Columbia "Twosome"

[wheelhorseman]

I got the old tandem going very easily by airing up the tires and oiling the chains. This is my first ever tandem. Riding solo is awsome. Like a limo. Handling is quite diffrent. I did add some medium hi rise bars to make it more comfortable. Havent tried two up yet.

Its a simple one speed coaster brake. A wee bit hi geared. Could I put a 36t front sprocket on to make it easier to pedal. Honestly I love riding it and since it was basically free thinking of keeping. Will be ridden solo pretty much always by me.

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[Fv2]

You should be able to replace the front chainring the same way you would any other.
Less teeth or more will change the ratio, if you're keeping it you may as well make it however you like.

 

[RustySprockets]

On this single-chain arrangement, one must replace the chainrings on both cranks as a set, else the pedals will quickly fall out of phase. They're out of phase right now. Riding solo, no problem. With a captain & stoker, you may end up kicking each other.

Perhaps you could exchange the hub sprocket for a larger one, and achieve the same ends?

 

[wheelhorseman]

Rusty thats a thought. I thought it would be a tank to pedal solo but actually not bad at all. As for changing chainrings and getting it out of "sync". It wont be rode 2 up. Wife wants the grandkids to try it. Yeah right. They wont make it 10 feet before they bust their butt. Thats when I say ENOUGH.

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[rickpaulos]

I had a Columbia Twosome. It rode pretty bad. One day I was at the local DQ and I leaned over the bike and saw the connecting chain snap tight. Turns out one end of the boob tube had broken it's brass brazing. The boob tube on these goes through a hole in the bb shell. When the brass was broken, the boob tube would just slide in and out and not do it's job. The weight of the riders was taken up by the connecting chain which greatly overloads the crank bearings. I re-brazed the joint, touched up the paint and viola. No difference. Still rode like junk.

As an experiment, I put 2 Shimano FFS Front Freewheeling cranksets on the Columbia. You get independent pedaling that way but you lose your coaster brake. Those cranks came off Schwinn Calientes with the Positron shifters. The rings have dual guards welded on so the chain never comes off.

I had a Huffy Daisy Daisy tandem with 2 different size connecting rings. That worked okay with the constantly changing phase. I took it on the Midwest Tandem Rally in Springfield, Illinois, in 1978. No date that year, I took a racer from my team. We could pretty much out ride anyone on their good tandems in the short haul. But the seats were so bad we couldn't take it for long. When we would ride with the mismatched rings, the tandem would keep alternating between bouncing up and down and then swaying side to side. I had the lower of the 2 gears so when we cranked it up, I couldn't keep up with the pedaling so I'd just put my feet up on the frame. You won't kick each other but you may catch a pedal on the ground in corners or going over big bumps (driveways, curbs) because the captain won't know where the stoker pedals are. If you don't have a rider in back, the rear wheel will skip out a lot easier when the crank hits the ground in a corner.

You could just change the outer ring in the stoker position to get a different gear ratio without changing the connecting rings. As long as the connecting rings are the same size as each other, their size has absolutely no effect on the gear ratio of the bike.

I've seen some guys riding tandems with, ahem, inflatable dates on the back. How they attach them in place, well I've never stuck around to see.

Rick

 

[GuitarlCarl]

Rick has it right, you do not have to change them both. Just the rear sprocket. The two crank sprockets do need to stay the same. I have a couple tandems. I'd put a multi speed rear hub on there and get some real use out of it, and leave the cranks synchronized. It makes hills easy and when there's a stoker available you'll be able to really haul (loads of fun but make sure your brakes get updated too) also note, you're going to want to have heavy gauges spokes not just any o' wheel will hold up to the weight. Awesome find.

Carl.

 

[Fv2]

Looks like I learned something new here. Atleast now I know what kind of parts to check into when I put together my divorce bike, I mean tandem.

 

[squirreldh]

I have a 40 hole sturmey 3spd laced to a 26x1 3/8" rim available from a vintage tandem if you do decide to gear it, let me know!

 

[deorman]

There should be 2 sprockets on the "stoker" crank, one the same as and linked to the front, and one which drives the wheel. The one that drives the wheel can be changed for different gearing. Changing the wheel sprocket is easier, but be aware that not all older snap ring sprockets are interchangable. I don't recall which is which, but the Bendix is either larger or smaller than the SA/Shimano. The version that's smaller can be ground out to fit, while the loose fit of the larger one can cause the snap ring to be dislodged. Newer ones are all the same.