Published on November 16th, 2016 | by Greg O'Keeffe
Ask a Mechanic | Bolt Tightening Patterns
Jeremy wants to know, “I’m installing a new chainring and am wondering if there’s a specific pattern or way that I should be tightening the bolts?”
Although this process may seem entirely too simple, there’s more to it than simply tightening your bolts one-by-one. This holds especially true for those folks utilizing carbon parts.
There are three separate components that will utilize a specific bolt tightening pattern, and they are:
Properly tightening your bolts in a specific pattern ensures that there is a uniform distribution of load across the part’s surface. If you were to simply go one-by-one and tighten the bolts, the part might seat incorrectly and will end up with uneven pressure across its surface.
Depending on whether you’re working on a 4-bolt, 5-bolt, or 6-bolt part, the process for tightening the part will differ.
Many different cranks and most stems utilize a 4-bolt pattern. Start by installing any bolts you’ll be using hand-tight. Start with the bolt in the upper left corner and tighten it down until it’s just begun to tighten. From there, you’ll repeat the same process on the bottom right bolt, then the bottom left bolt, and finally the upper right bolt, creating an “X” across either your stem or chainring.
Once all bolts are semi-tight, follow the same “X” pattern as before and go through one-by-one and tighten the bolts to their final torque specs.
For all 5-bolt parts, you’ll want to tighten them down using a “star” pattern. Starting at top-dead-center, tighten the first bolt until it’s just begun to tighten. Going clockwise or counterclockwise, skip the next bolt, and repeat the process. Keep tightening every-other bolt under all 5 are slightly tight. (I’d recommend a graphic overlay for this process to show the “star pattern”)
From here, follow the same “star pattern” and tighten each bolt to its final recommended torque spec.
All disc brake rotors have a 6-bolt pattern. After tightening all 6 bolts by hand, start at top-dead-center and tighten your bolt. From there, you’ll want to go straight down, upper right, lower left, lower right, and finally upper left.
Repeat the same process and tighten each bolt to the manufacturer’s recommended torque spec. Thanks for watching and we hope to see you next week!
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