I have this old Sekai that I got to turn into a singlespeed. Pic >>> https://img20.imageshack.us/img20/3071/p1010386r.jpg. It came with a cottered crankset. I'm looking to spend as little money as possible, so at first I was just gonna use it and keep going. Then I realized that there was a little movement between the 2 pedals. I took the crank apart. I'm assuming that the wiggling was occurring due to a messed up cotter pin. So I need some advice, should I 1. Get a new cotter pin ($4), or 2. Get a new crankset. Problem with #2 is that I don't know what kind of bottom bracket I'd need to get, and I'd like to spend $20 tops for crankset and bottom bracket =/. Anyone know their Sekais? Thanks for reading.

PS: Bottom Bracket stamp reads "18072" or "78072", can't really tell. Hope this helps!

if you can find a Bottom Bracket and Crankset for under 20 bux that is not totally borked you have found a good deal.

If cheap is what you want I'd say get 2 new cotter pins (measure the diameter of the old ones so you get the right size) and flip that rear wheel around the right way and let'er rip.

Thanks! I'll prolly get the new pins, since that's only a few bucks. But, I'd love for someone to tell me what kind of bottom bracket threading I have (or tell me what to look for), just so I know. I'd like to upgrade it at some point later on, in either case. Thanks!

PS: I just looked at this old Sekai catalog >>> https://www.yellowjersey.org/SEKAI75.JPG. I would say my bike resembles the Sekai Concourse 1500. Still don't know the BB threading though =/.

It's likely British/ISO threading, but I'd measure the hub shell to see if it's 68mm. If it is, you could easily pop in a cheap sealed bearing unit (such as this one) and start the hunt for a cheap crankset.

Neal

+1 its probably Brit/ISO threaded. Cheap cranksets are out there...just scour eBay. I got a nice Sugino Maxy for 20 bux a few months back.