txcrash

Picked up a Burley Duet tandem the other day, have logged a few miles - trying to increase stoker comfort.

I'm 6'3", and the bike is a large size - I'm comfortable. I am, however, dating a gal that's 4'11" and my kid (10 - 4'9 or so) is a bit shorter than that (she'll look down on the GF in no time).

What this means, of course, is that the stoker compartment is a bit oversized. Flipping handlebars, swapping out seat for something lower profile, and some pedal blocks (cut up flip flops) have made the bike comfortable for both, but I don't have high optimism for the long term longevity of the pedal blocks and nothing commercially available seems to be great quality either. Seems the best solution I can come up with is either short cranks, or crank shorteners. Neither stoker is a powerful biker, so I'm not too concerned about the torque that'll be applied. Is the ride2 crank shortener my best long term solution?

Did an easy 15 mile jaunt on Sunday, which we both enjoyed, despite a bit of mud on the road and no fenders. Bike is nice and quiet, and it's a joy having the GF be able to keep up while I'm getting a decent workout in. Sure, I stop and wait - but she feels hurried, and I annoyed, when that's happening.

Is there a relatively easy crank arm swap that'd set me back a similar amount? Any other easy mods that can be done to gain that inch or two? Bought used for a reason, don't want to dump a ton of money into making it fit, but I'd like to keep my stokers happy... Fairly mechanically adept, but haven't done any major bike mechanic work for 20 years....

Got a lot of oos and ahhs riding down the rail trail - looking forward to many more happy miles.

Darth Lefty 

I don't own a tandem but I've been researching and posting here about kidbacks for the last few weeks. That will raise the whole back comparment up.

PRECISION TANDEMS - Child Stoker Kit Installation Guide, child stoker, kid-back, kidback, kid kit, tandem, riding tandem with children,

Tandem-Specific Components
As someone pointed out here, kids grow up so these things are often for sale. A couple were offered to me when I posted about it, go down the page and find my threads.
https://www.bikeforums.net/tandem-cyc...nstorming.html
https://www.bikeforums.net/tandem-cyc...ack-ideas.html

There's an alternate way to rig the chain where, rather than adding another timing chain and cranks to the kidback, you move the stoker's crank and FD to the front BB, put the captain's crank in the kidback, and leave the rear BB empty. It's a lot of rigging and not as quick to convert, but all you'd need for hardware is some more chain and quick links, and the kidback bracket. This photo from Sheldon Brown's site shows the basic idea. Because the intermediate crank is gone, you can move the kidback lower than it normally mounted, so the height isn't too absurd for small adults.

txcrash

Wouldn't a kidback be a bit extreme? With a 5/8" block on the pedal and the seat as shown, the bike is rideable for the short stokers. If it'd move the pedals up 3", that'd be great, but my understanding is that it moves the pedals up quite a bit... (Center of gravity is a motha...)

WNY tandem

Crank shorteners would be the way to go. Because they have several options for shortening, it would be good for the wife and kids.

Darth Lefty 

With the forward drive setup, you could slide the kidback shell all the way down the rear seat tube until it hit the rear BB shell, I guess.

Or since this bike seems like an experiment for you anyhow, you could sell it and buy a smaller or MTB version with an appropriate rear standover. Shopping, I've seen a lot of MTB tandems converted to drop bars.

qspencer

Crank shorteners may shorten more than you need for riders just under 5 feet. The Ride2 offer lengths that are 25, 35, and 45 mm shorter than the base crank. I use them on 170mm cranks, so they are set at 145mm. That was fine a couple of years ago, but my kids are now both between 4.5 and 5 feet and I think something around 155-160mm is probably more appropriate at this point. I've also done short cranks inexpensively by buying square taper BMX cranks for my tandem that is set up with single side drive, but that won't work for two side drive setups. Da Vinci makes a crank that's threaded at multiple lengths like a shortener, starting at $220.

Philly Tandem

I have two sets of crank shorteners available if you are interested. PM me. One set of almost-new Ride2 shorteners, and one older set (possibly early Ride2). You can have the older set for free (pay shipping) if you just want to try it out, although they aren't nearly as nice as the newer Ride2 ones.

My 10 year old son is a few inches under 5', and they worked fine for him on our triplet. The only reason we took them off is I got a set of shorter cranks (145mm) and don't need the shorteners any more.

I think shorteners are the way to go for you based on what you wrote. If you get the fit dialed in with them and you want to get a bit fancier, down the road you could get a custom set of shortened cranks from this guy: Crank Arm Shortening

txcrash

I have too few posts to PM you, apparently.

Yeah, I'll definitely take the older set - please PM me payment details, along with what you're looking to get for the newer set (I may opt for those instead).

I think shorteners are the way to go, and if I can get a size dialed in, I have access to a shop where I could homebrew something, but projects such as those tend to end up still unfinished 2 years later.

And in 2 years, I fully expect to be the guy with 4 tandems in his garage...

txcrash

Well it looks like the crank shorteners are en route, and should be to me this weekend! A big thanks to Brian!

I'll post updated pictures and a short adults perspective on them once they're received.

Tony Marley

I have had excellent luck with crank arm shorteners on two tandems and a triplet.

dwmckee

Crank Shorteners is what we use in a similar situation. Child stoker crank conversions are for really little kids under 6. Get some fenders while you are at it!

txcrash

Shorteners got delivered on Saturday, I hope to get them installed this evening. It'll be very interesting to see whether the shorteners make it more comfortable or if the impromptu pedal blocks work better for the gal on the back. Will report back.

And yeah, I definitely need to add some fenders. Bike is filthy from the trail mud.

WillFam-Reno

Glad to hear you are riding.
I do not think that crank shorteners need to be limited to those under 6. I have a 10 and 11 year old that are able to use them just fine. The biggest limitation with blocks is that they either cause the pedal to be oriented with the block at the bottom or, if using blocks on both sides of the pedal, they cause a huge decrease in clearance while cornering or even normal pedalling.
Bottom line: figure out what works for you and your stoker. I think that tbe shorteners will work just fine.

WillFam

txcrash

Installed the shorteners this weekend, and the feedback over 40 miles from both child and adult stoker is that it feels slightly better than with the blocks. So a win for the shorteners!

ride on.