Alpine double - what's that then?

[Valbrona]

Looking at this another way, the big ring of a SRAM MTB double chainset is at 52.5, the small ring is at 44.5 the chainline of a Shimano road triple is 45mm which given the 8mm spacing mentioned above puts the big ring at 53mm. So the chainline for a SRAM MTB double is very similar to that for the outer and middle rings of a Shimano road triple. I'd certainly not be losing any sleep over the chainline.

I'm not sure what sort of frame the OP will be using, but given that these days many frames use 135 OLN (rather than 130) to use disc brakes, then there is a good chance that the cassette will be an extra 2.5mm further out, improving the chainline a little when using an MTB crankset.

It is interesting that SRAM now produce a "wide" version of their road doubles for use with bikes with 135 OLN which moves the big ring chainline out by 2.5mm to 50.6mm (v 52.5 for an MTB CS) and the inner ring to 42.9mm (v 44.5). Which means for a 135 OLN setup the difference road to MTB is 1.9mm for the big ring and 1.6mm for the small, considerably less than one sprocket.

Chainline isn't the problem. The fact that your feet are 2cm wider apart with SRAM MTB compared to SRAM road is. Maybe okay though if one just tootles along.

[gloomyandy]

Chainline isn't the problem. The fact that your feet are 2cm wider apart with SRAM MTB compared to SRAM road is. Maybe okay though if one just tootles along.

See my previous post. I regularly ride a road bike with both SRAM road and MTB chainsets and don't notice any real difference between them. The MTB equipped bike I use all winter and happily ride regular club runs with no problems. Perhaps some people are particularly sensitive to Q factor? Have you tried it for any length of time? What issues did you have?

[mnichols]

At the risk I highjacking my own post, is there such a thing as a Cyclocross groupset?

[rotavator]

Yes, I think the usual ring sizes on a cyclocross chainset are 46T and 36T, like this:

http://www.wiggle.co.uk/shimano-ultegra ... yclocross/

[mnichols]

Yes, I think the usual ring sizes on a cyclocross chainset are 46T and 36T, like this:

http://www.wiggle.co.uk/shimano-ultegra ... yclocross/

That's an odd combination. The small ring is no smaller but the big ring is. I can't see the point?

[mnichols]

Vanilla bikes are selling the SRAM Rival Groupset with a 36 cassette, but other sites say that the limit is 32. Anyone know which it is?

https://www.vanillabikes.com/products/sram-rival-22-groupset?variant=822997621&dfw_tracker=977-822997621&msclkid=62fdfd5fcd2a1153c4b6a763d94ab8e9&utm_source=bing&utm_medium=cpc&utm_campaign=Vanilla%20Bikes%20-%20Shopping%20-%20UK%20-%20Models&utm_term=4579534649911913&utm_content=DFW%20-%20UK%20-%20Models

Also, would I be able to combine with a spa 46/33?

https://www.spacycles.co.uk/m2b0s109p3070/SPA-CYCLES-TD-2-Double-Chainset-with-Zicral-Rings

Or even

https://www.spacycles.co.uk/m2b0s109p3383/SPA-CYCLES-TD-2-Super-Compact-Chainset-with-Zicral-Rings how low could i go

The frame is an Enigma Etape 56

[mattsccm]

Remember, cyclocross doesn't need low gears or usualy high ones so 36/46 makes sense.
Don't confuse cyclocross with riding a drop barred bike off road. Its flat out racing.

[gloomyandy]

The medium cage rival rear mech is not specified for use above 32 tooth sprockets, it may work with a 36 but who knows. The 11-36 cassette is normally used as part of the Rival 1x system, but this uses a different rear mech (a modified MTB one), so you might be able to get that to work with a double chainset but again who knows.

I've never seen details of the maximum capacity for a SRAM rear mech given in the documentation from SRAM so it is hard to know how well they would work when using them with non standard chainsets. When I was putting my bike together I looked at what some of the bike manufactures were doing with their not so conventional bikes, to get a feel for what might work. So for instance at one time the Salsa Vaya was being fitted with very similar gearing to what I used, so I was reasonably confident it could be made to work. It is worth looking around to see what some of the makers of bikes like this are doing.

[RickH]

The medium cage rival rear mech is not specified for use above 32 tooth sprockets, it may work with a 36 but who knows. The 11-36 cassette is normally used as part of the Rival 1x system, but this uses a different rear mech (a modified MTB one), so you might be able to get that to work with a double chainset but again who knows.

I don' think you'd get a 1x to play happily with a double chainset - the mech has shunned the slant parallelogram design for a horizontally pivoting one with a very rearward offset top jockey wheel. That means it need the chain takeup pulling the bottom of the mech far enough forward to to make the top jockey wheel drop to give clearance on the bigger sprockets (At least that's how I think it works! Speaking purely as an enthusiastic amateur rather than a professional -I can take things apart, I can put them back together & I can keep the leftover bits somewhere safe...)


(You can see here how far behind the cage pivot the top jockey wheel is)

Will the fact that the jockey wheels have alternating narrow-wide teeth, like 1x chainrings, cause further complication or not?

[gloomyandy]

Hmm yes I suppose that with that offset pulley using different chain rings will result in a different spacing from the sprockets to the top pulley which is probably not a good thing.

A safer bet would be to use the MTB 2x10 GX or X5 rear mech (which should work with 11 speed road as it shares the same exact actuation cable pull as the 11 speed road system - unlike the 11 speed MTB mechs). Note that if you do use a SRAM MTB rear mech you will need a cable adjuster in the system as the rear mech does not have one (unlike the road rear mechs). Note though that I've only used 10 speed not 11, with this sort of setup.

[elPedro666]

Remember, cyclocross doesn't need low gears or usualy high ones so 36/46 makes sense.
Don't confuse cyclocross with riding a drop barred bike off road. Its flat out racing.

I think they all (Shimano, Campag, Sram) make CX groupsets - Shimano conveniently denotes them CX50 (Sora/105 level) & CX70 (105/Ultegra) - but agree they aren't really chasing the same goal. A friend who races cx fairly seriously uses something like 39/44 so that he has rarely has to mess with the front shifter and doesn't have a large jump in cadence to interrupt power delivery.

CX is very much a wonderful world of its own! Which isn't to say that parts aren't useful elsewhere - the top-pull front mechs especially can be really useful.

22/36 (mtb kit) shifts easily for me, reckon 20/38 would work fine too.

Second the recommendation for the N-Gear Jump-Stop too; far superior to the Dog Fang things that just get chewed up and knocked out of place.

I'm a trendy consumer. Just look at my wobbly using hovercraft full of eels.