qspencer

I'm looking to upgrade a low-end tandem (2002 Raleigh SC tandem) to something a little nicer without spending too much money, so I've been looking at the used options out there. I would want to upgrade the shifting on anything old enough to not have STI-style shifters. If I recall correctly, the cassette size should be about the same for anything in the 8-10 speed eras, so an 8-speed system could be upgraded to a 10-speed system without changing the wheel (someone correct me if I'm wrong). I recently found a 7 speed Burley Duet (the seller says it's a 1993) and I wondered whether anyone knows what dropout spacing to expect on this bike, or others from the 7 speed era. Is it likely to fit an off-the-shelf mountain bike wheel?

waynesulak

Many tandems were made with 140mm spacing in that era. Hubs with that width can be found to purchase new and used or you can replace the axle and space out a 135mm mountain bike hub. Don't overlook that if the spacing is a little off on your purchased tandem it could be 142 or 143mm and would probably take a 145mm hub. Have to borrow a wheel and try it to find out.

Paul J

Our old Cannondale was spaced 140, we had no problem taking a 145 wheel and re-space and re-dish which worked great. Being Alum it couldn't be flexed enough to fit the 145 9nto the 140 spacing but I'd think a steel bike could. You could also have a frame builder or pro shop spread the rear triangle that little bit too.

ksisler

QSPencer; The path you are positing is one that will require a fair amount of cash to reach the end point. If I can recommend anything it would be to leave the old gal alone as she was originally built. You can then take the money you didn't spend or her and buy a decent used tandem that already has the gearing range and features you are wanting. With good Santana's and similar bikes in great condition selling from $300-800 on ebay, it is hard to go wrong in getting a more modern ride if that is what you need.

Hope that helps
/K

Leisesturm

This.

SJX426 

I recently purchansed a 94 Duet with a 6 speed rear freewheel. I believe it will take a 7 speed freewheel without modification. My issue is the barcons are sti for 6 spd though I can put them in friction mode. The wheel fits fine with the cogs clearling the seat stay. I have not assembled the bike yet so cannot say if there is enough clearence for the chain to move from one cog to the next. For this level of tandem, I don't think 12 speed plus granny gear is going to be a problem for us and given what it is, it would not be cost effective to invest much even though the bike was purchansed for around 250.

qspencer

For a long time, the only 7 speed STI option out there was buying used Shimano RSX shifters on eBay, which I did for my late '90s Bike Friday (7x3 DualDrive system). I haven't been impressed by the shifting accuracy, and I don't know if that's due to the age of the shifter or something else. It looks like Shimano has recently start started making a 7 speed STI shifter for the first time in quite a few years: the A070. It's got the thumb shifter like other lower end Shimano shifters and sells for under $100.