semaforo

Hi All,

I have cyclocross bike with 36-46 crank and 105 leavers 11spd short cage derailleur and 11-28 cassette, but I want to climb more confortable.
I would like to use 11-32 or bigger cassette, is it possible with current derailleur? do I need the long cage one?
or is it that I can put a mtb xt derailleur and cassette for 11sp 11-40 to match current 105 leavers?

thanks for your comments.

mstateglfr 

Options-

- You can try to use your current RD as 4 teeth beyond stated capacity can still work, but it isnt a certain. If it works, great. If it doesnt, then just get the 105 GS RD.
- If you get a new RD, look into an Ultegra RX RD or a GRX RD. Both are clutched which reduces chain slap. Obviously a 105 RD is fine too. Pair the GS RD to an 11-36 cassette.
- You can just change your 36t inner ring for a 34t inner ring. If its a Shimano crank, those replacement 34t rings should be $15-20 online. That will help give you easier gearing.
- Buy a different crankset- like a 46/30 or any of the other subcompact ones that are 48-46t for the big ring and 30-32 for the small ring.


You cant put an XT RD on because XT MTB RDs dont properly shift with 11sp road shifters due to different pull. You can kludge together a working system by using a Wolftooth TanPan to convert the road pull into the MTB pull. But why do that when you can just use a road GS RD and which can handle an 11-36 cassette?

Bob the Mech

This topic just covered something similar https://www.bikeforums.net/cyclocros...-says-34t.html

justin1138

I've got an 11-32 cassette with the short cage 105 derailleur on my road bike right now. Works great. With a larger cassette I'd go with the advice from mstateglfr

Badger6

As stated above 11-40 can be made to work in a "road"* oriented set up, but it's not ideal. It will require using components out of spec, and there are plenty of folks who have figured it out, but when you go out of spec that far you are inviting other issues. You may be able to get to a 11-32 with an SS RD, but 11-34 or 11-36 almost certainly will require a GS cage for reliable operation. You may be able to swap cages, rather than whole RD. But, as also noted, login up to an Ultegra RX or GRX RD with a clutch may be a better option because you can eliminate most of the chain slap that a standard RD will experience on rougher gravel.

How much lower do you really need it to be? I know that 11-40 sounds like a super low gear ratio paired with your current chainrings, but if you use the www.gear-calculator.com and plug in your current gearing, you'll find that it isn't a whole lot lower than an 11-36. My point is that for the 3 fewer gear inches on the lower end of 11-40, you're going to be cobbling together something that will likely be very finicky to adjust, when you could go with 11-36 that is out of spec, but not so far that you're going have issues. If 11-36 is not low enough, follow the advice of swapping your 36t small ring out for a 34t ring, and at that point you'll be 1.3 gear inches longer on the low end than if you retained your current chainset and paired with an 11-40.

Bottomline, use the gear calculator to see the effect of the various ratios. I am confident that you can get a much lower climbing gear without resorting to extreme measures, and inviting all sorts of other potential issues that could make the shifting really problematic.

Kanon25

46-36 is too close and not a good choice. Put in a 46-30. And then an 11-32 cassette which will fit fine on that derailleur

caloso

I'd try a smaller small ring like a 34 first. You may not even need to resize the chain.