Originally posted by RegularGuy
Whatever crankset you choose, you will almost certainly need a new bottom bracket with shorter spindles.
??? Why ??? I've built quite a few single speed/fixed gear bikes and have never had to shorten the BB spindle. Use the middle chainring position of the crank and you'll be fine. On a geared bike the BB and crank are spec-ed to provide a straight chainline w/ the middle ring.
Originally posted by RegularGuy
Whatever you do, use a chainring with no shift pins and ramps. Ditto the cog...use a BMX cog. Those shifting aids make your chain want to shift. On a singlespeed this is not good.
Agree that this is the best course, but you can make do with ramped cogs and chainrings though as long as your chainline is nice and straight and your chain tension is good. Let's you use existing spare parts to test out gear combos until you find the right one.