Originally Posted by
Loose Chain
are BMX freewheels the same as or compatible with our single-speed bicycles?
Some are, some aren't. BMX freewheels with a tooth count less than 15 use a metric thread to mount on the hub that isn't compatible with track or "flip-flop" SS/FG hubs.
What the advantage of going to a 42 on the chainwheel vs 18 on the freewheel cog?
Any chainring/freewheel combination that gives the same gear inches will feel the same on the road. Larger tooth counts will wear longer, since the wear is spread over a larger number of teeth. Smaller tooth counts weigh less. You have to decide which is more important to you.
I have a FSA Tempo crank set which does not seem to yield much for parts or places to order a smaller 42 chainwheel?
From what I can tell, the "Tempo" crank has a 110mm bolt circle diameter. Any 110mm BCD ring will mount on the arm; doesn't have to be FSA. 110mm rings are widely available in many tooth counts.