What 11 speed cassettes can fit on an Ultegra FH-6600?

[rogerzilla]

Any MTB ones?  Is there one with a 32T biggest cog that fits?

[BFC]

General opinion says "no". FH-600 freehubs (10sp) were only fiited on "road" 130mm axle set ups with shallow dished wheels, but..
There were MTB cassettes of that era that were 11sp that fitted onto 10sp freehubs (135mm axle), they relied heavily upon wheel dishing and sprocket size to clear the spokes on MTB.

it's a bit of pot luck, research and finding the parts in stock.

Probably cheaper/easier in the long term to get a new wheel that's 11sp compatible.

[grams]

The smallest dished MTB 11-speeds are 11-34. But they use the slightly longer 9 speed splines and won’t fit your wheel.

[rogerzilla]

Ok...looks as if a Tiagra rear hub is the only silver option, unless the freehub body can be swapped for one compatible with 11 speed?  Just trying to future-proof it since the wheel needs rebuilding.

[LittleWheelsandBig]

I don’t know if a Tiagra freehub will swap with yours, but that seems like a possibility.