crank length,.....my turn this time!
 

Call me crazy, I perfer a shorter crank length, and Im 6'5"!!!!!!! I remember ridng this old Panasonic road bike with a very short length crank, the thing was cake, I didnt have to move my legs that much.:D That is all.

Interesting smelly... are you by any chance very strong?

I'm 173cm (5'8) and 55kg (121lb) and my legs are 83cm (32.6"). I'm not particularly strong, but I am long legged... I think my 170mm cranks are too short and longer ones might be the go for me.

Just doing some calculations on crank length, torque, gear ratios, cadence and foot speed to try to understand all this. What I'm trying to get my head around is whether a longer crank at lower cadence but equivalent foot speed is really equivalent to a lower gear or if there's more to it than that, perhaps due to the range of motion of the leg muscles.

Still finding it hard to believe that 2.5mm makes a discernable difference.

You must spin a lot... It is easier to spin with shorter cranks...

I don't spin, I have clipless toe pedels so Im pushing and pulling on the pedel.

To Ants: I wouldn't bundle gearing with crank length. As for whether 2.5mm is discernable... yes it is. You will feel a tad more leverage hammerin' in to a head-wind or climbing. The down-side to this is the greater arc your foot must make. Make sure you lower your saddle appropriately. You knee also comes up higer by 2.5mm. If you ride with a good low and straight back you will also notice the higher knee. The thing to be careful about is damage to the knee. Although, I've never known anyone to run into problems going from 170mm to 172.5mm I have known guys to get carried away thinking 'more is better' and go to 175mm or longer. They did run into problems. If you go to 172.5mm don't expect a big difference. It's a small edge. Your legs are long for your height, that's for sure. 172.5mm would suit you well.:)

I am 5"9" before the crank arm length is 175 , I have change to 172.5 and I think I can spin for longer period of time, or maybe I have gotten stronger, what do you say guys,

I don't really know enough to know if it makes a difference. I have 170's on my Bianchi, and they feel fine to me at 5'-6" and 30" inseam. - Ted