Lightest Tandem?
11-18-14, 09:58 PM
#26
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Bikes: 2015 Calfee Tetra tandem,2016 Calfee Tetra Adventure Tandem, Ventana ECDM 26 mtn tandem, Ventana ECDM 29r full suspension Mtn tandem ,Ventana Fat tire tandem, Calfee Dragon Fly, Santa Cruz Carbon 5010, 907 Whiteout fat tire
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Here is a picture of a Calfee tandem in construction prior to wrapping Looks like the tubes are nicely mitered.
ATTACH=CONFIG]418549[/ATTACH]
ATTACH=CONFIG]418549[/ATTACH]
11-19-14, 03:43 AM
#27
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A long read but came from Santanas website. Seems Santana has done some evaluation of lightweight and finds light is simply a small advantage vs a properly efficient frame. The copy and paste below.
As for ISO GRID, EXO Grid info this is a good link
Vyatek - home
Personally I have attended lectures on this technology when it was being initiated for aerospace primary control and structure. The presentation was interesting but the presenter failed miserably to answer relevant questions and concerns. Since then, I do not recall seeing the technology presented to that industry in recent years.
PK
How much faster?
This age-old question—and the resulting debate between engineers and enthusiasts—has finally been settled. Engineers had claimed weight was relatively unimportant. They insisted that any bicycle, even one weighing 100 pounds, would be equally fast on a totally-flat century. Armed with cryptic formulas, engineers wanted us
to believe a heavier bike was only a disadvantage when accelerating or climbing. Cycling experts (including magazine editors, lionized builders and winning racers) knew better. A lighter bike, they declared, was the true path to speed and performance. Want to ride faster? Buy a lighter frame and equip it with lighter components! Saving a pound of rotating weight (wheels and pedals), they told us, was as good as saving two pounds of frame weight. Better yet, we were assured, saving two pounds at the frame was as good as saving four pounds of body weight. Whose argument won? Most of us (this writer included) sided with our heroes and ignored the engineers. After all, which is more fun: dieting, training, or shopping for lighter wheels?
After we invested in our carbon frames, titanium hardware and featherweight wheels we felt hours faster. At the very least, we convinced ourselves, our finishing times were improved by dozens of minutes. Now that thousands of enthusiasts are using watt me- ters that accurately record rear wheel power output, however, repeated 32 real world testing proves that those darned engineers were right. The effect of bike weight on speed is easily quanti- fiable, and conforms to Newtonian Physics. Even on an exceptionally long ride a lighter bike is only a few seconds faster. Minutes faster? That was an impossible fantasy.
Watt Meter Findings
• On a totally flat 100-mile ride, a pound of extra weight will slow a cyclist by about 8 seconds (due to increased rolling resistance).
• On a challenging century, a pound of extra weight will slow a cyclist by about 30 seconds.
• On Alpe d’Huez, where the gradient averages 7.9% for 8.6 miles, pro riders using watt meters have verified what Isaac Newton proposed centuries earlier. On this famous climb, the energy required to lift a pound by 3,500 vertical feet will cause solo competitors to reach the summit about 30 seconds later.
The difference between a pound of frame weight and a pound of wheel weight? Less than a second. Excess body weight, which needs to be both lifted and nourished, has a bit more impact than excess bicycle weight.
Discouraged by this news? For tandem riders it only gets worse. When engineers insert doubled power, their formulas confirm that
a tandem’s frame weight becomes half as important. If your tandem’s frame is a pound overweight, for instance, you and your partner will finish a challenging century (or reach the summit of Alpe d’Huez) about 15 seconds slower. Unless you can escape the laws of Newtonian Physics, on most tandem rides the speed advantage of a pound-lighter frame won’t exceed 10 seconds.
Can Lighter be Slower?
While a lighter frame can’t possibly save you more time than the aforementioned examples, it might actually make you slower. If your frame doesn’t adequately resist pedal-induced flex, energy that could have propelled you forward will instead be wasted in lateral frame distortion (which creates heat instead of propulsion).
Because the faddish “open” tandem frames are undeniably flexier, these suddenly popular designs with their missing frame tubes are apt to reach the summit behind a pound-heavier frame with all tubes present. (Legs are also heavy, but finding a tandem partner with missing limbs won’t cause you to win races.)
Although the advantage of a lighter frame is less than most of us formerly believed, the energy required to accelerate and/or lift excess weight cannot be denied. While your body weight is difficult to control, and the lightest bike components may fail or wear out, a light and well-designed frame should provide decades of reliable performance. Because a lighter and more efficient frame
is more enjoyable to ride, you’ll use it more often. Extra use is the factor that easily justifies a frame’s expense. If you spread the cost over a number of years, Santana’s lighter and more efficient frames become a healthy bargain and a superior long-term investment. Since the effect of weight is relatively small (and the lightest frames from leading tandem builders are all within a two-pound spread), is it possible to believe a new frame will allow you to keep up with faster couples? Better yet, some might ask, is there a new technology that will allow you to finish ahead of teams that are younger, thinner or stronger? Actually, there is. We call it Bilaminate Damping™.
More Important than Weight
Even though most cyclists haven’t yet heard of Bilaminate Damping™ (Santana’s specific application of a phenomenon engineers refer to as Constrained Layer Damping or CLD), this exciting technology is a game-changer that’s helping engineers at Boeing and Ford to define the next generation of airplanes and automobiles. Santana became aware of constrained layer damping after we tried to understand dozens of reports received from owners of our Beyond frames built with IsoGrid®* carbon tubing. Most of these couples had upgraded from a previous Santana, and nearly all reported longer rides at higher speeds. Especially intriguing were reports from competitive seniors who claimed their Beyond had “turned back the clock” and was allowing them to regain performance they’d lost through aging. Because Santana’s design team knew these fantastic reports couldn’t possibly be explained by the 6 lb. weight of our Beyond frame (which is only a pound-and-a-half lighter than our frames built with titanium or scandium), we challenged a group of engineers to provide an explanation. Their three word response, constrained layer damping, encouraged a surprising path of discovery.
Following four years of additional research and ride testing, Santana understands constrained layer damping well enough to explain why you’ll feel younger. Further, we realize how an advanced version of this technology (i.e., Bilaminate Damping™) is actually more critical than frame weight, and can enable you to enjoy longer rides and finish minutes faster.
Interested? Continue reading to discover an unexpected source of cycling performance months before your bike-racing buddies read about it in their favorite magazines.
What's the Buzz?
If you place your fingertips on your frame while you ride, you’ll sense the vibration that occurs as the result of your wheels rolling along the road surface. Experts confirm that all materials resonate, and that thin sections of high strength materials will continue to reverberate indefinitely. Your bicycle frame not only resonates like a cymbal, the lighter and stiffer the frame, the greater the vibration.
This explains why a resounding wind chime can be produced from the same materials that create light bicycle frames (i.e., aluminum, steel, titanium, carbon and even bamboo). The difference, of course, is that the sustained notes of a wind chime are pleasant. Sustained road vibration isn’t. While the vibration we sense through our fingertips seems innocuous, miles of exposure to road buzz has a debilitating effect on human joints and muscles. The faster the speed, the greater the road’s impact. The lighter the bike, the greater the reverberation. Even on the smoothest courses, competetive speeds and bikes take a toll on performance, limit your endurance and makes you feel old.
Doesn’t a carbon frame damp vibration? Although certain materials won’t resonate as efficiently as others (which is precisely why discerning cyclists prefer the comfort of titanium over carbon, and carbon over aluminum or steel), the degree of vibration damping between various high strength materials is comparatively small. A light and stiff racing frame built from titanium or carbon can be less comfortable than a recreational frame built from aluminum or steel.
How Bilaminate Damping™ Works
When two materials that resonate at different frequencies are bound together, each inhibits the other’s ability to resonate. Engineers call it “Constrained Layer Damping.” Additionally, if the weights of the materials are roughly equal, the two frequencies cancel each other. The effect of Bilaminate Damping™ is immediate and profound. Vibration is terminated. Boeing’s initial plan for their 787 Dreamliner was an “all-carbon” stucture. Partway through development they changed the design to approximately equal weights of carbon and aluminum. Through careful engineering and the use of constrained layer damping (CLD), weight did not increase. Instead, vibration disappeared. A flight in a 787 will change your perception of air travel. Because the quieter plane is more comfortable, flights are less fatiguing. Once you’ve experienced the difference, other jetliners become second rate.
The Ultimate CLD
Bilaminate Damping™ is Santana’s term for an advanced adaptation of constrained layer damping. Typical CLD is acheived by bonding structural and non-structural materials (usually elastomers) in unbalanced ratios. With this simple approach, vibration is merely reduced. Employing VyaTek’s patented ExoGrid® and IsoGrid®* technologies, Santana eliminates the bonding layer by using extreme heat and pressure to fuse together a proportioned and complementary pair of ultra-strong materials. In short, other CLDs add weight to reduce vibration. Santana’s Bilaminate Damping™ eliminates vibration without adding a single gram of non-structural weight.
*IsoGrid® and Exogrid® are trademarks for Vyatek's patented, cutting edge method for creating the world's finest hybrid composite carbon/metal tubes.
As for ISO GRID, EXO Grid info this is a good link
Vyatek - home
Personally I have attended lectures on this technology when it was being initiated for aerospace primary control and structure. The presentation was interesting but the presenter failed miserably to answer relevant questions and concerns. Since then, I do not recall seeing the technology presented to that industry in recent years.
PK
CARBON FRAMES
and BILAMINATE DAMPING™
Lighter bikes:and BILAMINATE DAMPING™
How much faster?
This age-old question—and the resulting debate between engineers and enthusiasts—has finally been settled. Engineers had claimed weight was relatively unimportant. They insisted that any bicycle, even one weighing 100 pounds, would be equally fast on a totally-flat century. Armed with cryptic formulas, engineers wanted us
to believe a heavier bike was only a disadvantage when accelerating or climbing. Cycling experts (including magazine editors, lionized builders and winning racers) knew better. A lighter bike, they declared, was the true path to speed and performance. Want to ride faster? Buy a lighter frame and equip it with lighter components! Saving a pound of rotating weight (wheels and pedals), they told us, was as good as saving two pounds of frame weight. Better yet, we were assured, saving two pounds at the frame was as good as saving four pounds of body weight. Whose argument won? Most of us (this writer included) sided with our heroes and ignored the engineers. After all, which is more fun: dieting, training, or shopping for lighter wheels?
After we invested in our carbon frames, titanium hardware and featherweight wheels we felt hours faster. At the very least, we convinced ourselves, our finishing times were improved by dozens of minutes. Now that thousands of enthusiasts are using watt me- ters that accurately record rear wheel power output, however, repeated 32 real world testing proves that those darned engineers were right. The effect of bike weight on speed is easily quanti- fiable, and conforms to Newtonian Physics. Even on an exceptionally long ride a lighter bike is only a few seconds faster. Minutes faster? That was an impossible fantasy.
Watt Meter Findings
• On a totally flat 100-mile ride, a pound of extra weight will slow a cyclist by about 8 seconds (due to increased rolling resistance).
• On a challenging century, a pound of extra weight will slow a cyclist by about 30 seconds.
• On Alpe d’Huez, where the gradient averages 7.9% for 8.6 miles, pro riders using watt meters have verified what Isaac Newton proposed centuries earlier. On this famous climb, the energy required to lift a pound by 3,500 vertical feet will cause solo competitors to reach the summit about 30 seconds later.
The difference between a pound of frame weight and a pound of wheel weight? Less than a second. Excess body weight, which needs to be both lifted and nourished, has a bit more impact than excess bicycle weight.
Discouraged by this news? For tandem riders it only gets worse. When engineers insert doubled power, their formulas confirm that
a tandem’s frame weight becomes half as important. If your tandem’s frame is a pound overweight, for instance, you and your partner will finish a challenging century (or reach the summit of Alpe d’Huez) about 15 seconds slower. Unless you can escape the laws of Newtonian Physics, on most tandem rides the speed advantage of a pound-lighter frame won’t exceed 10 seconds.
Can Lighter be Slower?
While a lighter frame can’t possibly save you more time than the aforementioned examples, it might actually make you slower. If your frame doesn’t adequately resist pedal-induced flex, energy that could have propelled you forward will instead be wasted in lateral frame distortion (which creates heat instead of propulsion).
Because the faddish “open” tandem frames are undeniably flexier, these suddenly popular designs with their missing frame tubes are apt to reach the summit behind a pound-heavier frame with all tubes present. (Legs are also heavy, but finding a tandem partner with missing limbs won’t cause you to win races.)
Although the advantage of a lighter frame is less than most of us formerly believed, the energy required to accelerate and/or lift excess weight cannot be denied. While your body weight is difficult to control, and the lightest bike components may fail or wear out, a light and well-designed frame should provide decades of reliable performance. Because a lighter and more efficient frame
is more enjoyable to ride, you’ll use it more often. Extra use is the factor that easily justifies a frame’s expense. If you spread the cost over a number of years, Santana’s lighter and more efficient frames become a healthy bargain and a superior long-term investment. Since the effect of weight is relatively small (and the lightest frames from leading tandem builders are all within a two-pound spread), is it possible to believe a new frame will allow you to keep up with faster couples? Better yet, some might ask, is there a new technology that will allow you to finish ahead of teams that are younger, thinner or stronger? Actually, there is. We call it Bilaminate Damping™.
More Important than Weight
Even though most cyclists haven’t yet heard of Bilaminate Damping™ (Santana’s specific application of a phenomenon engineers refer to as Constrained Layer Damping or CLD), this exciting technology is a game-changer that’s helping engineers at Boeing and Ford to define the next generation of airplanes and automobiles. Santana became aware of constrained layer damping after we tried to understand dozens of reports received from owners of our Beyond frames built with IsoGrid®* carbon tubing. Most of these couples had upgraded from a previous Santana, and nearly all reported longer rides at higher speeds. Especially intriguing were reports from competitive seniors who claimed their Beyond had “turned back the clock” and was allowing them to regain performance they’d lost through aging. Because Santana’s design team knew these fantastic reports couldn’t possibly be explained by the 6 lb. weight of our Beyond frame (which is only a pound-and-a-half lighter than our frames built with titanium or scandium), we challenged a group of engineers to provide an explanation. Their three word response, constrained layer damping, encouraged a surprising path of discovery.
Following four years of additional research and ride testing, Santana understands constrained layer damping well enough to explain why you’ll feel younger. Further, we realize how an advanced version of this technology (i.e., Bilaminate Damping™) is actually more critical than frame weight, and can enable you to enjoy longer rides and finish minutes faster.
Interested? Continue reading to discover an unexpected source of cycling performance months before your bike-racing buddies read about it in their favorite magazines.
What's the Buzz?
If you place your fingertips on your frame while you ride, you’ll sense the vibration that occurs as the result of your wheels rolling along the road surface. Experts confirm that all materials resonate, and that thin sections of high strength materials will continue to reverberate indefinitely. Your bicycle frame not only resonates like a cymbal, the lighter and stiffer the frame, the greater the vibration.
This explains why a resounding wind chime can be produced from the same materials that create light bicycle frames (i.e., aluminum, steel, titanium, carbon and even bamboo). The difference, of course, is that the sustained notes of a wind chime are pleasant. Sustained road vibration isn’t. While the vibration we sense through our fingertips seems innocuous, miles of exposure to road buzz has a debilitating effect on human joints and muscles. The faster the speed, the greater the road’s impact. The lighter the bike, the greater the reverberation. Even on the smoothest courses, competetive speeds and bikes take a toll on performance, limit your endurance and makes you feel old.
Doesn’t a carbon frame damp vibration? Although certain materials won’t resonate as efficiently as others (which is precisely why discerning cyclists prefer the comfort of titanium over carbon, and carbon over aluminum or steel), the degree of vibration damping between various high strength materials is comparatively small. A light and stiff racing frame built from titanium or carbon can be less comfortable than a recreational frame built from aluminum or steel.
How Bilaminate Damping™ Works
When two materials that resonate at different frequencies are bound together, each inhibits the other’s ability to resonate. Engineers call it “Constrained Layer Damping.” Additionally, if the weights of the materials are roughly equal, the two frequencies cancel each other. The effect of Bilaminate Damping™ is immediate and profound. Vibration is terminated. Boeing’s initial plan for their 787 Dreamliner was an “all-carbon” stucture. Partway through development they changed the design to approximately equal weights of carbon and aluminum. Through careful engineering and the use of constrained layer damping (CLD), weight did not increase. Instead, vibration disappeared. A flight in a 787 will change your perception of air travel. Because the quieter plane is more comfortable, flights are less fatiguing. Once you’ve experienced the difference, other jetliners become second rate.
The Ultimate CLD
Bilaminate Damping™ is Santana’s term for an advanced adaptation of constrained layer damping. Typical CLD is acheived by bonding structural and non-structural materials (usually elastomers) in unbalanced ratios. With this simple approach, vibration is merely reduced. Employing VyaTek’s patented ExoGrid® and IsoGrid®* technologies, Santana eliminates the bonding layer by using extreme heat and pressure to fuse together a proportioned and complementary pair of ultra-strong materials. In short, other CLDs add weight to reduce vibration. Santana’s Bilaminate Damping™ eliminates vibration without adding a single gram of non-structural weight.
*IsoGrid® and Exogrid® are trademarks for Vyatek's patented, cutting edge method for creating the world's finest hybrid composite carbon/metal tubes.
11-19-14, 04:05 AM
#28
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Well no one is making monocoque carbon tandems because the molds would be prohibitively expensive considering the number of units sold. We looked into it and could make a roughly 2kg frame but it'd take a decade to recoup the cost. I weighed all the Beyonds here and there's some mediums at 2780g. The larges and XLs are from 2900-3030. I'm hoping to beat that with careful tube selection and some minor changes. Also, despite appearances ditching the lateral tube doesn't really change weight unless you sacrifice stiffness. You have to use bigger thicker tubes and wider BB shells. It seems to be done more because it seems to be a modern look people like. I prefer the lateral tube look. Bikes have always been triangles and the big crooked square in the middle of a no lat tube bike looks odd to me.
Yes, the 160 rear end and wider cranks are a weight handicap that I'll struggle to overcome but coming from a DH bike background I can appreciate a dishless rear wheel. The special Spinergies I have are 940 & 690g. I may be able to skip using the 88g Ti QR skewers by having the axles threaded and using Ti bolts.
Yes, the 160 rear end and wider cranks are a weight handicap that I'll struggle to overcome but coming from a DH bike background I can appreciate a dishless rear wheel. The special Spinergies I have are 940 & 690g. I may be able to skip using the 88g Ti QR skewers by having the axles threaded and using Ti bolts.
Someone also made comment of nano technology being utilized. Sadly nano technology alone is not the key to lightweight or optimized load paths for stress or strength. I will offer though that if the lugged tube designed was nano enhanced, some weight could be reduced to achieve the same strengths.
Taken to the current limits available, a monocoque design, utilizing nano enhanced systems could provide the best efficiency for optimized power to the ground and lightest weight. Done correctly the cost should be similar to currently available designs.
All the best to the OP in his quest. So many comments can be applied...the devil is in the details...count the grams and pounds take care of themselves...it's only money...crashing sucks...and so on. Again all the best with it and I wait to see your final product.
PK
11-19-14, 08:19 AM
#29
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Yes, Santana does not stress light weight as a primary goal so this little project of mine isn't a priority for the company (that's why I can talk about it). They prioritize lateral stiffness and durability with excellent vibration damping. A Santana based build will always be a little heavier because of the wide hub and cranks but for most of our customers who put a rack and trunk bag on that's just fine. That's also why I started this thread cuz I figured the lightest builds you guys have seen would be from companies I'm not familiar with. However, the Beyond is a class leader in frame weight so the weight weenie in me couldn't help but see how light I can get one. Tandem on friends and I'll post my results when she's done.
P.S. Anyone here own one of those Paketa V2r frames that accommodate the timing belt on the drive side? That's a novel approach to ditching grams.
P.S. Anyone here own one of those Paketa V2r frames that accommodate the timing belt on the drive side? That's a novel approach to ditching grams.
11-19-14, 11:01 AM
#30
Clipless in Coeur d'Alene
Yes, Santana does not stress light weight as a primary goal so this little project of mine isn't a priority for the company (that's why I can talk about it). They prioritize lateral stiffness and durability with excellent vibration damping. A Santana based build will always be a little heavier because of the wide hub and cranks but for most of our customers who put a rack and trunk bag on that's just fine. That's also why I started this thread cuz I figured the lightest builds you guys have seen would be from companies I'm not familiar with. However, the Beyond is a class leader in frame weight so the weight weenie in me couldn't help but see how light I can get one. Tandem on friends and I'll post my results when she's done.
P.S. Anyone here own one of those Paketa V2r frames that accommodate the timing belt on the drive side? That's a novel approach to ditching grams.
P.S. Anyone here own one of those Paketa V2r frames that accommodate the timing belt on the drive side? That's a novel approach to ditching grams.
We have a RSD, Gates Centertrack setup on our Calfee with the belt on the outside. I used a standard road triple crank which allows us to still have a true 74mm BCD granny gear on the inside and a normal 130bcd big ring mounted in the middle spider position, all the while maintaining a narrow-ish Q-factor (~157mm). This also allows for a standard double FD mounting without any weird FD brackets. We are running 135mm spacing. I believe most (if not all) Paketa are also running spacings less than 160mm, to the order of 130-135mm as typical. With Santana's ubber wide crank setup, you might have room for an inner drive like Paketa, if your chainstay allows it, but I'm not 100% where that leaves you for gearing options.
Ours was something an experimental build as even Calfee hadn't figured out how to get the RSD + the wider CDX belt/centertrack rings and reliable shifting at that point in time, but ours is working great. It's setup with Di2 11spd now and awesome. In the future I might modify this build again and go back to "normal" left side drive with daVinci cranks (maintaining the narrow Q, plus the bonus of swapping in various drive spider sizes), but for now what we have is light and cool enough to appease the geek in me.
Last edited by twocicle; 12-21-14 at 03:25 PM.
11-19-14, 11:27 AM
#31
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I originally intended to set up our Calfee with RSD on an outer ring as well (with chain instead of belt), but daVinci made an error with the anodizing and did a set of crossover cranks instead. Rather than wait and have to have the whole thing re-done, they comped us a full set of alloy hardware for mounting the rings and the overall weight came in shockingly close to RSD since the difference in weight of their cranks with crossover ring "spider" is amazingly close to their plain non-ring bearing cranks. I'd have to look back through the original email thread with Todd from daVinci, but I think it was ~50g total difference in the end and not worth worrying about (since we weren't trying to build a 20 lb tandem 
). In some ways, having the "standard" crossover set-up saves us any of the concerns of getting the RSD cobbled together, so it all works out fine in the end anyway. If I were to do it again, I'd definitely still think of RSD, but the weight savings are generally pretty subtle and can be found other ways.
). In some ways, having the "standard" crossover set-up saves us any of the concerns of getting the RSD cobbled together, so it all works out fine in the end anyway. If I were to do it again, I'd definitely still think of RSD, but the weight savings are generally pretty subtle and can be found other ways.
11-19-14, 04:06 PM
#32
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I want to preface my comment with the fact that I own two Santana tandems and think that Santana make great bikes. Then again the marketing department (Bill?) at Santana sometimes illustrates what is unfortunate about much of bike industry marketing. For one example see the short quote taken from the document above:
It would be great if buying another frame would make us finish ahead of stronger teams. If that were true this team would be in line to spend at least the price of a Beyond or a Calfee or a Paketa. Sadly I don't believe this is the case. There are small advantages to be gained by using the right tires, a lighter bike and the other things we write about here but they all pale in comparison to the difference in speed from just putting out more watts.
The Beyond (like other premium tandems) is a great bike and there are lots of reasons to enjoy a great new bike. I don't think we would go much faster on it.
...is it possible to believe a new frame will allow you to keep up with faster couples? Better yet, some might ask, is there a new technology that will allow you to finish ahead of teams that are younger, thinner or stronger? Actually, there is. We call it Bilaminate Damping™.
The Beyond (like other premium tandems) is a great bike and there are lots of reasons to enjoy a great new bike. I don't think we would go much faster on it.
11-19-14, 09:48 PM
#33
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...is it possible to believe a new frame will allow you to keep up with faster couples? Better yet, some might ask, is there a new technology that will allow you to finish ahead of teams that are younger, thinner or stronger? Actually, there is. We call it Bilaminate Damping™.
...new technology that will allow you to finish ahead of teams that are younger, thinner or stronger? Actually, there is.
So if I were having a new tandem built, that's the direction in which I'd look: aero. Lightish but stiff and well-damped carbon frame and fork, aero carbon wheels, discs, short head tube, for us a more slanted top tube to drop stoker's stem further. Stock BB spacing is OK for us. We like our conventional triple/timing belt or chain componentry. I'd probably spend the weight for couplers. I'd want touring and fender brazeons and a fork that would allow 28mm tires for touring. We'd put on our clip-on aero bars just like we have now or maybe something fancier and carbon.
11-19-14, 10:51 PM
#34
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Thanks for the comments about the RSD on Calfees. This is the weird tandem specific stuff that appeals to the bike nerd in me.
As for the aero stuff you're preaching to the choir. I have a very aero roadbike with clip on bars and it makes a noticeable difference IF you're already going over 20mph or into a headwind. My tandem won't have clip ons or any aero shaped parts but will have a stretched out, low position for both riders. As for the Santana marketing line on Bilaminate damping making you faster, that's based on the concept that by transferring less vibration and impact to the rider you are fresher and stronger later in the ride. This is of course more true the rougher the roads are and and the longer you've been out and would have very little effect on speed with smooth roads and few miles or a very fit team. I can't really attest to it because after a lifetime on full suspension mountain bikes all roadbikes feel rock hard and I never do rides over 4 hours. However, several people have told me that they feel a significant difference in the comfort of some frames over others.
As for the aero stuff you're preaching to the choir. I have a very aero roadbike with clip on bars and it makes a noticeable difference IF you're already going over 20mph or into a headwind. My tandem won't have clip ons or any aero shaped parts but will have a stretched out, low position for both riders. As for the Santana marketing line on Bilaminate damping making you faster, that's based on the concept that by transferring less vibration and impact to the rider you are fresher and stronger later in the ride. This is of course more true the rougher the roads are and and the longer you've been out and would have very little effect on speed with smooth roads and few miles or a very fit team. I can't really attest to it because after a lifetime on full suspension mountain bikes all roadbikes feel rock hard and I never do rides over 4 hours. However, several people have told me that they feel a significant difference in the comfort of some frames over others.
11-20-14, 09:01 AM
#35
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Uh, maybe. IME well-designed carbon frames are also well-damped. For that matter, our steel Speedster is damped plenty well enough not to tire us on long rides. Be that as it may, IME Santana is correct about the role bike weight plays on a long ride. But . . .
We call it "position." Well, it's not new and it's not really technology, but it's how you really can go a lot faster. We use aero bars for both captain and stoker, even on rides with lots of climbing. It's only 2 lbs. Anathema to the weight weenies, but like Santana says, weight weenie isn't really how you go faster. I don't know if there's proof that Bilaminate Damping will make you faster, but there sure as heck is proof that aero will make you faster. It's free speed. The captain's position must be the usual roadie position, bars below saddle as far as the frame allows. We use a slammed -17° stem. Stoker must be completely hidden behind the captain. This may require a longer stoker compartment, depending on the stoker. Ideally, stoker should be able to rest her forehead on the captain's saddle, or close to it. Slammed stoker drops can work. We use a set of stoker aero bars, with stoker's hands beside the captain's butt. More comfortable for stoker and more aero than drops.
So if I were having a new tandem built, that's the direction in which I'd look: aero. Lightish but stiff and well-damped carbon frame and fork, aero carbon wheels, discs, short head tube, for us a more slanted top tube to drop stoker's stem further. Stock BB spacing is OK for us. We like our conventional triple/timing belt or chain componentry. I'd probably spend the weight for couplers. I'd want touring and fender brazeons and a fork that would allow 28mm tires for touring. We'd put on our clip-on aero bars just like we have now or maybe something fancier and carbon.
We call it "position." Well, it's not new and it's not really technology, but it's how you really can go a lot faster. We use aero bars for both captain and stoker, even on rides with lots of climbing. It's only 2 lbs. Anathema to the weight weenies, but like Santana says, weight weenie isn't really how you go faster. I don't know if there's proof that Bilaminate Damping will make you faster, but there sure as heck is proof that aero will make you faster. It's free speed. The captain's position must be the usual roadie position, bars below saddle as far as the frame allows. We use a slammed -17° stem. Stoker must be completely hidden behind the captain. This may require a longer stoker compartment, depending on the stoker. Ideally, stoker should be able to rest her forehead on the captain's saddle, or close to it. Slammed stoker drops can work. We use a set of stoker aero bars, with stoker's hands beside the captain's butt. More comfortable for stoker and more aero than drops.
So if I were having a new tandem built, that's the direction in which I'd look: aero. Lightish but stiff and well-damped carbon frame and fork, aero carbon wheels, discs, short head tube, for us a more slanted top tube to drop stoker's stem further. Stock BB spacing is OK for us. We like our conventional triple/timing belt or chain componentry. I'd probably spend the weight for couplers. I'd want touring and fender brazeons and a fork that would allow 28mm tires for touring. We'd put on our clip-on aero bars just like we have now or maybe something fancier and carbon.
What does Rudy say, Getting old is not for the weak?
Last edited by waynesulak; 11-20-14 at 09:05 AM.
11-20-14, 10:08 AM
#36
Clipless in Coeur d'Alene
Unfortunately none of the "aero" talk relates at all to this thread topic. The effectiveness of aero is highly questionable unless your average speeds are more in the +20mph range. or if you prefer to add those riding positions for comfort. Sure aero can also look cool, but it almost always add weight to the build, which is the opposite of the goal in this thread.
budhaslug , I completely agree that depending on the crankset used, RSD may not be noticeably lighter (if at all) than a regular crossover setup. For example, our FSA SL-K Light double/triple single bike cranks w/BBs, chainrings and Gates rings came in at something like 1538gm, which as you know is actually heavier than daVinci's regular tandem crossover setup. Ok, I paid $500 total for both sets of new FSA cranks so I'm way ahead there, but cost was not the lead factor to the setup. However, if you do compare the absolute weight winner... Lightning which is something like 200gm lighter than ours and $1650, or daVinci at $1000-1100 and only ~100gm lighter, then for sure you see the cost savings in our approach.
As it turned out, the RSD setup has another bonus of a little more direct drive, single bike, feel than my impressions of crossovers (and I've used some pretty stiff ones too). Unfortunately RSD also has a huge risk of tangling the timing chain or belt with the drive chain and that can get very ugly in a 1/4 revolution. Believe me, I had that happen a couple times early on in my setup and learning curve. So long story short, agree that RSD may not be worth the hassle especially if you already have a nice light crossover crankset.
budhaslug , I completely agree that depending on the crankset used, RSD may not be noticeably lighter (if at all) than a regular crossover setup. For example, our FSA SL-K Light double/triple single bike cranks w/BBs, chainrings and Gates rings came in at something like 1538gm, which as you know is actually heavier than daVinci's regular tandem crossover setup. Ok, I paid $500 total for both sets of new FSA cranks so I'm way ahead there, but cost was not the lead factor to the setup. However, if you do compare the absolute weight winner... Lightning which is something like 200gm lighter than ours and $1650, or daVinci at $1000-1100 and only ~100gm lighter, then for sure you see the cost savings in our approach.
As it turned out, the RSD setup has another bonus of a little more direct drive, single bike, feel than my impressions of crossovers (and I've used some pretty stiff ones too). Unfortunately RSD also has a huge risk of tangling the timing chain or belt with the drive chain and that can get very ugly in a 1/4 revolution. Believe me, I had that happen a couple times early on in my setup and learning curve. So long story short, agree that RSD may not be worth the hassle especially if you already have a nice light crossover crankset.
Last edited by twocicle; 11-20-14 at 10:23 AM.
11-20-14, 12:22 PM
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Wouldn't the lightest and best be right side drive with the timing ring inboard like the Paketa? Then there isn't as much chance of the drive and timing chain getting tangled and you can use the lightest single bike cranks available.
11-20-14, 12:50 PM
#38
Clipless in Coeur d'Alene
IMO, the outside RSD is actually less prone to issues and does not require a proprietary frame. It does however require enough space between the middle-mounted big ring and crank arm to insert that fat gates belt/ring with sufficient clearances on either side. The FSA SL-K Light cranks worked out great for this setup, but it is unknown about the others. Given the weight I posted above, you can see my FSA SL-K Light single bike RSD setup is actually no lighter than a regular set of FSA SL-K Light crossover tandem cranks, but I did achieve the narrower Q-factor we needed, so our setup is justified in that aspect.
Last edited by twocicle; 11-20-14 at 04:56 PM.
11-20-14, 02:25 PM
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I am thinking a double chainring. Couldn't imagine anyone using a triple on a bike that they are trying to get under 20lb. I know the weight penalty isn't much but to go for that weight you won't be able to give up anything.
I have noticed that when shifting onto the big rig the chain does not sometimes go on cleanly but will overhang the outside of the teeth for a portion before getting engaged properly. This then interferes with any outboard timing belt/chain if there is minimal clearance. On our bike it sometimes throws off the timing chain. This doesn't happen when dropping down onto the small ring.
I have noticed that when shifting onto the big rig the chain does not sometimes go on cleanly but will overhang the outside of the teeth for a portion before getting engaged properly. This then interferes with any outboard timing belt/chain if there is minimal clearance. On our bike it sometimes throws off the timing chain. This doesn't happen when dropping down onto the small ring.
11-20-14, 05:04 PM
#40
Clipless in Coeur d'Alene
I am thinking a double chainring. Couldn't imagine anyone using a triple on a bike that they are trying to get under 20lb. I know the weight penalty isn't much but to go for that weight you won't be able to give up anything.
I have noticed that when shifting onto the big rig the chain does not sometimes go on cleanly but will overhang the outside of the teeth for a portion before getting engaged properly. This then interferes with any outboard timing belt/chain if there is minimal clearance. On our bike it sometimes throws off the timing chain. This doesn't happen when dropping down onto the small ring.
I have noticed that when shifting onto the big rig the chain does not sometimes go on cleanly but will overhang the outside of the teeth for a portion before getting engaged properly. This then interferes with any outboard timing belt/chain if there is minimal clearance. On our bike it sometimes throws off the timing chain. This doesn't happen when dropping down onto the small ring.
1) TA Alize rings because those have an abrupt inner shoulder causing a sharp angulation for the chain when climbing up to the big ring teeth
and
2) an overstepping of the 10spd Di2 FD.
Solved the issue by switching to Stronglight rings that have a smoother shoulder transition, plus a 11spd Di2 FD (and 11spd chain) which provided some extra e-tube tuning of chain rub alignment. I would have preferred using the smoothly sloped FSA "Super Road" rings that came with our cranksets, but those were 52t and 53t, and we needed a 48t for our setup (running 48/30). Works like a charm, but we are still holding our breath as this is new territory.
Last edited by twocicle; 11-20-14 at 05:16 PM.
11-20-14, 09:25 PM
#41
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That Paketa frame has a specially shaped chainstay yoke to make room for the Gates ring on the inside. However, it still looks like it has a pretty long chainstay. My frame will have 16.25" chainstays for lighter weight, more lateral stiffness and better turning. The penalty there is a less comfortable ride which is why Santanas usually have 17" chainstays but that Paketa frame seems aimed at performance so I'd think they'd want the racier geometry and just leave the timing chain on the left side. Comparing two Lightning setups the left side system only has 1 extra spider and the spider interface added to one arm. That can't weigh more than 80 grams so what I'm saying is I'd take the 80ish gram penalty to run a left side timing chain and not have to compromise geometry or risk any of the mechanical issues mentioned above.
P.S. I dropped $70 on alloy and Ti bolts today out of pocket so yes, this is a weight weenie build (but that's also my only out of pocket expense
). Gotta make up for the "heavy" 25mm Conti 4 Seasons. I'm used to 23mm Grand Prixs on my single bike. We want to use SPD mountain cleats so I'm trying to get the Xpedo M-Force 8Ti pedals (215g/pr) but they're out of stock. Hopefully they'll be ready by the time my chainstay tubing arrives so I don't have to settle for their 230g model.
P.P.S. It's a shame Gates won't make a shorter timing belt. The belt is 250g lighter than a chain but the rings are 100g each and hang so far down. If I was running a chain I'd use 34t rings that weigh 40g and have much better clearance. I'd also save some weight running compact spiders instead of standard. I looked into it and the Gates timing belt is made from an existing much wider industrial belt that they cut into narrower strips and then cut the center track in. Apparently they don't have a suitable shorter belt to do the same thing with and don't want to dedicate the production capacity to making a perfect size tandem timing belt that they'll sell a couple hundred of a year. So the Gates setup ends up being lighter but only by about 120g when it could be 250g lighter and not touch the ground when the front wheel is off.
P.S. I dropped $70 on alloy and Ti bolts today out of pocket so yes, this is a weight weenie build (but that's also my only out of pocket expense
). Gotta make up for the "heavy" 25mm Conti 4 Seasons. I'm used to 23mm Grand Prixs on my single bike. We want to use SPD mountain cleats so I'm trying to get the Xpedo M-Force 8Ti pedals (215g/pr) but they're out of stock. Hopefully they'll be ready by the time my chainstay tubing arrives so I don't have to settle for their 230g model.P.P.S. It's a shame Gates won't make a shorter timing belt. The belt is 250g lighter than a chain but the rings are 100g each and hang so far down. If I was running a chain I'd use 34t rings that weigh 40g and have much better clearance. I'd also save some weight running compact spiders instead of standard. I looked into it and the Gates timing belt is made from an existing much wider industrial belt that they cut into narrower strips and then cut the center track in. Apparently they don't have a suitable shorter belt to do the same thing with and don't want to dedicate the production capacity to making a perfect size tandem timing belt that they'll sell a couple hundred of a year. So the Gates setup ends up being lighter but only by about 120g when it could be 250g lighter and not touch the ground when the front wheel is off.
Last edited by LelandJT; 11-20-14 at 09:38 PM.
11-21-14, 10:34 AM
#42
Senior Member
Just for the sake of curiosity what bolts are you replacing and how much weight are you going to save? $70 does not buy very many Ti bolts.
Also what chain weight did you use in your calculations? When I converted from chain drive to the Gates belt the total weight reduction was 232 grams. I was using an 8 speed timing chain that weighed 426 grams, the new Gates belt weighed 108 grams.
Also what chain weight did you use in your calculations? When I converted from chain drive to the Gates belt the total weight reduction was 232 grams. I was using an 8 speed timing chain that weighed 426 grams, the new Gates belt weighed 108 grams.
11-21-14, 05:40 PM
#43
Clipless in Coeur d'Alene
P.S. I dropped $70 on alloy and Ti bolts today out of pocket so yes, this is a weight weenie build (but that's also my only out of pocket expense). Gotta make up for the "heavy" 25mm Conti 4 Seasons. I'm used to 23mm Grand Prixs on my single bike. We want to use SPD mountain cleats so I'm trying to get the Xpedo M-Force 8Ti pedals (215g/pr) but they're out of stock. Hopefully they'll be ready by the time my chainstay tubing arrives so I don't have to settle for their 230g model.
). Gotta make up for the "heavy" 25mm Conti 4 Seasons. I'm used to 23mm Grand Prixs on my single bike. We want to use SPD mountain cleats so I'm trying to get the Xpedo M-Force 8Ti pedals (215g/pr) but they're out of stock. Hopefully they'll be ready by the time my chainstay tubing arrives so I don't have to settle for their 230g model.Although I use super stiff carbon soled shoes, I still prefer a pedal system with more platform IRL. For weight weenies I suppose that wouldn't matter.
11-21-14, 10:30 PM
#44
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Just for the sake of curiosity what bolts are you replacing and how much weight are you going to save? $70 does not buy very many Ti bolts.
Also what chain weight did you use in your calculations? When I converted from chain drive to the Gates belt the total weight reduction was 232 grams. I was using an 8 speed timing chain that weighed 426 grams, the new Gates belt weighed 108 grams.
Also what chain weight did you use in your calculations? When I converted from chain drive to the Gates belt the total weight reduction was 232 grams. I was using an 8 speed timing chain that weighed 426 grams, the new Gates belt weighed 108 grams.
I weighed a 9spd KMC non-SL chain cut to fit 40t rings but if I were to use a chain it would be a KMC X9SL with 34t rings on compact spiders so I figured all that into my rough "calculations". The end result is Gates is lighter but not as light as it could be and there's times when the large rings are a hassle.
Last edited by LelandJT; 11-21-14 at 10:41 PM.
11-21-14, 10:34 PM
#45
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Is this them? Amazon.com : XPEDO Mountain Force XMF08TT M-FORCE 8 Clipless Pedals MTB Bike TI Spindle : Sports & Outdoors
Although I use super stiff carbon soled shoes, I still prefer a pedal system with more platform IRL. For weight weenies I suppose that wouldn't matter.
Although I use super stiff carbon soled shoes, I still prefer a pedal system with more platform IRL. For weight weenies I suppose that wouldn't matter.
Last edited by LelandJT; 11-22-14 at 09:05 AM.
11-21-14, 11:06 PM
#46
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I dont understand the clearance issue with the larger gates rings. Unless you are dropping off of curbs how do you hit them? Even on our mountain tandems we seldom hit the timing rings and we go off some rather crazy drops.
11-22-14, 08:43 AM
#47
Clipless in Coeur d'Alene
Leland,
A couple comments:
SPD
I only indicated a preference for other pedals than those Xpedo spindles that have more platform, no suggestion to go with non-SPD. Even a XTR would qualify, but yes, not as super light as the Xpedo.
Gates
There are other considerations to ring sizing than simply making those smaller. You would need to understand how point load and tension would be effected and that smaller rings (chain or belt) can significantly increase those criteria. Tandem timing belts are a bit different than singles, where tandems have to deal 2 riders torquing on the cranks plus the possibility of a little frame flex. My guess is that if Gates reduced the timing ring size as small as you would prefer, the belt tension needed would be very high to compensate.
A couple comments:
SPD
I only indicated a preference for other pedals than those Xpedo spindles that have more platform, no suggestion to go with non-SPD. Even a XTR would qualify, but yes, not as super light as the Xpedo.
Gates
There are other considerations to ring sizing than simply making those smaller. You would need to understand how point load and tension would be effected and that smaller rings (chain or belt) can significantly increase those criteria. Tandem timing belts are a bit different than singles, where tandems have to deal 2 riders torquing on the cranks plus the possibility of a little frame flex. My guess is that if Gates reduced the timing ring size as small as you would prefer, the belt tension needed would be very high to compensate.
11-22-14, 08:58 AM
#48
Senior Member
Is the final weight going to include the cages and the pedals? If so you are leaving 130 grams on the table by not looking at the Bebop pedals, at 150 grams per pair you cannot get much lughter. They are fully compatible with mountain bike shoes. You could always carry a pair of SPD pedals with you for other people to demo the bike.
We have thousands of miles on Bebop pedals and the smallish platform is not an issue for us.
My guess is that Gates looked at the typical 130mm BCD for the timing side tandem drive and developed rings to fit the typical setup. In addition if they had a belt that was the proper length all they had to do was to design the rings.
We have thousands of miles on Bebop pedals and the smallish platform is not an issue for us.
My guess is that Gates looked at the typical 130mm BCD for the timing side tandem drive and developed rings to fit the typical setup. In addition if they had a belt that was the proper length all they had to do was to design the rings.
11-22-14, 09:06 AM
#49
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When walking the bike or when the front wheel is off.
11-22-14, 09:32 AM
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you might look at tandem geek's blog as he did quite a bit of testing on small diameter timing belt rings as his Calfee has an extended stoker compartment and the standard rings would not work.