This 50t sprocket and rear derailleur cage are intended to make your 11-42t Shimano XT 11-speed cassette a bit more versatile, extending the range of gears to help you tackle lung-busting climbs.
To make room for the massive crawler cog you need to start by removing the 17t and 19t sprockets. In their place goes the 18t sprocket included with the kit. The huge 50t sprocket then sits at the end of the freehub, next to the 42t one.
The next issue to overcome is shifting the chain onto that whopping 50t cog. To do this, OneUp includes a new cage to fit to your mech. It’s compatible with both GS (mid cage) and SGS (long cage) Shimano derailleurs, at XT (M8000) and XTR (M9000) level. Though fitting the cage is slightly fiddly, OneUp provides a clear video tutorial to help you out.
When I hit the Pyrenees, the 50t cog really got some use – and I was continually impressed by the smooth shifting and valued the bail-out gear
Once installed, the first thing you notice is that everything feels more or less the same. Push the shifter and things are just as crisp as smooth as ever. The only obvious difference is a slight lag when shifting up onto the 50t sprocket.
This final shift is also a touch noisier than the others, which gives you an audible warning to let off the power just a fraction more than usual before hitting really steep, grinding climbs. Once the chain is fully engaged with the dinner-plate sized sprocket, though, it’s straight back to business.
With such a large sprocket out back to help you on the climbs, you can fit a bigger chainring up front, effectively increasing the range of gears. I went from a 32t to a 34t ring, for example. The result was a lower climbing gear than with his original set-up (34x50t vs 32x42t) but also a higher top gear for properly fast descents (34x11t vs 32x11t).
Out on the trail, I did wonder if and when I’d need such an easy gear. Even after multiple trips to South Wales and an enduro race up in Scotland, I hadn’t spent that much time in the biggest sprocket.
It wasn’t until we hit the Pyrenees that the 50t cog really got some use and I truly appreciated it being there. In the mountains, I was continually impressed by the smooth shifting and really valued the bail-out gear on some torturous climbs.
If you’re keen on going to a 1×11 set-up but unsure whether you’ll be able to handle the more limited gearing, this is a great, cost effective option. The only real drawback here is the fact it’s only compatible with a single 11-speed Shimano cassette.