Road Bike Crankset Length

However the evidence leans towards mountain bike crank lengths being too long in general.

Road bike crankset length. Firstly the majority of crank manufacturers make a limited range of lengths in road cranks. Chainring choices aside road bikes have long come with 172 5mm crankarms regardless of frame size while stock sizing for mountain bike crankarms is generally 175mm. With few exceptions most xc and trail oriented mountain bikes shipped today come with 175mm cranks. Lengths most often range from 160mm up to 185mm in 2 5mm increments and typically bigger bikes will come with longer cranks.

Frame sizes crank lengths. Bike frames are typically offered in a range of sizes from about 50 cm to 63 cm for men and about 44 to 56 cm for women as shown in the example geometry chart from cannondale on the right. Zinn cycles offers zinn custom cranks for bicycles in a wide range of lengths from 130mm to 220mm. While some brands spec 170mm cranks it is often only on their smallest sizes.

If we look at the crank sizes fitted to bikes sold in the uk the majority are now on 172 5mm. The industry is still supplying bikes for riders of my height of 177cm 5 10 with the same length cranks some 20 years later. Most manufacturers will make some efforts to shed weight while maintaining stiffness with some favouring hollow crank arms and others machining away excess metal. Let s start with the basics.

One could also suggest the cycling industry is indifferent to crank length as the range of available sizes is quite narrow often just 170 175mm. Got longer or shorter than average legs you need longer or shorter cranks. Cranks are measured from the centre of the pedal axle to the centre of the bottom bracket spindle. A key consideration when upgrading or replacing crank arms or cranksets is crank length.

At one point during the dominance of the english bike industry prior to world war ii an attempt was made to standardise crank length 6 5in 165mm but road racers started to challenge that notion. What has changed however is a greater understanding of human mechanics in cycling and the upshot of findings is that swapping out to a shorter crank by at least 5mm.