Whatever type of crank you're fitting, make sure you take your time and get them on there properly. Here's how to install Race Face's Evolve and Shimano's Hollow Tech II external.
1. Install crank arm
This bike is having a Race Face Evolve XC crank fitted. Very similar to Shimano's Hollowtech II cranks, the Evolve runs on Race Face's X-Type external bottom brackets (also compatible with Hollowtech II bottom brackets). The spindle is attached to the left crank arm and the chainset is preloaded and secured in position at the right. Consult the owner's manual before installing for the correct number of preload washers.
Apply the preload washer to the left arm, lightly grease the bearing surface and feed the crank through the bottom bracket until the splined drive side protrudes from the right bearing cup. It's a tight fit and may require a tap from a soft-faced hammer. Install the spacer seals (consult the manual) and apply a generous amount of grease to the splines. It is the same procedure for Shimano Hollowtech II cranks only you start from the drive side and there's no need for the preload seals and spacers.
2. Align second crank arm
Align the chainset on the spindle so it runs opposite but in line with the crank arm on the other side. Insert an 8mm Allen key into the crank bolt and tighten lightly in a clockwise direction. You will be able to feel the crank engage on the splines. Check the crank arms are in line once more before tightening the crank bolt.
It's easier to align Shimano Hollowtech II cranks. Simply line up the left crank arm with the right and slide it onto the greased spline, ensuring it engages onto the splines. The splines on the Shimano spindle are machined in such a way that it is actually quite hard to mess up the alignment of the cranks. Simply press on the left crank as far as it will go.
3. Preload and secure
The X-Type Race Face cranks tighten to a dead stop and you can install them correctly without having to use a torque wrench. It takes between 35-50Nm to bottom out the cranks. The bottom bracket bearing on Shimano Hollowtech II chainsets must be preloaded pretty much like a headset. You'll need a special preload tool (Shimano TL-FC16) that fits into the crank's preload cap. Tighten the cap until all the play at the bearing is removed, finger tight is generally as much as you need go. Check the cranks spin freely before securing the crank arm.
Use a 5mm Allen key to tighten the crank bolts. Tighten in a 1-2-1 pattern going back and forth between both bolts until tight. Don't over tighten or you could damage the cranks. The bolts should be done up as tightly as stem bolts, to about 12-25Nm
¦ Check the tightness of the crank bolts after the first couple of rides. They should be okay for external type cranks but the bolts can work loose on splined and especially square taped bottom brackets.
¦ External bottom brackets have standardised the bearing but compatibility is a bit vague when it comes to replacing worn bearings. We've had Shimano Hollowtech II bottom brackets working with Race Face and FSA cranks and vice versa. Truvativ have a compression ring on their bottom bracket so we'd recommend sticking to TruVativ bottom brackets if you run Truvativ cranks.
¦ Crank manufacturers and their corresponding external bottom brackets: Shimano with Hollowtech II BB, Race Face (ISIS splined) with X-Type BB, Truvativ with Giga-X-Pipe (GXP) BB, FSA with MegaEXO BB
Race Face's external bearing crank system.
Apply a load to a bearing race in order to remove play.
Shimano's external bearing crank system.
FSA's external bearing crank system.