OneUP Components 42-tooth sprocket – first look

Extend the range of your 10-speed cassette

If you appreciate the simplicity of a drivetrain with a single chainring, but don’t want to spend the cash to upgrade your 10-speed drivetrain to one of SRAM’s pricey 1×11 systems, and you don’t think you can mash up the climbs with the range provided by your existing cassette, you may be in luck. OneUp Components has introduced a 42T cog that can be retrofitted to many 10-speed Shimano and SRAM cassettes.


This $100 (£61) cog allows riders to extend the range of their existing cassette; it also requires the user to remove the 17T cog in order to accommodate the pie-plate-sized 7075 aluminum sprocket.

Cassette compatibility



  • XT (CS-M771-10 11-36)
  • X5 (PG-1030 11-36)
  • XTR (CS-M980 11-36)
  • X7 (PG-1050 11-36)
  • X9 (PG-1070 11-36)

Shimano Deore and SLX and SRAM X0 (PG-1080) and XX (PG-1099) are not compatible

The clear advantage of the OneUp cog is that it offers an extension 10-speed gearing to nearly that of SRAM’s XX1 and X01 drivetrains for a fraction of the price. Here’s how they stack up against each other.

10-speed gearing with OneUp:


11-speed SRAM XX1 and X01:


Other considerations

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After sliding the OneUp cog onto the freehub, the remainder of the cassette, minus the 17T cog, is installed with the supplied spacer oriented as shown in the above diagram.

After installation, the rear derailleur’s limit screws should not need to be readjusted, as it will still be moving through the same range. The B-tension screw, which controls the distance between the rear derailleur’s upper pulley and the cassette, will need to be adjusted to accommodate the larger cog. (OneUp Components recommends that the B-limit screw be adjusted so that the upper pulley sits 5-8mm away from the 42T cog.) The chain may need to be re-sized as well. Last but not least, the addition of a chainring with a narrow-wide profile like those made by Race Face and Wolf Tooth should be considered to improve chain retention.

OneUp claims their cog adds an additional 51g to the cassette. A weight gain that is more than offset by the removal of a front derailleur, front shifter, the associated cables and housings, along with one or two chainrings.

While this looks to be an option tailored to 1×10 setups, it will also work for 2×10 drivetrains, provided you are running a long-cage rear derailleur. Check the compatibility page to see if your drivetrain is compatible.

OneUp components expects the cogs to be available in mid-january 2014: oneup components expects the cogs to be available in mid-january 2014

OneUp Components 42T cog can extend the range of 10-speed 1x and 2x drivetrains


OneUp Components is accepting orders now with availability expected to be mid-January 2014. For more information visit

What do you think? Are you willing to give up a bit of mid-range on your 10-speed cassette for mega range?