Tandems do not climb poorly
10-12-22, 05:07 PM
#1
pan y agua
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Tandems do not climb poorly
I hear this so often, it’s time to debunk this myth. While some tandem teams don’t climb fast, nothing inherent in a tandem dictates that result. A quality tandem, with two riders experienced in riding tandems together is not significantly slower climbing than a single rider with the same power to weight ratio.
I’ll address the arguments often given ffor why a tandem would be slower climbing.
First, weight. Our Calfee Dragonfly tandem weighs 24 pounds, or almost 6 pounds below the weight of two single bikes at the UCI weight limit. There is no reason a tandem has to be heavier than two singles. And given the tandem only needs one of many parts ( fork, cassette, 2 as opposed to 4 wheels, tires) a tandem of equal quality is often lighter than 2 singles. Even a mid range tandem, such as a Canondale, will be as light or lighter than two similar singles.
Second, Flex. A high quality tandem can be made as stiff as is productive, particularly with carbon fiber. If our Calfee was any stiffer it would be counterproductive.
Third, coordinating effort, standing. Admittedly, to get the most out of a tandem you need to work as a team. However doing so, including standing while climbing is simply a matter of a bit of practice.
Fourth, drive train loss. The drivetrain loss for the stoker is the same as a single bike. There is a slightly higher loss for the Captain, but the percentage is so small, it’s less than dirty chain and doesn’t make a significant difference, and is likely less than the the small aerodynamic advantage that remains even at slower climbing speeds.
Fifth, rolling resistance. I’ll admit I don’t have any data for this, but pretty certain the rolling resistance on a tandem with 2 tires is no greater, and likely less than the rolling resistance of two riders on 4 tires. Additionally, rolling resistance is lower at lower speed of climbing. Given that tandems are observably faster on the flats, any difference in rolling resitance between a tandem and two singles would not predict a slower climbing speed for the tandem for a given power output.
So why do tandems seem slow climbing? It’s not because they are slower climbing, it’s because they are faster on the flats. On flat ground aerodynamic resistance is more important than weight. Thus a tandem with only about one and a third the wind resistance of a single bike, but the power of two riders can be quite fast.
Thus a team with a combined power to weight ratio, lower than that ratio for a single rider can keep up with and even drop a stronger single rider on flat ground. However when they begin climbing the aerodynamic advantage of the tandem largely disappears, and the tandem team with the lower power to weight ratio will get caught and dropped by the stronger single rider.
So tandems aren’t slower climbing for a given power to weight ratio. It’s simply the loss of the speed advantage they have on the flats that make them appear so.
I’ll address the arguments often given ffor why a tandem would be slower climbing.
First, weight. Our Calfee Dragonfly tandem weighs 24 pounds, or almost 6 pounds below the weight of two single bikes at the UCI weight limit. There is no reason a tandem has to be heavier than two singles. And given the tandem only needs one of many parts ( fork, cassette, 2 as opposed to 4 wheels, tires) a tandem of equal quality is often lighter than 2 singles. Even a mid range tandem, such as a Canondale, will be as light or lighter than two similar singles.
Second, Flex. A high quality tandem can be made as stiff as is productive, particularly with carbon fiber. If our Calfee was any stiffer it would be counterproductive.
Third, coordinating effort, standing. Admittedly, to get the most out of a tandem you need to work as a team. However doing so, including standing while climbing is simply a matter of a bit of practice.
Fourth, drive train loss. The drivetrain loss for the stoker is the same as a single bike. There is a slightly higher loss for the Captain, but the percentage is so small, it’s less than dirty chain and doesn’t make a significant difference, and is likely less than the the small aerodynamic advantage that remains even at slower climbing speeds.
Fifth, rolling resistance. I’ll admit I don’t have any data for this, but pretty certain the rolling resistance on a tandem with 2 tires is no greater, and likely less than the rolling resistance of two riders on 4 tires. Additionally, rolling resistance is lower at lower speed of climbing. Given that tandems are observably faster on the flats, any difference in rolling resitance between a tandem and two singles would not predict a slower climbing speed for the tandem for a given power output.
So why do tandems seem slow climbing? It’s not because they are slower climbing, it’s because they are faster on the flats. On flat ground aerodynamic resistance is more important than weight. Thus a tandem with only about one and a third the wind resistance of a single bike, but the power of two riders can be quite fast.
Thus a team with a combined power to weight ratio, lower than that ratio for a single rider can keep up with and even drop a stronger single rider on flat ground. However when they begin climbing the aerodynamic advantage of the tandem largely disappears, and the tandem team with the lower power to weight ratio will get caught and dropped by the stronger single rider.
So tandems aren’t slower climbing for a given power to weight ratio. It’s simply the loss of the speed advantage they have on the flats that make them appear so.
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10-12-22, 05:09 PM
#2
pan y agua
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You can demonstrate the above with an online bike power speed calculator such as Bicycle Speed (Velocity) And Power Calculator, which can calculate for tandems as well as singles.
Take the case of 3 equally strong riders, two on a tandem, and one on a single. All at 160 watts and and 157 pounds. The tandem and the single climb at virtually the same speed up an 8% grade.. If you make the tandem 5 pounds lighter than the combined weight of 2 singles( such as for our Calfee) the tandem is actually faster.
For this example the Tandem is almost 5mph faster on the flats. So the faster tandem appears to not climb well, when all that has happened is that it lost the advantage it had on the flats and is now only equal in climbing.
Second case 2 tandem riders producing 140 watts each, and one single producing 220watts. All weighing 157 pounds On the flats, the weaker tandem team is still more than one mph faster than the stronger single. But when they hit the 8% grade, the stronger single is now 2 and half mph faster, more than 50%
in the second case the tandem team gets dropped by the stronger single, not because the tandem climbs slowly, but because they are weaker, i.e. lower power to weight ratio, or w/kg, a fact that only gets exposed when both bikes begin climbing.
Take the case of 3 equally strong riders, two on a tandem, and one on a single. All at 160 watts and and 157 pounds. The tandem and the single climb at virtually the same speed up an 8% grade.. If you make the tandem 5 pounds lighter than the combined weight of 2 singles( such as for our Calfee) the tandem is actually faster.
For this example the Tandem is almost 5mph faster on the flats. So the faster tandem appears to not climb well, when all that has happened is that it lost the advantage it had on the flats and is now only equal in climbing.
Second case 2 tandem riders producing 140 watts each, and one single producing 220watts. All weighing 157 pounds On the flats, the weaker tandem team is still more than one mph faster than the stronger single. But when they hit the 8% grade, the stronger single is now 2 and half mph faster, more than 50%
in the second case the tandem team gets dropped by the stronger single, not because the tandem climbs slowly, but because they are weaker, i.e. lower power to weight ratio, or w/kg, a fact that only gets exposed when both bikes begin climbing.
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10-12-22, 09:23 PM
#3
Junior Member
I agree if we put our tandem on a trainer and ride up a hill on zwift with our combined weight or something like that we'd be quicker.
10-13-22, 09:10 AM
#4
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Oh, the OP is absolutely correct. However . . . the real reason that tandems have a rep for being slow climbers is that the vast majority of tandem teams are the result of the stoker being a much slower rider than the captain. The couple got sick of not being able to have fun riding together and bought a tandem resulting in an improved relationship. That's all there is to it, and good on us and all those who've done the same. We rode RAMROD on ours when we were 135. Yeah, we were slow, but we made in under the time limit and got our matching jerseys. Yeah! As the OP says, on the flat we keep up with the singles or even pull, but on the climbs we're off the back, though we often get them back.
I have data from a tandem team, friends of ours. They used to ride singles together. She's a very good rider, but he is really strong, so on a pass climb his HR would be 110 and hers 145. So they bought a tandem. On the tandem, their HRs are about the same and they both get a good workout. She's actually the more aggressive rider.
I have data from a tandem team, friends of ours. They used to ride singles together. She's a very good rider, but he is really strong, so on a pass climb his HR would be 110 and hers 145. So they bought a tandem. On the tandem, their HRs are about the same and they both get a good workout. She's actually the more aggressive rider.
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10-13-22, 09:12 AM
#5
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Power around a pedal stroke is never constant and differs for each rider, this is one of the reasons small amount of crank offset are used by teams for improved comfort and power. Unfortunately none of the power modelling software has the ability to account for this. So Power(Team) is < Power(Captain) + Power(Stoker). I suspect this issue is more pronounced at lower cadences, such as used for climbing.
A well-matched, well-coordinated team can minimize these effects, but they never disappear. The aero advantage of the tandem overrides and masks these effects, but climbing reveals them.
10-13-22, 09:25 AM
#6
pan y agua
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This is definitely the reason we ride slower uphill. When standing it takes a lot of effort to keep the bike steady and not throw the bike side to side like we do on our singles. That effort to keep the bike steady reduces the effort on the pedals. What generally happens is we don't stand and instead stay seated riding an easier gear than we would on our singles standing. When we do stand on the tandem it's usually up a short hill.
I agree if we put our tandem on a trainer and ride up a hill on zwift with our combined weight or something like that we'd be quicker.
I agree if we put our tandem on a trainer and ride up a hill on zwift with our combined weight or something like that we'd be quicker.
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You could fall off a cliff and die.
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You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
Last edited by merlinextraligh; 10-13-22 at 09:38 AM. Reason: Typo
10-13-22, 09:35 AM
#7
pan y agua
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I think there is a bit more to the combined power and biomechanics of two riders than you've discussed.
Power around a pedal stroke is never constant and differs for each rider, this is one of the reasons small amount of crank offset are used by teams for improved comfort and power. Unfortunately none of the power modelling software has the ability to account for this. So Power(Team) is < Power(Captain) + Power(Stoker). I suspect this issue is more pronounced at lower cadences, such as used for climbing.
A well-matched, well-coordinated team can minimize these effects, but they never disappear. The aero advantage of the tandem overrides and masks these effects, but climbing reveals them.
Power around a pedal stroke is never constant and differs for each rider, this is one of the reasons small amount of crank offset are used by teams for improved comfort and power. Unfortunately none of the power modelling software has the ability to account for this. So Power(Team) is < Power(Captain) + Power(Stoker). I suspect this issue is more pronounced at lower cadences, such as used for climbing.
A well-matched, well-coordinated team can minimize these effects, but they never disappear. The aero advantage of the tandem overrides and masks these effects, but climbing reveals them.
For us, our climbing on the tandem is very consistent with what our individual w/kg would predict.
Breaking the rule of never publicly disclosing your ftp, for us, in race shape my ftp is right at 4 w/kg, my wife’s is 2.3 w/kg Because I weigh more than she does, our team w/kg is slightly higher than simple average at 3.3 w/kg.
In the real world, this translates to me me climbing faster on my single bike than her, and me being slower on the tandem, but her being faster on the tandem than on her single, and all 3 climbing rates being pretty much what Kruezotter would predict.
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You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
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10-13-22, 03:14 PM
#8
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One of the wonderful things about the tandem is that we are touching each other the whole time. Remotely of course, but we feel every little thing the other person does - unless of course we are synched up, in which case it feels like I'm pedaling my single, no difference except that it always feels like we're climbing a little, even on the flat. Something to do with crank inertial load I think. And no wonder you were faster than we were in Bellingham..
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10-15-22, 12:50 PM
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Oh, the OP is absolutely correct. However . . . the real reason that tandems have a rep for being slow climbers is that the vast majority of tandem teams are the result of the stoker being a much slower rider than the captain. The couple got sick of not being able to have fun riding together and bought a tandem resulting in an improved relationship. That's all there is to it, and good on us and all those who've done the same. We rode RAMROD on ours when we were 135. Yeah, we were slow, but we made in under the time limit and got our matching jerseys. Yeah! As the OP says, on the flat we keep up with the singles or even pull, but on the climbs we're off the back, though we often get them back.
I have data from a tandem team, friends of ours. They used to ride singles together. She's a very good rider, but he is really strong, so on a pass climb his HR would be 110 and hers 145. So they bought a tandem. On the tandem, their HRs are about the same and they both get a good workout. She's actually the more aggressive rider.
I have data from a tandem team, friends of ours. They used to ride singles together. She's a very good rider, but he is really strong, so on a pass climb his HR would be 110 and hers 145. So they bought a tandem. On the tandem, their HRs are about the same and they both get a good workout. She's actually the more aggressive rider.
10-15-22, 03:14 PM
#10
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And that's the reason that I prefer to ride the tandem outdoors. It makes me stronger, and makes my wife stronger, too. Our lowest gear is 26 X 40.
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10-16-22, 08:49 PM
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The drivetrain arguments are slightly different, but the same is true of recumbents on hills vs flats when compared to upright singles. In that case there is often a weight penalty, but the change in aero benefit at higher speeds vs not mattering as much on slower hills is what makes the difference.
10-23-22, 11:45 AM
#12
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IMO, teams need to assess and compare what their solo bike abilities would be before blaming a tandem, and then the quality of the tandem and it's overall performance characteristics along with team riding efficiency and technical ability. There is also a compounding effect, where one weak link (a bad rider day, or poorly tuned bike) will be somewhat exasperated on the tandem. If memory serves me correctly, my impression was that a low quality tandem will feel just about 2x as bad as a low quality single especially when climbing.
FWIW, our Calfee Dragonfly w/couplers isn't anywhere near as lightweight a build as Merlin's, but we still enjoy the benefits of a very efficient machine. There are also days when I need to tell my stoker to settle down and back off a bit and plenty of short climbs where she punches it nicely. Then other days where it seems there is a trailer back there. Realistic expectations is key and a lot more going on with tandem riding than single, but it's the only way we can ride together and enjoy the experience.
FWIW, our Calfee Dragonfly w/couplers isn't anywhere near as lightweight a build as Merlin's, but we still enjoy the benefits of a very efficient machine. There are also days when I need to tell my stoker to settle down and back off a bit and plenty of short climbs where she punches it nicely. Then other days where it seems there is a trailer back there. Realistic expectations is key and a lot more going on with tandem riding than single, but it's the only way we can ride together and enjoy the experience.
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10-29-22, 09:05 PM
#13
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It's interesting -- I'm 63 and my wife is 69. We got our T900 tandem about 11 years ago for our 20th wedding anniversary. Neither of us was ever a dedicated rider before we got the bike -- but we both liked the idea of doing something as a team and getting some solid exercise out of it. I don't think the T900 is a particularly light bike but we do pretty well on it. I saw a comment on here the other day that you'll usually have your middle chain ring wear faster because you use it more -- not us; we are 100% on the large chain ring and have been for a couple of years. This year, we got strong enough that I'm sometimes surprised that I find us in the top gear when we're cruising along on our daily rides. I've kind of been wondering if I could upgrade the chain rings so our current big one is the smallest of the three...
We don't really kill ourselves to go fast and generally sit most of the time. I'll occasionally stand to get us moving when passing someone on the paved bike trail or when a car stops to let us cross a street so I can get us out of their way faster. My wife prefers to sit, which is fine.
We used to joke about getting passed by other solo bikes all the time, but lately we've been doing quite a bit of passing (even on hills) even though we're not competitive about it -- of course the serious racing bikes blow past us like we're standing still! It's been a great year so far and I'm fortunate that my job (remote/home office since 1985) allows me to take time in the early morning (spring/summer) or afternoon (autumn) for us to take the bike out for a 15-20 mile ride. So far this year we've logged over 1200 miles (probably low compared to a lot of you!)
We don't really kill ourselves to go fast and generally sit most of the time. I'll occasionally stand to get us moving when passing someone on the paved bike trail or when a car stops to let us cross a street so I can get us out of their way faster. My wife prefers to sit, which is fine.
We used to joke about getting passed by other solo bikes all the time, but lately we've been doing quite a bit of passing (even on hills) even though we're not competitive about it -- of course the serious racing bikes blow past us like we're standing still! It's been a great year so far and I'm fortunate that my job (remote/home office since 1985) allows me to take time in the early morning (spring/summer) or afternoon (autumn) for us to take the bike out for a 15-20 mile ride. So far this year we've logged over 1200 miles (probably low compared to a lot of you!)
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11-01-22, 08:27 AM
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Good thread Merlin - interesting. We have a lot of data riding and racing the tandem. And we each have power on the tandem. If climbing were only a matter of metrics then I think that power to weight is the determining factor. I think there are a lot of variables when a team climbs a longer grade on the tandem. Motivation and how fatigue changes for each rider over the course of the climb matters.
On a single bike, one can change cadence to fit the feelings in ones legs, sit stand, wiggle around and do whatever we do to relieve muscle stress. On the tandem, a change in cadence has to feel right for both team members - and it may or may not.
And the shape of the power curves may be completely different for each rider and not all FTP is created equal. Being able to actually put out power for one hour is the gold standard but many times FTP is tested for a shorter period of time and then discounted. One team member may be really good for the last 15 minutes of an hour block and the other falls apart at 30 minutes into an hour climb and becomes a drag on the team. Without power metrics, the tandem gets the blame for poor climbing.
I also think teams can fight each other vis a vis pedal stroke. According to my coach, I have an excellent smooth pedal stroke and my wife pedals like there is an explosion with each downstroke. She just set a UCI masters hour record in Mexico so I think her pedal stroke is pretty efficient. But it begs the question how it matches up with mine. Do we fight each other? It is like two dancers kicking each other in the shins. We run the pedals out of phase and I can match up with her style and still keep mine smooth. Although, we have to practice on the tandem. And we can stand together or individually without a problem.
I think that a reasonably practiced team should climb well on a tandem and it should be a function of combined power to weight and should be the same as a single bike with the same power to weight ratio.
On a single bike, one can change cadence to fit the feelings in ones legs, sit stand, wiggle around and do whatever we do to relieve muscle stress. On the tandem, a change in cadence has to feel right for both team members - and it may or may not.
And the shape of the power curves may be completely different for each rider and not all FTP is created equal. Being able to actually put out power for one hour is the gold standard but many times FTP is tested for a shorter period of time and then discounted. One team member may be really good for the last 15 minutes of an hour block and the other falls apart at 30 minutes into an hour climb and becomes a drag on the team. Without power metrics, the tandem gets the blame for poor climbing.
I also think teams can fight each other vis a vis pedal stroke. According to my coach, I have an excellent smooth pedal stroke and my wife pedals like there is an explosion with each downstroke. She just set a UCI masters hour record in Mexico so I think her pedal stroke is pretty efficient. But it begs the question how it matches up with mine. Do we fight each other? It is like two dancers kicking each other in the shins. We run the pedals out of phase and I can match up with her style and still keep mine smooth. Although, we have to practice on the tandem. And we can stand together or individually without a problem.
I think that a reasonably practiced team should climb well on a tandem and it should be a function of combined power to weight and should be the same as a single bike with the same power to weight ratio.
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11-01-22, 08:48 AM
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My wife and I used to ride a tandem together.
I have enjoyed riding with a husband and wife team on some brevets, they are very fast and climb well. I think they always finish first at PBP for the mixed team. The first time riding on a 400k, we did it in around 13 hours which is fast because you have to stop at controls and have to stop to get food. It was apparent that the stoker was the engine, not that the captain wasn't real strong too. How they would both just naturally get out of the saddle to dance was fun to watch really. I mentioned to the captain that he is a good athlete but the stoker is nuclear powered. Her aunt won the gold medal for the marathon, so, it isn't always a weak stoker although in my case, my wife is weak.
One small detail about tires. Crr is not fixed. The "constant" increases with load and speed. Some tires are better than others. This phenomenon is important for heavy fast vehicles like racing velomobiles. This was studied fairly well by some German velomobile racers. Based on the weight and speed attainable by a strong tandem team, I should think tire selection is much more important than on a single. I tried to analyse on my racing recumbent where I can hold 30-35 mph for quite a long time but Crr measurement is not as easy as CdA. And, I did not succeed in my tests.
I have enjoyed riding with a husband and wife team on some brevets, they are very fast and climb well. I think they always finish first at PBP for the mixed team. The first time riding on a 400k, we did it in around 13 hours which is fast because you have to stop at controls and have to stop to get food. It was apparent that the stoker was the engine, not that the captain wasn't real strong too. How they would both just naturally get out of the saddle to dance was fun to watch really. I mentioned to the captain that he is a good athlete but the stoker is nuclear powered. Her aunt won the gold medal for the marathon, so, it isn't always a weak stoker although in my case, my wife is weak.
One small detail about tires. Crr is not fixed. The "constant" increases with load and speed. Some tires are better than others. This phenomenon is important for heavy fast vehicles like racing velomobiles. This was studied fairly well by some German velomobile racers. Based on the weight and speed attainable by a strong tandem team, I should think tire selection is much more important than on a single. I tried to analyse on my racing recumbent where I can hold 30-35 mph for quite a long time but Crr measurement is not as easy as CdA. And, I did not succeed in my tests.
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11-04-22, 11:03 AM
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Good thread Merlin - interesting. We have a lot of data riding and racing the tandem. And we each have power on the tandem. If climbing were only a matter of metrics then I think that power to weight is the determining factor. I think there are a lot of variables when a team climbs a longer grade on the tandem. Motivation and how fatigue changes for each rider over the course of the climb matters.
On a single bike, one can change cadence to fit the feelings in ones legs, sit stand, wiggle around and do whatever we do to relieve muscle stress. On the tandem, a change in cadence has to feel right for both team members - and it may or may not.
And the shape of the power curves may be completely different for each rider and not all FTP is created equal. Being able to actually put out power for one hour is the gold standard but many times FTP is tested for a shorter period of time and then discounted. One team member may be really good for the last 15 minutes of an hour block and the other falls apart at 30 minutes into an hour climb and becomes a drag on the team. Without power metrics, the tandem gets the blame for poor climbing.
I also think teams can fight each other vis a vis pedal stroke. According to my coach, I have an excellent smooth pedal stroke and my wife pedals like there is an explosion with each downstroke. She just set a UCI masters hour record in Mexico so I think her pedal stroke is pretty efficient. But it begs the question how it matches up with mine. Do we fight each other? It is like two dancers kicking each other in the shins. We run the pedals out of phase and I can match up with her style and still keep mine smooth. Although, we have to practice on the tandem. And we can stand together or individually without a problem.
I think that a reasonably practiced team should climb well on a tandem and it should be a function of combined power to weight and should be the same as a single bike with the same power to weight ratio.
On a single bike, one can change cadence to fit the feelings in ones legs, sit stand, wiggle around and do whatever we do to relieve muscle stress. On the tandem, a change in cadence has to feel right for both team members - and it may or may not.
And the shape of the power curves may be completely different for each rider and not all FTP is created equal. Being able to actually put out power for one hour is the gold standard but many times FTP is tested for a shorter period of time and then discounted. One team member may be really good for the last 15 minutes of an hour block and the other falls apart at 30 minutes into an hour climb and becomes a drag on the team. Without power metrics, the tandem gets the blame for poor climbing.
I also think teams can fight each other vis a vis pedal stroke. According to my coach, I have an excellent smooth pedal stroke and my wife pedals like there is an explosion with each downstroke. She just set a UCI masters hour record in Mexico so I think her pedal stroke is pretty efficient. But it begs the question how it matches up with mine. Do we fight each other? It is like two dancers kicking each other in the shins. We run the pedals out of phase and I can match up with her style and still keep mine smooth. Although, we have to practice on the tandem. And we can stand together or individually without a problem.
I think that a reasonably practiced team should climb well on a tandem and it should be a function of combined power to weight and should be the same as a single bike with the same power to weight ratio.
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11-04-22, 06:14 PM
#17
Senior Member
Your tandem only weighs 24lbs? Holly crap!
We have a very old Trek T50 and I would guess twice that. The Mrs. is not a dedicated cyclist, heck she doesn't even read BikeForum! So we mainly ride the local trails which are flat, flat, flat.
Every once in a while, I throw out, " maybe we should......" but she likes the old one. And on hills we are slow as heck. The only factor in our advantage is that the both of weigh about 250 pounds...combined.
Really? 24 pounds?
We have a very old Trek T50 and I would guess twice that. The Mrs. is not a dedicated cyclist, heck she doesn't even read BikeForum! So we mainly ride the local trails which are flat, flat, flat.
Every once in a while, I throw out, " maybe we should......" but she likes the old one. And on hills we are slow as heck. The only factor in our advantage is that the both of weigh about 250 pounds...combined.
Really? 24 pounds?
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