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  1. #1
    Senior Member joe@vwvortex's Avatar
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    So the new wheelset thing sent me off the deep end in a number of ways.......

    First off - I decided to get another set of the new Rolf Tandem Wheels - but this time with a front disc. After looking at my options and costing things out - I got a great deal on the Rolfs from Precision and since they are in stock won't have to wait over 2 weeks to get new wheels. While i've had a love/hate relationship with the Rolfs - my wife and I agreed we both really like the ride of the wheels so I figured i'd give them another chance.

    Of course going to the disc upfront resulted in the need for a new fork so a Wound Up CF Duo disc fork has been ordered along with an Avid Caliper and 203mm rotor. I've been wanting to do this for quite some time now.

    Of course in looking at the options - I decided to get a Campy freehub instead of Shimano on the Rolfs. I've been wanting to do that for as long as I've owned the tandem since I'm outfitted with Campy Ergo 10 Record levers. Since Campy doesn't make anything larger than a 29T rear sprocket and we are a 350lb team - i'm going to switch out my 28/42/54 in front to a 26/39/53. In the rear - i'm combining a Veloce 11-25 and 13-29 to get the 11-29 I want which will be 11-12-13-15-17-19-21-23-26-29. Will be so nice to have more gears with less gaps and less overlap as well as be within a fraction of the low gear I had with the 28-32.

    Needless to say - i'll be poor for a while - but I will have some stuff to sell. My current drivetrain setup is less than six months old - DaVinci X-9 which is modified by them to work directly with Campy Ergo 10 levers, new SRAM 11-32 cassette (990 model) and PC-90 chain. My 28 tooth small ring and 42 middle ring are less than six months old as well - and the 54 is like new. Then there's the Wound Up non disc fork for V-brakes.

    I'm really excited to get this all done. Just have to wait for the parts!
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    Senior Member mkane77g's Avatar
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    Perfect. Enjoy the stoppies! Get a tire for the front that will give enough traction to hold up to the extra braking power, something big and sticky

  3. #3
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    Hope it works out for you... but personally, I would not have bought Rolfs after your experience.
    I don't even use the offensive term "Fred." -- Sheldon "All Cyclists Are My Friends" Brown (1944-2008)

  4. #4
    Senior Member joe@vwvortex's Avatar
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    Quote Originally Posted by Phantoj View Post
    Hope it works out for you... but personally, I would not have bought Rolfs after your experience.
    That was the toughest part of the decision. Almost a devil you know vs a devil you don't know. A good set of wheels is all in who builds them - and while places like prowheelbuilder.com look like they are VERY competent - they are in Vegas. While I have a local wheelbuilder that I trust - since he's at a local shop (the one I bought my tandem through and spend a ton of $$ at) even at a discount - the cost of what I was considering was greater than the deal I got on the Rolfs. Rolf did provide excellent customer service when i had my initial issues which was a plus. What it really came down to was the ride - the wheels ride great and I didn't want to take the chance on a set of 36h wheels not feeling as good as the Rolfs.
    Who knows - I might get some built up anyway so that I have spare set down the road.
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  5. #5
    Senior Member mkane77g's Avatar
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    I borrowing a set of 36 holers this weekend while the Rolfs are being repaired. These have laster 3 1/2 yrs, 15,000 miles. Not bad for a performance wheelset. 560$ foer replacement rims/spokes, hard to beat. Next month I'll splurge on a spare set. I doubt the 36 holers will be as comfortable, the Rolfs ride is amazing. When I swap from conventional to low spoke count on my single, it's no contest.

  6. #6
    hors category TandemGeek's Avatar
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    Quote Originally Posted by mkane77g View Post
    I doubt the 36 holers will be as comfortable, the Rolfs ride is amazing. When I swap from conventional to low spoke count on my single, it's no contest.
    Boy, if that doesn't illustrate the subjective nature of riding impressions I don't know what does. Our impressions -- at least with regard to the transmission of road shock felt by the captain and stoker with a combined 280lb team weight -- are completely the opposite.

    In doing our back-to-back wheel comparisons of the '07 and '08 Rolfs against conventional wheels built up using 36h White Ind hubs with both Velocity Deep-V and Fusion rims in the same weight class as the Rolfs (1,850g - 2,050g) with the same Vredestien Fortezza 700x23 tires at 145psi, the Rolfs uniformly transmitted more road shock than the 36h wheelset. While not that all that bothersome on the Calfee, the Rolf's beat the hell out of us on our steel Erickson... even with the Alpha Q fork. Mind you, 'beat the hell out of is relative' as just about any tandem we've ridden since acquiring the Calfee feels harsh, at best. However, the difference between the Rolfs and the 36h wheels on the steel Erickson was very noticable, especially to Debbie.

    That said, the Rolf's do 'feel' a lot more lively and 'seem' to roll faster than 36h wheels even at lower speeds when riding alone on our familiar routes. However, there's never been a noticable difference when we've used them in group rides. Now, that could be because the Rolfs just aren't used all that much and the bearings still haven't fully worn-in... as even our newer 36h wheelsets don't roll as fast as nearly identical 36h wheelsets with 10x the mileage.

    On the down side, while the paired, high-tension spokes make the wheels feel less compliant to us in the veritical plane, the rear wheels have yielded a lot more under side loads vs. 36h wheelset which has been down right disconcerting under hard cornering at low speeds and high-speed curves. It is for this very reason that the Rolf's just don't get used much since so much of our riding finds us hitting 40+ on descents down twisty roads.

    Again, YRMV and all riding impressions are highly subjective. Moreover, teams who last point of reference may have been heavier, 2,200g OEM tandem wheels with larger volume tires will have competely different impressions when switching to the 1,850g Rolfs, especially if they have also adopted a narrower, higher-pressure tire at the same time. It's only when you start comparing conventional wheels with similar weights to the Rolfs that you get closer to a level playing field, which was the point of our back-to-back comparisons in 2008.

    As it is now, our Rolfs are our back-up wheels that we keep in the wheel bag when we go to rallies or weekend outings with our 'tandem family'. The Topolino's are only pulled out when I have a vanity-attack and want to add a little bling to the Calfee. Of course, I still need to true our Topolino's rear wheel so they haven't been used since last year's Southern Tandem Rally when the wobbly wheel condition was first discovered.

  7. #7
    Senior Member joe@vwvortex's Avatar
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    Quote Originally Posted by TandemGeek View Post
    Boy, if that doesn't illustrate the subjective nature of riding impressions I don't know what does. Our impressions -- at least with regard to the transmission of road shock felt by the captain and stoker with a combined 280lb team weight -- are completely the opposite.

    In doing our back-to-back wheel comparisons of the '07 and '08 Rolfs against conventional wheels built up using 36h White Ind hubs with both Velocity Deep-V and Fusion rims in the same weight class as the Rolfs (1,850g - 2,050g) with the same Vredestien Fortezza 700x23 tires at 145psi, the Rolfs uniformly transmitted more road shock than the 36h wheelset. While not that all that bothersome on the Calfee, the Rolf's beat the hell out of us on our steel Erickson... even with the Alpha Q fork. Mind you, 'beat the hell out of is relative' as just about any tandem we've ridden since acquiring the Calfee feels harsh, at best. However, the difference between the Rolfs and the 36h wheels on the steel Erickson was very noticable, especially to Debbie.

    That said, the Rolf's do 'feel' a lot more lively and 'seem' to roll faster than 36h wheels even at lower speeds when riding alone on our familiar routes. However, there's never been a noticable difference when we've used them in group rides. Now, that could be because the Rolfs just aren't used all that much and the bearings still haven't fully worn-in... as even our newer 36h wheelsets don't roll as fast as nearly identical 36h wheelsets with 10x the mileage.

    On the down side, while the paired, high-tension spokes make the wheels feel less compliant to us in the veritical plane, the rear wheels have yielded a lot more under side loads vs. 36h wheelset which has been down right disconcerting under hard cornering at low speeds and high-speed curves. It is for this very reason that the Rolf's just don't get used much since so much of our riding finds us hitting 40+ on descents down twisty roads.

    Again, YRMV and all riding impressions are highly subjective. Moreover, teams who last point of reference may have been heavier, 2,200g OEM tandem wheels with larger volume tires will have competely different impressions when switching to the 1,850g Rolfs, especially if they have also adopted a narrower, higher-pressure tire at the same time. It's only when you start comparing conventional wheels with similar weights to the Rolfs that you get closer to a level playing field, which was the point of our back-to-back comparisons in 2008.

    As it is now, our Rolfs are our back-up wheels that we keep in the wheel bag when we go to rallies or weekend outings with our 'tandem family'. The Topolino's are only pulled out when I have a vanity-attack and want to add a little bling to the Calfee. Of course, I still need to true our Topolino's rear wheel so they haven't been used since last year's Southern Tandem Rally when the wobbly wheel condition was first discovered.
    I remember reading your impressions on the Rolfs and I honestly have never felt that with the set we had - especially in terms of compliance on the vertical plane. We've been downhill at speeds over 60 many times and the bike has felt rock solid. They have also been butter smooth and felt plenty stiff. The lively feel is what I was after by purchasing the new set. I was concerned that the 36h would not feel as lively - regardless of weight. I'm hoping the new design isn't what contributed to the characteristics you described. We shall see.
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  8. #8
    hors category TandemGeek's Avatar
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    Quote Originally Posted by joe@vwvortex View Post
    I remember reading your impressions on the Rolfs and I honestly have never felt that with the set we had - especially in terms of compliance on the vertical plane. We've been downhill at speeds over 60 many times and the bike has felt rock solid. They have also been butter smooth and felt plenty stiff. The lively feel is what I was after by purchasing the new set. I was concerned that the 36h would not feel as lively - regardless of weight. I'm hoping the new design isn't what contributed to the characteristics you described. We shall see.
    The '08 models were the ones that really gave us trouble. We could easily get the rear wheel to rub against the left or right brake blocks by simply coasting while standiing with the bike leaned-over to one side or the other as well as while standing and climbing out of the saddle. The on-road stablity was horrible. However, no one in the supply chain seemed interested in checking the wheels to make sure the tension was set correctly from the factory or if anything else was amiss, so I sold them.

    Later I discovered that Mel at Tandems East had a set of NOS '07 Rolfs while we were at his Open House back in March '09 and we picked up those shortly after buying the Topolinos's just for kicks. After all, everyone we'd talked to with the pre '08 Rolfs were very happy with their wheels, even the ones who'd had problems where Rolf had addressed them under warranty. To my pleasant surprise, and as noted in my Calfee Journal, the '07's did not exhibit any noticable deflection when climbing, cornering, etc... UNTIL we used them at the Tennessee Tandem Rally. Even then, it was only on one very short, steep descent into a narrow valley between two hills along a ridge that had a nasty off-camber turn right as you went through the compression point at the bottom of the turn: that's about as tough of a test for rear wheel side loading that I can think of. We'd never had any problems with that section of road and actually looked forward to it, as it was one of 5 or 6 E-ticket rides at TTR each year. However, when running it with the Rolfs the tandem wouldn't hold a line and we ended up running into the on-coming lane which is just something I always try to avoid at all costs. So, to be fair, our '07 experience has been pretty good, but the stew was definitely poisoned by the '08 experience: I really wish they'd have taken the time to take them back in and check the tension so that I'd have a better point of reference vs. n=1.

    As for feeling lively, the conventional wheels will never 'feel' the way the Rolfs do, and they do feel fast and lively to be sure. Again, I'm not sure how much of that comes from the big reduction in air turbulence / drag on the fewer number and bladed spokes vs. how the large unsupported sections of rim between the the spokes react to the road surface. But whatever it is, it's intoxicating... just like lots of the other high-end goodies and bikes that tap into our emotional response mechanisms.
    Last edited by TandemGeek; 07-15-10 at 10:53 AM.

  9. #9
    Senior Member waynesulak's Avatar
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    Tandem Geek - "...However, there's never been a noticeable difference when we've used them in group rides...."

    I would chalk up the difference in feeling faster vs are faster to vibration and possible side to side flexibility of the Rolfs. On a group ride there is somewhat objective standard to measure against that doesn't exist riding alone. Feels faster is not always faster, but it may be fun just the same.

    Tandem Geek "... We could easily get the rear wheel to rub against the left or right brake blocks by simply coasting while standing with the bike leaned-over to one side or the other as well as while standing and climbing out of the saddle...."

    That would scare me.

  10. #10
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    As an aside, steady-state hard cornering doesn't put a side load on wheels -- the load is inline with the leaned-over wheel. Coasting and standing with the bike leaned over would create a high side load, though.
    I don't even use the offensive term "Fred." -- Sheldon "All Cyclists Are My Friends" Brown (1944-2008)

  11. #11
    hors category TandemGeek's Avatar
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    Quote Originally Posted by Phantoj View Post
    As an aside, steady-state hard cornering doesn't put a side load on wheels -- the load is inline with the leaned-over wheel.
    Care to explain what forces cause a bike's tires and wheels to skid out from under it when it looses traction after hitting a patch of sand, water or otherwise exceeding the tire's grip in a steady-state hard cornering maneuver?

    Seriously, I'm not trying to be a smart alec.

    As a long time cyclist and motorcyclist I have a pretty good appreciation for how two-wheeled bikes use countersteering and balance to maintain control and negotiate turns and cornering maneuvers. However, that said, just as riding two-up on a motorcycle requires a different approach to account for how the additional weight and change in CG affects a bike's handling, the same is true for tandem bicycles... even more-so because unlike a motorcycle which maintains the same wheelbase when you add a second rider, a tandem nearly doubles the wheelbase of a standard, single-seat bicycle.

    Therefore, while it is true that typical lateral wheel loads are perhaps only 10% as large as the radial loads that a bicycle wheel must deal with, it has been my experience that the significantly longer wheelbase and frame coupled with the higher gross weight of a tandem with two riders working together to maintain balance and control puts a much higher demand on lateral wheel strength. After all, even the most robust tandem frame will still experience some degree of torsional flex between the front and rear wheel axles during any demanding riding conditions... remembering that it's the combined deflection of the wheels, fork and frame that contribute to how the 'tandem' acts and handles. Therefore, when dealing with technical cornering maneuvers such as quick right-angle turns and switchbacks, negotiating high speed curves and esses, or when making evasive maneuvers to dodge road obstacles or other bikes, it has again been my experience that tandems place a very high demand on the lateral strength of wheels... just as they do torsional frame stiffness. I think it's also fair to say that for some teams, just trying to ride down the road in a straight line will create lateral loads on the wheels... easily observed just by riding behind such a team and watching the frame rock and how the wheels track.

    So, getting back to my original question... the role that Friction plays in the cornering equation can't be understated. Without the friction created by tires centripetal forces win and the wheels slide out from under the bike. To get that friction into the tires, an awful lot of rider weight has to be transmitted through the frame to the hubs and then into the spoke network and rims and with the average tandem team and the aforementioned tandem bike's torsional flex this does not always happen in a linear fashion as you negotiate turns.
    Last edited by TandemGeek; 07-16-10 at 07:04 AM.

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    Quote Originally Posted by TandemGeek View Post
    Care to explain what forces cause a bike's tires and wheels to skid out from under it when it looses traction after hitting a patch of sand, water or otherwise exceeding the tire's grip in a steady-state hard cornering maneuver?
    When the component of cornering force (horizontal) is added to the perpedicular component of normal force due to bike weight (vertical), the resultant force vector is directly in line with the leaned-over bike+rider center of gravity. (Otherwise the bike is not in balance and is either falling deeper into the turn or standing back up.) Assuming the riders have leaned over with the bike, that vector will be in the plane of the wheels.


    http://yarchive.net/bike/tire_roll_off.html
    Last edited by Phantoj; 07-16-10 at 10:03 AM.
    I don't even use the offensive term "Fred." -- Sheldon "All Cyclists Are My Friends" Brown (1944-2008)

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    Senior Member WebsterBikeMan's Avatar
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    To combine what you two are saying...

    If I take the force diagram apart another way, I can say yes the sum of the two components is in line with the plane of the frame, which is in line with the plane of the wheels if there is no deformation, but at the point where the wheel is in contact with the ground, the horizontal component is pushing on the tire, deforming it so that it bulges (slightly) more on the inside of the curve and stretches (slightly) on the outside of the curve. And this deformation can happen to the entire wheel to a greater or lesser extent.

    In an airplane, the net force vector always points down perpendicular to the plane of the wings. When banking for a curve, gravity feels like it is on an angle relative to the line to the centre of the earth. But the airplane is not in contact with a high friction surface called the road.

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    Also, the tire has a rounded profile; it is not a blade, so the contact point won't be directly on the bike's midplane...

    I'd just say that coasting in a straight line and leaning the bike is actually a pretty good test of lateral stiffness and probably not that different from how we stress the wheels when standing.


    However, this physics diversion isn't tandem-specific and would probably be more at home in the Road Forum.
    I don't even use the offensive term "Fred." -- Sheldon "All Cyclists Are My Friends" Brown (1944-2008)

  15. #15
    Elite Rider Hermes's Avatar
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    Quote Originally Posted by TandemGeek View Post
    Care to explain what forces cause a bike's tires and wheels to skid out from under it when it looses traction after hitting a patch of sand, water or otherwise exceeding the tire's grip in a steady-state hard cornering maneuver?

    Seriously, I'm not trying to be a smart alec.

    As a long time cyclist and motorcyclist I have a pretty good appreciation for how two-wheeled bikes use countersteering and balance to maintain control and negotiate turns and cornering maneuvers. However, that said, just as riding two-up on a motorcycle requires a different approach to account for how the additional weight and change in CG affects a bike's handling, the same is true for tandem bicycles... even more-so because unlike a motorcycle which maintains the same wheelbase when you add a second rider, a tandem nearly doubles the wheelbase of a standard, single-seat bicycle.

    Therefore, while it is true that typical lateral wheel loads are perhaps only 10% as large as the radial loads that a bicycle wheel must deal with, it has been my experience that the significantly longer wheelbase and frame coupled with the higher gross weight of a tandem with two riders working together to maintain balance and control puts a much higher demand on lateral wheel strength. After all, even the most robust tandem frame will still experience some degree of torsional flex between the front and rear wheel axles during any demanding riding conditions... remembering that it's the combined deflection of the wheels, fork and frame that contribute to how the 'tandem' acts and handles. Therefore, when dealing with technical cornering maneuvers such as quick right-angle turns and switchbacks, negotiating high speed curves and esses, or when making evasive maneuvers to dodge road obstacles or other bikes, it has again been my experience that tandems place a very high demand on the lateral strength of wheels... just as they do torsional frame stiffness. I think it's also fair to say that for some teams, just trying to ride down the road in a straight line will create lateral loads on the wheels... easily observed just by riding behind such a team and watching the frame rock and how the wheels track.

    So, getting back to my original question... the role that Friction plays in the cornering equation can't be understated. Without the friction created by tires centripetal forces win and the wheels slide out from under the bike. To get that friction into the tires, an awful lot of rider weight has to be transmitted through the frame to the hubs and then into the spoke network and rims and with the average tandem team and the aforementioned tandem bike's torsional flex this does not always happen in a linear fashion as you negotiate turns.
    Here is some more grist for the mill. Recently, I completed a 6 hour skills course as part of my Cat 4 upgrade which focused on cornering and criterium racing. Although, I could corner very well pre-clinic, I learned a great deal and improved my cornering.

    The key point emphasized was counter steering and getting the weight on the outside pedal while leaning the bike into the turn. To drive this point home, we had cone drills where we rode around a cone in the center of the street. You enter the cones and for a left turn one had their left hand on the drop and the right hand behind the back. The weight was shifted to the right pedal and the entire body shifted right over the right pedal. You had to lean the bike to the left to make the turn. The sound of the tires gripping the road was impressive. This took a little practice but by the end of the session, we were all whipping around the cone a lot faster and safer than I ever thought possible.

    The same is for high speed turns. One has to lean the bike but maintain weight over the outside pedal. This results in max traction such that if there is some debris, there is so much downward force your chance of surviving the turn is increased. This is especially true for off camber road.

    The instructor pointed out that for motor cycles it is not as critical because of the weight of the motorcycle.

    So the take away is one does not want to lean with the bike around turns. To the contrary, one wants max force pointing straight down on the sidewall of the tire as you lean the bike and this requires the weight to be on the outside pedal.

    For tandems, it is a little more tricky to get the weight coordinated. However, I think the captain can use the technique to counter steer (lean) the bike while keeping his weight over the down pedal.

    To your point, this puts a lot of lateral stress on the wheel.

  16. #16
    hors category TandemGeek's Avatar
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    Quote Originally Posted by Phantoj View Post
    When the component of cornering force....
    Was there an answer in there?

    What I was looking for was the removal of 'f' (friction) from the ubiquitous bicycle cornering forces formula... a real-world condition that cyclists encounter, along with less than theoretical or text-book perfect road conditions and rider behaviors. Yeah, I get tubular tires; I rode them for 15 years in the 70's and 80's.

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    hors category TandemGeek's Avatar
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    Quote Originally Posted by Phantoj View Post
    However, this physics diversion isn't tandem-specific and would probably be more at home in the Road Forum.
    No, because tandems impose all kinds of different demands on the basic bicycle wheel technology, performance models and dogma. If you're a tandem enthusiast as well as a single bike rider who tests the envelope of their equipment on a regular basis, then you will appreciate why these discussions are germane to the tandem forum.

    The last thing I need is a 140lb - 180lb single bike rider whose never ridden a tandem trying to tell me how a 310lb load on a tandem will influence wheel performance... you know, the same guys who can't figure out why tandems and single bikes will seesaw back and forth on hilly rides. It's about as useful as tandem handling and performance tips from teams who never venture off a bicycle path when your typical ride puts you out on public roads with 3k - 5k vertical feet of climbing and descending on twisty foothill and mountain roads.
    Last edited by TandemGeek; 07-17-10 at 11:55 AM. Reason: grammar

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    hors category TandemGeek's Avatar
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    Quote Originally Posted by WebsterBikeMan View Post
    deforming it so that it bulges (slightly) more on the inside of the curve and stretches (slightly) on the outside of the curve. And this deformation can happen to the entire wheel to a greater or lesser extent.
    Actually, it's a bit more complex than that, but doesn't really matter outside the classroom. Without going too far down the dirt road of wheel physics, remember that your wheel is still dealing with radial loads in a corner... higher radial loads than it must deal with when you're just riding in a straight line on a level road. The more speed you carry through turns adds to the equation and when you throw in a turn at the bottom of a sharp valley with an off-camber twisting uphill follow-through you no longer have that nice linear turn that's typically modeled. Instead, you find that throughout the entire complex turn you begin a maneuver where you're continually moving the bike in and out of balance by countersteering, leaning and shifting your weight to follow an unnatural line... and that seems to suggest that the wheels are under all kinds of fairly heavy radial and lateral loads where spoke tension becomes very dynamic.

    As Hermes points out from his bicycle handling seminar and training, there's also more than one way to position your body and weight over a bicycle as you corner and that too skews the equation and brings different forces into play. I've been a "weight the outside pedal and torque the handlebar" rider for most of my adult life, and it really does change how a bike or tandem corner and how they "feel" in a corner. In fact, if you want to make your stoker feel more confident in corners teach them this technique... as it eliminates the 'roller coaster' effect that often times makes them feel uncomfortable as cornering forces want to push them away from the apex of the curve and throw them off into space.

    Again, my cited example was used because it is an extreme condition that really tests the stability of a tandem and it's wheels. Not even negotiating a series of tight esses on a steep descent are this dynamic since they lack the G-loading at the bottom of the valley coupled with the off-camber twist in the road surface. I only introduced it in response to my personal impressions of Rolf wheels as it pertains to this thread, since it demonstrated some type of inherent stability difference between how a Rolf wheel is designed vs. a conventionally spoked 36h wheel. Frankly, I suspect it's the somewhat narrow flange spacing (50mm) & heavy right-side dishing used on Rolfs vs. the wider flange spacing (60mm) and nearly symmetrical shape and spoke tension of our conventionally spoked wheels that is coming into play more than anything else.

    Bottom Line: Forget the text books for a moment, this is simply subjective impressions from real-world riding experiences. If someone doesn't find themselves riding in these types of situations and/or are more cautious and don't push the limits of their equipment, bike handling skills and judgement all that far there's a pretty good chance they won't have similar experiences to draw on. The same is true for folks who do unsupported touring and ride with heavily laden tandems; their experiences and subjective impressions of how their tandems handle under the conditions they encounter may only resonate with other teams who have "been there and done that".
    Last edited by TandemGeek; 07-17-10 at 11:12 AM. Reason: grammar & a tweak to my thesis

  19. #19
    Senior Member mkane77g's Avatar
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    Wanna race!

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    Quote Originally Posted by TandemGeek View Post
    Was there an answer in there?
    lol, it's pretty confusing without a diagram!
    I don't even use the offensive term "Fred." -- Sheldon "All Cyclists Are My Friends" Brown (1944-2008)

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    hors category TandemGeek's Avatar
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    Quote Originally Posted by Phantoj View Post
    lol, it's pretty confusing without a diagram!
    Confusing to whom? (See Figure, below)

    I'm pretty sure I have a good idea of what I'm talking about: cycling, more-so than text book physics. How about you? So far what I've gotten from your posts is what anyone can find in a few moments using Google: sound bites regarding bicycle sciences to interject into a thread without a lot of context: kinda like those trivial CNN Factoids (do they even do those anymore?).

    How many different wheelsets have you tested back-to-back with the exact same tandem / stoker / tires / psi / road conditions to establish how they influence the handling of your tandem and under what conditions?

    I suspect there must be some way to get in and out of turns without applying lateral / side loading forces to bicycle wheels, but I'll be darned if it exists in the real world in which we ride our tandems. That's the gist of the more meaningful discussions we seem to try and have here.
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    OK, maybe if I can understand exactly where our disagreement (if any) lies, I can try to be more clear.

    All I'm saying is that, in your diagram above, assuming a steady-state corner, when you add the F and N vectors together, the resultant vector will lie right along the line from the contact patch to the center of gravity (C.G.) If you drew a bicycle on this diagram, this resultant vector would lie in the plane of the frame and wheels (i.e. no lateral wheel load).

    The wheels will have some lateral loads during non-steady-state events: initiation of the turn, straightening back up, loss and regain of grip. Also, if the riders' C.G.'s are not in the plane of the bike, this will result in lateral wheel loads (whether the bike is in a corner or not). I'm not a fan of the rider's (or riders') C.G. being out of the plane of the bike, but I guess there are some theories on cornering that promote this.

    I'm not trying to say anything about how lateral stiffness affects handling and stability.

    I was trying to point out is that "simply" leaning the bike while coasting is actually a pretty severe test of your wheels' lateral stiffness.

    If you disagree with anything in this post, point it out and I'll be happy to try explain myself.
    I don't even use the offensive term "Fred." -- Sheldon "All Cyclists Are My Friends" Brown (1944-2008)

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    hors category TandemGeek's Avatar
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    Quote Originally Posted by Phantoj View Post
    I was trying to point out is that "simply" leaning the bike while coasting is actually a pretty severe test of your wheels' lateral stiffness.
    This I can agree with.

    However, as for the "no lateral wheel load", it was an over simplistic model for the discussion we were having: an interesting, but irrelevant factoid. It is an important concept to be sure, but we were well beyond bicycle physics 101 while discussing the subtle nuances of the high-end wheel set our friend was considering.

    The basic cornering model ignores the influence of dynamic road conditions, how people actually ride bikes, the influence of the narrow flanges/dishing/bladed, high-tension spokes used by Rolf. Beyond the wheels, there is also the all important aspect of how things like tire side slip and pneumatic trail can influence how a tandem wheel set will react to changes in the small but still discernible lateral loads that can alter a known amount of under or over-steer on a given tandem... at least that was my experience and that is what Joe@ had called into question, i.e., our experiences were different.

    Peace...

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    just another gosling Carbonfiberboy's Avatar
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    More deep-ending it . . .

    This has all been very interesting to me. I never thought to check wheel stability by leaning while coasting. I'll try that tomorrow when we go out with the panniers on.

    Some confusion in my brain: I always thought "countersteering" referred to the method of getting the bike out from under you so you can turn, i.e. pulling back on the outside bar.

    I think I understand and have used the method of making short quick turns which I think Hermes is explaining, but only on my single. I don't quite understand how it works, but it seems to have something to do with rake and trail. And however that is, I don't see us practicing that as a team. Not any time soon, anyway. Stoker likes to have the bike under her.

    My usual method of fast cornering on the tandem is to drop my upper body into the turn ahead of the bike - again a way to get the bike out from under us so it will turn. I don't mess with the bars like I do for slower, sharper turns. We do weight the outside pedals, but only to get our center of motion closer to the contact patch. Thus if there's a skid, our effective CG will be lower and it's much easier to recover than if our major weight were in the saddle. Maybe that's not correct physics, but that's how it feels.

    Maybe more correctly, the length of the lever arm between the contact patch and the dropped pedal is much shorter than the arm between the contact patch and saddle. So when the bike's lean changes due to vagaries in pavement or traction, the movement felt in the feet is much less and easier to deal with.

    If we are really going on a nice road, I'll press my inside knee into the top tube and as the turn develops, rotate my lower body so the inside hip leads the outside hip and moves to the inside of the saddle. I guess this moves a little lower body weight into the turn. Seems fast and stable and kind of a fun little pas de deux on the bike. Some people do this by dropping the knee, but that seems slower because of wind resistance, though better in a hairpin, where you want that. I have the impression that leaning the bike a little less, and thus putting that lateral load on the wheels, changes the location of the contact patch on the tire and makes it a little stickier. Or maybe I'm just paranoid about those thin sidewalls. Seems to help, though.

    We've been running 25c, but I bought a set of 28s for a coming tour. They do change the handling - the bike understeers with them. It'll take some getting used to, but so do the panniers.

    So like TG was saying, a lot goes on in a corner.

    I have had Rolfs on a single for many years. They make a funny noise when cornering really hard that none of my other wheelsets make. Both my Rolf wheelsets have done that. I have no idea what it is, but it's like the pavement noise is amplified.

    Speaking to that feeling of roughness from different wheelsets and tires - I just built up a CADD9 climbing bike. Took it out on the road for the first time, with the Tricomps pumped up to 140 like usual, and with the Rolfs, too. The thing was a pogo stick. I never understood what people had against high pressure tires before - I've always used them either on a carbon bike or our steel Speedster. Pretty funny. Thought I'd lose my retinas.

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