When you install your Zinn custom cranks, it is especially important to use a torque wrench to tighten the crank bolts on. Use a torque setting of 450 inch-pounds (51 newton-meters) to tighten the bolts. Check the torque after the first few rides and then every 1000 miles of riding. If you follow these simple care instructions, your Zinn custom cranks will last forever. If the cranks are not installed and cared for properly, you will run the risk of stripping the interface between the bottom bracket spindle and the crank arm. If this happens, it will cost $90 to repair the crank arm and you will be without your cranks for the time it takes to do the repair. If you do not own a torque wrench, take the bike to a mechanic and ask them to torque the bolts according to these instructions. NOTE: If the square taper interface on your custom cranks gets stripped, it will NOT be covered under the 1 year warranty. This problem only occurs due to improper torque, and is not a manufacturers defect.