Most of us want our bikes to go as fast as possible. We check to make sure our wheels are spinning freely, our brakes are not rubbing, our chain is lubed, our pedals are good, and our shifters work properly.
However, even those cyclists who are pretty diligent about bike maintenance often overlook one key item: the bottom bracket.
Some of you are wondering, "Do I even have a bottom bracket? And if I do, where is it? (See previous blog post at http://bbandbbq.blogspot.com/2011/08/bottom-bracket-upgrade.html).
The bottom bracket is the set of bearings for your crankset. If your bottom bracket bearings are worn out or need service, you likely have a source of friction that is robbing you of power. So, how do you tell if the bottom bracket needs service?
First, start by removing your chain from the crankset. The easiest way to do this is to shift to the
smallest ring on your crankset and then reach down and move the chain off of the teeth and let the chain rest on the bottom bracket shell on your frame. Then, with very light pressure, gently turn the crank. If you feel a slight hesitation like a bearing is sticking every few degrees of rotation, then you need to replace the bottom bracket.
The sticking is caused by "indexing" of the bearings. This is where the ball bearing makes a slight
indentation in the bearing race.
The good news is this is a cheap fix. A new bottom bracket is about $25 and installation is about $20 at the shop. If your bike is over three years old, there's a good chance that this needs to replaced. The great thing about the modern bottom brackets is that they are all based on sealed cartridge bearing and need no further adjustment or lubrication. Ride it until it wears out and then replace it.
Ride fast, ride far, and be careful out there.