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I recently had a Shun SS-8001 crankset fail. When taking it apart, I saw that the right pedal has a sort of stop ring that prevents the pedal, presumably, from unscrewing itself:

enter image description here

Now I need to find a replacement and I have no idea what this part is called. The pedal itself has a 35mm thread; this part seems to have a thread but also a tightening bolt. What keyword should I be searching for?

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    Can you add a picture of the crankset, and indicate where this component was located? – Argenti Apparatus Aug 29 '18 at 19:11
  • Definitely need another photo. I know what I think it is, but am confused by your use of the word pedal... – Swifty Aug 29 '18 at 21:11
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It's a bottom bracket bearings preload collar/adjuster. Just like other bearing pairs (i.e. hubs, suspension pivots, headset), bottom bracket bearings need a way to remove slack, so spindle won't move sideways. There's a thread on the inner surface, so when you turn the collar, it will move left/right along the spindle. The bolt fixes the collar in place.

If you are looking for a replacement, I'd measure the axle diameter and collar thickness. If it's 30mm/5mm, I'd try a Race Face one, or contact any Shun vendor and ask about separately sold spare parts.

Some crankarm/BB systems don't use this exact method, and some do. For example, Race Face cinch crankarms have almost the same looking collar: RF cinch preload collar

SRAM has a similar tool as a part of their BB30 and now DUB crankarms: enter image description here

Sometimes there's not enough space for a collar, so other options to preload bearings are:

  1. Optional stack of flat shims on spindle and a wavy washer, here's a screenshot of Zipp Vumaquad manual, figure 3 shows a wave spring: Zipp VumaQuad manual wavy washer

  2. Shimano's Hollowtech 2 crankarms use the non-driveside arm bolt to preload the bearings: enter image description here

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