Bolt Circle Diameter (BCD) is the diameter of the circle that goes through the center of all of the bolts on your chainring. On bicycle chainrings, this dimension is usually measured in millimeters. It is critical to know the BCD of your crankset when you are selecting a new chainring for your bike.
What is compact crankset?
A compact crank refers to a road bike crankset with relatively smaller chainrings that can make pedaling easier. While ‘standard’ cranks come with a 53-tooth large chainring and a 39-tooth small ring, compact cranks usually feature 50- and 34-tooth rings.
Are smaller chainrings less efficient?
Bigger chainrings and cassette cogs run more efficiently than smaller ones but extreme cross-chaining can cancel out those efficiency gains. Bigger chainrings and cassette cogs run more efficiently than smaller ones but extreme cross-chaining can cancel out those efficiency gains.
Why do chainrings increase in mass when the BCD decreases?
When the BCD is decreased, the same tooth count chainring requires greater mass due to the increased distance between the bolts and the teeth. In order to maintain a certain degree of stiffness, material requires to be added thus also increasing mass.
Can I fit a 37T chainring to a 130bcd crankset?
We’ll be making our own proprietary chainring setup that can be retrofitted to any 130BCD crankset, including a 37T, providing the crankset spider offers sufficient chain clearance. With a 37T there really is no need for a compact, so that also saves on having to manufacture separate models and double the selection of chainring sizes.
What’s the difference between 37T 130bcd and 37T 110bcd?
Poor shifting due to flexier chainrings can really ruin someones ride experience. While achieving greater chainring stiffness, a 37T 130BCD will also be lighter than its 110BCD equivalent. In my view, those who prefer still smaller chainrings need not even consider 130BCD, let alone a high performance crankset.
