Alias530

Or would I be better off just getting a CX1 crank?

I just figured it might be nice to have the option to throw on a front derailleur and run 2x11 if I don't end up liking 1x11. I run 1x11 on my mountain bike but a 10-42 cassette covers way more range than an 11-32 so I might want the other ring up front.

I'll be running Ultegra shifters/rear derailleur so the fact CX1 can't run a front derailleur won't matter the frame I'm getting is BB30 and I don't want to run an adapter so I'll be using a SRAM crank.

ColinL

It'll work, but your chainline will be different. Let's talk about that first and then about 2x vs 1x spiders.

Check out this doc. It says that the 2x11 big ring is 48 mm from center and the 2x11 inner ring is 40 mm. The 1x11 ring is 43.7 mm, which is unsurprisingly right in the middle of the inner & outer rings on the 2x.

But wait! Sram road cranks might be still optimized around a 130 mm road bike rear end. So which chainline is better for a particular 135mm CX frame? I honestly don't know. It might be best to email/FB post/tweet/call the reseller or manufacturer to get their opinion.

But what I do know is that if your crankset chainline is too narrow, you get a lot of chain noise in small cogs. If your chainline is too wide, you get a lot of noise in large cogs. On a bike with a front derailleur, the chain could rub on the derailleur cage when cross-chaining. On a 1x bike with a narrow wide ring, you get more noise from the chain itself because the NW ring keeps the chain going in a straight line for a while after it comes off the ring. The sideplates of the chain get a lot of load.


Ok... so about 1x vs 2x sram cranks. All the X9 and higher MTB cranks, the Rival 1 road cranks, and Force or higher have removable spiders. Generally you can buy 2x or 3x spiders, but the 1x Force CX1 spider is not in the 2015 spare parts catalog! (A pessimist might say that sram wanted to make sure CX riders bought the whole cranks, and not just the spider for their existing 2x sram cranks...) So what really makes a Sram crank is the length of the spindle that is pressfit onto the drive-side crank arm.

So, if you think you might run 2x11, or if you learn that your frame will work better with 48 mm chainline that is a good reason to buy Red cranks. If it's better with 43.7mm, buy the Force 1 / CX1 cranks.

Alias530

Good answer!

I wonder if anyone knows which side of the hub gets wider with the jump from 130 to 135? That might help pick... The CX1 cranks are half the cost of Red so I might just go with those. Anyone think it's weird to run SRAM cranks and Shimano everything else? Shimano just doesn't really sell lightweight cranks...

MudvilleStomper

Great answer. However, I thought the Force CX1 chainline was based on the chainring that is designed to go on the outside, but is offset so as to be more towards the middle of the inner and outer rings.

ColinL

Both sides get wider by 2.5mm (half of the 5mm) on nearly all frames. There are a few bikes with asymmetric chainstays but those are very rare exceptions. I can't guess as to whether the Red outer ring of the Force single ring would be better on any given 135mm frame.

Nothing too weird about running Sram cranks and bottom bracket with Shimano everything else. BTW if your new frame has some kind of pressfit BB, you might want to consider installing a Praxis Works conversion bottom bracket and using GXP threaded cranks.

ColinL

Force CX1's chainline, in my opinion, was probably built with a 130 mm road rear axle in mind. Because that's what >90% of cyclocross bikes on the market in 2014 (when it came out) were using.

So, I think this is an intriguing question. Using the outer ring of a 2x might indeed be better.

BUT - buying the 2x 110 BCD spindle is not that expensive. So that's another reason to buy the Force 1 cranks and save money now.

ColinL

Here's the Sram 2x10 110 BCD spider. I researched this previously because I was looking to put MTB cranks on a MTB hardtail frame with road gearing. (I ended up buying the wide S series cranks instead and there's a thread on it.)

This is also what you would use to convert a Force 1 crank to 2x.

New SRAM Spider for S900 Crank BCD 110mm 10 Speeds Black 11 6115 547 010 | eBay

It's PN #11.6115.547.010

MileHighMark

No problems here running Force (CX) 1 with 135mm rear spacing.

FlashBazbo

I'm running Red 22 cranks (Quarq) with a Force1 chainring up front. The rear is 135mm spacing and I'm using a Shimano XTR Di2 rear derailleur with 10-40 cassette. The combination works great -- the Force1 1x chainring and SRAM 1x chain help a lot, but the XTR clutch probably helps, too. Silent running and completely reliable. I never miss the other ring on gravel grinders.

Fattrucker

Sorry to resurrect an old thread but this is the closest (via search) that I have found to my problem .

Does anyone know of a BB30 2x 104/64 spider that would fit on the CX-1 crank arms ?
As I have found out , not all SRAM BB30 spiders are compatible (Who would have thought ? LOL)


TIA

P.S. Chain line is of no concern as I can adjust for it .

P.P.S. Sorry guys , Hi. Perhaps I should have done an introductory first

Fattrucker