Box 9-speed Drivetrain Boasts Eagle Range, Lower Price [Review]

Ten years ago, I rode a 1×9 mountain bike and it was a revelation. Up until that point I didn’t realize how much I hated my front derailleur, and for the most part, I haven’t looked back.

As drivetrain designers added more gears to cassettes — first 10, then 11, 12, and now 13 — single chainring systems became more practical for a wider range of riders, so much so that today they’re pretty much standard for every type of mountain bike, from XC to DH.

Box Components has chosen to take a different path to a wider range, one that sticks to the tried and true 9-speed cassette, just with larger cogs and a longer chain. What’s the advantage, and more importantly, how does it ride? I decided to find out.

I’ve been testing the Box Three Prime 9 X-Wide Multi-shift groupset, which is a mouthful for sure. Obviously the 9 denotes the number of gears while Three refers to the price point and performance level. Box offers drivetrains at multiple price points with One being the top, and Four being the most affordable. The 11-50 gear range means this group is X-Wide compared to the Wide group which spans 11-46. Finally, this version of the drivetrain allows the rider to shift up multiple gears at a time, hence Multi-shift. (A single shift version is available, but it’s designed for e-bikes.)

Advantages, on paper

Most readers are familiar with 12-speed drivetrains from Shimano and SRAM, so for much of this review I’ll be comparing the Box Prime 9 group to SRAM NX Eagle, which shares many similar attributes.

Clearly riders can benefit from a wide range of gears, and the X-Wide Prime 9 group delivers a 454% range. This range is pretty close to a standard 2×11 setup, and it’s equal to SRAM’s NX Eagle group. However, more expensive SRAM groups and the latest Shimano 12-speed group offer 500% and 510% range, respectively, with both starting at a 10t cog on the cassette.

Box begins with an 11t cog which makes the cassette compatible with a standard driver body rather than SRAM’s XD driver or Shimano’s new Microspline. For those with an existing wheelset, this makes the Box drivetrain an easy upgrade.

Fewer cogs means a 9-speed cassette can be made lighter than one with 12 speeds. It will be interesting to see how the high-end, Box One cassettes compare to Shimano and SRAM’s lightest, but even at the low end the advantage is clear: my Box cassette weighs 554g compared to a 615g (claimed) SRAM NX cassette.

Grime time.

Another advantage of having fewer gears is an improved chainline. Box says “Prime 9 drivetrains significantly reduce the chain angle in the lowest gears when compared to 12 speed. This allows the chain to run straighter across all gears, increasing the life of the chain and cassette.”

Speaking of chain and cassette life, the Box Three Prime 9 cassette features all steel cogs which will wear more slowly than lighter aluminum versions. Not only that, the 9-speed chain is thicker than 12-speed chains, which should make it more durable. Standard 9-speed link connectors appear to work just fine with the Box chain.

Pricing for the Box Three groupset is $199.99. This doesn’t include a crankset or bottom bracket (BB), as Box doesn’t currently make either. A SRAM NX Eagle group (minus the crankset and BB) is priced at $275, which makes the Box group $75 cheaper.

Potential disadvantages

One of my first concerns upon installing the Box Three Prime 9 drivetrain was dropped chains. Back in the days of 9-speed drivetrains most riders were running a front derailleur which effectively served to keep chains in check on jangly descents. Modern 11- and 12-speed chains and chainrings feature a narrow-wide design that aids in chain retention. Box says their 9-speed chain has internal dimensions similar to 11- and 12-speed chains while the outer dimensions are similar to standard 9-speed chains. The upshot is thicker side plates that resist stretching better than 12-speed chains and decreased wear on the cassette and chainring.

Due to the massive cassette and longer derailleur, standard 9-speed chains generally aren’t long enough to fit the Box Three Prime 9 drivetrain. As a result, buyers may need to borrow links from a second 9-speed chain which is inconvenient and increases the cost. While a regular 9-speed chain can work in a pinch, riders will want to purchase the 126-link, Box 9-speed chain for its chain retention abilities and added length. The weight of the Three Prime 9 chain is significantly heavier (319g) than the SRAM NX Eagle chain (252g). A chain is included in the $199.99 group, and an extra chain can be purchased for $19.99.

The other side of chain retention comes down to the rear derailleur, where clutches are well, clutch. The derailleur clutch never trickled down to 9-speed derailleurs since the tech was developed after the big players had moved onto more gears. However Box includes a feature they call “Limited Slip Clutch” to address this issue, and while there’s no button or lever on the Three derailleur like on SRAM and Shimano clutched models, the tech essentially performs the same function.

With fewer gears, the Box Prime 9 drivetrain needs to make larger jumps between cogs. Potentially this means not having just the right gear in certain situations, or awkward jumps between shifts.


I asked Patrick at Loose Nuts to install the Box Three Prime 9 drivetrain for me to make sure everything was set up correctly. We went with a Truvativ (SRAM) Stylo crankset and a Dub bottom bracket, essentially the same one would use when installing a SRAM NX Eagle group.

Patrick says the installation went smoothly and setting the derailleur limits was a cinch. As far as the shifter quality goes, he says it’s certainly not on par with Shimano or SRAM, with more of a Microshift feel to it. Patrick’s test ride of the install confirmed everything was working smoothly and the process was on par with what he’s experienced with other big-name systems.

On the trail

Like I said, one of my biggest concerns with the Box Three Prime 9 drivetrain was dropped chains, having suffered them on my original 9-speed drivetrain ten years ago. One of my first tests was to repeatedly blast down sets of staircases to see if I could wrestle the chain from its teeth. I didn’t manage to drop the chain during my tests, and to date it hasn’t happened on a trail ride either.

My next question going into this test wasn’t if the gear jumps would be annoying; it was how annoying would they be? I mean, obviously SRAM and Shimano have been at this a long time and decided 12 speeds, rather than nine, are necessary for smooth shifting along a similar gearing range.

So far I have to say the jumps between gears are no big deal. Looking at the percentage increase between gears, the Box drivetrain sees identical gains between the first and second cogs (11 to 13) as a SRAM NX cassette. And the three gears at the top end of the range are identical as well ( 36 – 42 – 50). Consequently the “non-standard” jumps are happening in the middle gears three through six.

Everyone has a different pedal cadence and riding style so the middle jumps may be more or less annoying depending on who is on the bike. Even the terrain plays a role here. In my experience, I spend more time at the extreme ends of my cassette: I’m either puffing up a steep climb, or pedaling fast through the flats and downs. Mountain bike trails seldom keep a steady grade for long, unlike roads, so it’s rare that I find myself in the same gear for long anyway.

Yes, the shifts particularly in the middle of the range, feel a bit jarring and chunky. But I never felt like I couldn’t find a proper gear, or that I needed something in between. I’m sure there are specific grades where I might find one gear is too fast, the other too slow, and this limitation would be particularly frustrating if it occurred over a long distance.

Part of the chunky feel comes from the shifter, which as Patrick noted comes down to the quality of materials at this price point. To me the shifting feels much closer to the decisive clunk I associate with Shimano rather than the quiet smoothness of SRAM.

The Box Three Prime 9 drivetrain is no lightweight, adding almost exactly 3 pounds to my build (33g heavier than SRAM NX Eagle parts). It’s hard to discern a performance hit from the weight of any single component, but the overall bike weight is not ideal when I need to throw the bike over my shoulder to hike-a-bike. Box’s Two and One drivetrains offer weight savings over the level I tested, though at a higher price point ($269.99 and $626.99, respectively).

After a few rides I noticed a faint clicking in the lowest gear. I checked with Patrick and he says it’s probably due to cable stretch since the sound wasn’t there during his initial test ride. Aside from that, the drivetrain still shifts perfectly and the chain stays put wherever it’s placed.


Box Three Prime 9SRAM NX Eagle
Total weight1351g1318g

After studying the specs and riding the Box Three Prime 9 drivetrain for more than a month I have to say the brand has put together a solid system. By rethinking some of the assumptions that have been made about mountain bike drivetrains, they’ve created an affordable product that should offer improved compatibility and reliability over the long haul without major performance concessions.

According to Box, the Prime 9 drivetrains should begin shipping in February, 2020.

⭐️Find the Box 9-speed Group at Amazon and World Wide Cyclery

Thanks to Box Components for providing these parts for review.