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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!

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Old 04-05-10, 10:24 AM   #1
flypaca
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Crank arm length vs cadence

my stoker (the better half) likes to push vs spinning. I am only a moderate spinner <95 but she would rather ride at 70. Would a set of crank arms of different legnths be appropriate to help keep us both comfortable and happy. We have ridden a lot on a 72 paramount tandem with ta cyclotourist 170s but not always the most comfortabley. Have seen a lot of good advise and info here but being new have not seen this issue covered. Thanks!
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Old 04-05-10, 10:54 AM   #2
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Short crank arms for her and long for you would help... not nearly enough for you to do 90 and she 72... compromise. You could ride at 83 and she, with the short cranks, would feel like 79 or there abouts.
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Old 04-05-10, 11:35 AM   #3
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If your stoker has shorter legs, then shorter cranks may help (165mm).
That would have the effect of slowing down her leg speed and make it easier for her to spin.
Our old tandem had 170mm front and back and my wife prefers the 165mm cranks on her single.
So on the new tandem we went with 170mm front and 165mm back and its worked out well.
We seem to be more in sync and standing is smoother. She also has a slightly slower cadence than I do.
Some people who like to ride at lower cadence sometimes use longer cranks to get more leverage, but that scenario works best if you have longer legs and are riding a single.
In your case it could make things worse because your cadence is locked together and would result in your stoker having to increase leg speed and range of motion.
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Old 04-05-10, 11:43 AM   #4
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I'm an ex-racer, train on the track, and ride a fixie on long randonneur rides, so I'm quite used to spinning. I ride 165mm cranks on the track and on the road fixie, but my tandem is equipped with 175mm cranks on the front and 170's for my stoker, who is a total recreational rider. Some adapation happens on both sides; I will slow down the cadence a bit and use a gear that will be a bit more comfortable for the stoker cadence-wise; she might spin at a slightly higher cadence, but she doesn't complain. I don't really notice the difference in crank length (between 165 on the fixie and 175 on the tandem), and pedal cadence really ain't no big thing... On fast descents, we tend to just coast, a luxury for me after coming off the fixie!

L.
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Old 04-05-10, 01:06 PM   #5
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Keep you leg lengths in mind before changing crank length for either of you. Some people can change crank length without a problem but other people can develop problems from the incorrect crank length.
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Old 04-05-10, 01:12 PM   #6
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IMHO the difference you are talking about is simply too big to correct with a crank length change. Even is you went to extremes of long for you and short for her, the difference in the ability to spin is not significant enough that either of you will feel comfortable. This is one of the reasons DaVinci has it independent crank system so that stoker and captain can blissfully pedal at their own cadence totally oblivious to how fast or slow the other is pedaling. Short of this the only other thing I can suggest is training so that one of you is more comfortable with the other's cadence. (I would say it would need to be her getting faster, but I can say that since my stoker is my daughter and not my wife!)

This in addition to what tandem_rider says above
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Old 04-05-10, 01:14 PM   #7
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our leg length is about the same her inseam is about 1 inch longer. I had heard that the crank arm length might make a difference and so I thought to inquire of the more experienced. the Paramount is short coupled I heard that it was used for tandem racing prior to our purchase. It sure is light 38 lb and used 700-35 clinchers. I would concider a new crankset with the arm differece. Tandem riders never compromise we just cooperate!!! What would a new crankset be set up we used to live in flat Ohio and now are in the foothills of the Rockies?
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Old 04-05-10, 03:57 PM   #8
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[QUOTE=WheresWaldo;10626379...This is one of the reasons DaVinci has it independent crank system so that stoker and captain can blissfully pedal at their own cadence totally oblivious to how fast or slow the other is pedaling....[/QUOTE]

I don't pretend to be an expert on DaVinci's independent coasting system but I'm pretty sure all it does is allow either crew member to coast independently of the other. (That's why they call it an independent coasting system on their website and they make no mention of different cadences.) Once pedaling, the two crew members have to pedal at the same cadence, though not necessarily in phase. I could be wrong -- I've only seen them underway, haven't ridden one. I just would want any team contemplating buying a DaVinci in order to pedal at different cadences to be absolutely sure on this with a test ride before springing for it.

Realistically, this is one of those areas where compromise is necessary, but where improved training of the neophyte rider (which is more likely to happen if the veteran is willing to compromise!) generally leads to higher comfortable cadence eventually.
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Old 04-05-10, 06:05 PM   #9
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We have a daVinci and it's certainly possible to put a larger chainring on the stoker's crank, but the phase would constantly be changing underway. A low-power stoker or one with a very smooth pedal stroke and you might not notice the variable phase, but a masher would be very disconcerting as the phase would shift a bit on every pedal revolution. I've had my strong, 6' 200 lb son on the back of our tandem; he never bothered getting into phase, but I could hardly tell the difference since he's a pretty experience cyclist.

Of course, wouldn't buy a daVinci to solve a non-problem. My wife's cadence as moved up from 80 to 90 over about 10 months. She's comfy at 90 and ok to 95 which works fine for us. Lot's of other reasons to buy a daVinci, however
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Old 04-06-10, 07:48 AM   #10
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Quote:
Originally Posted by WheresWaldo View Post
Even is you went to extremes of long for you and short for her, the difference in the ability to spin is not significant enough that either of you will feel comfortable. This is one of the reasons DaVinci has it independent crank system so that stoker and captain can blissfully pedal at their own cadence totally oblivious to how fast or slow the other is pedaling.
The DaVinci does not allow different cadences. The cranks are in 1:1 except that either one can coast - in which case they contribute nothing to the forward motion of the bike. The only bike I know that offers different cadence is the ViewPoint (and it's direct relatives). Here the stoker is in front, in a recumbent position, while the captain is in a diamond-frame position on the back. Because the stoker's pedals are way up in the air there are no issues with separating the cadence, and there's lots of room to throw in the extra drive train complexity.
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Old 04-06-10, 04:37 PM   #11
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Learned something new
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Old 04-06-10, 07:00 PM   #12
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good info ,never looked at it from the recumbant / traditional standpoint but I can see it. glad to see this thread hashing this out. This is why I come here...
Cheers.. Gentlemen...
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