Tandem w/ shift kit?

[smittyman]

Hey all you master fabricaters...I have been dreaming of a tandem with a shift kit from SBP. I am thinking that if you had both chainring sprockets freewheeling that it would work perfectly and there would be no need for the long drive-chain setup. Has anyone done this yet? I have been shopping for used tandems that I can try this on. Any thoughts, problems or ideas? Thanks, Smitty.

[Ghost0]

I would love to assist you with this project but until I can see the bike, its mounting options and drive train there is not much I can do at this point. Start posting photos of possible donor bikes and I will make some recommendations.

[mwarning]

May I submit a donor bike?! I've got experience building two motorbikes in the past year and am ready for my next challenge. The biggest drawback to these things is riding side by side while trying to talk to someone....down right dangerous! So why not a tandem? I started poking around on the Forum for info while at the same time looking for a bike to be my next victim. Just picked up this 5-speed tandem on Saturday.

This post led me to your site, and I think a shift kit would be the right way to go on a tandem. I really don't need 2 big long chains slapping around. After looking over your kit, here's my thoughts

Mount the motor up front in the "normal" spot. Jack shaft across, and then chain back to the free wheel sprocket in the second rider's(2) position. Somehow we'd have to add a sprocket to the "hard" side of the (2) freewheel sprocket, and chain that up to the first rider's(1) crank...that way no mods would have to be done to the (1) assembly. From the pictures you can see the (2) sprockets are bolted together, so it would nice to take the sprocket we need and add it to your freewheel assembly.

What do you think? Any info you can provide would be helpful---looking forward to getting started!

[Ghost0]

I think your idea should work. My only concern would be the chain from the jackshaft to the stoker crank will be a bit long but it shouldn't be a problem. Now that we have a good selection of chainrings you should be able to get the gearing you like. Oh but you would need a freewheel on the front crank as well or your pedals would be spinning. So you would need freewheels on both cranks.

[mwarning]

Hi Ghost0, thanks for the quick response! I've never been able to see the shift kit in 3-D, so I'm guessing how this thing is built. I would like to connect the captain's crank sprocket to the freewheel portion of the stoker's crank (I googled "stoker crank" so now I know the correct lingo). I envision a sprocket attached to the stoker freewheel assembly that I can connect to the captain sprocket....both will freewheel together...I think.

Are there better pictures of the assembly somewhere out there in case I am totally missing the boat on this thing?

[Ghost0]

Download the installation instructions and it gives you a pretty good idea of how it all works.

[...ladies]

I'v got a tandem but it wouldn't work with a happy time.. Might try a rear rack engine sometime tho..

[mwarning]

OK, Ghost0, I looked over the manual and have a good idea how it works. Can you tell me the difference between the Standard front freewheel and the Heavy Duty version? How does one determine if the Heavy Duty version should be used over the Standard version? Hard to tell from the pictures, but I'm pretty sure each has the internal threads on one end and the 4 lobe crown on the other, right?

Sorry for all the questions but I would like to make somewhat sure the unit can be modified to do what I need.

[Ghost0]

Functionally they are the same as one is just a direct replacement for the other. One is made in Taiwan and one is made in the USA. I think that pretty much sums it up.

[mwarning]

10-4, I can do that math. Just a little more cipherin' to do and I can get this project underway----