Sunday, October 26, 2014

How To: Convert Shimano XTR M980 Triple to Double Chainrings

Searching around the internet on this matter has returned negative result. Many people asked about it but it seems no one has really done it. I started to have this idea when I realized I had not been using the 42T ring for long time and few friends jumping to Sram XX1 single chainring setup. I wondered if this is possible without changing a brand new crank which is costly. After some study on Shimano XTR components and technical details, I am glad to share the result here. 

Here's the "before" - Shimano XTR M980 Triple 42-32-24T setup...


Check out after the break for the result.

Here's the "after" - Shimano XTR M980 Double 38-23T setup...


There are many aftermarket chainring options but very rare that you can change and maintain the good look, for instance, the chainring comes in some who-know-what odd colors that totally damage the aesthetic of the bike. Something like this...


This is not to bad but nothing beats the original design. I must admit that I am fussy on the overall aesthetic of my lovely bike, the aesthetic of the bike must be maintained if not improved for all change out and upgrade. So there left me very limited option.

First, I checked Shimano website and found out that the M980 triple and double crank are of the same spider arm...


Compare the triple and double by spot-the-difference methodology, I needed component labelled #16, #17 (see next paragraph) and #18. One challenge in Malaysia very few and close to non-existence of bike shops carry component parts, so eBay and Amazon were my savors. Knowing the correct part number is key to a successful search on the components...


Another challenge I had was 26T granny chainring might be a bit tough for me. I needed a ring either 22T or 23T. Unfortunately Shimano do not carry such ring and hence I had to look for aftermarket option, which I got myself a Rotor Bike's Q-Ring. As you can see from the photo above, the granny does not impair the overall aesthetic of the bike as the it is shy hiding behind the bigger ring. 

Here are all the components...



If your XTR looks like this... 


Sorry to say that you have no option as this is M985 model :(

Following are the links to where I bought: 
Rotor Q-ring 23T chainring (Cycle Studios is a LBS in KL, Malaysia)

One last note if you are upgrading, you may need to change the fd front derailleur if the mounting is too high for the 38T chainring. Check with your LBS.

Happy riding and modding your bike! :)