I pulled the XTR cassette off the rear hub and tossed out the 17 cog and its accompanying spacer. I then slid on the 1mm OneUp spacer and their 42T cog, and then the rest of the XTR stack (minus the 17T), and cranked it down to specs. I liked that the OneUp 42T cog had a small arrow pointing at the notch, so it made it easy to line everything up on the free hub body. Swapping everything out increased the cassettes weight by 50 grams.
Update – I located an old 16t cog in my parts bin, so I swapped out the 15t with the 16t to create a more even range in gearing: 11-13-16-19-21-24-28-32-36-42
I wasn’t sure how long of a chain I might need for the 42-tooth rear and 34-tooth front combination, so I bought a new 120 link SRAM PC 1071 chain, and ended using 111 links plus the PowerLock connector (112 total). As shown above, that chain length worked fine for both the highest and lowest gearing options on my medium X0 derailleur.
I knew that I would need to crank out the B-tension screw on the rear derailleur since the derailleur was optimized for a maximum of 36 teeth, and I ended up getting it close to its limit to keep the pulley the proper distance from the cog. While in the stand, the derailleur shifted up and down without any problems, and it all seemed fine until I actually pedaled it under power while riding, and it wouldn’t downshift from the 42-tooth cog. So I cranked the B-tension screw to its limit and tried again, and it still seemed to have an issue with rolling down from the large cog while under power. I followed OneUP’s suggested trick of removing the small lock washer on the screw to gain additional length, and it then shifted properly under power. They even state that you can reverse the screw to gain more length, though I think just getting a longer one at the hardware store (4x22mm) is a better choice, and it gives you a spare backup in case you break one, which I did during my initial tweaking.
So how does it ride and shift? It works surprisingly well, and in direct comparison to the 32T to 36T up shift, there is a slight loss of smoothness, and a bit more of a thunk during the 19T to 15T drop due to the missing 17T; otherwise, I didn’t notice any outstanding issues. I have taken it out for several days of riding, and it shifted flawlessly, in fact; I would be hard-pressed to realize that I had this gearing installed on the bike. Although they suggest using a narrow-wide chainring, I never suffered any dropped chains during my test period with my set up. I cranked things under heavy loads on some pretty steep terrain, in both loose and smooth conditions, and the shifting and power transfer worked fine. I certainly liked not having to roll up and down through the front derailleur to get my desired gearing options, and I felt as though I could spin better with the larger chainring compared to a granny sizing.
Once I had the derailleur tuned properly and chain at the correct length, the OneUp 42T system has worked exceptional well, and I really didn’t notice any difference in usage compared to original 2×10 normal setup (11-36T rear and 24×34 front). I think this simple system, with its low-cost and fewer part swap outs will appeal to a lot of people. The $100 price, and maybe a new chain, clutch derailleur and a narrow-wide chainring will get you a pseudo alternative to the XX1/X01 wide range of gearing.
- Wide range 1×10 gearing – XX1/X01 range
- 1x and 2x usage
- Low-cost and fewer part swap outs
- Great shifting characteristics
- Simplicity – no front derailleur
- Weight saving for 1×10 – depending on components used,.6 to .75 lbs
- Missing 10T cog of XX1/X01 cassette
- Clunky 19T to 15T shifting (due to missing 17T)
- Might need clutch derailleur and a narrow-wide chainring (didn’t have an issue with the latter)
- Only works with Shimano XT and XTR, SRAM X5, X7 and X9 11-36T cassettes
For more information visit https://www.oneupcomponents.com/.