My bottom bracket is creaking. It might not be!

Is it, is the first question? Yes I know it sounds like it but is it really the bottom bracket? The challenge with bikes, especially carbon framed bikes is that noises tend to resonate through the frame. It only occurs when I pedal so it must be the bottom bracket! Not necessarily and quite often it is something else.

Let's dive into this a little deeper. Potential sources include the bottom bracket, pedals, chain ring bolts and freehub bearings. It could also include the saddle, seat post, chain, derailleur and shoe cleats. Some are easy to diagnose others require patience and some effort.

In order of priority the first thing to check is the bottom bracket itself. Most don't own the tools to remove a bottom bracket but that is ok for now. The first thing to do is to position the cranks vertically. Grab a crank in each hand and push hard back and forward to determine if there is any free play. Don't push in the direction of crank rotation, that is called pedalling, but push across the frame from left side to right side and vice versa. If it feels good then it could still be the bottom bracket but we will come back to that later. 

The most common area of drive train noises is the rear wheel and specifically the free hub bearings. The bearings are small, under load and susceptible to water ingress, The easiest way to confirm this diagnosis is to change the rear wheel. Borrow one from a riding buddy and give it a quick try. If it is silent, you now know where the problem is. If it still creaks and groans it could well be the bottom bracket. Either the bearings themselves or and this is often hard to diagnose, the interface between the bearing shell and the frame or the bearing housing and the frame. To check the bearings the cranks will need to be removed so that they can be inspected.

Before that there are a few other easy checks to make. Take the pedals off, grease the threads and install. check that chain ring bolts are tight. Saddles and seat posts often creak. If the noise only occurs when sitting you have the answer. However, be aware that a high power output while standing, can make the frame flex and creak but not so common.

Don't forget to check your cleats. Even if the cleat bolts are tight ride the bike for a couple of hundred meters with ordinary shoes. This process is all about eliminating what isn't causing the problem.