Box One Prime 9 X-Wide Rear Derailleur
The Box One Prime 9 Rear Derailleur takes the advantages of our legacy 9-speed drive-train but adds the advancements of a modern 1 by; a fully adjustable Tri-Pack™ Clutch, and an x-wide cage optimized for an 11-50T cassette. Forged construction steps up the durability and performance to an unparalleled level. Suited for the most demanding terrain.
- View Prime 9 Drivetrain Compatibility Manual
- How is the Ebike variant different?
- View Prime 9 Comparison Chart
- View Prime 9 E-Bike Comparison Chart
- Why Prime 9?
Prime 9 Box One & Two Installation
No, Shimano direct mount hangers are proprietary and are not compatible with Box derailleurs.
Q: Can I install this on my bike that uses a b-link for my current derailleur?
A: Yes! All you need to do is remove your old derailleur and the b-link leaving the standard hanger attached to your bike frame. You can now mount your Box Components derailleur directly to the hanger on your frame.
Q: Can I install this on my bike that currently has a direct mount hanger?
A: Possibly, you will need to see if your frame manufacturer or a third party like wheelsMFG offers a standard mount hanger for your frame.
No, traditional 9 speed systems use a Cable Pull that is not compatible with Prime 9.
No, Box Prime 9 derailleurs are not currently compatible with drop bar shifters, but we do offer a clamp for our shifters to mount on some 31.8mm drop handle bars.
We suggest removing the derailleur from the bike and using a soft bristle brush or rag with soapy water or a mild de-greaser. We do not recommend pressure washing, strong solvents or de-greasers as they could degrade the surface coating.
Please see our installation video at https://boxcomponents.com/collections/support
Tough & Reliable
Box 1 Prime 9 Perfect
This thing will take a beating. Going on over a year with no issue
The Box One 9 speed derailleur and shifter is a bit sloppy, which makes too much noise for me. The sitting is also too clunky. It works fine, but I switched back to SRAM XO.
Pretty Good Option Over 11 Speed
I have been using the Box One derailleur for 5 months, two of which for racing. One issue I have noticed is that the derailleur goes out of adjustment quite often and the jockey wheels have a small bit of play in the bearings. Once, the clutch on the derailleur lost the chain tension and I took the clutch cover off and removed the derailleur cage screw and noticed it had a lack of Loctite. I resolved this issue by adding some Loctite and re-tightening the clutch to my desired cage tension. Besides those issues, the derailleur is holding up well and the cassette range (11-46) is very good. I am a XC racer running a 1x oval chain ring and a ten-speed chain with no problems. I recommend this to trail/enduro guys looking for simplicity in a drivetrain. I cannot completely recommend this to aggressive XC/XC racers or to anyone who shifts under load often. I have reviews for the Box Three shifter and deraillieur.