I am building a fixed gear bike out of a late 70s Concord (Kuwuhara) frame. I am good to go on newer bike hardware but some of this older stuff looks a bit foreign to me.
The spindle on my bottom bracket has square taper fit ends. Is it possible to find a single speed set of crank arms for this type of BB? I'd love to run an older 44 tooth BMX sprocket on this thing. Also, the sprocket on the bike seems as though it's pressed or interference fitted to the drive side crank arm (the sprocket carrier is bent to hell and unusable). Would I be better off going with a new, sealed BB, if this exists? The BB cups thread into the frame and the cranks arms are Sugino.
Aside from that, I was hoping some people on this forum could point me in the right direction for some cool websites/stores for fixed gear parts.
I figured the cranks would be paper weights. I repacked the BB bearings after cleaning them and they look like they'll hold up. The spindle was in great condition. I've been looking at stuff on the "Eighthinch" website. The Eighthinch cranks look pretty nice/cheap...just wondering about the quality. Also, I read a thread about some knock off wheels that you and a few others tested and liked for the price paid. I'm wondering if these Eighthinch "Tessa" wheels are any better. Another dumb question...the seatpost on this old Concord frame. Any ideas on the size?
I've got these Eighthinch cranks, and they're fine for the price. They're really about the same as any OEM crank, but would be perfectly suited to your conversion. The Tessa wheels would definitely be better than the knockoffs, but they also cost a bit more. The knockoffs are a good deal if you want an inexpensive deep aero section wheel. I have no doubt that the Tessa's will perform better.
I keep a digital micrometer handy for measuring posts and clamps, but if it's a steel frame, 27.2 would be my best guess. Take it to a bike shop and have them measure.
As for cranksets, the first thing you need to figure out is what you're going to do about chainline. The easiest solution is often to get a new track wheelset, which usually has a 42mm chainline, then get a crankset and bottom bracket to match that. I would guess that any of the cranksets available in the $50 range (Eighth Inch, Origin8, Sugino XD) are probably of similar quality (all decent) and generally give you a 42mm chainline with a 103mm bottom bracket.
You can also use road double cranksets by removing one ring and getting short stack bolts. In general, with the recommend bottom bracket length the inner ring position will be at 41mm, but a carefully chosen shorter than recommended bottom bracket will put the outer chainring around the magic 42mm. This is actually what most of the above crankset are doing.
I got a used pair of Shimano 600 (FC-6400, predecessor of Ultegra) cranks on eBay recently for about $20. I think this will give me a good chainline on the outer ring with a 103mm bottom bracket, and I would guess this will be slightly better than the comparably priced "new" "singlespeed" cranksets.
Your cranks need to be compatible with the bottom bracket, with regards to how steep the taper is on the square spindle ends and on the inside of the crank connection point. JIS vs. ISO. Also, your rear cog and the chainring up front need to agree about how far outboard of the centerline of the bike the chain will be, otherwise the chainline will be cocked. So, buy your parts in an order that will allow you to consider these things.