sram groupset compatability
 

is there any huge reason I couldn't use a long cage sram force 1 rear derailleur with a 34x46 crankset? Has anyone tried to do such a thing? or use any mountain bike derailleur with sram force levers? I'm trying to build a low range of 34x36 or 34x40 if possible.

The "X-Horizon" design (straight parallelogram) used in SRAM's 1x RDs is not designed to work well with a double crankset. Road ("Exact-Actuation") compatible 2x MTB RDs would include X7, X9, X0, and GX 2x10 (NOT 2x11 -- that's only compatible with MTB 11-speed shifters).

The SRAM road 1x rear mechs aren't designed for use with 2x cranks. If you're using 10-speed shifters you can mix/match road and mtb mechs and shifters.

Is the inverse true as well? Older DR's not made to work with 1x cranks?

so there's no decent way to have a 2x system under sram that would handle the range i'm looking for

Does it have to be 11-speed? What's the cassette range that you need?

It doesnt HAVE to be, but i already have the groupset was hoping i could just grab a new cassette and derailleur instead of shifter,cassette,derailleur

The 2x RDs (especially the clutched "type 2" versions) actually work quite well with a 1x setup. There is a slight chance of ghost shifting when things get really bumpy -- that's what the X-Horizon is intended to address -- but for most that's not a big problem. I've used an X7-2.1 in a 1x setup for a couple years and it has worked very well.

All the options I mentioned will work fine with the 2x11 setup you described. Number of speeds is determined by the shifters, not the RD. The RD just has to be able to move the correct distance with each shifter "click" (that's what the "Exact-Actuation" refers to).

so i could use a sram mountain bike derailleur you listed and it would be fine? If so, I totally misunderstood your comment lol.

Correct. Any 2x SRAM RD (road or MTB) labeled "Exact-Actuation" will work with 2x11-speed SRAM road shifters & 2x crankset (even if it was originally for only 9 or 10 speed). Any RD labeled "X-Actuation" (all 11-speed MTB RDs) will not.