by Nick Ducharme
Single chainring drive trains are becoming increasingly popular on the trail. With 11-speed upgrades still expensive, and the lack of proper wide-range 10-speed cassettes on the market, several manufacturers have jumped onboard the oversized replacement cassette cog bandwagon. These larger cogs take up the cassette real estate that one of your smaller cogs would usually occupy and installing one means you are typically forced to choose if you love your 15 or 17 tooth cog more. OneUp is cool enough to include a 16 tooth cassette cog with your 40/42t up-sized ring which bridges this shifting gap and provides a better solution than the typical 15 to 19, or 13 to 17 step created when you ditch the red-headed step-cog. To further improve your shifting experience OneUp now offers a new “RAD” cage that replaces the outer cage on your Shimano Shadow+ GS (medium cage) rear derailleur. The new cage relocates the upper pulley so that it can follow the contours of the cassette more closely throughout the movement range of the derailleur which allows for crisper shifting and more chain wrap in the taller gears. It also means you don't need to mess around with a longer/modified B-screw. So is it wide range 1 x 10 Nirvana?
OneUp Components RAD Cage Highlights
- 7075-T6 Aluminum
- Designed to improve shifting performance for Shimano GS (medium cage) Shadow+ clutch rear derailleurs
- Improved rear derailleur tuning range to match an 11-42 cassette
- Works with stock B-screw adjustment (no more removing washers or reversing B-screws)
- Improves chain wrap
- Weight: 26g
- MSRP: $35 USD
The RAD cage is made from extra tough 7075-T6 Aluminum and is nicely anodized in what I'm sure is meant to be Vital green but they are available in black for that “sleeper” look too. The RAD cage package comes complete with the replacement axle bolt that you'll need, a card directing you to the website and a link to the YouTube video with the installation instructions and a sweet OneUp sticker. If I've learned anything from Honda Civic drivers it's that stickers make you go faster, so that's a pretty sweet freebie!
Looking at my expensive XTR derailleur and then imagining performing surgery on it made me cringe at first but the installation video put my mind at ease, and also informed me that I would need a beer, so after watching it I was much more relaxed and ready to go elbow deep in XTR Shadow+ clutch and cam guts.
Installation was indeed a snap and while the derailleur was disassembled I had some time to look at the differences between the original part and the new one. It was pretty obvious how OneUp have moved the cage's pivot location from the center of the pulley to slightly not-so. That slight movement away from concentric is all it took to get the top pulley hugging the smaller cogs on your cassette without banging into the monster 40 or 42t cog on the other end.
On The Trail
Prior to installing the RAD cage we wanted to check the function of our as-yet unmodified Shimano derailleur. With the OneUp 42t and 16t cogs installed we got rolling. The additional low gear was much appreciated on the long grinding Santa Ana mountain trails and the steep climbs of Laguna where the parts were being tested. There were some notable compromises in the set up however. OneUp's inclusion of a 16 tooth cog helped a lot with negating most of the between-gear feeling that a 4 tooth jump creates, when you feel like one gear is too hard and the next one you're spinning like mad. There's still a bit of bog from the cadence change, but not as bad as it would be without the 16t. The other issue was the B-screw tension adjustment. In order to get the upper pulley to not hit the huge 42t cog you have to do some extreme B-screw adjustment. We've heard stories of additional spacers, longer screws and/or needing to flip the B-screw around. Fortunately I just needed to bottom it out on the XTR derailleur and that gave me just enough clearance to keep the noise down in the 42t gear. Lastly, because of the extreme B-screw tension adjustment, the shifting in the smaller cogs became very, well, not Shimano-like. Cable tension had to be set up very slack in order to get the chain to drop to the next smaller cog in some kind of orderly fashion but this also meant that you need to give a little extra push beyond the typical shift point when climbing up to a larger cog. The situation was manageable, but far from ideal. Next step, perform the Add-a-RAD surgery on the RD.
Before even getting the bike out of the repair stand it was obvious that the RAD cage was doing exactly what OneUp was saying that it would. The B-screw no longer needed to be buried into the B knuckle and the pulley was certainly following the cassette cogs more closely throughout the full shift range. OK, that was me intrigued.
Once on the dirt the difference in shift performance was immediately noticed. The delay that was always there previously in the smaller cogs was almost completely gone and there was no noise in the large 42t cog that I was running either. Great success all around!
Things That Could Be Improved
It could be free?! On a more serious note, without doing extensive analysis on exact pulley movement I can't say that the shift quality can be further improved. That said, this is still OneUp's attempt at band-aiding another manufacturer's part to fit a modification that the original part was never meant to be compatible with. It's close to as-good-as the original but not 100% Shimano shift quality.
The only downside to the RAD cage is that it is an aluminum part and my XTR cage was carbon. There's about a 10 gram weight penalty for the OneUp cage vs. XTR. The XT/SLX/Deore derailleurs employ an alloy outer cage so I'm sure the weight penalty there is less. In reality, 10 grams is not going to be the difference in winning or losing however a missed-shift-to-stem-cap-cup-check will certainly cost you precious seconds during your next #Enduro.
Long Term Durability
300+ miles on the OneUp RAD cage and the 42/16 OneUp cassette upgrade cogs have not caused any significant drama for those parts. The cage itself as well as all of the surgery performed on the derailleur have all held together formidably. There has not been any interference between the aftermarket and original parts causing excessive wear. In fact, the increased chain wrap offered by the RAD cage is supposed to improve chain and cassette life (which is compromised by the addition of a larger inside cassette cog), so long term reliability is potentially improved. The durability of the RAD cage itself is good and if it even helps your other parts last longer, bonus!
What's The Bottom Line?
The ultimate testimony to how well this part works is that before I installed the RAD cage I would definitely not have raced with the larger 42t cog. Shifting was too finicky and not consistent enough to make me confident that I would get the gear I needed when I requested it. I'd rather suffer through the climbs with a 36t cog than risk my entry fee and podium shot for an easier trip to the top of the transfer stages. Now, with the RAD cage I get consistent enough shifting that I'd trust the system to keep up with my too-tired-to-think late stage panic shifts. If you are a casual rider who appreciates the anti chain drop security that a single ring system offers but aren't concerned with having the most precise shifting, then maybe you don't “need” the RAD cage but for the $35 price to play, it's frankly almost a no brainer. No matter what wide-range cog you're using, get yourself a OneUp RAD Cage. It makes all the difference.
Visit www.oneupcomponents.com for more details.
About The Reviewer
Nick Ducharme is a long time bike industry corporate monkey (most recently working as a suspension engineer/frame designer) but has since left that glorious lifestyle and started up his own MTB suspension maintenance and tuning operation in sunny Orange County, CA, Formula 4 Speed Suspension Personalization. Passing on prototype development and trips to Asia to join the elite crew that is the Vital Thrash Team. A former XC and DH racer now turned Enduro aficionado, he's the inaugural California Enduro Series expert champ shooting to retain that title for this year as well. Big miles and high speeds are more his thing than big air and high flying so his riding style is more engineer than flashy but that calculated and fearless approach has gotten results (and destroyed lots of tires). When not shredding in the hills he's elbow deep in motorcycle guts or a 350Z engine bay.