Disc brake rotor sizes (silly Q alert)

This may be a dim q, but here goes…

If you have a (road) frame currently running Shimano ultegra rotors 140mm front and back (flat mount), and you wanted to put a SRAM groupset on it which came with 160mm rotors, what are your options?

Can you just use the existing Shimano 140mm rotors in the SRAM calipers (as a friend is adamant they will), or do I need to swap for 140mm SRAM rotors? I know that a 160mm will go in the fork (pretty sure I just flip the mounting bracket the other way up), but the frame manufacturer states “140mm is the maximum recommended diameter for the rear but a 160mm will go” - make of that what you will!

Best solution here folks?

Check with your Frame Manufacture.

Frames are designed to be either 140mm or 160mm from the get go.

Some might say adapters are all you need. I still say check with the people who designed and built your frame.


The rotors are cross-compatible. When new, Shimano rotors are 1.80mm thick, and SRAM centerline rotors are 1.85-1.90mm thick. I’m currently running SRAM Centerline X rotors with Di2 setup on my 2020 Domane and it works great (I just think the CLX rotors look better :grin:).

As far as changing rotor size, yeah, I guess check with the frame manufacturer, although if they state max=160mm dia, you can use that, I reckon.

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Excellent, thank you. So basically I can just leave the 140 mm shimano rotors on and crack on?

Yep, although make sure the brake pad compound of the old brakes is the same as the brake pad compound of the new brakes, otherwise you may have issues with noise and sub-optimal braking. The pads should have a number on the back. You can Google that number to find out what the old compound is.

If you’re changing compound, I would advise to change rotors too, and re-do the break-in etc. I suppose you could sand the old ones down and re-use them, but I haven’t had that process work.

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