Race-proven alloy cranks for trail, enduro and downhill. 5DEV machines the R-SPEC arms from 7050 billet aluminium in San Diego, offers them from 135 mm to 170 mm, and lets you pick the spindle to suit your frame. 5DEV lists results on these cranks including a 2024 junior world championship win and second at Red Bull Hardline 2025.

Highlights

• 7050 billet aluminium arms, 610 g at 165 mm with a 29 mm spindle (5DEV figure)
• SRAM 3-bolt direct-mount chainring interface; chainring mounting hardware included
• Chromoly steel crank bolts with self-extracting hardware; CNC-machined 7075 aluminium preloader
• Lengths from 135 mm to 170 mm
• Boost (167 mm Q-factor), 55 mm chainline, SuperBoost+ (176 mm Q-factor) and DH spindles
• 5-year warranty from 5DEV

Pick your spindle

The spindle sets the width and chainline. 5DEV's standard Boost spindle (29 x 130 or 30 x 130 mm) works with a 52 mm chainline and suits 68–73 mm shells, for a 167 mm Q-factor. The 29 x 136 mm spindle is 5DEV's 55 mm chainline "DUB Wide" option. SuperBoost+ spindles (139 mm) give a 176 mm Q-factor on 73 mm SuperBoost+ frames, and the 145 mm DH spindle is for downhill bikes. 5DEV lists a 56.5 mm chainline for its SuperBoost+ and DH spindles. Diameter follows your bottom bracket: 29 mm is the SRAM DUB size, 30 mm is for 30 mm bottom brackets.

Options

Purple is available only as 165mm 29x130mm Boost. Weight and Q-factor for the 55 mm chainline and DH spindles are not published by 5DEV.

Compatibility & fit

Bottom bracket: sold separately. Choose the 29 mm spindle for a SRAM DUB bottom bracket, or the 30 mm spindle for a 30 mm bottom bracket. A Shimano 24 mm bottom bracket has to be replaced with one or the other (5DEV).

Chainring: SRAM 3-bolt direct mount. The mounting hardware is in the box; the chainring is not listed as included.

Setup: 5DEV suggests the standard 3.5 mm SRAM DUB spacer on the drive side, then the preload collar and spacers on the non-drive side to leave a 0.5–1 mm gap. Each arm should sit at least 3–5 mm from the chainstay; if it doesn't, 5DEV recommends the 136 mm spindle.

The Tune Cycles workshop can fit the bottom bracket and crankset for you as a separate workshop service. Threaded shells need the right bottom bracket tool and press-fit shells need a proper bearing press, so it pays to have the shell checked and the bottom bracket fitted correctly first. 5DEV's torque spec is 40 Nm for the R-SPEC crank bolts and 9 Nm for 3-bolt chainring bolts.