21667

hi all,

can i mix match MTB Shifters and RD (same brand and type) with Road Sprocket (Diffrent Brand, same 12 Speed)?
for example 12speed Shimano M6100 deore Shifter and RD, with 12Speed Road Sprockets?
or 11speed Shimano m5100 Shifter and RD with 11Speed Ultegra or 105 Sprockets?

i am building a hybrid gravel bike which is based on mtb parts. since nowadays MTB sprockets are too huge, especially for 12 speed.
i thought on changing the hubs and sprockets to road specific ones.

thx in advance for the reply

Badger6

If I understand your basic question, “using 12-speed MTB RD with 12-speed road cassette", yes it will work. The only issue you may run into is the B-screw adjustment, since the MTB RDs were designed for cassettes with really big low gear sprockets. Even fully backed off, the RD may not get close enough to your largest sprocket (innermost, aka the low sprocket) to allow for smooth shifting. In theory, however, it would work because it would be within the capacity of the RD.

21667

thanks for the reply,

i am worrying about the spacing between sprocket gears, since MTB 11Speed and Road 11Speed doesn't share the same sprocket lenght.
since i already have the 12Speed Deore M6100 Shifter and RD, i am hoping if ican use them on R8100 Ultegra 11-34T 12Speed Sprockets

shelbyfv

Shimano specs are 51t for both min and max large cog, FWIW.

21667

there are 45T for SLX, XT and XTR
i am not worrying about the B screw, i think i can forgive a bit sluggish on the RD side.
but i want to make sure that if the spacing between cogs are the same

if it is not the same spacing, then it is absolutely not cross compatible

Badger6

I can’t quickly find the spec right now, but I recall reading something shortly after the new 12-speed DA/Ulty was announced that indicated they use the same width chain…which to me means the cogs on the cassette are spaced the same MTB or Road. Before you're ready to forgive a b-screw that cannot get the RD in the correct positions (generally the top pulley sitting 5-6mm from the bottom of the largest cog), you need to ensure that running the RD with a gap larger than that is going to be fine…again, in general, it can be, the question is how large can the gap be before th4 shifting performance drops or worse it just wont shift reliably.

As I said before, in theory, what you’re looking to do is workable, but no guarantees.

21667

again thx for the reply mate...
i got this idea when i saw in the official website that GRX groupset RX810 11Speed actually have XT M8000 and Ultegra R8000 Sprockets compatibility on the page.
i have emailed shimano about that and havent got any reply from them

Badger6

GRX to Rx000 compatibility is no brainer….GRX is “gravel” but it is really road. XT/XTR cassettes in 11-speed are compatible to road RDs as well, with a 1.85mm spacer placed behind it, again because the cog spacing for 11-speed is specific to 11-speed, bit use case of the cassette, because 11-speed chains are a specific width (at least for Shimano and SRAM). Not sure if 12-speed requires a spacer behind the cassette, but as I said, the spacing between cogs should be the same since they use the same width chain.

dsaul

The space between the cogs is the same for MTB and Road 12 speed cassettes. The same goes for 8/9/10/11 speed.

Aside from the tooth count on the cogs, there is no difference between a road and MTB cassette. There are differences in 11 speed cassettes, in terms of what freehub body they will fit on, but not in cog spacing. 11 speed cassettes with a 34t or larger low gear will fit on a 10 speed freehub body. This has nothing to do with the spacing between the cogs, it has to do with the spoke clearance of the largest cog. Since the largest cog has more clearance from the spokes, they were able to recess the back of the cassette to make it fit 10 speed freehub bodies.

dwmckee

Yep, all 11-speed cassettes are same spacing and all 12-speed are same spacing, even between Sram & Shimano. Thank goodness the industry standardized at least on this! Your only possible issue is B screw adjustment to be sure derailleur pulley can get close enough to the new smaller inner sprocket to ensure good shifting. If you cannot get it close enough you will have slow/imprecise shifting in your lower gears.

Fentuz

The gap between sprockets on a cassette is controlled by the number of gears on the free hub and consequently the chain chain width (5.25 mm for 12s). it is the same regardless the application.

The thing that changes between road/mtb groupset from 10 and above speeds is the shifting mechanical advantage; for some reasons, manufacturers have applied different mechanical advantage ratio per click so while a mtb and road derailleur moved by 5.25mm on 12 speed, the actuating cable pull length is different so, it you mix road and mtb shifter and derailleur, you will either move to far (more than 5.25) of not enough (less than 5.25).

Then, depending of you cassette, bigger sprocket, you need different derailleur cage size so that the derailleur clear the sprocket and allow the shifting. But, if you run a long cage, as it has more clearance for the bigg gears, it also has less "chain wrapping" on the smallest sprocket (less teeth engaged) so the action on small gear is less engaging, crisp and shifting is less reactive as the engagement on the next gear may happen for example 30 deg later.

So, depending of what you do, there is a compromise to be made.

Badger6

Fortunately the OP is not going to run into this issue *by design" or just good luck, since they intend to use a MTB (aka, flat bar) shifter with the MTB RD.

Fentuz

yes, you re correct. I was only trying to give the OP a clearer pictures as as i read the OP comment , I though things were mixed together and some replies (not yours) partially explained what someone has to do but not why this someone has to do it.

21667

hi all, thanks fot the reply.

i got a XT780 RD (which is advertised as 10Speed) usually works on smaller sprockets (which i hope will eliminate the B screw problem)
so i will try to mix and match with the 12Speed deore m6100 shifter (if this works i am planning to change the m6100 to xtr m9100) and a very light 12 speed 34T road cassette from some chinese brand.

i understand that MTB shifter should work only with MTB RD and Road Shifter should only work with Road Shifter.

i am still waiting for my hub cassette body and cassette to arrive,