The transition from ED10 to ED11 began with the addition of a 0.55mm spacer. Mavic part number 10603401. Probably more useful if using older hubs that had larger DS flanges with the then new 11s cassettes. After Mavic shaved any large flanges down and settled upon a common flange envelope across the range it all became a bit unnecessary to use the spacer, but it's useful to have in the spares box as it works well with other freehubs on wheels with limited clearance.http://glorycycles.blogspot.com.au/2009 ... heels.html
If you buy a new ED11 freehub it comes with the spacer so you can use the freehub on the older wheels. If you buy a new Mavic wheel with Campagnolo freehub it doesn't come with the spacer as it doesn't need it.
I found that linked document pretty confusing. This part especially:
The 11 speed cassette is designed to fit on regular ED10 freewheel bodies. However, to fit 1 more cog and spacer, Campagnolo not only had to make the cassette parts narrower, but also to “cheat” on the bigger cog and “bend” it toward the spoke bed.
That's just not true, since 10-speed cassettes also "dish" the biggest cog towards the wheel. This was not a new thing with the introduction of 11-speed. There is a difference of about 1/2 a mm however.
The Mavic freehub that I have is about 10 years old at least on a Ksyrium SL. No problems and no spacers. Both an 11-spd and 10-spd cassette mount and spin fine.
Did a bit more research. Looks to me like although Mavic don't like to admit it, they had a problem with a specific run of certain wheels that only lasted a matter of months. Those wheels require a 0.5mm spacer for the Campy cassette to clear the hub.
Other than this batch, Mavic wheels with Campy freehubs do NOT need a spacer whether it's a 10 or 11-speed cassette.
If your cassette spins OK without hub interference, you don't need a spacer.
There's sometimes a buggy.
How many drivers does a buggy have?
So let's just say I'm drivin' this buggy...
and if you fix your attitude you can ride along with me.http://www.youtube.com/watch?v=GekiIMh4ZkM