We mostly cover Box Components’ all-mountain & DH drivetrains, with the Box One & Box Two 11 & 7-speed derailleur systems offering affordable alternatives to Shimano & SRAM. But trickling down beyond those top tiers, Box also produces a lot of BMX specific gear that can sometimes bleed onto the trail, especially to gravity mountain bikes, as with the new affordable Box Four crankset.

Box Four Crankset, tough enough for BMX or 1x SS MTB

Box Four Crankset, tough enough for BMX or 1x MTB

The new Box Four cranks are all about keeping it simple.  A cold forged 6061 T6 aluminum, two-piece crankset with a 24mm chromoly spindle, and a classic 4-bolt 104 BCD spider. That should work with many 1x chainrings on the market. But it isn’t really designed for mountain biking directly, so it’s not clear how close its chainline will be to a Boost setup which is certainly wider!

Update: Box confirmed that the Box Four crank has a 44.5mm chainline. That will probably suit most singlespeed mountain bike setups (and of course BMX), but won’t really work properly for multi-speed MTB setups and certainly won’t fit bigger single chainrings. Standard MTB chainline is usually at least 46mm or 49mm for Boost, sometimes climbing to as much as 53mm.

What it is though is a no-nonsense crankset, that can handle the abuse of BMX or even all-mountain riding, at a price more than 60% less than the Box One or Two cranks.

Box Four Crankset, tough enough for BMX or 1x MTB

The $150 Box Four cranks weigh in just under 800g, and include an external BSA threaded bottom bracket (or can be used with a pressfit BB & 24mm axle adapters.) The cranks come in BMX & smaller rider friendly short 160mm, 165mm or 170mm lengths.

Just a reminder that Box is one of many companies in our Black Friday Deals roundup – 15% off everything, including these cranks. Head over to that post to find Box, among many other discounts.



  1. Chainline will be way off. Bmx cranks have a chainline of 44mm, 9mm less than the 53mm of boost mtb’s. They have shorter spindles too since there are no 73mm shells in bmx, only 68mm.

  2. All can be adjusted with the offset chainrings (yes the internet is full of 104 BCD spaced versions) and/or spacing with spacers.

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