SRAM Crank compatibility question
 

Building up an Alchemy Atlas frameset that came with a DUB BB installed. Shifters and derailleurs are 11 speed SRAM etap, sourced here. Was going to do an Easton crank, but thought that maybe just picking up something SRAM might be easier. Will a 12sp crank work with 11? What are some good options for a 2x build with compact chainrings? I suppose that I should look to see if the BB is what TPC says it is...

TIA,
-Ari

I would not run 11 speed with 12 speed AXS chainrings, however you should be able to find a 110 bcd 8 bolt spider that you can attach to the dub crank arms to run 11 speed chainrings.

I've run a red 22 chain on an AXS 42T chainring for SSCX without an issue, however, the switching of gears would be the issue.

SRAM makes tons of lower geared 2x chainrings, but the mounting is specific to their crank arms.

+1. Just watch out if you buy a sram 12-speed crank. If you move down to rival the 1x crank is 8-bolt direct mount (adapter compatible) but the 2x is 107 bcd only. Force/Red look like they are direct mount only so you could use a 110/130 bcd adapter with those as well as the rival 1x crank.

The Force/Red D1 crank arms are being phased out in favor of the newer D2 version so you can find some pretty good deals on those if you look around. I was in the same boat recently but am running 1x. I decided to go with a 110 bcd adapter so that I'm not locked into Sram's proprietary 107Bcd if I move to 12spd in the future.

Current setup is Force D1 Crank - Quarq 110 Bcd PM - Sram 11speed CX1 Ring

Force and Rival D1 cranks have plastic covers that are prone to cracking. Some owners have had multiple replacements. I much prefer Shimano BB function, but use wheels manufacturing BBs with angular contact bearings.

I've been using Shimano GRX cranks, but the chain line does need correction with spacing washers to get a normal road bike chain line. With the new 12 speed models out, the remaining 11 speed models are heavily discounted. I bought new 12 speed models recently, at significant discounts.

Thanks for all of the info and ideas, when cranks are listed as BB30/PF30 instead of GXP, is it safe to assume this means that they are DUB -compatible?

-Ari

No. Pf30 is a 30mm spindle. Dub is a 29mm spindle.

Do SRAM cranks come in 3 versions then; GXP, DUB, and PF30?

Yes. And the BB30/PF30 cranks come in different spindle lengths too.

Well, not all cranks have been available in these different spindle types, but yes, there have been SRAM cranks with GXP, DUB and BB30/PF30. Also note that SRAM cranks labeled BB30/PF30 may different spindle lengths; some have a shorter spindle that only work with actual BB30/PF30 BB shells, and others have longer spindles that also work with other BB shell types such as BB86/386, BSA, and T47.

Older models of SRAM cranks tended to come in both GXP and BB30/PF30 versions, whereas new models tend to be DUB only.

Not for 12 speed. It's 100% Dub now. You buy a compatible dub botton bracket for PF30, T47, GXP, etc and then a dub/axs crank which either comes in wide or narrow. The crank is the same for all three.

Although if you have a bike that is currently gxp stay the f away from dub since the way they made it work is an engineering hack.

12-Speed GXP cranksets exist, I have some.

Looks like sram might have made a some gxp axs at some point. At least according to their official product pages it's all dub now.

Any tips or tricks for determining if the existing BB is DUB or BB30? Might be hard to measure if the difference is only 1mm between the 2 types.

This looks like a good crank option for this project:

https://www.coloradocyclist.com/sram...speed-no-bb-c2

If it's a sram-branded bottom bracket they look very different. Maybe you could share a picture.

If it's another brand, you probably need calipers or a dummy axle to test if it fits.