Robert C. wrote on 04/18/17 at 8:58pm:


I won't be much help but here's my experience. I added a Hope 40T-Rex to my 10 spd 11-38 cassette but tacoed it under moderate torque on a climb. Hope would not replace. Then I bought a 11-42 Sunrace Cassette but my X0 mid cage would not work with it so I'm back on the 11-38 and just going to suck it up. My next move is 2x10 but I doubt I'll end up doing it.

I wasted a lot of money trying the shortcut modifications mentioned above in converting from 3x10 to 1x10 on my Trek Fuel EX-7 29".   The single 32T up front was the easy part. 

For the rear, first I tried the Wolf Tooth 42T.  Shifting back and forth to the 42T was fine, but the changes required in the middle with removing a cog to make room for it resulted in inconsistent shifting when crossing over the middle. I tried various cog combos trying to improve things, but it still occasionally hopped a gear on the way down or delayed a bit on the way up. (Stock Shimano SLX Shadow Plus Rear Derailleur).

I bagged that and tried the Sunrace 11-42 Cassette.  It was better but still not 100% consistent up and down the range and I was always waiting for that next skip. (Stock Shimano SLX Shadow Plus Rear Derailleur).

I finally bit the bullet and put all that stuff on eBay...for a loss.  I bought the Shimano XT M8000 1x11 groupset (11-42T Cassette, XT Derailleur and XT Shifter with a KMC X11L chain).

More expensive for sure, but in hindsight I should have gone straight to that last option. Incredible shifting accuracy and functionality.  It was like getting a new bike.

I have the One up components 42t i think it is on my 1x10. Only had a med. Cage shimano derailleur and got it shifting ok but shifts were still kinda chunky and didn't always shift well all the time. If you have a a long cage rear derailleur you won't have as many issues because you can run the B screw where it should be without the jockey wheels hitting the extended ring. I would recommend if you have a shimano getting a One Up Components RAD cage or RADr if you do the upgrade my bike shifts so well now I have to double check if it actually shifted sometimes ! 
Once I got it dialed in I love mine. Not being a super strong cyclist I think it helped me about on long climbs just having that little extra gearing. 
Hope my input helps!

I ran a OneUp 42t with their Radr cage fitted to a xt rear derailleur.  Swapped out the 15t and 17t for a 16t to narrow the shifts in the mid range.  It worked great with minimal setup, for 3 years.  I got my use out of it I figured.  Once the chain started hopping in the 42t, it was still fine through the rest of the range and I could visibly tell that the 42t cog was worn beyond usable, I decided to try the Sunrace 11-42t 10 speed cassette instead.  I have about 60 miles or so on it now.  It shifts fine, a little chunkier than my previous setup, but haven't had any ghost or missed shifts yet.  The problem I have with it is that I can't back pedal in the 42t without it dropping cogs.  I've read and found that this problem is common and may go away as it wears in more, not keeping my fingers crossed on this.  I've checked derailleur hanger alignment, added an extended b screw for more clearance and went to see my local witch doctor, all to no avail.  Since I've made my short story long, let's get to the point.  Save your lunch money a little longer and get a full 11 speed setup.  I've got 1 bike with SRAM XX 11 speed and wish I could afford to have it on my other ride, but I sold 1 kidney already so no dice there.  Shimano XT and SLX 11 speed are both very good and cheaper.  I am awaiting the magical brown panel van as we speak to deliver my new  XT 11 speed group.  You can make the extended cogs work well, yes, but since they are now offering 11 speed groups in the lower end groupsets, I personally think you would be better off saving a little more and getting a full 11 speed set.  You can always sell your old 10 speed stuff to get a few bucks back in your pocket, too.

I went through the same thought process a year ago, but I realized buying the 11x42 1x Shimano XT M8000 setup is rather cheap compared to "rigging it" with the ten speed stuff. The Shimano cassette fits on a regular ten speed free hub which helps the savings. It will "work", but IMO, just bite the bullet now. 

I think the extended range cogs were a good solution before the XT setup came out, but now you can jump into a complete drivetrain (shifter, cassette, RD) for around $200. If your current 10 speed stuff is worth anything, makes the jump even better.

I love my XT setup and would buy it again in a heartbeat. For the price, it cannot be beat.