Figuring Out the Type of Bottom Bracket Your Bike Has

The bottom bracket (BB) is at the core of every bike. It connects the cranks to the frame so they can rotate freely and turn the pedals. So, it’s the hero that turns your pedaling power into bike movement. There are three main types of BBs: threaded, press-fit, and T47. It’s super easy to find out what your bike has.

1. Check Your Bike Manual

Your bike manual should tell you the exact type and size of the bottom bracket that works with your frame. If you have it, great—the work is done! But maybe you aren’t the first bike owner or your manual got lost or thrown away. If so, keep reading.

2. Check the Bottom Bracket Shell

The shell is in the same place where the pedals connect to the frame. Look for markings or labels that tell you what type of bottom bracket is used. If there are threads, it’s a threaded bottom bracket. No threads generally mean press-fit.

3. Measure the Bottom Bracket Shell

Measure the shell with a caliper or bottom bracket tool. Different types of bottom brackets have distinct diameters. It’s usually 34.8mm for BSA, 42mm for BB30, and 46mm for PF30. BB86 (road bikes is around 41mm, and BB92 (mountain bikes) is 46mm. T47 is 47mm.

4. Get Professional Help

You might need more help with your bottom bracket. Visit a local bike shop or a trusted bike mechanic. They’ll figure out the exact type and size you need and give you brand recommendations so you can get the perfect fit!

Get More Help With Your Bottom Bracket

Still can’t figure out which bottom bracket to use on your bike? Visit us at Airpark Bike Co in Scottsdale or Phoenix. We’ll tell you the exact type that works and install it. You can also buy a new bike, other spare parts, and riding gear from us. Whatever you need for cycling, we’ve got, or we can order it for you! Call us or visit our shop today.