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On a standard tandem frame, is it possible to build a tandem bicycle with independent drivetrains for the two riders? Is there a custom frame builder that would build a tandem like this?

I'm aware of the half-recumbent tandem that has independent drivetrains, but I'm specifically interested in the classic/normal tandem frame.

EDIT: By independent drivetrain, I mean that I would like each rider to be able to coast independently of the other. The cadence can remain constant between front and back when both are pedaling.

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    What do you mean by "independent drive trains"? Ultimately, they've gotta connect at the rear wheel. Even if you put a chain down each side and had separate freewheels, that would just mean that only the rider who was pedalling hardest would be contributing, so you'd have only half the power. – David Richerby Mar 19 at 17:24
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    It's important to be clear what exactly you're after: do you want one rider to be able to pedal while the other rests? This would take independent freewheel mechanisms or equivalent. Do you want the riders to pedal at different cadences? A fixed ratio could be achieved with a front chain that doesn't use 1:1 gearing but this might have issues starting and the effort would come in and out of phase, with rather odd effects. There are various harebrained schemes for front wheel drive bikes. The captain could power a system like that while the stoker powered a normal drivetrain – Chris H Mar 19 at 17:26
  • You'd need a left free-wheel and most importantly at least a left-sided rear derailleur which I both doubt to exist. To apply power both riders would need to keep the free-wheel engaged at all times. If there's only the slightest freewheeling on one side, no power is applied. And there will always be the risk of hitting heels and toes unless the frame is rather long. – Carel Mar 19 at 18:21
  • @Carel there are BMXs with left side freewheels aren't there? Single speed though – Chris H Mar 19 at 18:56
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    It needs to be noted that one reason such schemes are not more popular is that there is an advantage, in terms of the balance of the bike, in having the two cranks more or less in sync. (And, yes, cyclists on a tandem are always cranks. ;-) ) – Daniel R Hicks Mar 19 at 20:16
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Here's a picture of a half recumbent tandem enter image description here from https://www.ucycle.com/merchant/2856/images/zoom/hase-pino-allround.jpg

Here is a link to a video of people riding a recumbent tandem. https://binged.it/2TXkxJC The video does a good job of explaining that the front crank has a freewheel mechanism that lets the riders pedal at different speeds. The front rider can also stop pedaling.

If this is what is meant as "independent drivetrains" then the functionality is in the crank rather than the frame itself.

The key to having a regular tandem like the recumbent tandem in the video is to find someone who makes a crank with a freewheeling chain ring. Like the old school Schwinn Suburban's from the late 70s with Shimano Positron FFS (Front Freewheel System).

Here's a link to a product for mountain bikes with a freewheeling chain ring https://dirtmountainbike.com/news/hxr-easy-shift-crankset-allows-change-gear-without-pedalling.html

With this part - or something like it - any tandem frame builder should be able to get you going.

  • One downside of the front rider being able to stop pedalling but not the back is that at least on conventional tandems the front rider is commonly the stronger rider. That may not be the case here of course – Chris H Mar 20 at 9:41
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As Chris H points out in his comment, this could mean two different things.

The half-recumbent/half-upright design does have separate gearing for each rider.

There's a different system that some conventional recumbents use that gives each rider the ability to coast independently, but they pedal at the same cadence: both sets of cranks drive a jackshaft (located just in front of the stoker's crank), which in turn drives the rear wheel.

There have been numerous ideas for bike drivetrains over the past century, and it's easy to imagine that other ideas have been tried out and lost to history.

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I know of two solutions to your question - I'll post two brands, however they are not meant as an advertisement, rather as a starting point for further search.

One is used by Onderwater Fiets from Amsterdam. Their tandems (and also more persons bikes) combine the stoker and pilot function and are meant for families. There, the drive is permanent between the last bottom bracket and the rear wheel and other bottom brackets are somehow free-wheeled so the passengers in front can pedal individually.

The other is R&B Fly, not much can be found about those on the Internet. Funny thing, I own one, hence the independent drive can be further inspected. There, each chainring (single for the pilot; double, same size for the stoker) attached to the crankset is freewheeled, thus pedalling can be done independent. Anyway, this bike awaits some renovation, I haven't ridden it yet.

Thus, it is possible to build a tandem with independent drivetrains and with enough invention you can even build one where the cadence don't need to match (add a front derailleur and triple chainring to the pilot's seat for higher / same / lower cadence as the stoker).

  • You might also need to add a chain tensioner (last para), but that shouldn't be too hard. Those Amsterdam ones you mention are presumably rear-steer rather like the ones I asked about a few years ago – Chris H Mar 20 at 17:03

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