Hi all, just a quick one as I seem to have missed much of the last 10+ years of freehub evolution…  Not surprising given my newest/main MTB came with and is still running 9 speed…..

I’ve recently picked up a couple of pairs of secondhand road wheels that have 11spped Shimanon HG freehubs, so slightly longer than the traditional 8/9/10speed freehub design.  I’m currently running these with a random coassette spacer bodged on them, and that works fine, though I understand a 1.8mm spacer is optimal.

However, are all 11speed cassettes the same overall width?  IE: MTB and Road cassettes?  I’m considering an upgrade to 11speed on one of the bikes as the STI’s are on the way out, and it would seem like an opportune moment to change.  But would want to go 1×11, with a wide range cassette, and many cassetted don;t state if they are HG or HG/11 compatible…

Or did MTB’s jump the 11speed freehub and have gone straight to XD/Microspline?

Cheers! Keith

11 speed HG MTB cassettes (and Shimano HG700, HG800 11spd road cassettes) need a 1.85mm spacer on an 11spd freehub – the largest sprocket is dished over the back of the freehub splines. With a standard 8/9/10spd freehub they just fit on without a spacer.

Mtb 8/9/10/11 are all the same overall width.

11spd road are in general wider, but there’s a handful of 11spd road cassettes that are the same as the mtb

That’s cleared that up once and for all then!

Personally I’m in the “mtb 11 is same as 10” camp as I have wheels that have had 9 10 and 11 speed mtb cassettes on with no thought given to spacers

edit although re-reading the first reply I think it’s saying the same thing

mtb cassettes fit mtb freehub 8-11

if you have a road 11 free hub you will want a spacer for any non road 11s cassette

presumably that means those road 11 cassettes won’t fit your old hg freehub

i think 🤔

Billimin confusing, as far as I can tell

HG hub body 35mm wide  for MTB (9/10/11/12) and road up to 10 speed, Road 11/12 speed HG11 hub 36.85mm wide. MTB cassettes will fit HG11 hubs with 1.85mm spacer. 11/12 road cassettes will not fit HG (35mm) hub body. 10 speed Shimano cassettes are 1mm narrower than 9/11/12 speed so require 1mm spacer on HG hub body and 1mm+1.85mm on road HG11 hub body. The cassettes should come with the 1mm spacer. I’ve read online that the 1mm slack can be taken up by the lock ring without the 1mm spacer. SRAM 10 speed cassettes are not 1mm narrower.

10 speed Shimano cassettes are 1mm narrower than 9/11/12 speed so require 1mm spacer on HG hub body

Not all of them 🙂

Thanks simondbarnes,If I wasn’t already confused enough.

upon further reading

Most Shimano 10-speed cassettes road cassettes come with a 1mm spacer. It is intended to and should be installed whenever it can fit on the freehub body.

Mountain cassettes never include or use this spacer.

It’s even more confusing than this, Shimano sold 10 speed specific hub body for a while which had taller splines on the hub body. I give up and off to the pub.

don’t Mavic include the space with their 11spd wheels?

My son just changed to Nukeproof wheels, running 11spd NX cassette and didn’t need a spacer, I was quite surprised.

It’s a bleedin minefield when you’re trying to support someone’s MTBing when they’re 200miles away 😣

It’s even more confusing than this, Shimano sold 10 speed specific hub body for a while which had taller splines on the hub body

Yeah, I had one. Had to use the posher cassettes.

Tiagra / HG500 level 10spd shimano cassettes don’t use the 1mm spacer

105 / ultegra / dura ace need the 1mm spacer (which they come with) although I think the 105 5700 and DA 7900 are now discontinued

Thanks all.  So buying a wide range, 11 speed Sensah SRX Groupset from AliExpress means having a selection of cassette spacers to hand, and bodge to fit.

Which is fine, if you know!

Cheers!