Hope someone can answer this. I have a 10 speed 1x setup. I have a 2011 10 speed long cage XTR rear derailleur and a 36 tooth cassette. The cassette needs replacing and I want to replace it with a 40 tooth version. Looking at the original 2011 documentation for the derailleur it states that the derailleur ‘capacity’ is 41 tooth. Anyone know if a 40 tooth cassette is gonna work? Sounds like it will, but just checking from someone with experience of trying this.
Thanks.

There is no 10 speed with a 40t unless you expand it.

Capacity is the difference between front rings + the difference between top and bottom sprocket. how much slack the cage is capable of taking up.

You need to be looking at maximum sprocket size. How the top jockey and mech geometry works.

A Lindarets goat link *may* help if your max sprocket size is too small.

Yes,it’ll work – people use 40t and 42t expanders with them. Depending on frame design you might be at the extremes of extension, some folks use a longer B-screw to get aroudn that, or use a OneUp Rad Cage or Lindarets adapter to improve the shifting. I ran mine with both 40 and 42t adapters, shifting was fine, but did fit a Rad Cage later, and shifting was better.

mikewsmith – Member
There is no 10 speed with a 40t unless you expand it.

Praxis & Sunrace both make wide-range 10s cassettes.

Thanks HonourableGeorge, that is my understanding too. I have looked at the Praxis cassette, I realise Shimano don’t make one.

http://www.tritoncycles.co.uk/components-c9/cassettes-freewheels-c68/sunrace-mx3-10-speed-cassette-p14800

So, taking the ‘capacity’ definition, my original question related to a 40t cassette, but would the same setup work with a 42t cassette?

To make my xt get up to 42t I used the Wolf backplate expander for the mech. It doesn’t really work well at that range otherwise

I’ve just had a different thought. Would the existing 10 speed XTR derailleur work with an 11 speed cassette and new 11 speed shifter? The shifter dictates the distance the derailleur moves between rear sprockets, so the only concern I can think of would be the total distance across the cassette. Is this greater than 10 speed?

geven it looks strained on the expanders I’d guess not easily, as I said above it needed the wolf expander to get to 42t the number of steps doesn’t really matter