r0gue

Posted this in the wrong section first. I think this is a better location. Can you help?

I just picked up an older used frame that I like, and it fits me, and... threaded BB shell. It came with some serviceable 105 on it, and I can ride that for a while with no problem. But I have a nice SRAM Red group that I'd love to use if I can. But it's got a BB30 crankset. I searched about but this voodoo is confusing me. I thought about buying a SRAM Red GXP crankset, but it seems they're all 22 speed now.

I'm wondering, ..Is there a good adaptor technology? -- or should I avoid that path at all costs?

Thanks!

SkyDog75

No, you can't install a BB30 crankset on a bike with a threaded bottom bracket shell. The shells are the same width, but the threaded shell is smaller in diameter. You can't mount bearings big enough for the 30 mm spindle inside the threaded shell. You can't mount the bearings outboard because it would require a longer spindle.

There's nothing to stop you from using the 105 crankset & bottom bracket with the rest of your SRAM groupset, though.

r0gue

It has crossed my mind to try to figure that out. The only concern I'd have is the 105 is the new 22 speed stuff. But perhaps the teeth and gear spacing are the same? Actually, now that I say that I recall the chain is different huh? My Red is 10 sp, the the 105 is 11.

SkyDog75

According to what I've read, 10 speed cranks generally work fine in otherwise 11-speed drivetrains and vice versa. Here's a link to a Q&A written by Lennard Zinn, who's a pretty well-regarded wrench in the cycling world:

Technical FAQ: 10- and 11-speed drivetrain component compatibility - VeloNews.com

Dilberto

Cannondale only makes a BB30 shell reducer to standard 24mm spindle size, via a threaded, reducer sleeve pressed into their own BB30 shells. Or, simply go BB30 bearings and get Wheels Manufacturing adapters, allowing you to run a Shimano Hollowtech II, FSA MegaExo, Race Face X-Type and SRAM GXP cranks:

SkyDog75

You can mount cranks designed for threaded bottom brackets on a BB30 frame via an adapter, but it doesn't work the other way around. The original poster is looking to mount a BB30 crankset to a frame with a threaded bottom bracket shell, and there's no adapter for that.

HillRider

IIRC, I recently saw mention of an adapter that threads into an English bottom bracket shell but allows 30 mm crank spindles with external bearings. It was called something like "English 30". A Google search didn't turn up anything but I do remember seeing it mentioned somewhere.

SkyDog75

BB30 is 68 mm wide, as is an English bottom bracket shell. If you mount external bearings to an English threaded shell, it's now wider than 68 mm and thus too wide for a BB30 spindle.

You can use a crankset with a 30 mm spindle along with a threaded bottom bracket shell, but not a BB30 crankset. A 386 EVO crankset has a 30 mm spindle and is designed for a shell that's 86.5 mm wide. That extra shell width means the crankset's spindle is longer, allowing space for outboard bearings on a threaded bottom bracket shell.

r0gue

This is super interesting. So 11 speed drivetrain cranksets can run 10 speed chain with a 10 speed front derailleur. It seems to me he is saying that as well.

r0gue

As I read this, he has used 10-speed cranks and chainrings on many 11-speed road bikes without a problem. But he has not used an 11 sp crankset with 10 speed derailleurs and drivetrain. That said, I think it should carry through. I am likely to try this.

Dilberto

Correct. The only solution is to buy a BB30-specific frame.

r0gue

I've definitely from this an other sources taken that you can run a 10 speed crankset on otherwise 11 sp drivetrain. I believe that I can run 11sp cranksets with the derailleur of a 10 sp group (throw would be the same. Diameter of rings... what else is there?).

My current question is chain. I read somewhere a statement that through doubt into my mind. It seemed to suggest that if the crankset was 11sp (even when the rest of the group is 10 speed) that you'd want to stick with 11 speed chain.

Thoughts please?

SkyDog75

Match the chain to your cassette.

Reading Zinn's articles on 10/11 compatibility, There's no spacing difference between 10 & 11 speed chainrings (at least with SRAM), therefore that spacing will work with either chain. Cog spacing *is* different between 10 & 11 speed cassettes, though, so choose your chain to match your cassette.

FastJake

No need to use an 11 speed chain. 10/11 speed cranks are going to be virtually identical and possibly exactly the same. You can use an 11-speed crank with an otherwise 10-speed drivetrain.

dr_lha

That kind of depends on the crank. For example, a SRAM Force22 BB30 crankset can be mounted on a English threaded frame with a "BSA30" adapter like this one:

Threaded to 30mm ABEC-3 BB - Black

Because it has a longer spindle than a "regular" BB30 crank. See this photo for reference:



However, SRAM Red cranks have the regular spindle length (for now) so will not work.

r0gue

So my plan now is to run a complete SRAM Red 10sp system including the chain, with the exception of the crankset and BB. Those will be Shimano 105 in 11sp. For clarity, the front shifter and derailleur WILL be SRAM Red operating SRAM Red chain on a Shimano crankset.

From what I'm reading here and seeing linked up here, it sounds doable. Am I missing anything?

ThanKs!

FastJake

Sounds good to me.