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Hi,
Need a bit of of a sanity check please...
A roadie friend has WH-7850-C24 wheels, currently on 10 speed Ultegra but is replacing all transmission with 11-speed. The freehub is 10-speed only on these wheels.
An 11-speed shimano road cassette won't fit, as it's longer. There's a thread on Weightweenies where someone dremeled down the stops on the base of the freehub and part of the hub shell, but I don't want to go there.
But, I know that the freehub difference is 1.85mm, which is the same size as the spacer required to fit shimano 11speed mtb cassettes (or the 11-34 ultegra CS-HG800-11 road cassette) onto 11-speed road freehubs.
Sooooo the older dura-ace wheels should have the right size freehub to take CS-HG800-11 (11-34), or an 11-40 11 speed SLX cassette - but only if the 34 or 40 sprockets or their carriers don't foul the spokes!
Does this sound right, has anyone tried this exact combination, and does anyone have an idea about the big sprocket clearance?
If this works, then my friend with have a very lightweight wheelset with a very big sprocket and can happily spin up near-vertical walls.
7850 wheels were 8 / 9 / 10 speed compatible so CS-HG800 will fit on them fine.
There were some earlier Dura-Ace wheels which were 10 speed only which meant the freehub body was slightly shorter and would only accept a 10 speed Dura-Ace cassette. Thankfully the 7850 was much more sensible.
Thanks - I'm more concerned about the sprocket carrier touching the spokes really - I don't have the weels to hand, but they're straight pull and I seem to remember that the spokes are quite widely spaced behind the cassette.
I must have taken the grinder or file to about a dozen Shimano free hubs. Take about 1mm off and an 11 speed road cassette will fit any 10 speed freehub. You won't need to touch the hub itself and the spokes won't touch anything. I use this to run old 11 speed road cassettes on my rough stuff bike. 25 t cassettes work fine. If you don't like it just shove a spacer in at the back where you have done the grinding.
If you prefer, the back of the cassette may well be "machinable" instead - pretty soft alloy generally and rarely look to me as though the loss of a small inner radius around the centre will do any harm
(I've done 1 freehub and 3 cassettes in my time; prefer to do cassettes these days, even though it takes a bit longer (just with a dremel 😳 ))
The Ultegra HG800 11spd cassette you refer to has a narrower base and will fit a 10spd road freehub, or 11spd with spacer. Only comes in 11-34 - I've got two of them as some of my 'cross tubs are 10spd hubs.
Or, if your friend can bear to lose the 11t then use the 11speed cassette with the 10speed 1.85mm spacer behind it, on the 10speed freehub with a 12t lock-ring. Set the high and low limit screws and the 11 speed groupset will work as a 10 speed with one redundant shift.
I've also filed down the end stops on an old hub to fit 11 speed. It was a pretty straightforward job with a hand file, and the wheel is working fine.
Or, if your friend can bear to lose the 11t then use the 11speed cassette with the 10speed 1.85mm spacer behind it, on the 10speed freehub with a 12t lock-ring. Set the high and low limit screws and the 11 speed groupset will work as a 10 speed with one redundant shift.
I'm running a 105 11-28 cassette with one of the rings removed, can remember which, with 105 11s shifters + derailleur.
It works perfectly but was no good with a 1.85mm spacer, I'm using a 1.5mm spacer from here behind the 28t cog.
I can machine 11 speed road cassettes to fit 10 speed freehub bodies, I've done 20 or do in the past year with no problems. See my Instagram pic here of one:
DM me on Instagram for details.
Greg
^ that's quite a bit neater than my dremeled ones, but then mine are artisanal