And for all of you 180mm crank arm afficionado's, here's an excerpt from this week's RBR newsletter:

One rule of thumb says this about matching crank length to leg length:

---Inseam to 31 inches, use 170-mm crankarms
---Inseam 31 or 32 inches, use 172.5-mm crankarms
---Inseam 33 inches more, use 175-mm crankarms

You'll also hear recommendations to use longer cranks to increase power. Does that work? We're sharing Dr. Baker's answer from Bike Fit in this week's eBook excerpt.

CRANKARM LENGTH

There has been much debate, considerable empiric evidence, and little convincing scientific study to support the above length recommendations.

Track riders generally choose crankarms up to 5 mm shorter and mountain bikers up to 5 mm longer than the above recommendations.

Shorter crankarms allow for faster cadences and improve cornering clearance on
velodromes and in criteriums.

Although longer crankarms have been favored for hard steady efforts such as time trialing, hill climbing and mountain biking, studies have shown that they change torque, not power -- they require the rider to pedal a larger circle.

In time trialing in an aerodynamic position, longer crankarms mean that the rider closes the hip angle, reducing power.

(Tip! The length of most crankarms is stamped on the back.)


I've got the Arnie Baker "Bike Fit" e-book and it's a bloody good read. Covers all elements of bike fit (not just simple sizing formulas). Get it from RBR.