Your Guide to Common Bike Terms

Brush up on your cycling lingo and stay in the loop.

Ever wonder what all the numbers mean that riders throw down in the peloton?

"I just switched out my 58 SuperSix with Nine G wheels, a 12-25 and a 54/39 up front," says rider number one. "And now I climb cat-threes at 156 max in a 39/21."

"I can't push a 25 on anything steeper than eight percent with 172.5 cranks," says rider number two, "...unless I'm running a compact crank—and then I just drop it into the 36 and motor. Are you spinning 175's?"

Of course, every cult has to have its secret handshake, and ours is a jargon of numbers and techno-babble that is tossed between interested members of the peloton when the pace settles in at 150 bpm. For those new to the game, we offer the following Cliff notes:

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130 BCD (Bolt Circle Diameter): The diameter of an imaginary circle that intersects the center of each chainring bolt on the crankset. The standard is 130 millimeters; Campagnolo uses 135 millimeters. 110 BCD is typical for compact cranksets.

172.5 Cranks: Crank arms are measured from the center of the bottom bracket to the center of the pedal axle. Available crank lengths range from 165, 170, 172.5, 175, 180 to 185 millimeters, with the accepted standard being 172.5 millimeters.

10-Centimeter Extension: Refers to the length of the handlebar stem between the center of the fork steerer and the center of the handlebar. A 100-millimeter stem is the same as a 10-centimeter extension.

Five degrees of float: Refers to the amount of angular play built in to clipless pedals between the cleat and the engagement mechanism. Pedals that have "float" allow the cyclist's foot to self-center in the pedal.

59-centimeter top tube: The length of the toptube (or an imaginary line) running from the center of the frame's head tube to the center of the seat tube intersection. Because many frames have sloping toptubes, the correct method to measure the toptube's length is level with the ground, along an imaginary line from the center of the frame's head tube, just below the upper headset race, to a line extended through the center of the seattube.

BB30: A 30-millimeter diameter aluminum bottom bracket axle with oversized bearings that are pressed directly into the frame's bottom bracket shell. BB30 was pioneered by Cannondale and spearheaded by FSA.

BB30 has gained popularity with carbon frame producers like Specialized, because the system eliminates threads and uses larger, more durable bearings than threaded, cup-type bottom bracket types. Because BB30 uses the narrow, 68-millimeter bottom bracket housing (instead of the 90-millimeter overall width of present external types), the crankset can be tucked away from the rider's feet and the pedals can be moved closer to center, which is considered optimal.

120-millimeter bottom bracket: The standard width of the crankset's bottom bracket axle.

Three-cross drive-side spokes: When a spoke on one side of a wheel crosses over three of its neighbors on the way to the rim, it's called a three-cross pattern. Most pro-level wheels use a combination of two-cross spokes and "radial lacing" where the spokes radiate at 90 degrees from the hub and do not cross.

Bigger gear (or taller gear): Shifting from the small chainring to the large one, or shifting from a larger cog to a smaller one. Bigger gears for speed—smaller gears for climbing.

44 handlebar: The width of a handlebar is usually between 42 and 44 centimeters measured from outside to outside the widest part of the drops.

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