![\"ccs-41808-0-85498900-1402994384.jpg\"](\"https:\/\/wp-media.bikehub.co.za\/production\/uploads\/2023\/02\/ccs-41808-0-85498900-1402994384.jpg\")
<\/a>Image credit: Zoon Cronje<\/span>\n<\/div>\n[blockquote]First learn to spin a small gear. Then get strong enough to turn a big gear. Then get fit enough to spin a big gear.[\/blockquote]<\/p>\n
So what is best for you?<\/h2>\n
The first thing that should be taken into consideration is the nature of riding and the terrain you will be attempting to conquer. Will you be riding mountainous or flat terrain? Will you be looking for short sharp accelerations, or longer sustained efforts? Are you a rider that prefers to \u201cmash\u201d a heavy gear, or alternatively use cadence to spin over tough terrain? After reflection on all previous factors, additional aspects such as leg length, leg proportions, foot length and flexibility should also be taken into account.<\/p>\n
\u201cCranking it up\u201d<\/h2>\n
Most crank manufacturers only make a limited range of crank lengths. For road use the three most common lengths are 170mm, 172.5mm and 175mm. On the mountain bike there is a choice between 170mm and 175mm. However, there are extreme lengths ranging between 180mm and 190mm (albeit uncommonly).<\/p>\n
The shorter 170mm crank length can help with spinning to maintain a higher cadence, and minimise the chance of a \u2018messy\u2019 or untidy pedal stroke. A longer crank arm must progress further past TDC (top dead centre\/ 12 o\u2019clock in the pedal stroke) than a shorter crank arm before the rider can apply the same mechanical force to it. Therefore, a shorter crank in some cases may be the more economical approach when making this selection. A longer 175mm crank though, can improve torque output for steeper hill climbing but at the same time affect ground clearance when cornering and pedalling through rocky off road terrain.<\/p>\n
Ultimately, a longer crank length does not necessarily mean more power. At first glance one may think more leverage = more power. It is however overlooked that greater leverage or crank length will create more extension at the bottom of the pedal stroke, with the crank arm at 6 o\u2019clock. But this increased length will also result in an increased bend in the knee at the top of the pedal stroke at 12 o\u2019clock or top dead centre in the crank arm. Therefore, longer crank length can result in a potential increase in knee problems as excessive flexing in the knee will cause greater shear force on the knee (when the upper leg pushes extreme force onto the knee cap).<\/p>\n