fixed gear crank lenght

[connje]

So I just started commuting by bike, for now I am riding a pieced together fixed gear.
My question is what crank arm length should I use on the fixed gear? I have a set of 165s and 172.5s.
My logic said I should ride the 172.5s because that is the same length I have on my steel Fierte. Someone told Rapid Tourist she should use the 165s on the fixed gear she is planning for.

My commute is 4 miles of mostly flat terrain. I am using a 42x16 ratio.

Does someone know the evolution of popular crank arm length over the last 50 years? My 165s came with the frame I am using, a 70s SR SemiPro size 58. That seems small to me, especially for the size of the frame.

thanks
jeremy

[Rapid Tourist]

Ahhhhh, fixed gear crank length. A controversial topic.

Now, many of the gurus on this board will tell you to run 165s because the shorter crank length helps insure that you do not slam your cranks into the ground while peddling around corners. As you know, you don't have an option to coast thru corners on a fixie, and you don't want to slam your crank into the road on a fixie because it will make you go :bike:

I recently changed out my old 170 cranks on my fixie to 175s. I ride a fixie that has a higher bottom bracket than a true road bike (its a cyclocross frame).

I'm loving the 175s on my fixed gear. I find that a longer crank gives me more leverage when pulling up a steep climb, which you need on a fixed gear. But if you go with a somewhat longer crank, like a 175, just make sure your bottom bracket is high enough to get away with it.

I'm designing my new fixed gear right now, and we specifically placed the BB high so I can use longer crank arms. To each his own, and ride on!

[Too Tall]

What R.T. said. Change is bad.

[spiderman]

...as i have been riding fixed for only a month
and am a fellow commuter.
i also run 172.5's on my road bike
and elected to go with the same on the fixed build.
...because as TT said...change is bad.
i am happy i did.
i have 600 plus outdoor miles
and have experienced no problems with the current set-up.
maybe i'll run into trouble if i get up the nerve
to try a reverse 360...
...i'll let you know!
so, as far as i can tell
ignorance is bliss!

[Fixed]

bro urban riding fast short ,light to light .weve between cars no brakes last min.turn and tradition 165 's if you want to play in traffic .
i.m.h.o. cheers

[IXXI]

I haven't felt the need for longer cranks on my fixie. Especially up hills I find I rely more on the momentum you get from being fixed than actual leverage from the cranks.