Crank Arm Length

Crank set

I am going to discuss about the different crank arm length and the performance of mountain bike. Please bear in mind that mountain bike performance is dependent on the person and not on the engine like motorbike. So, it is very subjective. 

Crank arm

Crank arm comes with different length from 180mm, 175mm, 170mm, 165mm, 160mm and the most widely use by majority of riders is 175mm in length. About 98% of Gerek Baru riders use 175mm crank length. For me, I chooses shorter 170mm over the other length because of several reasons even though I used to have 175mm before.

I am not going to elaborate on mathematical formula in calculating the drive ratio between front teeth (also crank arm length) and rear teeth. I am more interested in sharing my experiences.

Longer crank arm 175mm- more speed and of course higher top speed, more horse power. 

Shorter crank arm 170mm- more torque, more acceleration, more pick-up, faster acceleration, more pulling power especially on climbing and wind resistance.

Since my biking styles more on off-road riding, 170mm is the best for me. I am not for top speed but I need more torque for climbing. Also from my experience, 170mm gives me more control when climbing a steep curves. You are able to slow down your speed and at the same time in control of your motion on steep curve because of shorter pedal stroke, thus taking deep breath in style.

For those with knee pain, you should consider using shorter crank arm length to avoid injury. The knee will less bend either on top or bottom of pedal stroke.