OneUp Components 42t cog

There’s a buzz about the one-by gear set-up. Let’s face it: it’s simpler, quieter and does the job just as well as two-by.

But the downside is you either have to man/woman up enough to push some bigger gears, invest heavily in a 1×11 drivetrain or move somewhere with smaller climbs. While 1×11 drivetrains offer the gear range necessary to make other set-ups redundant, they’re currently expensive and out of reach to a fair proportion of riders. Step forward the extender cog for 10-speed set-ups.

OneUp’s 42t cog is double-sided and supplied with a spacer to allow fitting to either SRAM or Shimano cassettes. It also comes with a steel 16t cog to allow a sequential shift up and down to be maintained when you drop a cog to make room for it. Fitting the OneUp is easy, although it obviously requires a splittable cassette. Where it gets a little messy is the adaption of the rear derailleur for something it wasn’t designed for. In my case that meant unscrewing the B-tension screw completely, removing the plastic spacer and then screwing it back in as far as it would go to get enough clearance for the new cog.

In use, shifting has been acceptable with a pretty good movement up and down the block and no noticeable jumps that break smooth pedalling. It’s not quite as smooth as it used to be, or as seamless as 1×11 but for the price it’s OK. The only real niggle has been when motoring in the bottom end of the cassette where a reduction in chain wrap, due to derailleur bodging, has occasionally caused the chain to jump.