Road Bike Crank Length Advice

Alan d 5 7 170cm with short legs for height 74 8cm had recently bought a new bike and started to experience hip pain. He had traded in his pain free old bike so was not aware of the crank lengths on that bike. Crank length changes may help solve long simmering aches and pains but they re most effective when you re doing everything you should be doing to be strong on the bike.

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Is There A Correct Crank Length On A Road Bike Cyclist

Bikedynamics Bike Fitting Specialists Crank Arm Lengths

I Created This Guide To Setting Up And Maintaining Your Road Bike

Crank length is measured between the pedal hole and spindle hole center to center and perpendicular to the spindle.

Road bike crank length advice. Some riders agonize over crank length differences of 5 mm. If power in martin s study was affected only 1 6 with a 25 mm change in crank length we can safely assume that it would change less than 1 when comparing the normal range of available crank lengths. If you are changing the cranks on an existing bike. Get a bike fit and then buy a cheap crank or borrow a crank.

I just thought that the longer crank on the mountain bike was because mountain bikers required extra leverage for slow. 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. For some riders though with ongoing knee hip or lower back issues crank length could be a factor. Many cranks carry markings identifying the length.

My first mtb frame 17 5 came with 175mm and the equivalent sized road bike with 172 5mm. A good bike fitter will help you find the best crank arm length for you. Even if you are in that range then the crank length that your bike came with may not be ideal for you particularly if you like to ride far. Currently adapting to the new crank length and working toward the triathlon world championships.

Some older british cranks like the one in the photo above are in inch sizes. Although using cranks 170mm and under is better spending time with a bike fitter to find your optimum length is key. Phil cavell cyclefit director bike fitter on the trek factory racing team. Some bike fitters will have an adjustable crank so the pedal can be moved to simulate crank lengths from 155 185mm.

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. Femur length in inches should be the same as crank length in cm alternately femur length in cm divided by 2 54 equals crank length yields the same result this is based around the idea that the upper leg is the major lever when applying force to the pedals and that the lower leg is the connecting rod and plays little part. It was just a number however. Should i get a bike or a new crankset with 170 mm arms or 175 mm arms.

You can try this during a bike fitting. Almost all crank lengths are multiples of 5 mm making super accurate measurement unnecessary.