CYCLING PERFORMANCE TIPS
Last updated: 12/6/2009
Decisions on appropriate crank length are often steeped in mystique and
considered part of the "art" of coaching for the competitive
cyclists. Knee pain, especially chondromalacia,
is a common cycling complaint that can occasionally be an indicator that
your crank length is incorrect for you.
A few links that might be of interest:
Other issues that have might be considered (you can make up your own mind on
So if you feel more comfortable turning big gears at
lower cadences, you'll like your crank arms a little longer. But if you
prefer to spin at a higher cadence go with shorter crankarms.
- It has been recommended that competitive cyclists use shorter cranks than the normally
recommended to reduce the dead spot at the top of the cycle, from 9 to 12 o'clock
(viewed from the rider facing to the right) and to allow a shorter stroke through the strongest
leg movement. This would avoid having the knee bed less than 90 deg.
- There is data showing that the shorter the crank, the higher the cadence that is
possible (ultimately up to the rider). Shorter crankarms allow for faster cadences
and improve cornering clearance on velodromes and in criteriums. They also avoid the
effect of long crank arms to close the hip angle and reduce power - a benefit for
velodromes and time trials.
- An increase in crank length leads to an increase in the lever arm and the ability
to more force. Longer crankarms have long been touted as superior for hard steady
efforts such as hill climbing and mountain biking. But studies have shown that while
they change torque, power is unchanged and they require the rider to pedal a larger circle.
- Competitive cyclists ride comparatively smaller gears on the track in sprinting events
(as opposed to the road) to allow optimal cadence in the shortest time. This is especially the
case on banked tracks where the sprinter needs to changed direction suddenly at times. This facilitates
reaching optimal cadence in the shortest time ( accelerating out of the bends). The same effect
occurs with shorter cranks. The use of longer cranks allows for more leverage and so more power but
can lead to a dead spot at the top of the stroke for those with a less than perfect pedal
action & strength . In endurance events where the requirement for high cadence is not as great,
the extra leverage is of benefit.
If you change your crankarm length on your current set up, don't forget to
adjust your seat height as changing crankarm length will change the
distance from your seat to the lowest point of the crank cycle.
Here's a starting point for suggested crank lengths based on traditional
wisdom - you can start here and then tailor them (up or down) to your own
style and preferences:
54 cm or less
80 cm or less
55 - 58 cm
81 - 86 cm
59 cm or greater
87 cm or above
And from another source (referencing your inseam in inches):
Track riders generally choose crankarms up to 5 mm shorter and mountain bikers up to 5 mm
longer than the above recommendations.
- inseam < 29 inches - 165 mm crank
- inseam 29 - 32 inches - 170 mm crank
- inseam 32 - 34 inches - 172.5 mm crank
- inseam > 34 inches - 175 mm crank
And for those of you wanting to delve further into the subject, here is a link to a beta test
version of a Crank Calc
Program being developed by Nigel Jones of
To reinforce the above, here is a question posed to "Coach Fred" at
www.roadbikerider.com entitled "Do Long Crankarms Help Time Trialing?"
Question: I'm a 36 and a competitive triathlete, usually placing top-5 in my age
group. I use 170-mm crankarms but have heard that for time trialing, longer is better.
Is that true? -- Harold F.
Coach Fred Matheny Replies: There have been studies of crankarm length, but the
results aren't consistent. Some show that longer cranks provide greater leverage for
turning big gears. Some show that shorter cranks foster greater speed via a faster
cadence. And some show that crank length is completely individual. So, longer crankarms
aren't a panacea for time trialing. In fact, there are dangers associated with them.
The added length makes your knees bend more at the top of pedal strokes and extend more
at the bottom -- both of which can lead to biomechanical injuries if you jump from
170 mm to, say, 180 mm. Also, longer cranks reduce cadence -- and a brisk cadence is
the key to good time trialing. All this said, many time trialists use crankarms 2.5 mm
longer than those on their normal road bike. Because 2.5 mm (one-tenth of an inch) isn't
much, it rarely causes an injury. But the jury is still out on whether that bit of extra
length actually improves performance.
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suggestions to improve this page are
Cycling Performance Tips
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