The Box One Prime 9 drivetrain might last longer than SRAM’s offerings – thanks to the chunkier chain and cassette – but I don’t think you’d be able to live with the high-resistance shifter lever once you’ve experienced a lighter system. Weight-wise, the full 1,375g Box One Prime 9 setup I’ve reviewed is roughly equivalent to SRAM NX Eagle’s 1,362g weight and Shimano Deore M6100’s 1,330g. The cable-pull lever can shift four gears at once if pushed far enough, but accessing the last shift is virtually impossible while riding because of the amount of travel required to engage the gear. The clutch interferes with the derailleur’s ability to easily move into lower gears because of the mechanical coupling between the shifter and derailleur via the gear cable, leading to heavy shifter paddle operation. The cassette uses Shimano’s Hyper Glide (HG) freehub body which is different to SRAM’s XD Driver and Shimano’s Micro Spline system.

The cable port is vertically positioned. Alex Evans Box Components Box One Prime 9 drivetrain details Shifts are stiff and vague-feeling, while the cable-pull lever has too much travel. The balance between chain control and shift performance isn’t quite right either.The chain, made from hardened alloy steel, has chamfered shifting edges to increase shifting performance, and solid plates and pins to make it stronger. I didn’t find myself stretching lower gears out with increased cadences on flatter sections or grinding up steeper hills in higher gears for longer because the gear ratios were too far apart.

However, general shifting was good and with a positive push of the lever (more on this below) the derailleur didn’t miss any shifts and wasn’t hesitant in its operation. It also happily shifted gears under power.The lever has a lot of travel before a shift is engaged, too, so a fair amount of sustained force was required to change each gear, which didn’t feel particularly natural. The cable release lever was also quite stiff but felt way more positive. It was only possible to shift one gear at a time, though.