Hi there,

I have a refurbished single-speed coaster brake style bike from around the 60-70's, and unfortunately the threading is buggered where the bottom bracket would go...

I saw this sekine 5-speed for sale locally and I wonder if I could strip it down and switch the frames. So the coaster brake wheelset would be on the sekine frame. Both bikes have 26" wheels.

Style-wise the frames are quite similar, but I'm not sure if the spacing for the back wheel would be the same.

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OR ---

Is it possible to fix the threads on the original frame?

Thanks for any help, cheers!

There's a good chance the BB can be re-threaded, I'd check with an LBS. The five speed frame is likely to have wider rear dropouts than your coaster hub, 120mm instaed of 110mm.

I've stuck a coaster brake hub in a derailleur frame once, and on first application of the brake the chain stay promptly got a bad bend by the reaction arm.

YMMV though.

It's possible, but as IGH pointed out it may require narrowing and realigning the frame. This is easy-ish to do on an old steel frame like your Sekine. Read on: https://sheldonbrown.com/frame-spacing.html

Many years ago I laced a Bendix coaster brake hub onto a sew-up rim and put that on a Schwinn Paramount track bike. Demented, but it worked and it didn't bend the chainstay.

I had a late 80s mountain bike converted to coaster brake and it worked flawlessly and never bent the chainstay. This is the first time I have ever heard of a bent chainstay caused by the brake arm.

Well, I'm running a MTB with a pair of drum brake hubs, with reaction arms, and that frame is holding up fine. Maybe that road frame had unusually narrow stays or something.