Originally Posted by
shapelike
If you're using a cassette hub in the back, any road double will work nicely.
I ended going for some ridiculously convoluted setup - SRAM Omnium track crank with a 42T Sugino Messenger ring. You can also get a 42T Salsa ring that's 144bcd.
Race Face makes a nice ss mountain crank (chainline issues if you've got 120/130 spacing maybe).
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In the end I decided nix this idea - an FSA Gossamer or Energy crankset (110BCD) with either a 38 or 42 on it will make my life a lot easier.