how to install zinn split30 cranks

Split 30 Crank Installation Instructions

Split 30 cranks combine the stiffness and reliability of a 30mm-diameter spindle with the versatility to fit on a wide variety of bottom bracket shells. One spindle half is integrated into the left crankarm and one into the right arm; a bolt connects them together in the center so that ramped crenellations on the end of each spindle half tightly engage each other and a spacer in between to obtain proper total length.

Install BB386-type bottom bracket (or BB392-type for a mountain bike). These have wide-spaced, 30mm-ID bearings. Installation instructions for these bottom brackets are in Zinn & The Art of Road Bike Maintenance or Zinn & The Art of Mountain Bike Maintenance.

Install the right crankarm.

Back out the spindle-adjusting ring on the left crankarm all the way out until it is butts up against the left crankarm. (Turn it counterclockwise until it stops.)

Install the left crankarm with a supplied 30mm-diameter crenellated central spacer on the end. Apply NO grease on the spacer. Put the bottom-bracket dust seal on the spindle first so it ends up between the bearing and the crankarm. Line up the arms so that they are straight in line with each other before pushing them together so the crenellations on the ends of the spindle halves and the spacer notch into each other.

Place the crank bolt into the center of the drive-side spindle. Loosely screw it into the left spindle. It takes a 12mm socket on the end of a socket extension. Apply Blue Loctite or anti-seize grease on the bolt threads.

Tighten the crank bolt to 47 N-m (35 FOOT lbs.) of torque. Exact torque on this bolt is critical.

Turn the spindle-adjusting ring clockwise to remove side play. No tools required; tighten it by hand until the cranks can no longer shift side to side.

Tighten the bolt on the adjusting ring with a 2mm hex key. Torque is low—just snug it up; do not overtighten this little bolt.
Install each pedal with a pedal washer between it and the crankarm. Apply anti-seize grease on the pedal threads.

To increase overall spindle length, 30mm-diameter crenellated spacers of various thickness mate with the ends of the two spindle stubs (wider spacers may require a longer M10 crank bolt). These cranks can fit threaded or unthreaded bottom bracket shells from fat bikes with 100mm- or 121mm-wide shells to 92mm or 73mm-wide MTB or 86mm or 68mm-wide road BB shells. Like BB386/BB392 and SRAM DUB cranks, Split 30 cranks can be installed in BB386 (or BB392 for MTB) bottom bracket shells, PF30 (Press Fit 30), Cervelo BBright shells, and BB30 shells.

Split 30 cranks are made in the USA in any length. Different crank lengths for the left and right arm can be ordered to deal with leg-length or joint-flexibility discrepancies.

The removable spider comes in different hole patterns and offsets for different chainring drillings and configurations. The eight-hole spider-retaining lockring is removable with a special cylindrical 8-pin tool for the purpose. (Older models use a notched spider-retaining lockring.)

Split 30 cranks are lighter than other cranks we offer that come in lengths outside of the normal 170-175mm (or 165-180mm) range.

Connecting the cranks in the middle of the bottom bracket moves the stress away from the crankarms, precluding a crankarm loosening up on the end of the spindle.