Box 2 Prime 9 review

UPDATE October 2024: This review is still very valid but I have written a new review of the Gen2 Prime 9 here.

So, back in 2021 I wrote this bit on 9 speed drivetrains and ended by saying that the Box Prime 9 would be my go to if the upkeep of the old school 9 was becoming too much effort. Well, guess what…? Yes, you’ve read it here first – I’ve finally ditched the old school and gone new school, that’s kinda old school but not. Yes, Box Prime 9 now adorns my bikes.

I’d finally hit the point I wanted to be done with futsing with the bikes. I’ve never really been a tinkerer like many bike riding folk, rather I build, ride, and do the services when needed. But going out and spend hours fettling? No, not me; especially these days. So it was a perfect storm – a lack of desire to keep futsing, the increasing difficulty to keep the old school 9x going, and realising that even though I could, grinding up those steep singletrack climbs is not good for my knees or lower back these days so something a little gentler would be nice. When I saw a great sale on the Box 2 Prime 9 drivetrain, that was it… I bought three sets hoping that it was just what I hoped it would be.

I did the whole thing arse backwards mind you. I bought the kit and THEN read some reviews. And while the system is a few years old now, there are amazingly few in-depth reviews to be had. The two I did find were this on Vitalmtb, and this on Bike Radar. Forget the Bike Radar review, it’s a wolf in sheep’s clothing… total shit. But having done this arse backwards gave me an interesting perspective – I’d already ridden the system before reading the reviews, so I can say that the Vitalmtb review is pretty much spot on. So if you’re looking for all the low down, nitty gritty, have a read of the Vital review as they have it covered, then come and read my ride review…

Out of the box (!) Box gives you everything you need to set up and get going – shifter, cassette, rear mech, cable, cable outer, chain, speed link and most importantly, a sticker. And if you’ve set up old school SRAM, dropping on the Prime 9 will be a breeze; put everything on the bike, adjust the barrel adjuster on the shifter and the D-ten screw and you’re literally good to go; just make sure you allow for a decent loop of housing at the mech end. Really, it’s that simple. What was harder for me was seeing my bike now with a 50T up the back. Really, what’s become of me?!

My initial ride on the Box setup was a little… interesting. The first thing I noticed was the upshift was quite stiff, especially compared to the SRAM X.0 I was used to. It’s also somewhat notchy. The stiffness can be attributed to the heavy active clutch in the derailleur (which probably accounts for the notchy feel), and while on the Box One it’s adjustable, allowing you to adjust the heaviness of the clutch, on the Two it’s not. The second noticeable thing was the downshift is VERY positive, with a resounding clunk on the drops. The best way to describe the lever feel is that it’s ‘mechanical’, similar to the way Campy Record used to be (still is?). It’s not bad, not detracting, just different to the light, lifeless feel Shimano has pushed the market towards. Personally I like it and after the first ride stopped noticing it altogether and simply enjoyed the crispness of shifting.

But at the same time as dropping on the Box, I’d also put some fancy new Praxis carbon Girder cranks on the bike, foolishly upping the chainring from 32T to a 34T as I went; pushing an additional 2T may not seem like a lot but it’s noticeable, especially on a 160mm bike. This skewed my initial impression of the Box gearing range, making the lower end of the Box cassette seem like a lot more work to push, though the reality is that would have been the case with the old cassette as well. What the 2T jump did do though was accentuate the step from the lower to the upper gears. On a ‘traditional’ 9 speed the steps are quite linear, and from what I hear, on 11/12 there are so many steps it’s shift madness. On the Box though there is a, be it small, gap right in the middle of the cassette, which is understandable given the range the 9 speed covers. So my daft mistake of jumping two teeth on the front made this gap quite noticeable and the first ride was a case of getting used to the shifting, the new gearing and dealing with the amplification of mid cassette jump by the taller chain ring.

The second ride though was much better as all the change value had dissipated and I no longer noticed the new gearing, giving me the mental space to get a proper feel for how the system worked as a whole. And when it comes to shifting, the Box does not miss beat. Ever. Up down and under load, it shifts without fail and I was finding the mechanical feel to be a positive as it eliminated any potential vagueness lighter sprung systems inherently posses. This is also undoubtedly attributed to the excellent chain line the 9 speed offers, along with the robust and smooth Box chain. You get the instant feeling that the drivetrain is built to take a beating and keep going.

The third ride is where the strengths of the Box philosophy shone through. With everything settled, I was able get a real feeling for the new setup by tying together several of my favourite singletrack climbs and sections. By now my legs were fully accustomed to the gearing and the shifting, be it my perception or otherwise, seemed to be breaking in and felt not quite as heavy…

And to my surprise it all felt completely natural… which is ultimately what you want. The small jump in the middle of the cassette vanished, as I had instinctively adjusted my pedalling and gear selection to work with it – the ‘gap’ is more a by-product of conditioning, quickly replaced with the new normal. That’s not to say it’s not there, it is, but it’s not an issue… at all. On singletrack climbs, where I usually floated in the middle of the cassette, I now found myself going slightly lower than I normally would have coming into tight steeps or more technical sections, making clearing them not only quicker but also significantly less work. On the stretches that were more flow, I was dropping higher and getting some extra speed where I might not have otherwise. In other words, I was being a lot more efficient and judicial with gear selection and if any credence is to be paid to Strava, even though I was not actively trying to be, the numbers backed it up – I was quicker on the technical ups. While the 50T up back did not get a look in, the 48 was hit up a few times in transport fire road sections that were always an uncomfortable grind after hectic technical climbs and being able to spin out for 30 seconds between trailheads turns out to be nice way to easily pick up the momentum again when hitting the next bit of singletrack. Overall, the 11-50 cassette is exceedingly well thought out. Not once did I find myself wishing for more gears, or steps between them. Yes, there is that small step in the middle but I think the truth lies in it being more of a ‘real world’ performance aid than hindrance. And did I mention that shifting? Flawless.

In all how would I rate the Box Prime 9 drivetrain? Simple… it’s an honest, real world solution for mountain bikers who actually ride. Well designed, well made, robust, and performs exceedingly well – everything you need and no more. It’s what mountain bike components should be about. As much as I liked my old school 9 speed, I realised it was time to move on from it and Box’s solution delivered everything I liked about 9 speed in a modern package. As for that aforementioned Bike Radar review? Reviewing something like Box’s Prime 9 honestly would more than likely cause your biggest advertisers to get more than a little pissed off; and you don’t want to do that because you need their money. Trust me when I say I know how most of these mastheads work…

And yes, I have put the 32T back upfront.

Update: After writing the above I managed a fourth ride to close the week, this time all singletrack climbing. Despite being somewhat sore from martial arts training the night before and again, with no intention to do so, I still managed to pull top two and personal bests (yea, that Strava thing again) on some of the hardest sections of the climb. The Prime 9 ratios shone through with the spread of gearing active the entire time with no dead spots. As I mentioned above, the gearing invites you to use the entire cassette to keep momentum and certainly this proved to be the case – instead of backing off where I would usually have, I simply moved to a lower gear to keep pace through technical hairpins and dropped down as soon as it leveled out. In fact, I kept so much momentum I came into some tech sections much faster than I expected and got caught out a few times.

Paired with the right chainring (duh!), you just don’t need 11 or 12 gears…

Box Components did not give me gear to try. I bought this out of my own pocket and my opinions are mine and mine alone.