T47 Bottom Bracket
T47 bottom brackets are fairly new to all of us. Two advantages of the T47 system are that it can be used across a large spectrum of frames and with almost any crankset. Wheels Manufacturing currently offers T47 cups with either inboard bearings or outboard bearings. Both types of cups can accept 22/24mm GXP spindles, 24mm spindles from Shimano, FSA, RaceFace, etc., 29mm SRAM DUB, and 30mm diameter spindles. So how do you determine which T47 bottom bracket to use?
Choosing the Right Bearing Diameter
Start with the crankset to be installed in the bottom bracket. Choose the bearings that work with the spindle (30mm, 29mm, 24mm or 22/24mm). On the our T47 bottom bracket page, you can filter the BBs shown by Crank Spindle Diameter to narrow down your choices.
With any bottom bracket, the wider the bearing stance you have, the more durability you will get out of the bearings. Select BB cups that position the bearings on the spindle as close to the crank arms as possible. Crank spindles come in a number of different lengths, so taking proper measurements will point you in the right direction. The most accurate measurement is going to be from the inside face of one crankarm to the inside face of the other with both arms attached to the spindle. This is the usable space on the spindle that the frame plus bottom bracket can fit into.
If you have a customer with a creaky metal PF30 or 386EVO frame you may be able to run T47 taps through it and install a more secure T47 bottom bracket.
T47 is Adaptable
Because each cup independently threads into the frame, T47 cups can be used on any width bottom bracket shell from 68mm to 132mm wide. The determining factors for which T47 bottom bracket cups to use are the width of the shell and the length of the crank spindle. For more information on how to determine the proper T47 bottom bracket for a frame, click HERE.
The most exciting development is that Trek has begun to build frames with T47 shells. The Domane frames are built around T47 shells, some of them shipping with Wheels Manufacturing BBs installed.