Box calls their new Prime 9 Tech a counter-intuitive approach, but when we think back… fewer gears meant lighter weights, less wear & less finicky shifting. So why was it that we keep embracing more gears in our cassettes these days?
Box Prime 9 speed MTB drivetrains – Nine is fine!
Sure, the reasons we have adopted 10, 11 & 12 (OK, even 13 a bit) drivetrains have not disappeared overnight – smaller steps in between gears for smother shifts, more optimal cadence due to those smaller steps, plus the ability to offer unprecedented cassette gearing spreads that allowed the adoption of many single chainring 1x setups. But mountain bike drivetrain disruptor Box thinks the simplicity, durability & performance of their new 9-speed groupsets outranks those small improvements, and in many cases still matches them.
Prime 9 conceptual details
Simple. Dial 12 cog back to 9 and you get a more simple setup. And yuo will shift less. Box still offers 11-50 cassettes in 9-speed (close to the SRAM 10-50 benchmark.) And with 25% fewer cogs in that cassette, obviously you are going to save weight.
Durable. Box’s Prime 9 still uses the modern standard 11-speed Shimano HG freehub, but has more tightly spaced cogs in the back. As chains got narrower the inner chain width decreased which actually increased chain strength, but the side plates got thinner too, making for a wash in overall chain durability. Instead, Box 9 keeps the latest 11/12-speed internal chain spacing (that means it works with any modern narrow/wide 11 or 12-speed chainring), but gets thicker plates for an overall 9-speed chain width. That’s strength improvement on both aspects, making a more durable chain. Plus, the narrower overall cassette width delivers straighter chain line for quieter running, longer drivetrain life span & faster shifts. Fewer gears (with the same spread) also means less shifting, so shifting components will last longer.
Compatibility. Box 9 all-steel cassettes fit on the same Shimano 9/10/11 freehub, so nothing proprietary or hard to get ahold of (no XD, XD-R, or even MicroSpline). That means every wheel out there will work, but also that those steel cogs will last longer than alloy.All work with standard HG freehub bodies, but also are more tolerant to a mm or two outside of spec.
Prime 9 technical details
Box’s Prime 9 drivetrain is available in 3 spec levels – box one (orange), box two (red) & box three (blue). Interestingly, the 2020 Box line also includes a 8-speed box four (yellow) drivetrain too. Each gets a 11-50 tooth spread in its cassette (the same as SRAM NX Eagle 1×12). They also all include a modern clutch to eliminate chain drops.
Each Box Prime 9 group includes a two button 9-speed trigger shifter (bigger internal gears, fewer shifts, less wear & longer life); a new 9-speed rear derailleur with a clutch, less cage movement, more reliable chainline & lower wear & tear; a lighter wide range 9-speed cassette that fits on a regular Shimano hub, then the unique 9-speed chain.
What’s the catch?
In reality, it looks like Box 9 is the near the top in all aspects. Sure, gearing steps are bigger than normal, but special shift pins mean smooth shifts when needed. And Box contends that mountains bikers don’t need such small cadence jumps, instead preferring consistent steps, as well as broad top & bottom gearing options. And while the cassette loses weight, the stronger 9-speed chain is heavier than a 12-speed chain.
To us that sounds like worth concessions, and for sure something worth giving a try. Plus, Box is typically a more-affordable alternative – from top-spec Box One down to entry performance spec Box Three.
Pricing & availability
Prime 9 groupsets and individual components are available for pre-order now direct from Box, with availability projected by the end of the year – December 2019. A complete Box One Prime 9 groupset with its light & carbon goodness will set you back $627. The alloy Box 2 is just $270, and a much easier sale to commit to. Then at $195 including shifter, derailleur, cassette & chain, Box Three is the lowest cost of entry. Take it one stop lower to Box 4 and it is just $155, but with a smaller gearing range.
Maybe it’s time to upgrade your mountain bike drivetrain by dropping some gears….