Classic & Vintage - BB swap, any issues I should know

Hey All-

I came across a cheap ($20) Concord Bently 5sp frame that I'm gonna convert to a SS w/a coaster hub for my wife. It's solid, but the components are in sorry shape, so I'm just gonna start w/ the frame and forks. Anyway, it's got cottered cranks that I'm going to swap for square taper. Are they any foreseeable issues I should no about before taking this on. I'm guessing that it should be english thread. But the BB should be interchangle for the new one, right?

As it's a Concord, not a Concorde, I'm guessing your talking a mass market Japanese bike from the early 70's. Which means an English threaded BB. Check your fixed cup, it should be left handed thread. If so, truck on with no worries.

yep, concord, however, I wish I could magically change it into a concorde... Thanks.

Don't complain too much - that was the first Japanese bike I ever saw come through the shop I worked at (Schwinn/Raleigh dealer, sidelines of Roger Rivere, Astra, Concord and Columbia), and while nothing special, it was a good quality product for the money ($89.95 if my memory is still good).

Then a buddy opened a Fuji/Atala dealership, and we all saw what Japanese bikes could be like . . . . .

Are you sure the cups are threaded? I have two bikes with cottered cranks that have pressed in cups.

Okay, so update w/ one more question. BB is threaded. But the shell measures 70mm. I thought this was the width for italian thread? Yet everything else so far has been english. Headset, etc. So is this just some weird one off? I'm guessing I wouldn't be able to use a sealed cartrige BB?

More help please. Thanks for the info so far.

Okay, so update w/ one more question. BB is threaded. But the shell measures 70mm. I thought this was the width for italian thread? Yet everything else so far has been english. Headset, etc. So is this just some weird one off?


No, its not just one a weird one off. I own a gaspipe Fuji Sports 10 that I bought new in 1978. A few weeks ago I pulled its cottered cranks and bottom bracket and found that it is Japanese threaded but 70 mm in width, not 68mm or 73mm.

I had made a very copacetic BikeForum trade with Cyclotoine for the correct asymmetric 3-P spindle to match the nice 48 38 28 Sakae FX crankset I wanted to install--but the extra two mm width made the inner chainring hit the chainstays. I gave up and reinstalled the heavy as sin beautifully chromed original Fuji cottered 52 40 cranks. No low gears for me on this still nice grocery bike.

Hope your persistence results in a solution.

one more thing.

Check the 'effective' width of the existing spindle outside to outside where the cottered crank arms fasten, then subtract off a mm or two for each side where the cottered spindle sticks out past the crank(s).

Then you can start looking for cotterless spindles of similar width so as to maintain proper chainline. This issue defeated me, as I require a spindle width of 140mm. Who knows, might find one at a bike swap. Until then I'm stuck on the cottered crank setup.

I bought an '81 Concord Freedom 12 from a friend for $10 and it had an early steel Shimano splined(!) crankset. Forget the model of the crank but it heavy as lead and had the chainrings held in by screws. Wierd! I had him take that off and just keep it.

I'm turning it into a ss/fixie. It's at my paint shop now at work and I hope to have it done between the holidays.

Ooooh, I'm glad I read here that your Concord has a 70mm bb shell, seaneee. Now I'm wondering if mine is the same. I'll have to check it.