Review: OneUp Components RADr Cage and 42T Sprocket

RADr Cage and 42T Sprocket from OneUp Components
RADr Cage and 42T Sprocket from OneUp Components

First, a bit of history…

I’ve been a big fan of 1x drivetrains since I was running 9-speed gear. It wasn’t about saving weight or proving that I was a harder-core rider than anyone else. My reason was more practical than that.

During a particularly miserable muddy day racing the Snake Creek Gap Time Trial, I almost couldn’t finish because of the terrible chain suck I was experiencing. I had to leave the chain in the granny ring up front and pedal as softly as I could. It was a frustrating day, to say the least.

After the race, I went home and removed the big and granny rings, and installed a mini upper guide like the XCX from e*thirteen. And it was awesome. Granted, the range was somewhat limited, but having a trouble-free drivetrain was a tradeoff I was willing to make.

All of my mountain bikes to this day have been single ring affairs, including my most recent addition, a Kona Process 153. While the Kona is an awesome bike, it ain’t light. Mine comes in around 31 pounds. On really long rides, a 10-speed cassette with a 36T cog just didn’t feel like enough.

OneUp’s 42T Sprocket

Enter OneUp Components and their first product, a range-extending 42T sprocket. Hurrah!

Right? Eh, sort of.

While I really appreciated the super-low gear, the shifting was like a bunch of celery you forgot was in your refrigerator’s vegetable drawer. That is to say, not crisp. With the B-tension screw maxed out, shifting was slow and sloppy going up and down the cassette.

That wasn’t a trade off I was willing to make, so off came the 42T sprocket. It spent the better part of a year in my toolbox until OneUp sent over their new RADr (Radial Appositioned Derailleur) cage for review.


Image: OneUp Components
Image: OneUp Components

The RADr cage replaces both the inner and outer cages on any Shimano Shadow+ 10-speed rear derailleur. (Shadow+ means that the derailleur has a clutch mechanism.) I installed it on my SLX derailleur by following their excellent instructional video, embedded below. As they said, it took about 15 minutes and one beer to complete the job. I made sure to drink a second beer, just to be on the safe side.

The stock cage on the SLX is a simple stamped steel affair, so the machined 7075-T6 aluminum RADr cage was a serious upgrade. It’s anodized in OneUp’s signature green color, which looks good. If green doesn’t mesh with your bike’s looks, the RADr cage is also available in black.

Maxing out in the 42T Sprocket
Maxing out in the 42T Sprocket


With the RADr cage mounted up I was able to keep the B-tension screw at a more normal level with the 42T sprocket installed. Running through the gears with the bike in the work stand, I could tell that the derailleur was moving much more quickly than it had with the stock cage. Very promising.

Out on the trail, shifting with the RADr cage was excellent. It felt indistinguishable from the stock derailleur with a 36T cassette. That’s a good thing. I know SLX isn’t the fanciest of Shimano’s offerings, but it shifts nearly as well as XT at a fraction of the price (which is why I like it).

Before the RADr cage and 42T sprocket, I would change out my front ring between a 32T for local riding and a 28T for long days up in the mountains. Now with OneUp’s cage and sprocket, I can leave the 32T ring on all the time without sacrificing any range on the low end.


None about the RADr cage or the 42T sprocket.

However, I did have an issue with their 16T sprocket that’s provided with the 42T. Shifting into and out of the 16T was just fine, but no matter what I did, the chain would skip on the 16T when I put any kind of power into it.

The 16T can be used with either a Shimano (which I have) or SRAM cassette by adjusting its position on the freehub body. I tried the sprocket in both positions extensively–and even put a new chain on–but to no avail. Anything but the most gingerly pedaling would result in a chorus of a popping chain and expletives from me.

I removed the 16T from OneUp and put the stock 17T back on instead. The jump in cadence from 13 to 17 is a bit odd, but not a deal-breaker.

Final Verdict 

Super-low gear and stock shifting? Yes, please.

OneUp nailed it with the RADr cage. For a reasonable $55 you’re getting a quality product that may outlast the rest of your derailleur.

If you’ve been toying with the idea of going to a 1x setup, but don’t want to drop the cash on a 1×11 drivetrain, this is your solution. Grab one of their 40 or 42T sprockets ($85-$90) along with a RADr cage, and you’ve got a wide-range setup for less than the cost of an 11-speed rear derailleur.

Thanks to OneUp for providing the RADr cage for review.