I posted in the ISO thread, but since doing some research I have become even more baffled than before, so I'm starting a thread. I have an awesome single speed coaster brake project in mind for a bike frame that I've had sitting around for about two years, but unfortunately it needs a Thompson bottom bracket.

Do they only come as a cottered crank? This isn't a deal breaker, but I was planning using a square taper.

Is there anywhere to buy them or any alternative? There are a couple on eBay, but I'd rather see what else is out there before I bid on one.

Why were they used, why did they stop being used, and what was the quality like? The bike this is going on isn't high performance or anything like that, but was it a sign of the lowest of the low?

Thanks,
DE

Okay, I don't know much about Thompson BB's. There's one on my wife's bike, and I haven't messed with it.

How much of the BB do you need? As I understand it, the cups are pressed into the shell, as on an Ashtabula crank. Are those cups present?

I wonder if the cups are the same as the cups on a Strida BB. If so, then possibly a Strida BB (which has square tapers for cotterless arms) might work. If you don't know what I'm talking about, take a look at this post on the Strida Forum. As it happens, I have some Strida BB parts in my parts bin, because the freewheel crapped out on me, and they sent a whole new crank with BB.

Give me some measurements-- shell width, shell diameter; and tell me if those cups are there; and I'll check what I have. If a Strida spindle and cones etc would work, that would be a pretty neat solution.

Dang it, it is Thompson.

I'll be at the shop a little later today, so I'll get some measurements. Unfortunately it doesn't have any of the bottom bracket parts, not even cups. I've never heard of a Strida BB, it definitely would be a perfect solution, though the more I think about using a cottered crank, the more appealing it seems to be. I've always immediately upgraded to square taper as soon as possible but since this will be a cruiser type bike it doesn't really need to be light or shift.

I'm all for going cottered, but in that case I can't help at all. I'll get back to you about what Strida BB parts I have. If you need a whole Thompson BB and crank, I have a feeling you'll be getting it on ebay.