Crank Removal-Square Spindle Type
This article will discuss the removal and installation of cranks from square spindle bottom brackets. Crank pullers are used for two basic crank types: the square spindle type arms, and the splined type spindle arms. The left image below is a crank with the bolt removed. The square spindle can be seen inside the square fitting in the arm. The right image shows a bottom bracket bearing unit with square spindle.
For the splined Shimano® Octalink and ISIS Drive® type crank arms see Spindle Cranks..
Typical Tools and Supplies Required:
- Crankbolt wrench:
- Crank puller- Park Tool CCP-22 or CWP-7
- Adjustable wrench
- Torque wrench, if available, such as TW-2, or TW-6 and correct socket bits for crank bolt/nut such from theSBS-1.
Cranks connect the pedals to the bottom bracket spindle. The arms are pressed tightly to the bottom bracket spindle. Cranks must be removed from the spindle to service the bottom bracket bearings. On some models of cranks, the cranks must be removed to replace the chainrings. "One-key release" systems do not require a crank puller. The one-key system cap is seen below.
Crank Removal (Square Spindle Type)
a. Shift chain to largest chainring to protect hands against chainring teeth.
b. Look for bolt or nut at end of crank in line with bottom bracket spindle. If no bolt is visible, remove dust caps. Some caps pry out and some thread out. NOTE: If the bike has a one-key release system, leave this cap in place. A retaining ring surrounds the bolt. Simply turn the center bolt counter-clockwise to remove arm of one-key release system.
c. Turn bolt or nut head counter-clockwise and remove bolt or nut. Inspect inside arms for washers. Remove washers if present.
d. Before installing crank puller into crank, turn puller nut away from internal driver as much as possible. If puller nut happens to unthread from internal driver, thread it back on only 3-4 turns.
e. Thread large external thread of puller (nut) into arm, taking care not to cross thread. Tighten puller nut into crank using wrench. If puller nut will not thread into arm, or if threads in arm are stripped, see crank Removal with Damaged Threads.
f. Thread internal driver into puller nut. Using handle or adjustable wrench, tighten driver until crank is loose on spindle. Pull arm from spindle and unthread both parts of tool from arm. Use care not to skin knuckles when removing tool.
g. Repeat process on other crank.
Crank Installation(Square Spindle Type)
Cranks are pressed tight onto the tapered square spindle. The square spidle is made with a slight upward sloping taper. The crank square fitting also has a slight taper. The crank bolt or nut acts as the pressing tool and forces the arm up the slope of the spindle. The bolt or nut must be tight enough to keep from loosening, but not so tight that the spindle splites and damages crank. If possible, use a torque wrench. See Torque Recommendations.
Aluminum cranks typically do not require lubrication of this press fit. Aluminum by its nature is self-lubricating as it is covered with a thin layer of oxidation. Adequate torque is typically enough to keep arms from creaking.
a. Wipe both sides of spindle and inside crank mounting holes with a rag.
b. Grease under head and threads of both bolts or nuts.
c. Install right crank onto right side of spindle.
d. Thread crank bolt/nut to spindle.
e. Tighten crank bolt/nut to manufacturer's recommended torque.
f. Grease threads of dust cap (if any) and install snug.
g. Install left crank onto left side of spindle with arm pointing opposite direction of right side arm.
h. Install crank bolt/nut and tighten.
i. Grease threads of dust cap (if any) and install snug.