A Useful Thing To Know About Shimano Cranks 

from Rookie’s keyboard,

Hello, friends

Today, I am going to tell you a little-known peculiarity (at least among rookies) about Shimano’s cranks.

Here’s the thing…

I learned the hard way that only Shimano’s square taper cranks can be used with a SRAM bottom bracket. The rest of SRAM’s BBs are proprietary and thus incompatible.

To understand what the issue is, we have to start with the basics. 

The bottom bracket is a system of bearings and cups threaded or pressed into the frame (the part of the frame where the BB resides is known as the bottom bracket shell).

The BB of a bike has one purpose only – to allow smooth rotation of the cranks with no play.

The cranks are the “levers” through which the rider transmits force to the chainring.

Modern BBs have external bearings sitting outside of the BB shell.

The benefits of external bearings are:

  • Unrestricted size since they don’t have to fit inside the shell.
  • Spindles of greater diameters thanks to the larger bearings size.

SRAM GXP Bottom Bracket

SRAM GXP bottom brackets operate with a spindle that’s 24mm on the drive side and 22mm on the non-drive side. 

Modern Shimano cranks have a spindle with a 24mm diameter on both sides.

Ergo, a Shimano crank cannot fit through the non-drive side of a GXP bottom bracket.

The image above illustrates the reduced spindle diameter of SRAM’s GPX cranks.

Cranks designed for bottom brackets with external bearings come with a spindle that’s press-fitted into the drive-side crank. Therefore, it’s not possible to replace the original spindle.

You can’t use a SRAM crankset with a Shimano BB by default either asthis combination faces the same problem – dissimilar spindle thicknesses. 

However, in this case, the spindle can fit through the bottom bracket because it’s slimmer on the non-drive side. And if you can find an adapter reducing the non-drive side part of the bottom bracket from 24mm to 22mm, the combo becomes viable.

SRAM DUB Bottom Brackets

SRAM DUB bottom brackets aren’t compatible with Shimano either as they’re designed for a 28.9mm spindle and make for a poor, unstable fit.

Square Taper For The Win

Square taper bottom brackets are often hated, but I consider them awesome.

SRAM square taper bottom brackets can operate with any square taper crank. 

That said, the crank should correspond to the bike model. In other words, you need road cranks for a road bike and MTB cranks for MTBs and hybrids.


If you have Shimano cranks with non-compatible SRAM BB, the solutions are:

  • New cranks

The first option is to get SRAM cranks compatible with the bottom bracket in question. The benefit of this approach is that it doesn’t require the removal of the old bottom bracket. The downside is the extra cost.

  • New bottom bracket

The other approach is to get a new bottom bracket compatible with the frame and the cranks. The advantage of this choice is that a bottom bracket is cheaper than a set of quality cranks.

The con is that you will have to remove the old bottom bracket and install a new one. 

If you pay a bike shop to perform the conversion and install the cranks, the final bill could be relatively high in comparison to the bike’s value.

Thus, you will truly save money only if you do the work yourself. 

Make sure that the new and the old bottom brackets attach to the frame the same way. If the bottom bracket is threaded, the new one should be too. If it’s press-fitted, the new one should rely on the same retention method.

Until next time

– Rookie






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