Which chainring? Shimano M785 So I've never changed a chainring before. But the first step is finding the right one.

I have a Cube Hyde SL 2012 . It describes the crankset as

Shimano Deore XT FC-M785 Hollowtech II 42x26T., 175mm, integrated BB

By which I assume the 42 refers to the number of teeth on the outer ring - which is the one I need to change.

The closest thing I can find is this (M780):

But a) it suggests it's a triple chainring, and b) in the Q&amp;A on that site someone has asked


  "I'd like to swap out the 40t large ring on my Shimano XT M785 10
  Speed Double Chainset with this 42t ring, would that work?"


With the answer


  The chainrings for the M785 crankset have a specific design and
  unfortunately are not listed as having a compatible interchangeable
  option.


So.. err.. what now?
You are correct that the 42x26 is telling you that the large ring has 42 teeth (and the small 26).

I did a search on "M785 replacement chainring" and found a number of sources (but nothing a Chain Reaction). Looking at what I found it appears that the options for the large ring are 38 and 40 teeth. So…

Either Shimano has changed the specs on the M785 and the 42 tooth ring is no longer available, or there is s typo on the Cube site. I'd say it's worth looking at your bike to see if the tooth count is stamped on the chainring or, failing that, count the teeth.

If it is a 42 tooth ring (and you want the higher gears) it might be worth going to your LBS to see if they can order the 42 tooth ring, or else look for NOS (new old stock) rings on places like Ebay.