Gday everyone, since mentioning in PYR of my Shimano WR 11-41t 10Spd cassette I've had many an inquiry of how I did it.
Bit of a story first......
For me this is an evolution of a WR cassette which I started experimenting with in 2009 when Shimano released their SLX 12-36t 9spd cassette. With XT/XTR 9spd not having a 36t option then I bought the SLX cassette and removed the 36t and placed it behind my XTR cassette (removed the 11t and installed a 12t lockring). With this experiment working it got me thinking about a larger cog and the possibilities of going 1x.
Research led me to a US company called Action Tec who do all sorts of specialty bike gearing from individual cogs to complete cassettes. An early morning phone call to them confirmed that in their experience a Shimano 9spd derailleur with the B screw turned in and cable tuning it would shift to their 39t Ti cog, so done....I ordered one.
Within 2 weeks I was riding a 12-39t 9spd cassette and with the benefit of the then new 28t Widgit, I had gearing close close enough for the trails I was riding. With a solid 12 months, several hundred+ Kms of singletrack and a 6Hr race I was very happy with this experiment, but eventually succumbed to the allure of a 10spd drivetrain in 2010 and then I moved to the true hills (Toowoomba) and went back to 2x up front needing a granny gear again.
Then a couple months ago I had a front derailleur fail? and went back to a 28t Widgit as an easy fix, then my mind started thinking again especially with SRAM's XX1 now available. So back into my parts bin I go and grab the 39t Action Tec cog and some cassette spacers and pull apart the 11-36t XT cassette. I had a result........11-39t by putting the Action Tec cog at the back + 3mm spacer, removed the XT17/15t cogs and place a 16t cog in their place and rode.
Like I did when on 9spd, I screwed in the B screw on the Shimano 10spd XT GS Shadow+ derailleur and it changed gears as per normal, gearing though was a little funky simply the change from 16t>13t was just a little too tall depending on the terrain, not a complete deal breaker but something again to make me want to fix it.
With SRAM's 42t XX1 cog it got me thinking and researching as to what was out there, I emailed Action Tec who said that they would look into it and get back? and Paul from Widgit who said the same but it could be done at a price?.....again this was all with no guarantee that the 10spd XT derailleur would shift that far. Then I stumbled upon the 41t cog from US ebayer "mtbtools", again I took a gamble.....which paid off.
The cassette is now in it's final stage, with the 41t cog fitting and working as advertised and I've fixed the gap between the 16<>13t by using some of the individual Shimano 9spd SLX cassette cogs and Shimano 10spd spacers... with the B-screw now all the way in and cable tension adjusted the WR cassette is working like a charm despite the mix of cogs.
The gear spread on the Shimano WR cassette is 41-36-32-28-24-21-18-15-13-11t below is a photo of it all apart.
What I used.....
* 41t cog + .5mm spacer (supplied) from "eBayer mtbtools" or 39t cog from Action Tec + (3mm spacer)
* Shimano XT 10spd 11-36t cassette
* Shimano SLX 9spd 12-36t cassette
* Shimano 2.35mm 10spd cassette spacers
Preferring Shimano over SRAM, I would hope that Shimano would have a rebuttal to the XX1 or at least a WR 10spd cassette similar to mine.