Box Prime 9… take 2 > Updated

2025 Review update

I wrote a review last year about Box Components Prime 9 drivetrain. If you want the low down, go read it, the guys at Box did. So when they came to me and asked if I would like to review Generation 2, G2, of their excellent wide range 9 speed system, I naturally said no.

Well no, I didn’t. I said hell yes (duh!).

Of course after the eagerness died down, a type of buyer’s remorse set in. I’ve been around bikes and the bike biz long enough to know that despite Jonny From Marketing’s best efforts to convince me otherwise, nine times out of ten, new bike stuff is either just a rehash of old bike stuff, or some daft new direction no one really wants, or needs, but know we are going to be forced into using anyway. So while I was waiting for the G2 to arrive, I pondered just what I was going to say that I had not already said.

Turns out I need not have worried so much.

When I unpacked the box of Box from the box (see what I did there?), I was greeted with the familiar packaging – I have installed four Box setups on the racked bikes, so have got to know it well. This time though, when I opened the box of Box (there it is again!), apart from the chain and cassette, that have remain unchanged, what greeted me was something very different. G2, it turns out was not an update, or a tweak, which if I am being honest was what I was expecting, but a whole new thing. The only similarity the G2 derailleur has to its predecessor is that it’s 9 speed. Everything else, and I do mean everything, is all new…

It’s always the little things that grab my attention first, so the first detail I noticed (after getting over the all-newness of it all) was not some glorious, big ticket thing but one that I guarantee that you never notice… the B-Gap (B-tension) screw. The new B-Gap screw is now offset and pushes against a seating block, taking over from the traditional role of the screw itself. I found this to be a blessing as the Syntace hanger on the bike has a very minimal seating step for the screw and I’ve found that B-Gap screws can ‘jump’ the step and make a mess. This system completely eliminates this issue meaning that on the bike I tested it on, there was no issue setting everything up just right, and it staying that way (if you’ve ever had a B-Gap setting go wrong, you’ll know what I mean).

That cable feed is not quite right. Paying attention to set it up right makes all the difference… duh!

The next detail to shine was the shift cable, which now exits into a roller and then a grooved track in the derailleur body itself (the upside of moulded composites). This creates a smooth cable path to the pinch bolt, usually a minimal afterthought on many derailleurs, as well as seats the cable firmly.  The new cage design too has a beefiness to it that inspires a level of confidence that it’s going to hold up to abuse. So if you ride trails that have sticks and branches sticking out all over the place, ready to snag and kill your derailleur, this thing has your back.

And most noticeable of all, like the elephant sitting in the corner of the room? G2 is substantially beefier than the G1, which was far more traditional in its design. The G2’s body is hefty, boasting…

• New geometry > Near Horizontal actuation = light gear pulls & less ghost shifting.
• Tri-Pack 2.0 clutch with larger discs & finer threads > increased torque & adjustability = less chain slap & easier to set up.
• Wide offset cage > more pulley offset & cage surface = crisper shifting & tougher.

Did I say it was beefy? And made from composites?

But not stopping there, the shifter unit too has been redesigned. Gone is the more traditional shape of the G1 and in its place is a slender square that nestles nicely away under the brake lever and with that packaging change also comes…

• Metal injection gears > tougher & harder = increased service life & crisper feedback.
• Magnesium top-shell > added structure without weight = crisper feedback.
• Magnesium pull-lever > added structure without weight = crisper feedback.
• No-loss gear changes > immediate engagement = shorter & faster gear pulls.

And there are nice graphics. Clever even. That’s important… and I never really liked the graphic treatment on the G1.

All sounds like the business, doesn’t it? But let’s get to the juicy bit… all the design and construction refinements are one thing but how does the G2 perform when used in anger?

Truth be told, I was expecting much of the same as G1, which if you’ve read my previous review will know that that’s a good thing. But like the G2 design, the shifting performance was all new. I ride a lot of up and down singletrack, so shift through the block a lot during a ride. Right from the get go I noticed that the lever feel was crisper, faster, and somewhat more comfortable. I’d become used to the G1’s shifting, which requires just a little bit of ‘over push’ on the up-shift to make sure the shift sticks (a tiny thing you get used to in no time) but the G2 was on mark every time, meaning that the shift speed has not only increased but, if at all possible, feels crisper.

Down shifts too are noticeably snappier, so pushing through the singletrack sections, moving up and down the block in rapid succession, the G2 delivers a definite step up from the G1 in terms of overall performance – I have not had a single misshift or even the slightest hint of complaint from the derailleur during some less than well timed shifting ,a.k.a shifting under load; something I put down to its solid construction coupled with the actual functional redesign, which delivers a stiff unit that offers no hint of flex or complaint, even under the most rubbish shifting conditions.

The chain and cassette, unchanged from G1, are as rock solid as always; the advantages in a 9 speed system are abundantly clear with the sheer punishment the chain can handle and the cassette provides clean and crisp shifts. It’s business as usual.

Overall, what can I say? I was not really expecting G2 to be such a radical redesign of a system that I thought was pretty damn good to begin with. That the G2 takes that pretty damn good and makes it better, noticeably better, is really what redesign should be about and Box has done it in spades. Where I had no hesitation is recommending Box’s Prime 9 to ‘serious’ riders, I will have even less doing so with the G2. The catch for me now is trying to prevent myself from replacing the remaining three G1 systems on the other bikes…

2025: Review update

With over 12 months of solid riding put into the Gen2 Prime 9, I thought it’d be a good time to do a bit of an update to this original review..

First, I’ll come clean. I made a snafu installing the cable into the derailleur. It seemed right. It worked right. But in talking to the guys at Box after noticing a niggle in shifting through the centre of the cassette, well after I wrote the above review, they pointed out that, well, I’d got it wrong. Like I said, the mech worked just fine but after routing the cable properly it worked… even better! Who would have thunk it? So with that confession of stupidity out of the way, how has the Gen 2 held up?

In a short, if not a somewhat anti climatic and even boring summery, it really has been flawless.

With the entire drivetrain now installed on my new Nicolai, I’ve been pushing it harder as the bike has been taking my riding to the next level (for me). The Nicolai is not the sort of bike that takes fools and average performing kit lightly, so any flaws or inconsistencies become very obvious. The Gen 2 Prime 9 has proven to truly be a champion.

The derailleur has remained tight with no visible signs of pivot play developing, and the cage remains straight and true, even after some fairly rough treatment and gnarly shifting. Shifts, especially after the cable correction, have remained crisp with a firm mechanical feel and no signs of that quality waning, even after 12 months of bedding in. Maintenance wise, other than the cable, there’s been none, on either bike its been installed on. Once set up properly the system works and just seems to keep on working, with next to no additional tweaking required. Even after several months of not washing the bike (yes, I know, ok?), and a firm layer of the local powder coating the entire derailleur, it just kept on shifting without batting an eyelid.

Now that all may sound like I am blowing smoke, but it is the honest truth. I’ve run enough systems over the years, from mid tier through to top shelf, Shimano, SRAM and Campag, and other than the flawless 9spd SRAM systems of the early 2000’s, I can’t think of a single drivetrain that has been this robust or hassle free. As I noted in my original article, the Box Prime 9 is a system designed for people who ride bikes and know better and after the past 12 months, and the time before that on the Gen 1, I think this statement could not be truer.

For those out there pondering if a wide range 9 speed is right for them, I put a G1 system on my boy’s Ibis, with a 32T up front. He’s had zero issues with lack of range, even with his stick like, now 13 year old, legs! Where ten speed was pointless and eleven or twelve more marketing products than real world, the wide range 9spd covers everything you need to be able to ride everything you want, no matter who you are.

Recently Rich and I had been talking sore hands and I remembered the SRAM twister I had in a drawer, thinking that it might be a solution where one’s thumb is getting sore; if it would actually work with the Box system. And I discovered a dirty little secret…

Going through the part drawers, I found a bunch of 9spd SRAM shifters, notably a X.0 trigger. With curiosity now firmly getting a hold of me, I measured the spacing on a SRAM 9spd cassette and, comparing it to the Box, discovered the gaps are identical. This made me think that there was a very good chance the Box derailleur/shifter set up would also be a 1:1 ratio, and after hooking up a SRAM shifter to test the idea, I was more than a little chuffed to find out it worked flawlessly with the Box derailleur.

A little shifter shuffle saw me putting my Gen2 shifter on the boy’s Ibis, which he loves as the G2 shifter is a real step up from the G1 in terms of lever throw and feel; it actually feels very much like the late model SRAM x9 shifter… which is a compliment BTW! The X.0 went on the Nicolai and I was more than a bit keen to see if it would make any difference.

As I noted in the main review, the Box’s Gen2 shifter is very good. Sharp, crisp, the lever throw is short and accurate. If you know the SRAM 9 spd X.0 though, you’ll know then that in many respects it was the pinnacle of 9 speed shifters. Stupidly expensive at the time, even now they fetch a hefty price when you find them second hand, the units were made from all the good stuff, featured adjustable lever positioning and a zero loss shift. The whole 9spd X.0 range was as good as stuff got and, in terms of sheer bling and trying to prove a point, still is as good as it gets, at least from the big players. But all that aside, how does the shifter work with the Box?

Oh. My. God!

The only way to describe it is it’s as if someone put a Formula 1 gearbox on the bike. Shifts are instant, zero dead space in the shift – push the lever, which has an incredibly short throw, and BANG! the gear changes. The same for the down shift, where the release is equally short. And as you can adjust the position of the main lever, I’ve made it so my thumb can activate it with zero fuss, only increasing the speed of the shift and making this combo possibly the fastest shifting system you can get your hands on, mechanical or electric.

But the X.0 shifter also shows just how good the Box Gen2 derailleur is. The derailleur responds to the shifter without the slightest hint of lag or complaint, something that could be hidden with its own shifter. Don’t get me wrong here, the Box Gen2 shifter, as I have said, is very good and I have no qualms at all to keep using it, it’s just that the X.0 was, and still is, the pinnacle of trigger shifting performance. So if you like the idea of the Box system AND want the fastest shifting system on the planet, then try to find a NOS or near unused X.0… just be prepared to spend a lot more for it than you’d think a bit of 10+ year old kit is worth!

While I seem to be gushing like some sort of fan boy, I can say with certainty that I am a Box convert for the foreseeable future. Box proves that there are people in the industry that still understand that riding is about riding and not some sort of deranged FOMO activity only for those that can afford it. Bike kit should be understandable, robust and be fit for purpose; affordable is always appreciated too. It should not make you cry if, for some unfortunate reason, you break it. But more than that, bike kit should be something you install and then forget about, so you can concentrate on the actual riding part, and that is something Box’s Gen2 Prime 9 does in spades.