Originally Posted by
zandoval
I have found the 5mm difference between 170 and 165 to be relatively insignificant. For a good looking, on the cheaper side (80 USD), silver, square tapper, crank consider BikinGreen.
Ebay: "bikinGreen Classic 170mm 46/30T BCD 110mm Crankset Silver Retro bike"
5mm can be very significant depending on it and many other factors.
Quite awhile back I swapped some cranks in a hurry for a ride at Crater Lake.
I had 172.5's on the bike and wanted to change the granny from 28 to 24, another crank I had was handy with out a granny on it so I set it up and put it on the bike.
Took it out for a quick test ride and immediately thought
, what did I do wrong?
Inspected the set up to find the swapped in crank was 170, huh, changed it all back out with the 172.5's and it was fine.
Couldn't believe there was such a difference but there was to me.
Later on, Dave Levy at TiCycles explained how it adds much more than 2.5mm to just the top and or bottom of the pedal stroke, it multiplies exponentially through the whole pedal stroke revolution, affecting cadence, time to revolution.
Just 2.5mm adds 15.7mm to the total distance your foot travels with each revolution, multiply that X RPM.
This is what accounts for such small increments of crank lengths.