TandemTrailDog

My current tandem has 170mm cranks for both captain and stoker. I like to spin, but most of my stokers are quite a bit less experienced as cyclists and don't like to spin as much. I have to really watch myself to keep the revs down.

The new tandem that I'm getting comes with 172.5mm (captain) and 170mm (stoker) cranks, but 165mm cranks are available for the stoker. I'm leaning toward the 165mm cranks.

Is anyone running a 7.5mm (or more?) gap in crank lengths between captain and stoker?

merlinextraligh

I think it's more a matter of getting the right length for each rider, than a concern about the difference between the two. How tall is your stoker? Does he/she have a single bike and what's the crank length on that?

In theory at least, it should be easier to spin a shorter crank, so going to a longer crank for you, should help somewhat in evening out the desired cadence.

Nonetheless, I'd be more concerned about individual fit, than the difference between the 2.

waynesulak

I agree with merlinextral light if talking about the best crank length. It sounds like you however have multiple stokers so I think you are asking about what is acceptable rather than what is the best. I think people can adapt and use cranks that are shorter than optimal much easier than one that is a too long. I use 170mm cranks and would much prefer using 165mm rather than 175mm cranks and especially rather use 160mm than 180mm cranks.

WillFam-Reno

I agree with both comments so far. To answer your question, I run 170 Captain, 150 or smaller (I'll check if you want to know) middle stoker, and 165 for the rear stoker on my triplet. They work fine, as the middle stoker has pretty short legs (8 years old). All of us are comfortable with the travel.

p2templin

My standard spiel goes here:
Stand with your back to a wall, barefooted.
Measure from your crotch (a magazine or right-angle thingy for carpentry can help) to the floor.
Crank length should be somewhere between leg length * 0.21 and leg length * 0.216.

jnbrown

170 front 165 rear works for us.

prathmann

Sounds like you want to have most of your stokers increase their preferred cadence by a significant (or at least noticeable) amount. In that case I'd go for at least the 165 to 172.5 differential between the two cranks. Matching the crank length based on height seems much less important to me - my bikes have a range of crank lengths, 165mm (tandem), 170mm (touring and folder), and 175mm (road) and I feel comfortable pedaling all of them. But I do naturally choose a slightly higher cadence on the tandem with its shorter cranks than on the road bike.

Stealthammer

I use 175mm/170mm cranks on my 56x53cm Santana road tandem because I am generally the more experienced rider as the captain, and the 175mm captain cranks help to remind me not to go into a 130+rpm spin with a less experienced rider on the back, and the 170mm stoker cranks will help them to keep up if I do. I've done the same thing on all of my tandems, but on the mountain tandems I usually went with 180mm/175mm or 175mm/170mm cranks so that I would have the extra leverage when we needed it because I (thus we) often stand on steeper climbs or on more technical trails, but I don't want my stoker feeling like they are walking on a treadclimber.

I don't know what will work best for you, but for me, height and leg length are only part of what should be considered when selecting crankarm lengths on a tandem. On a tandem you ride as a team, and each rider's needs and abilities should be taken into account.

ksisler

Keeping the length of the cranks tuned to the stoker and the type of ride is increasing vexing. While I have kept multiple cranksets standing by to do this ride prep tuning; Of late I have begun to see it as somewhat exhausting. Thinking it is about time to update the primary rig with a 11-36 10 speed rear cogset and a 4-ring crankset (maybe 24-40-48-58 or similar silliness like we did with the TA Cyclotourist in the 70's due to lack of widerange freewheels) to enable the one bike configuration to go anywhere at any pace...and accepting the need to carry a few extra ounces of alloy to avoid the prelaunch wrenching. Also thinking that the Davinci Bicycles IPS system may be onto something I need to consider. I think it was Bill G who has one with the 4 rings on the front and the pictures he posted here were enticing to say the least or at least ultra cools... Allowing the stoker to self pace wiht the IPS probably solves most of the remaining crank length tuning problems. Would also allow my stoker to drop out without having to unclip and put her feet up on the lateral tube... as I am tiring of touching up the paint

TandemTrailDog

That was my original thought, and this thread has convinced me that it's the right choice.

My biggest challenge is that I don't have a primary stoker, but several and they're all different:
5'0 (and growing)
5'4
5'10
5'11 (and growing) - might get only one season on the new tandem


Thanks to all who replied to my question.