Go Back  Bike Forums > Bike Forums > Tandem Cycling
Reload this Page >

Different Spin Rates Causing Problem

Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

Different Spin Rates Causing Problem

Reply

Old 07-10-18, 03:06 PM
  #26  
noglider 
aka Tom Reingold
 
noglider's Avatar
 
Join Date: Jan 2009
Location: West Village, New York City
Posts: 34,207

Bikes: 1962 Rudge Sports, 1971 Raleigh Super Course, 1971 Raleigh Pro Track, 1973 Raleigh Twenty, 1974 Raleigh International, 1975 Viscount Fixie, 1982 McLean, 1996 Lemond (Ti), 2002 Burley Zydeco tandem

Mentioned: 321 Post(s)
Tagged: 0 Thread(s)
Quoted: 3866 Post(s)
It's about compromise. The tandem, used well, evens out your different abilities. It's Marxism in action. From each, according to his/her abilities.
__________________
Tom Reingold, [email protected]
New York City and High Falls, NY
Blogs: The Experienced Cyclist; noglider's ride blog

“When man invented the bicycle he reached the peak of his attainments.” — Elizabeth West, US author

Please email me rather than PM'ing me. Thanks.
noglider is offline  
Reply With Quote
Old 07-10-18, 03:13 PM
  #27  
ksryder
Senior Member
 
Join Date: May 2014
Posts: 1,292

Bikes: yes

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 468 Post(s)
I have limited experience on tandems but I could swear reading some ad copy a few years back for a company that made tandems with some sort of independent drive setup that would let both stoker and captain spin at different rates. Can't for the life of me find it now.

So what's the verdict on that setup -- actually useful or does it have problems? Does it even exist or is it just something I dreamed of and thought it was real? That happens sometimes when I eat pepperoni too close to bedtime.
ksryder is offline  
Reply With Quote
Old 07-10-18, 03:23 PM
  #28  
noglider 
aka Tom Reingold
 
noglider's Avatar
 
Join Date: Jan 2009
Location: West Village, New York City
Posts: 34,207

Bikes: 1962 Rudge Sports, 1971 Raleigh Super Course, 1971 Raleigh Pro Track, 1973 Raleigh Twenty, 1974 Raleigh International, 1975 Viscount Fixie, 1982 McLean, 1996 Lemond (Ti), 2002 Burley Zydeco tandem

Mentioned: 321 Post(s)
Tagged: 0 Thread(s)
Quoted: 3866 Post(s)
Originally Posted by ksryder View Post
I have limited experience on tandems but I could swear reading some ad copy a few years back for a company that made tandems with some sort of independent drive setup that would let both stoker and captain spin at different rates. Can't for the life of me find it now.

So what's the verdict on that setup -- actually useful or does it have problems? Does it even exist or is it just something I dreamed of and thought it was real? That happens sometimes when I eat pepperoni too close to bedtime.
You can't have that system on a tandem with traditional geometry, because the cranks or feet would bump into each other. The Counterpoint design works, and my wife and I tried one. The captain is in the back and sits upright. The stoker is in front and is recumbent. Because the cranks are so far apart, they can go at different rates. The stoker's crank is attached to the drivetrain with a five-speed freewheel which provides more than enough difference from the captain's cadence. The stoker can also coast while the captain pedals.
__________________
Tom Reingold, [email protected]
New York City and High Falls, NY
Blogs: The Experienced Cyclist; noglider's ride blog

“When man invented the bicycle he reached the peak of his attainments.” — Elizabeth West, US author

Please email me rather than PM'ing me. Thanks.
noglider is offline  
Reply With Quote
Old 07-10-18, 08:53 PM
  #29  
jethro00
Senior Member
 
Join Date: Jun 2016
Posts: 64
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
That is the DaVinci line of tandems. We have one and like it. We can spin at different rates, though my stoker usually syncs with me. We rode non-DaVinci tandems for 30 or so years before getting the DaVinci, so we were used to spinning together. I like being able to stand up and stretch while she pedals and we both like that she can control her pedals to avoid hitting in a turn or going over something. We ride every day, but do not consider riding a major work out. Our heart rate monitor is manual (if we're both breathing we keep going) and we pedal at unknown rpms (somewhere between 1 and 100). I can't speak to how the DaVinci tandems perform for riders who have more challenging roads than what we have (all flat except up and down the river levee and a few bridges). We have experienced chain suck on occasion when going from the middle ring to the big ring. But, that is infrequent since I let the stoker know to stop pedaling before I switch.

Originally Posted by ksryder View Post
I have limited experience on tandems but I could swear reading some ad copy a few years back for a company that made tandems with some sort of independent drive setup that would let both stoker and captain spin at different rates. Can't for the life of me find it now.

So what's the verdict on that setup -- actually useful or does it have problems? Does it even exist or is it just something I dreamed of and thought it was real? That happens sometimes when I eat pepperoni too close to bedtime.
jethro00 is offline  
Reply With Quote
Old 07-10-18, 09:27 PM
  #30  
ksryder
Senior Member
 
Join Date: May 2014
Posts: 1,292

Bikes: yes

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 468 Post(s)
Originally Posted by jethro00 View Post
That is the DaVinci line of tandems. We have one and like it. We can spin at different rates, though my stoker usually syncs with me. We rode non-DaVinci tandems for 30 or so years before getting the DaVinci, so we were used to spinning together. I like being able to stand up and stretch while she pedals and we both like that she can control her pedals to avoid hitting in a turn or going over something. We ride every day, but do not consider riding a major work out. Our heart rate monitor is manual (if we're both breathing we keep going) and we pedal at unknown rpms (somewhere between 1 and 100). I can't speak to how the DaVinci tandems perform for riders who have more challenging roads than what we have (all flat except up and down the river levee and a few bridges). We have experienced chain suck on occasion when going from the middle ring to the big ring. But, that is infrequent since I let the stoker know to stop pedaling before I switch.
Ah yes that's what I was thinking. Curious.
ksryder is offline  
Reply With Quote
Old 07-11-18, 07:10 AM
  #31  
Mr IGH
afraid of whales
 
Mr IGH's Avatar
 
Join Date: Apr 2009
Location: Front Range, CO
Posts: 4,292
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 327 Post(s)
"Power struggle", LOL. I never intimated any such idea. It's just that I'm old school. I was raised to accommodate women and give them comfort. I am strong enough to adjust my cadence so that my stroker feels welcome to ride on my tandem. We can stay with the strongest teams in the club without too much effort. That's a big win in my book. Others have been raised differently and they struggle with this concept....

BTW, I didn't change cranks, the used Santana I bought came with 175/170 combo from the factory. Hmmmmmm, why does Santana do that. Can't imagine why.....
Mr IGH is offline  
Reply With Quote
Old 07-11-18, 08:28 AM
  #32  
ksryder
Senior Member
 
Join Date: May 2014
Posts: 1,292

Bikes: yes

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 468 Post(s)
Such virtue. Very wow.
ksryder is offline  
Reply With Quote
Old 07-11-18, 08:59 AM
  #33  
124Spider
Senior Member
Thread Starter
 
Join Date: Feb 2017
Location: Seattle, Washington, USA
Posts: 106

Bikes: 2016 Cervelo R3 2018 Rodriguez Tandem

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 39 Post(s)
Originally Posted by ksryder View Post
Such virtue. Very wow.
Yeah; so much smug in one little post!

Last edited by 124Spider; 07-11-18 at 07:27 PM.
124Spider is offline  
Reply With Quote
Old 07-11-18, 02:21 PM
  #34  
LV2TNDM
Senior Member
 
Join Date: Apr 2005
Location: Northern CA
Posts: 241

Bikes: Cannondale tandems: '92 Road, '97 Mtn. Mongoose 10.9 Ti, Kelly Deluxe, Tommaso Chorus, Cdale MT2000, Schwinn Deluxe Cruiser, Torker Unicycle, among others.

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 24 Post(s)
Originally Posted by Mr IGH View Post
"Power struggle", LOL. I never intimated any such idea. It's just that I'm old school. I was raised to accommodate women and give them comfort. I am strong enough to adjust my cadence so that my stroker feels welcome to ride on my tandem. We can stay with the strongest teams in the club without too much effort. That's a big win in my book. Others have been raised differently and they struggle with this concept....


BTW, I didn't change cranks, the used Santana I bought came with 175/170 combo from the factory. Hmmmmmm, why does Santana do that. Can't imagine why.....

Santana does this to accommodate different rider sizes, but doesn't address the cadence issue. If you can spend the rest of your tandeming tenure riding at a cadence rate well below (or above) ideal, then more power to you. But that probably isn't a solution for the majority of riders. I wouldn't expect my stoker to do so; I don't imagine she'd expect me to do same. This discussion aims to find an equitable solution for both parties. It has nothing to do with "being a man," chivalry or however else you want to define it.


Let me share a related story. My college roommate trained and raced for years riding 180mm cranks. In hindsight, it never felt quite right. In fact, well into his racing career, he suffered a somewhat unique injury. His quadricep tendon actually pulled a piece of bone off his femur at his knee. I'm not exactly sure this is what happened, but it's close. He recovered and continued training and racing. Many years later, he took advantage of a comprehensive bike fitting and discovered the crank lengths he was using were FAR shorter than they should be. His ideal crank length ended up being something like 197mm. Now, many might assume a 17mm difference in length isn't much. Well, I can tell you that it's a HUGE difference. I rode 170mm cranks briefly. I happened to be riding with a friend who has the same saddle-pedal distance I do. We switched bikes because he wanted me to feel how his rode. His bike had 175mm cranks and I could not believe how much longer they felt. It was like I was turning a circle twice the size of the one on my bike. All by a "mere" 5mm in crank length difference. So this friend of mine, after switching to 197mm cranks, rediscovered his love for riding and racing. It was like he had never ridden a bike properly. He said he felt so much better and that before he never realized how stifled his legs were in terms of strength, feel and fit. And shortly thereafter he realized his unique injury he suffered years earlier was almost certainly caused by training and racing hard on cranks WAY too short.


Well, asking a captain or stoker to simply accept a cadence rate above or below their ideal rate is kind of the same thing. If I were to embark on a long riding season of high mileage, but riding at 20 rpm lower than my ideal cadence, I'd be miserable and most likely suffer adverse knee effects. So achieving a sensible solution is far better than just "sucking it up" in my opinion. Especially given the expense many couples go to with full carbon tandems with carbon wheels and electronic shifting, sacrificing cadence seems like a completely unacceptable and untenable compromise.
LV2TNDM is offline  
Reply With Quote
Old 07-11-18, 03:03 PM
  #35  
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 34,395

Bikes: 8

Mentioned: 122 Post(s)
Tagged: 0 Thread(s)
Quoted: 4728 Post(s)
Yup, Davinci tandems do that daVinci Designs - Performance Handbuilt Tandem Bicycles | Independent Coasting Drivetrain .. Drivetrain Info - da Vinci Designs
fietsbob is offline  
Reply With Quote
Old 07-11-18, 05:13 PM
  #36  
LV2TNDM
Senior Member
 
Join Date: Apr 2005
Location: Northern CA
Posts: 241

Bikes: Cannondale tandems: '92 Road, '97 Mtn. Mongoose 10.9 Ti, Kelly Deluxe, Tommaso Chorus, Cdale MT2000, Schwinn Deluxe Cruiser, Torker Unicycle, among others.

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 24 Post(s)
Your link provides information about the independent coasting system (ICS), not gearing. Even though the Sheldon Brown website states or implies DaVinci and Bilenky offer tandems with independent gearing, I don't see it on their websites. Bilenky does offer their Viewpoint, but this is only one model, a semi-recumbent tandem whose technology isn't available on traditional tandems. I can only find independent coasting. If anyone can find a link showing otherwise, I'm all ears.

Last edited by LV2TNDM; 07-11-18 at 05:18 PM.
LV2TNDM is offline  
Reply With Quote
Old 07-11-18, 08:02 PM
  #37  
jethro00
Senior Member
 
Join Date: Jun 2016
Posts: 64
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
I am not 100% clear on what you are asking. On our DaVinci tandem, we can spin at different rates. Is that your question?

Originally Posted by LV2TNDM View Post
Your link provides information about the independent coasting system (ICS), not gearing. Even though the Sheldon Brown website states or implies DaVinci and Bilenky offer tandems with independent gearing, I don't see it on their websites. Bilenky does offer their Viewpoint, but this is only one model, a semi-recumbent tandem whose technology isn't available on traditional tandems. I can only find independent coasting. If anyone can find a link showing otherwise, I'm all ears.
jethro00 is offline  
Reply With Quote
Old 07-12-18, 07:13 AM
  #38  
Mr IGH
afraid of whales
 
Mr IGH's Avatar
 
Join Date: Apr 2009
Location: Front Range, CO
Posts: 4,292
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 327 Post(s)
Opps, sorry for the triggering! In any case the idea that a weaker-sex, significant other doesn't want the stronger-sex types to accommodate their lesser physical abilities is interesting. I'm a door-holding, chair pulling kinda guy and I always get compliments from from the women I date, "So refreshing to be with a gentleman." is a typical comment. I wouldn't captain a tandem any other way and it works very well. Perhaps some of the new-age metro-types could do a little learning instead of blindly following the dogma....

As for crank length, longer cranks require faster foot speed compared to a shorter cranks for a given rpm and that does help the cadence mis-match. Crank length calculations that resolve optimum crank length using only the rider's physical parameters are silly.
Mr IGH is offline  
Reply With Quote
Old 07-12-18, 07:48 AM
  #39  
ksryder
Senior Member
 
Join Date: May 2014
Posts: 1,292

Bikes: yes

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 468 Post(s)
Originally Posted by Mr IGH View Post
Opps, sorry for the triggering! In any case the idea that a weaker-sex, significant other doesn't want the stronger-sex types to accommodate their lesser physical abilities is interesting. I'm a door-holding, chair pulling kinda guy and I always get compliments from from the women I date, "So refreshing to be with a gentleman." is a typical comment. I wouldn't captain a tandem any other way and it works very well. Perhaps some of the new-age metro-types could do a little learning instead of blindly following the dogma....

As for crank length, longer cranks require faster foot speed compared to a shorter cranks for a given rpm and that does help the cadence mis-match. Crank length calculations that resolve optimum crank length using only the rider's physical parameters are silly.
Get over yourself, you're derailing a legitimate discussion with your completely bizarre argument that how a person rides a tandem somehow equates to chivalry.

*looks at some users post history*

Oh nevermind. Welcome to the ignore list.
ksryder is offline  
Reply With Quote
Old 07-12-18, 09:35 AM
  #40  
Leisesturm
Senior Member
 
Join Date: Jul 2005
Posts: 3,474
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 917 Post(s)
Originally Posted by 124Spider View Post
To clarify, this is not about a power struggle between captain and stoker (as I'm pretty sure I made clear earlier). It's about how best to deal with significant physical differences causing problems.

If I could painlessly (and effectively) pedal uphill at 75 rpm, and get us there, I'd do it in a heartbeat. Likewise, if my wife could pedal at 95 rpm, and put down power, she'd be happy to do it. We're not fighting; we're trying to solve a systemic problem!
Your problem is that you think there is a problem. Yeesh, look at this thread. I've rarely seen this level of hostility on the tandem forum. How did I manage to miss the fun for so long? But that's what happens when well meant individuals collectively try to make sense out of a non-issue. 1/3 power ... you know what they say about tandems? First thing me and mine did when we moved here was join a tandem club. ~50 teams, and rides every week between June and September. Over time we got friendly with three other teams and started to socialize independently of the main club. At the present time (4 yrs later) me and mine are the only team of the four still riding twogether. We haven't kept up with the greater club in 8 years but have heard that it is on hard times and may dissolve. Tandems aren't for every couple. They aren't even for most couples. It's not for me to say whether or not a tandem is the bike you and yours should be putting all this effort into learning to ride effectively but I can suggest that it does not bode well when either rider starts to question the power output of the other. Even after more than a decade of near daily riding I couldn't tell you exactly how much power my Stoker does or does not contribute. The difficulty experienced in climbing has not one whit to do with *power*. I'm pretty sure that has been told to you. If you used the exact same technique in climbing on your single as you must do when climbing on a tandem, the amount of time it takes to get to the top would be about the same. In addition, there are the undeniable intrinsics of being the Captain of a bicycle that masses many, many times what your single bike does. But none of that really matters. Me and mine tandem because we must. The other three teams we got friendly with, they could still ride single bikes separately. So can you two.
Leisesturm is online now  
Reply With Quote
Old 07-12-18, 09:39 AM
  #41  
Leisesturm
Senior Member
 
Join Date: Jul 2005
Posts: 3,474
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 917 Post(s)
Originally Posted by LV2TNDM View Post
Santana does this to accommodate different rider sizes, but doesn't address the cadence issue. If you can spend the rest of your tandeming tenure riding at a cadence rate well below (or above) ideal, then more power to you. But that probably isn't a solution for the majority of riders. I wouldn't expect my stoker to do so; I don't imagine she'd expect me to do same. This discussion aims to find an equitable solution for both parties. It has nothing to do with "being a man," chivalry or however else you want to define it.


Let me share a related story. My college roommate trained and raced for years riding 180mm cranks. In hindsight, it never felt quite right. In fact, well into his racing career, he suffered a somewhat unique injury. His quadricep tendon actually pulled a piece of bone off his femur at his knee. I'm not exactly sure this is what happened, but it's close. He recovered and continued training and racing. Many years later, he took advantage of a comprehensive bike fitting and discovered the crank lengths he was using were FAR shorter than they should be. His ideal crank length ended up being something like 197mm. Now, many might assume a 17mm difference in length isn't much. Well, I can tell you that it's a HUGE difference. I rode 170mm cranks briefly. I happened to be riding with a friend who has the same saddle-pedal distance I do. We switched bikes because he wanted me to feel how his rode. His bike had 175mm cranks and I could not believe how much longer they felt. It was like I was turning a circle twice the size of the one on my bike. All by a "mere" 5mm in crank length difference. So this friend of mine, after switching to 197mm cranks, rediscovered his love for riding and racing. It was like he had never ridden a bike properly. He said he felt so much better and that before he never realized how stifled his legs were in terms of strength, feel and fit. And shortly thereafter he realized his unique injury he suffered years earlier was almost certainly caused by training and racing hard on cranks WAY too short.


Well, asking a captain or stoker to simply accept a cadence rate above or below their ideal rate is kind of the same thing. If I were to embark on a long riding season of high mileage, but riding at 20 rpm lower than my ideal cadence, I'd be miserable and most likely suffer adverse knee effects. So achieving a sensible solution is far better than just "sucking it up" in my opinion. Especially given the expense many couples go to with full carbon tandems with carbon wheels and electronic shifting, sacrificing cadence seems like a completely unacceptable and untenable compromise.
If you are correct then millions ... no, billions of cyclists are using a crank length that is completely wrong for them and might in fact be injurious. Hmmm.
Leisesturm is online now  
Reply With Quote
Old 07-12-18, 09:48 AM
  #42  
Leisesturm
Senior Member
 
Join Date: Jul 2005
Posts: 3,474
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 917 Post(s)
Originally Posted by noglider View Post
You can't have that system on a tandem with traditional geometry, because the cranks or feet would bump into each other. The Counterpoint design works, and my wife and I tried one. The captain is in the back and sits upright. The stoker is in front and is recumbent. Because the cranks are so far apart, they can go at different rates. The stoker's crank is attached to the drivetrain with a five-speed freewheel which provides more than enough difference from the captain's cadence. The stoker can also coast while the captain pedals.
I think you have misread the other poster. Of course you can have IPS or ICS on 'traditional geometry' tandems. No foot bumping of any kind. IPS is exactly what all DaVinci tandems have, and when the IPS is offered as an option on other tandems. But there is no free lunch. On an IPS tandem the 'slower' cadence will not provide a proportionately reduced level of power to the drivetrain. The slower cadence will provide ZERO power to the drivetrain. But IPS sure is popular.
Leisesturm is online now  
Reply With Quote
Old 07-12-18, 10:11 AM
  #43  
jethro00
Senior Member
 
Join Date: Jun 2016
Posts: 64
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Is this true? If so, that means on all DaVinci tandems, if the stoker has a slower cadence, it makes no difference whatsoever whether the stoker is pedaling or coasting since there is no power gain from the stoker pedaling.

Originally Posted by Leisesturm View Post
I think you have misread the other poster. Of course you can have IPS or ICS on 'traditional geometry' tandems. No foot bumping of any kind. IPS is exactly what all DaVinci tandems have, and when the IPS is offered as an option on other tandems. But there is no free lunch. On an IPS tandem the 'slower' cadence will not provide a proportionately reduced level of power to the drivetrain. The slower cadence will provide ZERO power to the drivetrain. But IPS sure is popular.
jethro00 is offline  
Reply With Quote
Old 07-12-18, 10:32 AM
  #44  
79pmooney
A Roadie Forever
 
79pmooney's Avatar
 
Join Date: Oct 2014
Location: Portland, OR
Posts: 5,607

Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

Mentioned: 70 Post(s)
Tagged: 0 Thread(s)
Quoted: 1117 Post(s)
It sounds to me like the solution is a very stiff tandem with the timing chain running between say a 36 in front and a 48 in back. Very stiff because the forces will be changing from in sync to opposed and back. A flexible frame will change feel through every cycle, one "cycle" being 12 pedal strokes for the captain in the above example.. (The Counterpoint tandems with the reclined stoker in front of many years ago would work very well here.) I've seen tandems where the stoker has their own derailleur so this is not a new concept.

I am not a tandem rider, just an engineer and long time bike rider who has been fascinated by them as machines. And I " get" some to the tandem issues as I have ridden road fix gears many, many miles. I like to joke with the tandems at Cycle Oregon that I am a captain from the waist up, stoker from the waist down and my bike is a tandem front and stoker drive train. (And the stoker frequently curses the captain for his complete refusal to change gears or coast!)

Ben
79pmooney is offline  
Reply With Quote
Old 07-12-18, 10:33 AM
  #45  
124Spider
Senior Member
Thread Starter
 
Join Date: Feb 2017
Location: Seattle, Washington, USA
Posts: 106

Bikes: 2016 Cervelo R3 2018 Rodriguez Tandem

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 39 Post(s)
Originally Posted by ksryder View Post
Get over yourself, you're derailing a legitimate discussion with your completely bizarre argument that how a person rides a tandem somehow equates to chivalry.

*looks at some users post history*

Oh nevermind. Welcome to the ignore list.
Exactly!
124Spider is offline  
Reply With Quote
Old 07-12-18, 10:43 AM
  #46  
124Spider
Senior Member
Thread Starter
 
Join Date: Feb 2017
Location: Seattle, Washington, USA
Posts: 106

Bikes: 2016 Cervelo R3 2018 Rodriguez Tandem

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 39 Post(s)
Simple question: My wife is 5'4" tall, with proportional legs. She has a 175 crank on her single bike, and a 170 crank on the tandem.

Would replacing the 170 on the tandem, with something shorter, perhaps help her spin faster (and perhaps help with limiting body movement when pedaling fast)?
124Spider is offline  
Reply With Quote
Old 07-12-18, 11:13 AM
  #47  
Leisesturm
Senior Member
 
Join Date: Jul 2005
Posts: 3,474
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 917 Post(s)
Originally Posted by jethro00 View Post
Is this true? If so, that means on all DaVinci tandems, if the stoker has a slower cadence, it makes no difference whatsoever whether the stoker is pedaling or coasting since there is no power gain from the stoker pedaling.
Sad, but true. It's no different from when you switch to a lower gear that you need to spin faster to 'catch'. You either spin fast enough to engage the gear or maybe the bike slows to the speed at which your cadence is contributing power, or you just flail away. The tandem with IPS and a strong Captain never slows to the speed that the Stoker can 'catch'. However, some IPS systems allow the Stoker to change gears independently and a committed Stoker could select a gear that allows them to feel pedal resistance at any reasonable cadence.
Leisesturm is online now  
Reply With Quote
Old 07-12-18, 11:25 AM
  #48  
Leisesturm
Senior Member
 
Join Date: Jul 2005
Posts: 3,474
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 917 Post(s)
Originally Posted by 124Spider View Post
Simple question: My wife is 5'4" tall, with proportional legs. She has a 175 crank on her single bike, and a 170 crank on the tandem.

Would replacing the 170 on the tandem, with something shorter, perhaps help her spin faster (and perhaps help with limiting body movement when pedaling fast)?
IME spin is intrinsic. It can be modified with training and effort of will but it cannot be influenced by equipment. I 'spin' the same regardless of the length of crank I am using. A 5'4" woman is not exactly short. A womans legs are proportionately longer than a man of similar height. I know really tiny women that do as well as any man they ride with on standard size cranks. I don't think anyone really knows for sure what changing crank length actually does or does not do. Racers have winning as an incentive to use a rapid cadence and as high a gear as possible to win. Maintaining the set speed of the A, B, or C riding group on a club ride offers a different kind of incentive. And no, excessive body movement is completely independent of crank length and if anything says the gear is too high. Shortening the crank actually raises the gear because it reduces the torque the rider can apply. She might actually need a longer crank. There is that. FWIW.
Leisesturm is online now  
Reply With Quote
Old 07-12-18, 12:09 PM
  #49  
jethro00
Senior Member
 
Join Date: Jun 2016
Posts: 64
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
I ran this by da Vinci and received the following response:
"On our tandem, the person pedaling at a slower cadence is not contributing, nor are they robbing power from the other rider. On a traditional tandem, if one person does not keep up, the other rider is pulling there(sic) legs around and being robbed of power. Todd Shusterman"

Originally Posted by Leisesturm View Post
I think you have misread the other poster. Of course you can have IPS or ICS on 'traditional geometry' tandems. No foot bumping of any kind. IPS is exactly what all DaVinci tandems have, and when the IPS is offered as an option on other tandems. But there is no free lunch. On an IPS tandem the 'slower' cadence will not provide a proportionately reduced level of power to the drivetrain. The slower cadence will provide ZERO power to the drivetrain. But IPS sure is popular.
jethro00 is offline  
Reply With Quote
Old 07-12-18, 12:30 PM
  #50  
Hermes 
Version 3.0
 
Hermes's Avatar
 
Join Date: Oct 2006
Location: La Jolla, CA
Posts: 10,542

Bikes: Too Many

Mentioned: 233 Post(s)
Tagged: 0 Thread(s)
Quoted: 305 Post(s)
Originally Posted by 124Spider View Post
We're running up against a problem we really hadn't anticipated, and I'm hoping we don't have to reinvent this wheel; any help would be much appreciated.

We're really enjoying the tandem, and my wife is working hard to up her game to contribute more than 1/3 of the total power. Obviously, I don't really need a lot of help for level or downhill portions, but uphill on a tandem is not a lot of fun (and I'm a guy who enjoys charging up a hill on my half-bike), so I can use all the help she can give on the uphill portions.

When I'm going up a hill (or, indeed, when I'm working hard even on level ground) my cadence can go quite high, well into the 90s. On a long ride where I'm putting in a fairly maximal effort on my half-bike, I'll average 85-88rpm; when riding by herself, my wife will be in the low-to-mid 70s.

She's happy to spin as fast as I want, but she literally is doing all she can do to move her pedals at 98rpm; she cannot apply significant force to the pedal at cadence above 90. And I need the high cadence to comfortably put down high power.

We'll be experimenting on local long, fairly steep hills to see if perhaps we can comfortably slog up a hill at 85rpm (I don't mind going slowly, as long as it's fast enough to not fall over); we think that she'll be able to contribute meaningfully at that cadence.

Any other suggestions?

Thanks!

Mark
We have been riding tandems beginning in 1980 and I thought it was this year that we truly clicked in a tandem race. My wife and I are both trackies and race road and track with focus on timed events such as road time trials and pursuit and team events such as team pursuit at the track.

Over the last 10 years, we have both done a lot of motor work on the track chasing a motor cycle around on fixed gear bikes. Motor efforts are a great way to develop leg speed both by riding behind the motor in the draft and attacking the motor to put in more power at higher speed.

At the other extreme of the spectrum is low cadence work. We both do a lot of low cadence work riding a road or TT bike in a large gear on flat terrain and maintain the cadence below 60 rpm. This drill builds muscle fiber recruitment, strength and neurology.

For your wife, her problem at higher cadence probably is underpinned by lack of strength and neurology. Something to try is to do some low cadence work on her road bike to build strength and get the feeling of applying torque throughout the pedal stroke. When on the tandem at higher cadences, she may find that her neurology is able to fire the muscles to keep up and produce more power. You can do low cadence work with her on the tandem.

In 1980, we got our first tandem and the pedals were 90 degrees out of phase. We learned to ride it that way and we have not changed ever since. Although I changed the configuration to stoker leading by 90 degrees. That way she cannot ride my power. This keeps the stoker in the game at all times. We ride with pedal power meters so that we each have power. My stoker focuses on power production. In our last race, she rode tempo power with VO2 power on the climbs for 55Km. I provided whatever power was necessary above that. So give the stoker something to do other than worry about keeping up with your cadence or fretting about her lack of power or whatever may be in her head. Make her experience totally positive.

With respect to high cadence and effectiveness, there is a certain amount of energy required to lift the weight of ones leg as the pedal rises. The faster one spins per MPH the more energy one uses to lift the legs. That means lower cadence uses less energy per mile. However, low cadence and high torque can cause fatigue and for long tours or stage races, higher cadence generally produces less fatigue. A couple of years ago, Team Sky was trying to slow down Froome’s TT cadence because they thought he would be faster at a lower cadence. You may want to take a play out of the Sky playbook.

So we are back to the tandem dilemma. Syncing up the teams cadence so that a couple can enjoy a day of cycling together. It only took us from 1980 to our race last month to finally sync up and have a great week of chainless cycling. And we produced a lot of speed without a lot of power. So getting a tandem team totally in synch pays speed dividends. Hopefully, you will synch up sooner than we did. Although, I think the 10,000 hour rule applies. Stick with it.
Hermes is offline  
Reply With Quote

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Terms of Service