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Repair Help and Education

Chainring Spider Removal

This article will discuss the use of the BBT-18 (or older BBT-8) to remove some crankset spider lockrings.

Some MTB crankarms use a detachable spider or chainring mounting arms. These spiders use internal splines at the center, and are held to the crankarm with a lockring. The Park Tool BBT-18 (or older BBT-is designed to fit this eight notched lockring. The tool also fits the cups of the Shimano® XTR 950 Bottom Bracket.

If the lockring becomes loose, it will cause a creaking sound when the bike is ridden, similar to a loose crankarm bolt. Check the security of this ring using the BBT-8.

Cassette type crankset

Procedure for Servicing Lockring

 

  1. Remove the crankarm from the bike. For help removing the crankarms, click here
  2. Notice there is a snap ring over the lockring. Remove this with a screwdriver.
  3. Place the BBT-8 in the notches.
  4. Hold the crankset secure in the soft jaws of a vise. Use a rag to minimize any scratching on the arm.
  5. Loosen the lockring counter-clockwise. Note the BBT-18 has a 36mm wrench flats. The Park Tool HW-2 wrench in preferred, as it wraps around the tool flats.

     

  6. To assemble, grease or oil the threads. Alternatively, you may apply a mild thread locking compound such as Loctite® #242.
  7. Secure the lockring fully. Shimano® recommends 443-620 inch-pounds on their lockring. If you are attempting to torque by feel, that is 38 to 50 pounds of effort on a wrench held twelve inches from the center of the lockring.

     

  8. Reinstall the arm.

This should keep the spider secure and noise free. If the bike was ridden much with the locking loose, damage to the spline system may occur. Replace the arm if this is the case.