Originally Posted by
Monstermash
The ONLY question here is if the Mtn bike 11 speed cassette has the same cog spacing as the 11 speed road stuff.
I'm not planning on using road shifters with the mtn derailleur or vice versa. So cable pull ratios are not relevant.
Do you have 11-speed (road) compatible wheels? The road cassette is wider than the 10-speed cassette, so you need an 11-speed specific wheelset. For 11-speed road, basically everyone needed to buy new wheels. XTR cassette let the 40t overhang the freehub so they can fit an 11-speed cassette on a standard 8/9/10 freehub.
I would imagine that you could use the Ultegra cassette, but you'd likely need a new (probably custom) wheelset to do it. So you'd probably save $300 on the cassette but need to spend $800 on new wheels...