MTB crank length

[wavedancer]

I am setting up my GF Big Sur GS with some semi-slick tires for riding on the road/dirt roads this fall and winter and went out for a spin today. After not riding that bike for awhile,and spending a fair amount of time on my road bike with 165mm cranks, I think I might like to try 165's on my mountain bike. I really notice a lot more flexion in my knees with the 170's that are on the MTB, and I seem to go past what is comfortable or efficient. I keep raising the saddle to compensate, but I am just about maxxed out on what I can adjust there. I have a 44cm frame and a 27-inch inseam.

Does anyone have any suggestions, pros or cons, for doing that? The cranks that are on the bike are Bontrager Select 170's. I checked the Bontrager website and they don't make them in 165's. If you have 165's on a MTB, what brand/model do you use?

Any help is greatly appreciated!

[fixedgeargirl]

I, too, have a 27" inseam and don't care for the sensation or loss of power I feel with long cranks. I have 165 XTs on my MTB.

[Adventure Girl]

My road bike and two of my mountain bikes have 165mm cranks. I have very short legs and spinning was difficult for me with longer cranks.

My older mountain bike has Truvativ Team Stylo cranks (about 5 years old). They required a different bottom bracket. But I don't think that will help you because I don't think they make them in 165's anymore.

My new mountain bike has Shimano XTRs. I had to order them and they took about 2 weeks to get. Luckily/unluckily for me it took almost 7 months to get my frame, so I had plenty of time to wait.

Some people say that you have less power with shorter cranks. Theoretically and mathematically that is correct (because you have a shorter lever). But for me the advantage of easier spinning outweighs that.

[wavedancer]

Thanks for the input. I don't really notice the difference when I am on the trail, but it was quite noticeable when I was spinning on the road. I may go ahead and look for some 165's.

[eofelis]

I have a set of XT 165s. They are on my towner bike right now. I have 170s on my mtn bike, Truvative I think. The 170s are fine for now, but I'd like the 165s on my mtn bike someday. 3 of my 4 bikes have 165s on them.