have seemed much better, though likely not as good as the Trek for your team. By the time you got to the Trek, your wife had changed to a more balanced pedal stroke, and you had gotten better at countersteering for the remaining unbalanced inputs. It is precisely because only the captain can countersteer for unbalanced stoker inputs that smooth pedaling by the stoker is so important on higher-trail-steering tandems.

    I think that in the current market, the steel ride is an acquired taste that is limited to weaker and lighter teams. The combined requirements of wall thickness sufficient to resist denting (which can lead to beer-can failure, i.e., dent leads to tube failure by bend toward dent) and marketable weight limits the tube sizes that can be used, and that limits frame stiffness.

    "So perhaps this is the reason - must learn to ride as a team."

    This instruction does work, to motivate captains and stokers on a tandem to pedal in a balanced way without shifting their weight left and right. But that is just as important on single bikes. Every once in a while when you are on singles, somebody will point to an accomplished (not experienced, not old) roadie, and they will say something like "Look at that smooth pedal stroke...." and the person they are pointing at will be notable by almost no upper body motion, straight up and down leg motion (fix your cleat angle/float so you can do that), 90-plus rpm cadence, bike goes in very straight line, frame stays straight up and down, etc. This appalling (when you are competing with it!) efficiency leads to remarkable endurance and power output. And when you put two people like that on a tandem, it goes straight from the very beginning. The team concept is helpful but overrated.

    Want the short but steeper road to that kind of pedal stroke? Try one-legged pedaling, and if you are daring, rollers. The one-legged pedaling will teach you to recruit muscles all the way around the pedal circle, and the rollers will require a balanced effort, or you will have difficulty staying on them and riding straight. This experience is very beneficial.

    There is a good chance that the Cannondale frame will prove to be a better tandem for you than any other. I have heard that the tubing has been upgraded, but given that they are still using 6061-T6, the tubes are likely to have greater wall thicknesses (heavier, but that is good for you) and to be stiffer.

    It doesn't seem to me that your criteria should be the same as other shoppers. Right now you are looking for the best tandem for the price for a 500lb team. Manufacturers do not design tandems to be perfect for you. 6061-T6 aluminum may coincidentally drive the designers to features that are better for you than ZR-9000 or 7005 aluminum.

    I think you tested two tandems in good working order. But deficiencies in tire size or pressure, hub bearing adjustment, spoke tension, or headset tightness could have placed a handicap on the Santana. I would be inclined to accept my ride impressions, but to reverse the test order next time.

    "Any suggestions why we expierienced the floppies on the Santana that should have ridden like a cadilac would be helpful."

    I blame the small steel tubes and the ride order. At 190 lbs I find steel tandems to be too rubbery. Thin aluminum isn't as nice in a sprint as thick aluminum, but I would trade the sprint quality of the thick aluminum for the ride quality of the thin aluminum the rest of the time. In your weight class, it could be that the thick aluminum will be better than the thin aluminum all the time, which would favor the Cannondale even at the same price. My team weight not counting the tandem is at or below 335 lbs, though occasionally it hops up to 430lbs. I have a pre-'98 6061-T6 Cannondale tandem and a 7005 Easton (I think that is the correct designation) Meridian tandem. The Meridian is long, and that may have favorably slightly changed the cruising (not sprinting) ride quality. I can honestly say I have extensive tandem experience with both materials.

    Depending on your road quality, I would recommend 700 X 32 tires at 120 psi. Smaller tires might risk pinch flats. You might be at the upper limit for wheel reliability. If you have wheel problems (trueness, spoke failure, frequent going out of true), I recommend Aerospoke tandem wheels.

  3. #3
    Senior Member Retro Grouch's Avatar
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    I think that people tend to have assumptions about how different frame materials are going to act and then allow those assumptions to color their subjective feelings during the test ride process.

    I think that there's lots and lots of differences in bicycles that are more important than what basic alloy the frame is made out of. Number 1 on my list is tire air pressure but nobody wants to talk about that except for the tire companies who say that most of us use way too much air pressure. If this was your first ride on a tandem, I'd guess that even a couple of miles more experience might have a HUGE impact on your perception. The list goes on. Maybe your position on the different bikes made you feel more stable on the Trek. I'd buy the one that I liked best overall and not worry too much about other people's opinions. What's to say that their subjective experience should be more valid than mine?

  4. #4
    hors category TandemGeek's Avatar
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    A couple of thoughts, some of which echo what Scott (SDS) wrote:

    1. Learning Curve: The second tandem you test ride always feels more stable than the first when you're shopping for your first tandem, and the third one will feel even more stable. Of course, I think you already figured that one out: you came up a learning curve, rode "better" as a team on the second ride and were more attentive to what you were doing on the tandem. There are some tandem dealers who use this newbie phenomenon -- stacking the test rides -- to sell certain brands or models of tandems. The best way to deal with the learning curve during test rides is to re-ride each of the tandems you test rode in reverse order. The second rides don't need to be all that long; just long enough to recalibrate your initial first impressions.

    2. All Tandem Dealers Are Not Created Equal: The last thing any good bicycle or tandem dealer should do is bias buyers with predictions about how a bike or tandem will feel. Every tandem has it's own ride characteristics and new buyers will perceive them to be good or bad depending on their exerpeince, expectations, and biases -- the last thing they need is to be told what to expect IF they are truly trying to be objective about the tandems being test ridden.

    3. Frame Differences: The "Cadillac" feel of steel is real; bearing in mind that -- despite their current re-incarnation as a performance car producer -- "Cadillac" implies luxurious and cushy. All other things being equal, steel flexes and aluminum doesn't. Given your combined weight and what you described as something less than ideal riding form from your beloved, the steel tandem frame would have exhibited a lot of undesireable lateral (side-to-side) flex on your test ride. The aluminum tandem frame, on the other hand, does not flex and would have felt a lot more "stable" on it's own merits to any new team, and certainly more stable than the first tandem ridden (see above). However, I would note that the (with the exception of the small frames) the Trek tandems share the same steering geometry as the Santana and as Burley (~1.85") . Cannondale is a bit more racy at 2" and then Co-Motion has the raciest at 2.125".

    4. Other Differences: As already noted, tires and wheels factor into the ride impressions. The Santana would have been sporting 28mm Conti Gatorskin tires on 40 spoke wheels (comfy and durable) whereas the Trek would have been sporting 28mm Conti Ultra 3000 tires and a pair of Bontrager RaceLite Tandem wheels which would would certainly be a "stiffer" wheelset than the Santana's.

    Anyway, keep on test riding. As Scott noted, a Cannondale would be a good tandem to include in your comparision. The RT1000 is equipped very much like the Trek T2000 (Ultegra) and comes in at a similar price point; both of these tandems are "better values" than the Santana Arriva SE that comes with 105 level components, etc... Aluminum is a very popular frame material for many good reasons. Steel is also a perenial favorate with the traditionalists and lightweight teams. However, you'll need to trust your instincts when it comes to sorting out which brand/model "feels" best to you. On the bright side, I don't think there are any bad tandems at the price point you have indicated is included in your search.

  5. #5
    Cat 6 Steve Katzman's Avatar
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    Quote Originally Posted by livngood
    SNIP All other things being equal, steel flexes and aluminum doesn't. Given your combined weight and what you described as something less than ideal riding form from your beloved, the steel tandem frame would have exhibited a lot of undesireable lateral (side-to-side) flex on your test ride. The aluminum tandem frame, on the other hand, does not flex and would have felt a lot more "stable" on it's own merits to any new team, and certainly more stable than the first tandem ridden (see above). SNIP
    All things being equal (ie: tubing diameter and tubing wall thickness), steel would be approximately three times stiffer (and three times heavier) than aluminum. The reason aluminum has a reputation for stiffness is because of the larger tubing diameters typically used for bike frames. Back before Klein pioneered the oversize tubing used for aluminum frames today, aluminum frames were considered too flexy to be used by most folks, although there were a few manufacturers making them.

    Today, bike tubing (of any material) is manufactured in a range of diameters and thicknesses, giving the frame designer lots of latitude on how his frame will perform.

    The point I am making is that the material that a single or tandem bike is made of has much less to do with the ultimate stiffness of the bike than the design or implementation of that material. This includes, steel, aluminum, titanium or carbon. Any one of the above materials can be made into a flexible frame or an extremely stiff one. Bicycle frames made of specific materials should not be generalized as having inherent properties, unless taken in the context of the specific design implementation of the materials (ie: tubing diameters and wall thicknesses).

  6. #6
    hors category TandemGeek's Avatar
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    Quote Originally Posted by Steve Katzman
    All things being equal (ie: tubing diameter and tubing wall thickness), steel would be approximately three times stiffer (and three times heavier) than aluminum. The reason aluminum has a reputation for stiffness is because of the larger tubing diameters typically used for bike frames. [snip] Today, bike tubing (of any material) is manufactured in a range of diameters and thicknesses, giving the frame designer lots of latitude on how his frame will perform.
    What is possible is often times quite different than what is produced for the masses, so let me rephrase...

    Given the tubing that tandem builders such as Santana, Co-Motion, Cannondale, Trek and Burley are actually using today, the Aluminum tandem frames they produce are lighter and more rigid than the steel framed models. This is done for a variety of reasons, but mostly because steel frame buyers are looking for certain ride characteristics while aluminum frame buyers are looking for something light and stiff. Thus, if you discount the wheels and tires and focus only on the frame (e.g., all things being equal), you'll find that the production model steel tandem frames are not as stiff as the the production model aluminum frames.

  7. #7
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    Quote Originally Posted by Steve Katzman
    ...The point I am making is that the material that a single or tandem bike is made of has much less to do with the ultimate stiffness of the bike than the design or implementation of that material. This includes, steel, aluminum, titanium or carbon. Any one of the above materials can be made into a flexible frame or an extremely stiff one. Bicycle frames made of specific materials should not be generalized as having inherent properties, unless taken in the context of the specific design implementation of the materials (ie: tubing diameters and wall thicknesses).
    Yes, for the most part. But material properties definitely guide -- if not dictate -- design and implementation. A tandem manufacturer certainly could build a steel frame with all the stiffness and comfort of a current butted-aluminum frame. But it would either weigh much more or be much less robust and durable than current steel models.

    On the other hand, that same manufacturer could build a very light aluminum tandem frame with "steel is real" flexibility. However, the cost of servicing a no-time-limit warranty on such a frame would cut way into the maker's already slim profit margin. [Have you ever noticed that few if any ultra-light aluminum (e.g. "Scandium") singles come with a no-time-limit frame warranty?]

    Given the current state of the frame builder's art, aluminum really is the best material for low- to mid-priced tandems.

  8. #8
    Cat 6 Steve Katzman's Avatar
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    Quote Originally Posted by bikeriderdave
    Yes, for the most part. But material properties definitely guide -- if not dictate -- design and implementation. A tandem manufacturer certainly could build a steel frame with all the stiffness and comfort of a current butted-aluminum frame. But it would either weigh much more or be much less robust and durable than current steel models.

    On the other hand, that same manufacturer could build a very light aluminum tandem frame with "steel is real" flexibility. However, the cost of servicing a no-time-limit warranty on such a frame would cut way into the maker's already slim profit margin. [Have you ever noticed that few if any ultra-light aluminum (e.g. "Scandium") singles come with a no-time-limit frame warranty?]

    Given the current state of the frame builder's art, aluminum really is the best material for low- to mid-priced tandems.
    You and Mark are probably right about what tubing is readily available for tandem builders and I will not argue that.

    Years ago, before Klein and Cannondale made oversized aluminum tubing commonplace, manufacturers such as Alan and Vitus made aluminum frames with tubing diameters that were similar to those on steel frames. These frames were very flexible (more so than steel), but they weren't light enough to have longevity problems, as their wall thicknesses were thicker than steel or present-day aluminum. Great pros like Sean Kelly successfully rode these frames in the grand tours, despite their lack of stiffness. Probably a very comfortable ride.

    Todays stiffer steels such as Columbus' UltraFOCO thermochrom, which are produced in oversized diameters (at least for single bike use) permit the builder to build steel frames that are as stiff as most aluminum frames out there. It is quite possible that these alloys have not yet been produced as tube sets for tandem use. However, if a large enough tandem builder wanted to make an order which was economically feasible, it would be technically possible to do.

    When highly respected folks like Mark L. make generalizations on the internet like "steel flexes and aluminum doesn't", although I'm sure he knows this isn't the case, the less educated repeat it to their friends, who spread it to their friends... I think you get the point. When I hear people say, "I didn't consider an aluminum frame because they have a harsh ride" or "I wouldn't ride a steel (or Ti) frame because they are too noodley" I realize that the generalizations have been taken too far.

    I didn't mean to ruffle any feathers.

  9. #9
    I couldn't car less. jeff williams's Avatar
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    'cause it's filled with cold beer.

    (wipes a tear..) O.k, not to be a waste, seems to me that the 'ride' versus weight with Alu is moot as a bike made from Alu requires suspension to make it smooth. So it becomes heavy.
    30+lbs Alu mtb, give me a break, or possibly, I'll break it.
    Recumbent, I have no idea. Not fond of Alu as a traditional frame geometry metal.
    I also have seen BEAUTIFUL Alu bikes, incorporating the best of this metals casting abilities (DH overbuilt frames.)
    Sucks though, I want a new steel hardtail frameworks. $$$ WOW. Like above 7 for the FRAME.
    Last edited by jeff williams; 06-03-04 at 10:01 AM.

  10. #10
    hors category TandemGeek's Avatar
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    Quote Originally Posted by Steve Katzman
    I didn't mean to ruffle any feathers.
    No worries and no fluffy down flying around at our household. You were correct to point out the overgeneralization and I merely clarified the context of my remarks.


    Quote Originally Posted by jeff williams
    'caus it's filled with cold beer.
    While politically incorrect to make bad jokes that compare aluminum frames to beer cans, it's still hard not to chuckle. I have a couple Aluminum bikes, including our Ventana off-road tandem; the boom tube is literally the size of a beer can: http://www.ventanausa.com/frame_elconquistador.html
    Last edited by TandemGeek; 01-30-05 at 09:21 PM.

  11. #11
    I couldn't car less. jeff williams's Avatar
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    I like lotsa bikes, most new ones are Alu or Ti and steel bits.

    I like beer in a bottle.

    It's wild that new steel frames are exotic\ I'm sure I can get a better price\selection in Alu. There are inherent properties to the metal that makes me avoid unless @ the same level of competency I'd expect from custom steel builds.
    $$$$. Both ways.

  12. #12
    Banned. galen_52657's Avatar
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    Quote Originally Posted by Steve Katzman
    All things being equal (ie: tubing diameter and tubing wall thickness), steel would be approximately three times stiffer (and three times heavier) than aluminum. The reason aluminum has a reputation for stiffness is because of the larger tubing diameters typically used for bike frames. Back before Klein pioneered the oversize tubing used for aluminum frames today, aluminum frames were considered too flexy to be used by most folks, although there were a few manufacturers making them.

    Today, bike tubing (of any material) is manufactured in a range of diameters and thicknesses, giving the frame designer lots of latitude on how his frame will perform.

    The point I am making is that the material that a single or tandem bike is made of has much less to do with the ultimate stiffness of the bike than the design or implementation of that material. This includes, steel, aluminum, titanium or carbon. Any one of the above materials can be made into a flexible frame or an extremely stiff one. Bicycle frames made of specific materials should not be generalized as having inherent properties, unless taken in the context of the specific design implementation of the materials (ie: tubing diameters and wall thicknesses).
    I think Steve has his act together. I do not own a tandem (yet) but am about to purchase one. I tested 5 different tandems, 3 steel and 2 aluminum. I found the steel tandems to suffer much less from stoker-initiated-steering. My favorite was the Longbikes tandem with oversized steel tubing. My next favorite was the el-cheapo KHS Milano. The KHS tracked like it was on a rail, especially at speed down a winding road. I think a lot of dealers push the expensive brands because...they make more money!

  13. #13
    Banned. galen_52657's Avatar
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    Quote Originally Posted by livngood
    A couple of thoughts, some of which echo what Scott (SDS) wrote:

    1. Learning Curve: The second tandem you test ride always feels more stable than the first when you're shopping for your first tandem, and the third one will feel even more stable. Of course, I think you already figured that one out: you came up a learning curve, rode "better" as a team on the second ride and were more attentive to what you were doing on the tandem. There are some tandem dealers who use this newbie phenomenon -- stacking the test rides -- to sell certain brands or models of tandems. The best way to deal with the learning curve during test rides is to re-ride each of the tandems you test rode in reverse order. The second rides don't need to be all that long; just long enough to recalibrate your initial first impressions.

    2. All Tandem Dealers Are Not Created Equal: The last thing any good bicycle or tandem dealer should do is bias buyers with predictions about how a bike or tandem will feel. Every tandem has it's own ride characteristics and new buyers will perceive them to be good or bad depending on their exerpeince, expectations, and biases -- the last thing they need is to be told what to expect IF they are truly trying to be objective about the tandems being test ridden.

    3. Frame Differences: The "Cadillac" feel of steel is real; bearing in mind that -- despite their current re-incarnation as a performance car producer -- "Cadillac" implies luxurious and cushy. All other things being equal, steel flexes and aluminum doesn't. Given your combined weight and what you described as something less than ideal riding form from your beloved, the steel tandem frame would have exhibited a lot of undesireable lateral (side-to-side) flex on your test ride. The aluminum tandem frame, on the other hand, does not flex and would have felt a lot more "stable" on it's own merits to any new team, and certainly more stable than the first tandem ridden (see above). However, I would note that the (with the exception of the small frames) the Trek tandems share the same steering geometry as the Santana and as Burley (~1.85") . Cannondale is a bit more racy at 2" and then Co-Motion has the raciest at 2.125".

    4. Other Differences: As already noted, tires and wheels factor into the ride impressions. The Santana would have been sporting 28mm Conti Gatorskin tires on 40 spoke wheels (comfy and durable) whereas the Trek would have been sporting 28mm Conti Ultra 3000 tires and a pair of Bontrager RaceLite Tandem wheels which would would certainly be a "stiffer" wheelset than the Santana's.

    Anyway, keep on test riding. As Scott noted, a Cannondale would be a good tandem to include in your comparision. The RT1000 is equipped very much like the Trek T2000 (Ultegra) and comes in at a similar price point; both of these tandems are "better values" than the Santana Arriva SE that comes with 105 level components, etc... Aluminum is a very popular frame material for many good reasons. Steel is also a perenial favorate with the traditionalists and lightweight teams. However, you'll need to trust your instincts when it comes to sorting out which brand/model "feels" best to you. On the bright side, I don't think there are any bad tandems at the price point you have indicated is included in your search.

    Somehow, I think people are confused on what 'trail' is and how it effects the stearing dynamics of a single-track vehicle (bicyles and motorcycles). Trail, as measured on a level surface, is the distence between were the steering axis intersects the road and the center of the front tire contact patch. The front tire "trails" behind the steering axis. For a given head tube angle (say, 73 deg.) the more rake in the fork, the SHORTER the trail. The shorter the trail, the quicker the steering of the vehicle (all other factors being the same). Quick steering crit bikes have short trail. Slow steering touring bikes have long trail. Some slow-steering touring bikes have a lot of fork rake but, they also have a slack steering angle so they still have a lot of trail. Tandems, having a very long wheelbase, steer slow no matter what the trail is, compared to a single bike. I have never ridden a Co-Motion tandem, but I would bet that if the trail quoted above is correct, the "racy" feeling must be attibuted to something other than the trail. With the longest trail of the group, it would be the most resistant to initiating a turn.

  14. #14
    hors category TandemGeek's Avatar
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    Quote Originally Posted by galen_52657
    I think Steve has his act together. I do not own a tandem (yet) but am about to purchase one. I tested 5 different tandems, 3 steel and 2 aluminum. I found the steel tandems to suffer much less from stoker-initiated-steering. My favorite was the Longbikes tandem with oversized steel tubing. My next favorite was the el-cheapo KHS Milano. The KHS tracked like it was on a rail, especially at speed down a winding road. I think a lot of dealers push the expensive brands because...they make more money!
    What were the other 3 tandems?

    What order did you ride them in?

    How did the other 3 "feel"?

    What was said or done during your test rides to make you think dealers push the expensive brands?

  15. #15
    hors category TandemGeek's Avatar
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    Quote Originally Posted by galen_52657
    Somehow, I think people are confused on what 'trail' is and how it effects the stearing dynamics of a single-track vehicle (bicyles and motorcycles). Trail, as measured on a level surface, is the distence between were the steering axis intersects the road and the center of the front tire contact patch. The front tire "trails" behind the steering axis. For a given head tube angle (say, 73 deg.) the more rake in the fork, the SHORTER the trail. The shorter the trail, the quicker the steering of the vehicle (all other factors being the same). Quick steering crit bikes have short trail. Slow steering touring bikes have long trail. Some slow-steering touring bikes have a lot of fork rake but, they also have a slack steering angle so they still have a lot of trail. Tandems, having a very long wheelbase, steer slow no matter what the trail is, compared to a single bike. I have never ridden a Co-Motion tandem, but I would bet that if the trail quoted above is correct, the "racy" feeling must be attibuted to something other than the trail. With the longest trail of the group, it would be the most resistant to initiating a turn.
    No, the problem with trail and tandems is three fold: the lexicon, trying to make direct comparisons to bikes designed for single riders, and different rider expectations assigned to similar words. In other words, while everything you've written about steering trail is consistent with bicycle science dogma, how the different geometries that are actually used on the tandems you can test ride actually behave and how those handling characteristics are perceived by different tandem captains or teams may not track with strict "dogma".

    As you already note, different types of personal bikes, e.g., track, road & touring bike, tend to have application specific steering geometry: road racing bikes having shorter steering trail than touring bikes. Short trail makes for nice, precise handling (fast steering) and is very responsive to steering inputs which matches up nicely with short rear stays and wheelbases. The longer trail on touring bikes tends to be less responsive to steering inputs and more responsive to bike lean, making them less nimble (slow steering) at slow speeds but "more stable" when combined with their somewhat longer wheelbases and lower bottom bracket heights once underway. It's also worthwhile to note that the steering trail for any of these given types of bikes is based on a design standard that is then adjusted throughout the size range, in most all cases with steering trail becoming shorter as the wheelbase/size of the bike (and presumably the size of the rider) increase to "null" the lean effect of the larger rider on the handling. However, tandems -- with their long wheelbases, higher rider weights, and center of gravity sitting mid-span -- are a different animal and how they "feel" with longer or shorter steering trail is quite different from their short wheelbase counterparts.

    Lets baseline ourselves here: Steering trail on production road bikes is about 2.2" (56mm). Production tandems range from the shortest at 1.65" / 42mm (Bilenky) to the median at 1.9" / 48mm (Santana, Burley, Trek) to the longest at 2.125" / 54mm (Co-Motion). Note custom tandems are available with as much steering trail as you can stand; ours happen to have ~2.35". Unlike most production road bikes, a brand/model of tandem from a given producer will tend to have the same steering trail on all but the smallest model of that given model which usually uses a slacker head tube to give the captain more toe clearance, hence it the smallest tandems like the smallest personal bikes have the longest steering trail.

    Back to your "bet" that something else is behind "racy", let me quantify "racy". To me, "racy" means longer steering trail (anything over 2"), which in practice is appealling to tandem teams who like to carve through corners and down steep descents at high speed. This recognizes that tandems are not nible machines and perform best when they are going fast and carrying lots of momentum. It is the latter -- all that momentum -- that gives the nod to longer steering trail for high speed stability as long trail bikes are highly responsive to the use of leaning inputs and countersteering for direction control. What's the down side of these highly desireable high-speed handling characteristics that some (but certainly not all) tandem teams seek? Sluggish steering and instability at low-speed -- at least when compared to a tandem with shorter steering trail and most personal bikes -- and a great deal of responsiveness to what you referred to as "stoker induced steering". This is why many new tandem teams are put off by Co-Motion's and, to a lesser extent, Cannondale tandems on their initial test rides -- in comparison to the other brands that have shorter steering trail with their better low-speed handling (quicker steering) and more "stoker-resistant" behavior. However, it has been noted by many cycling enthusiasts who have jumped over to tandems that the long trail tandems like Co-Motion "seem to handle" more like their personal road bikes than say the Burley or Santana tandems, which is very appealing to many captains who are willing to work through the "stoker-induced" handling issues that come with it.

    As a quick counterpoint, clearly, the short trail tandems tend to inspire more confidence in first time tandem teams because they are easier to control right out of the box. While quick steering & low speed stability seem like no-brainer qualities that almost anyone would desire in an tandem, at higher speeds and in steep lean angles those same low-speed advantages result in understeer: pushed hard enough, you will eventually experience front wheel "chatter" (been there done that; 1st tandem was a Santana Arriva). Of course, by percentage of ownership, not too many teams will push a tandem hard enough to discover this characteristic and, if they've never ridden anything but tandems with steering trail under 2", they will have a hard time believing that their tandem could handle any better than it already does.

    Bottom Line: On tandems, short steering trail = low speed stability with quick steering. Long steering trail = high speed stability with slow steering. As to which one is "better", each team must decide which they have a preference for (much the same as the different brands and frame materials). What one team or a dealer "likes" about a certain tandem may or may not mean diddly to you. Thus, you are left to ride as many different tandems as you can if you are looking for what is 'best to you'.

    As always, just my .02.
    Last edited by livngood; 06-14-04 at 09:45 AM.

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    Mad Town Biker Murrays's Avatar
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    On tandems, short steering trail = low speed stability with quick steering. Long steering trail = high speed stability with slow steering
    Just curious, what do you consider "low speed" and "high speed". I'm thinking low speed would be negotiating through the parking lot or up hill and high speed would be cruising along the flats at 20-25 mph and downhill.

    -murray

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    It's relative, so your characterizations for low speed are just fine, i.e., 3 - 8mph is low speed. High speed is dependent on what you're doing. If your diving through right-hand or left hand turns, even 15mph could be "high-speed" in terms of how well a tandem handles when heeled-over at a steep lean angle.

    Bear in mind, these characterizations are meant to explain initial impressions, all of which are highly subjective for any one of a variety of reasons (To make an analogy - Do you like your steak medium rare, medium or well done?). Morover, most tandem captains / teams who take up tandeming on regular basis quickly adapt to how most tandems handle by the second or third ride and their inherent handling characteristics become "normal". You don't often appreciate (or come to lust-after something new and different) until you take a test ride on a different tandem after becoming accustomed to the one you regularly ride.

    Again, case in point, anyone taking either of our tandems out for a test ride (which is a small population given how small they are) is usually put-off by how "twitchy" they are at low speeds, e.g, starting out and climbing steep hills. They also quickly discover how much their stoker moves around and re-institute the "tell me when you're going reach down and grab for a waterbottle" rule. However, after the first 40+ mph descent or diving through a corner heeled over ala personal race bike an evil grin appears on the captain's face...

    Not everyone will appreciate the trade-offs between high vs low-speed handling characteristics, particularly teams with larger stokers. The higher the stoker's CG, the more pronounced "stoker-induced steering" becomes on long-trail tandems (remembering, this is why steering trail is reduced on personal bikes as the frames get larger). Also, teams where the stoker isn't predisposed to enjoy steep lean angles or blistering fast descents may or may not reap the benefits of the longer trail.

    Again, the take-away from these postings is, initial impressions are not always the most reliable ones nor can you assume that what one team or dealer thinks is "great" will be great for all teams. Therefore, go into your tandem test rides with an open mind and remember that only you can decide what brand or model of tandem is the "best for you". Knowing which tandems have long trail vs. short can help explain some of the handling differences, but not all. It's just one factor. Moreover, if you take up tandeming you may find that your performance expectations of your tandem change and something different might be called for: that's why they're called your "first" tandems.

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    Banned. galen_52657's Avatar
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    Quote Originally Posted by livngood
    No, the problem with trail and tandems is three fold: the lexicon, trying to make direct comparisons to bikes designed for single riders, and different rider expectations assigned to similar words. In other words, while everything you've written about steering trail is consistent with bicycle science dogma, how the different geometries that are actually used on the tandems you can test ride actually behave and how those handling characteristics are perceived by different tandem captains or teams may not track with strict "dogma".

    As you already note, different types of personal bikes, e.g., track, road & touring bike, tend to have application specific steering geometry: road racing bikes having shorter steering trail than touring bikes. Short trail makes for nice, precise handling (fast steering) and is very responsive to steering inputs which matches up nicely with short rear stays and wheelbases. The longer trail on touring bikes tends to be less responsive to steering inputs and more responsive to bike lean, making them less nimble (slow steering) at slow speeds but "more stable" when combined with their somewhat longer wheelbases and lower bottom bracket heights once underway. It's also worthwhile to note that the steering trail for any of these given types of bikes is based on a design standard that is then adjusted throughout the size range, in most all cases with steering trail becoming shorter as the wheelbase/size of the bike (and presumably the size of the rider) increase to "null" the lean effect of the larger rider on the handling. However, tandems -- with their long wheelbases, higher rider weights, and center of gravity sitting mid-span -- are a different animal and how they "feel" with longer or shorter steering trail is quite different from their short wheelbase counterparts.

    Lets baseline ourselves here: Steering trail on production road bikes is about 2.2" (56mm). Production tandems range from the shortest at 1.65" / 42mm (Bilenky) to the median at 1.9" / 48mm (Santana, Burley, Trek) to the longest at 2.125" / 54mm (Co-Motion). Note custom tandems are available with as much steering trail as you can stand; ours happen to have ~2.35". Unlike most production road bikes, a brand/model of tandem from a given producer will tend to have the same steering trail on all but the smallest model of that given model which usually uses a slacker head tube to give the captain more toe clearance, hence it the smallest tandems like the smallest personal bikes have the longest steering trail.

    Back to your "bet" that something else is behind "racy", let me quantify "racy". To me, "racy" means longer steering trail (anything over 2"), which in practice is appealling to tandem teams who like to carve through corners and down steep descents at high speed. This recognizes that tandems are not nible machines and perform best when they are going fast and carrying lots of momentum. It is the latter -- all that momentum -- that gives the nod to longer steering trail for high speed stability as long trail bikes are highly responsive to the use of leaning inputs and countersteering for direction control. What's the down side of these highly desireable high-speed handling characteristics that some (but certainly not all) tandem teams seek? Sluggish steering and instability at low-speed -- at least when compared to a tandem with shorter steering trail and most personal bikes -- and a great deal of responsiveness to what you referred to as "stoker induced steering". This is why many new tandem teams are put off by Co-Motion's and, to a lesser extent, Cannondale tandems on their initial test rides -- in comparison to the other brands that have shorter steering trail with their better low-speed handling (quicker steering) and more "stoker-resistant" behavior. However, it has been noted by many cycling enthusiasts who have jumped over to tandems that the long trail tandems like Co-Motion "seem to handle" more like their personal road bikes than say the Burley or Santana tandems, which is very appealing to many captains who are willing to work through the "stoker-induced" handling issues that come with it.

    As a quick counterpoint, clearly, the short trail tandems tend to inspire more confidence in first time tandem teams because they are easier to control right out of the box. While quick steering & low speed stability seem like no-brainer qualities that almost anyone would desire in an tandem, at higher speeds and in steep lean angles those same low-speed advantages result in understeer: pushed hard enough, you will eventually experience front wheel "chatter" (been there done that; 1st tandem was a Santana Arriva). Of course, by percentage of ownership, not too many teams will push a tandem hard enough to discover this characteristic and, if they've never ridden anything but tandems with steering trail under 2", they will have a hard time believing that their tandem could handle any better than it already does.

    Bottom Line: On tandems, short steering trail = low speed stability with quick steering. Long steering trail = high speed stability with slow steering. As to which one is "better", each team must decide which they have a preference for (much the same as the different brands and frame materials). What one team or a dealer "likes" about a certain tandem may or may not mean diddly to you. Thus, you are left to ride as many different tandems as you can if you are looking for what is 'best to you'.

    As always, just my .02.
    So, the selling point on the Co-Motion is realy high-speed stability....and they call this 'racy'?

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    Quote Originally Posted by livngood
    What were the other 3 tandems?

    What order did you ride them in?

    How did the other 3 "feel"?

    What was said or done during your test rides to make you think dealers push the expensive brands?
    The test rides were on 2 different days. I road an aluminum Santana first, then the steel Longbikes, then a Cannondale and lastly a steel Trek on the first day (short rides). The second day I road the KHS first, then the Cannondale again (longer rides - 14 miles each time). I wanted to try more bikes, but my stoker, being a novice rider, was pooped.

    Being that the Santana was my first tandem ride, inexperience could have played a part. But, on seated climbing it wandered, needing many steering corrections to keep it strait. The Longbikes went strait up the hill. The Cannondale wondered less than the Santana but more than the Longbikes. The Trek had Rolf wheels which seemed way to flexible and scared the crap out of me going down hill. On the second day, being more confident and riding a longer route, we took out the KHS. The stem was way to short so I was cramped, but I must say that it was smooth and responsive. It carved up a section of road that was flat-to-down-hill with a quick succession of S turns at approximately 30 MPH. On the fastest part of the 14 mile loop, a strait downhill with a tail wind, it was rock solid. On this part of the course, the Cannodale did not feel as solid. The front end of the Cannondale felt softer and more apt to wonder off line. We tried standing on both the KHS and the Cannondale but... did not have much success... needing more practice.

    The dealer stated that most people buy the Santana.

    Just a beginer's impression.

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    Quote Originally Posted by galen_52657
    So, the selling point on the Co-Motion is realy high-speed stability....and they call this 'racy'?
    I called it racy and am neither an employee nor a dealer.

    I believe they refer to their overall line of tandem products as "performance tandems". The "Multi-Performance, Travel, & Racing tandems all share the same steering trail and similar frame geometry. They offer steel and aluminum frames in all configurations which is where the biggest differences come in to play: the Speedster and Big Al feel quite different as do the Supremo and Robusta.

    But, yes, their longer steering trail is what differentiates them from all of the other tandem builders. As already noted, Cannondale comes the closest to Co-Motion with it's 2" of steering trail, and then Burley, Santana, and Trek come in a ~1.9". I don't know what fork rake KHS uses, but their head tube Geometry is fairly steep at 74 degrees. Assuming they use a fork with conventional rake I would presume their steering trail is no longer than Santana/Trek/Burley -- but that's a guess. Longbikes? Don't know, but would also assume it's more likely in the Santana/Trek/Burley range. Not really sure if Longbikes is even actively marketing tandems these days... Greg was underwhelmed by the market response after jumping in with both feet a few years back, about the same time as Meridian. Meridian has, from all indications, ceased to be a going concern.

    Co-Motion's other selling features are the quality of their frames (welds/finish), a longer stoker compartment than Santana, Burley, Trek and the smaller Cannondale models, fantastic customer support and a transferrable frame warranty (not offered by anyone else), and so on.
    Last edited by livngood; 06-14-04 at 04:18 PM.

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    hors category TandemGeek's Avatar
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    Quote Originally Posted by galen_52657
    The test rides were on 2 different days. I road an aluminum Santana first, then the steel Longbikes, then a Cannondale and lastly a steel Trek on the first day (short rides). The second day I road the KHS first, then the Cannondale again (longer rides - 14 miles each time). I wanted to try more bikes, but my stoker, being a novice rider, was pooped.

    Being that the Santana was my first tandem ride, inexperience could have played a part. But, on seated climbing it wandered, needing many steering corrections to keep it strait. The Longbikes went strait up the hill. The Cannondale wondered less than the Santana but more than the Longbikes. The Trek had Rolf wheels which seemed way to flexible and scared the crap out of me going down hill. On the second day, being more confident and riding a longer route, we took out the KHS. The stem was way to short so I was cramped, but I must say that it was smooth and responsive. It carved up a section of road that was flat-to-down-hill with a quick succession of S turns at approximately 30 MPH. On the fastest part of the 14 mile loop, a strait downhill with a tail wind, it was rock solid. On this part of the course, the Cannodale did not feel as solid. The front end of the Cannondale felt softer and more apt to wonder off line. We tried standing on both the KHS and the Cannondale but... did not have much success... needing more practice.

    The dealer stated that most people buy the Santana.

    Just a beginer's impression.
    Let me guess, test rides were at one of Larry Black's two bike shops (Mt. Airy / College Park)? That being the case, Larry was telling you the truth when he said that most people buy the Santana. Santana has for many, many years been the most popular brand of tandem -- earned due to early innovation, brand recognition, customer satisfaction, and very aggressive marketing. Santana's have also been the most expensive brand and model of tandems -- apples to apples -- but that doesn't seem to bother most buyers who are already pre-disposed to drop $3 - $5k on a new tandem. In short, Santana = Lexus in the minds of many buyers who 'want the best'. As to whether or not they are the best, that's for each buyer to decide.

    Riding impressions: Bearing in mind that wheels and tires can have a lot to do with how tandems "feel" and handle, I'll venture some guesses here...

    Santana: First ride, novice/new stoker, any climbing = a lot of fighting your stoker's movements. I suspect if you re-rode the tandem now it would feel a bit more stable.

    Longbikes - Nice bikes, brilliant builder, bad business plan: Not sure if Greg Peek is still building tandems as a production item or only to order, but I seem to recall that Greg used about the same or perhaps even a bit less steering trail than Santana/Trek/Burley and his oversized steel tubing received excellent reviews. My guess is, Santana & Longbike frames were about equal on stiffness and steering was similar but your first ride experience helped to make the Longbikes test ride more stable.

    Cannondale: Frames are super-stiff, but the forks are a bit lacking. Handling difference between it and the Longbikes on the climb was most likely the longer steering trail or perhaps the tires. New C'dale tandems come with fat 700x30 tires whereas a lot of tandems come with 700x28. We run 700x23 and 700x25. Regardless, it would have felt better than the Santana which, because it was first, would have been the worst ride of the day no matter what.

    Trek: If it was steel it was a much older tandem. Trek stopped producing the T100 and T200 steel tandems many years ago and only re-entered the tandem market in '02 with their ZR9000 aluminum models, the T1000 and T2000. The steel Trek tandems were heavy and stiff and did not lend themselves to swift riding; however, first rate for rallies, touring, etc... where weight wasn't a big concern. Not sure what to tell you about the Rolf wheels (hopefully it was a Rolf Prima Vigor Tandem Wheelset) as I'm not a big fan of integrated wheelsets for everyday tandem use.

    KHS: The only off-shore frame of the bunch; about 1/10th the cost to produce compared to a Cannondale; hence, a price performer. As for the handling, again, stiff frame and what I believe is very conservative steering -- perhaps even shorter than Santana/Trek/Burley. I can't be sure as I haven't measured a fork, but I know the head tubes are pretty steep.

    Cannondale Day 2: Again, for whatever reason, Cannondale's forks really don't inspire a lot of confidence on fast downhills; they may be too stiff for their own good particularly if you're a lightweight team. We ride with one couple (about 260lbs soaking wet) who have an RT3000 that recently test rode our travel tandem with a carbon fork. He was amazed as how "rock solid" it was compared to the RT3000, noting that his C'dale often had a lot of shimmy and chatter on high-speed descents. I think he summed it up best when he said, "I'm sold"... indicative of a future purchase from our builder friends up in Seattle. Back to the C'dale shimmy, I've heard this from other folks with RT's. Again, there is also the issue of wheels and tires. Cannondale equips its stock tandems with some pretty fat, squishy tires (700x30) compared to most others who send them out the door with 700x28's. If the stock tires were fitted to this tandem it could certainly be a factor in how the tandem felt.

    For what it's worth, I'd do some shorter re-rides on the Santana & Longbikes. After riding those, try a Co-Motion (assuming this is Larry's shop and he has one in stock in your size). I'm partial to steel and the Primera and Speedsters are both very nice steel tandems. The Supremo is my favorite of the Co-Motion like-up, although I wouldn't turn down a Robusta if one was offered to me at cost and had a bit more room out back for Debbie.

    Good hunting. Lots of variables, but personal taste is perhaps the biggest and most important.
    Last edited by livngood; 06-14-04 at 07:32 PM.

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    Quote Originally Posted by livngood
    Let me guess, test rides were at one of Larry Black's two bike shops (Mt. Airy / College Park)? That being the case, Larry was telling you the truth when he said that most people buy the Santana. Santana has for many, many years been the most popular brand of tandem -- earned due to early innovation, brand recognition, customer satisfaction, and very aggressive marketing. Santana's have also been the most expensive brand and model of tandems -- apples to apples -- but that doesn't seem to bother most buyers who are already pre-disposed to drop $3 - $5k on a new tandem. In short, Santana = Lexus in the minds of many buyers who 'want the best'. As to whether or not they are the best, that's for each buyer to decide.

    Riding impressions: Bearing in mind that wheels and tires can have a lot to do with how tandems "feel" and handle, I'll venture some guesses here...

    Santana: First ride, novice/new stoker, any climbing = a lot of fighting your stoker's movements. I suspect if you re-rode the tandem now it would feel a bit more stable.

    Longbikes - Nice bikes, brilliant builder, bad business plan: Not sure if Greg Peek is still building tandems as a production item or only to order, but I seem to recall that Greg used about the same or perhaps even a bit less steering trail than Santana/Trek/Burley and his oversized steel tubing received excellent reviews. My guess is, Santana & Longbike frames were about equal on stiffness and steering was similar but your first ride experience helped to make the Longbikes test ride more stable.

    Cannondale: Frames are super-stiff, but the forks are a bit lacking. Handling difference between it and the Longbikes on the climb was most likely the longer steering trail or perhaps the tires. New C'dale tandems come with fat 700x30 tires whereas a lot of tandems come with 700x28. We run 700x23 and 700x25. Regardless, it would have felt better than the Santana which, because it was first, would have been the worst ride of the day no matter what.

    Trek: If it was steel it was a much older tandem. Trek stopped producing the T100 and T200 steel tandems many years ago and only re-entered the tandem market in '02 with their ZR9000 aluminum models, the T1000 and T2000. The steel Trek tandems were heavy and stiff and did not lend themselves to swift riding; however, first rate for rallies, touring, etc... where weight wasn't a big concern. Not sure what to tell you about the Rolf wheels (hopefully it was a Rolf Prima Vigor Tandem Wheelset) as I'm not a big fan of integrated wheelsets for everyday tandem use.

    KHS: The only off-shore frame of the bunch; about 1/10th the cost to produce compared to a Cannondale; hence, a price performer. As for the handling, again, stiff frame and what I believe is very conservative steering -- perhaps even shorter than Santana/Trek/Burley. I can't be sure as I haven't measured a fork, but I know the head tubes are pretty steep.

    Cannondale Day 2: Again, for whatever reason, Cannondale's forks really don't inspire a lot of confidence on fast downhills; they may be too stiff for their own good particularly if you're a lightweight team. We ride with one couple (about 260lbs soaking wet) who have an RT3000 that recently test rode our travel tandem with a carbon fork. He was amazed as how "rock solid" it was compared to the RT3000, noting that his C'dale often had a lot of shimmy and chatter on high-speed descents. I think he summed it up best when he said, "I'm sold"... indicative of a future purchase from our builder friends up in Seattle. Back to the C'dale shimmy, I've heard this from other folks with RT's. Again, there is also the issue of wheels and tires. Cannondale equips its stock tandems with some pretty fat, squishy tires (700x30) compared to most others who send them out the door with 700x28's. If the stock tires were fitted to this tandem it could certainly be a factor in how the tandem felt.

    For what it's worth, I'd do some shorter re-rides on the Santana & Longbikes. After riding those, try a Co-Motion (assuming this is Larry's shop and he has one in stock in your size). I'm partial to steel and the Primera and Speedsters are both very nice steel tandems. The Supremo is my favorite of the Co-Motion like-up, although I wouldn't turn down a Robusta if one was offered to me at cost and had a bit more room out back for Debbie.

    Good hunting. Lots of variables, but personal taste is perhaps the biggest and most important.
    Mark,

    You are a wealth of information! I hope you spend as much time riding as you do writing....! It was Larry's shop in Mt. Airy. All nice people.

    At 6'4" tall and 210 lbs. with a 150 lb. stoker, all the tandems I tried were large, x-large or jumbo ('dale). Larry does have a Co-motion so I think I will take your advice and try one.

    I still am not convinced that aluminum is the best material for a tandem frame. I had lots of racing buddies who cracked Cannodale singles on a regular basis. Steel is way easier to repair in the event of a crash. I think a lot of the aluminum craze is hype and marketing. Are the aluminum frames realy stiffer? I would like to see the test results. The weight thing is not an issue with me. I raced at 195-200 lbs back in the day. If I ever get that light again (and am not in a hospital bed) then, 3-4 lbs of frame weight may make a differnece...

    Galen

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    hors category TandemGeek's Avatar
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    You can take a look at the methodolgy used and the results of some 100 or so frame deflection tests conducted by Damon Rinard in the mid-90's now hosted on Sheldon Brown's Web site: http://www.sheldonbrown.com/rinard/r...frametest.html

    Even though he tested regular solo frames, the material properties of the various types of tubing are consistent with what you'll find used on most tandems produced since the mid-90's. Not included in these tests is Gary Klein's ZR9000 alloy (used on Trek's T1000 & T2000) which may have some subtle differences from the more conventional alloys, e.g., 6061, 7005.

    As for cracked frames, yeah... there's a reason Cannondale earned the nickname "Crack-n-Fail" and it wasn't aluminum, per se, it was how C'dale made it and more recently poor manufacturing methods or bad welds that result in the occasional bad frames or joint failures. But, Cannondale 1/2 bikes and recall notices on Gemini's notwithstanding, Cannondale has been building nothing but aluminum tandems since 1986 and they have a great reputation for unmatched stiffness and durability. We owned a '98 MT3000 hardtail that we beat the living heck out of and routinely see teams who have been riding the same C'dale tandems for 8 - 10 years, on and off-road. In fact, we have some friends who easily tip the scales upwards of 500lbs who have several thousand miles on a '95 C'dale. I've had to rebuild their wheels twice, but the frame is rock solid. They now have a bomb-proof 48h rear wheel laced 5x that will last as long as the frame.

    Cannondale's success with Aluminum and buyer desire for it didn't go unnoticed by Santana who in 1993 introduced it's own line of Aluminum tandems. Just five years later Santana's aluminum tandems surpased their venerable steel tandems as their most popular models. Co-Motion jumped in with an Aluminum tandem in '99 and then Trek jumped back in with it's ZR9000 frames in '02 along with Burley who initially had Trek producing their aluminum tandem models.

    Bottom Line: Aluminum should not cause you any major concerns with regard to it's suitability as a tandem frame material. Of the tens of thousands of aluminum tandems that have been sold over the past 18 years, there have been very few pure "failures" and those that I have heard about all seemed to involve a manufacturing defect (weld blow-through, etc..) or were precipitated by previous crash damage.

    Again, I prefer steel for our road tandems and reserve Aluminum for our off-road tandems (but also have or have owned aluminum, carbon & Ti personal road and off-road bikes). But, then again, I'm only 5'8", Debbie is 5'2" and our combined team weight hovers around 275lbs so just about any frame material used to build a tandem in our size will result in a stiff frame. For larger teams, Aluminum just seems to be a far more popular choice. But, as always, every team who goes shopping for a tandem needs to decide what's right for them.

    Parting Shot: Aluminum gets a bad rap; it's a great frame material for many applications. But, that's not to say it's the "best material" as there is no such thing as "the best", only "what's best for you".
    Last edited by livngood; 06-15-04 at 09:39 PM.

  24. #24
    Cat 6 Steve Katzman's Avatar
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    Quote Originally Posted by livngood
    Even though he tested regular solo frames, the material properties of the various types of tubing are consistent with what you'll find used on most tandems produced since the mid-90's. Not included in these tests is Gary Klein's ZR9000 alloy (used on Trek's T1000 & T2000) which may have some subtle differences from the more conventional alloys, e.g., 6061, 7005.
    Also not included in Rinard's tests are the latest several generations of steel tubing. While the steel frames were not identified in the tests, back in the mid 90's most steel frames used small diameter tubing due to their limited tensile strength of approximately 130,000 psi. With today's steels such as Dedacciai EOM 16.5, Columbus Ultra Foco, Reynolds 853, True Temper S3 & OX Platinum, having tensile strengths of 180,000 to 200,000 psi and up, steel tubing can have thinner walls. With thinner walls, this enables the diameter of the tubing to get much larger. Since tubing stiffness is a function of the diameter cubed, it is easy to see that todays steel tubing can be, and is, made as stiff as most aluminum tube sets out there today.

    I am no expert on what steel tubing is generally used by tandem builders today. I don't even know exactly what tubing is used on my 2003 Co-Motion Speedster, except that Co-Mo calls it air-hardening and it is definitely oversized diameter. I believe that Santana steel frames are similarly oversized. Based on this, I would conclude that the differences in stiffness between aluminum and steel are much smaller than those reported in Rinard's tests.
    Last edited by Steve Katzman; 06-16-04 at 10:11 AM.

  25. #25
    hors category TandemGeek's Avatar
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    Quote Originally Posted by Steve Katzman
    I am no expert on what steel tubing is generally used by tandem builders today. I don't even know exactly what tubing is used on my 2003 Co-Motion Speedster, except the Co-Mo calls it air-hardening and it is definitely oversized diameter. I believe that Santana steel frames are similarly oversized. Based on this, I would conclude that the differences in stiffness between aluminum and steel are much smaller than those reported in Rinard's tests.
    Santana & Co-Motion have been using oversized steel tubing for many years, noting that even our '96 Arriva had Santana's "Megasize" 8/5/8 tubing and, with the exception of the newer ZR9000 and a few scandium tandems built by Erickson & Bushnell, there haven't been too many tandem frame material changes in the steel and aluminum camps as carbon has been the focus of most builders, forks or frames. But, be that as it may, what you suggest could very well be the case. So, rather than guessing and relying on old data I'll see if I can get an answer as to whether or not the deflection gap has been narrowed and let you know.
    Last edited by livngood; 06-16-04 at 09:02 AM.

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