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I am familiar (we are all familiar) with the standard figure-8 shape of a chain link.

regular figure-8 chain link

I also somewhat understand the justification for the "flat-top" chain link.

flat-top chain link

This style is used when the link is too narrow, and the flat-top adds material that makes the chain sturdier. This material will never be in contact with the chainring or the sprockets. If anyone ever thought of extending the life of a chain by using the other side (a futile endeavor), this style will at least dissuade them.

In the preceding two styles, importantly, all chain links look like this, whether they are the regular links or the pair used to join the chain ("power link" in SRAM's jargon).

But there is also a style we could call "convex top".

convex top chain link

What's the story of this style? In particular:

  • Only the power-link looks like this. The remainder of the chain is a figure-8 style. Hence it can't be for additional strength; can it?
  • It looks like it would wrap around the chainrings and, especially, around the sprockets more tightly. Is the idea to make the chain pull act in the direction of the slant in this style of power-link's offset-from-the-main-line notches?
  • Is it necessary to use that style with all 12s SRAM? Can another style be used?
  • Chain compatibility is usually good. Any 11s chain can be used with any 11s system. Is the use of this style optional or mandatory, and can it be used with Shimano, or can Shimano's (or KMC's, ...) 12s chains be used instead, along with their own connectors, in a SRAM 12s system?
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    I think the oil slick, convex links were an attempt to make SRAM’s MTB drivetrains stand out.
    – Paul H
    Oct 17, 2022 at 0:09
  • @PaulH Even as merely a clever ploy, it certainly worked. Those links do make it look like something profound is going on.
    – Sam7919
    Oct 17, 2022 at 2:08
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    One possible explanation is that the convex shape offers a slightly better angle to push against when disassembling the link. Those figure 8 links were unnecessarily difficult to undo compared to the asymmetrical designs. And by the way this is a well formatted interesting question, keep it up!
    – ojs
    Oct 17, 2022 at 7:51
  • "Only the power-link looks like this. The remainder of the chain is a figure-8 style. Hence it can't be for additional strength; can it?" Maybe they use different alloys? Maybe it’s to make incorrect installation of the link impossible and very obvious?
    – Michael
    Oct 17, 2022 at 7:57
  • @Michael ... at the price of a mild slap of the connection link every time it passes over the guide pulley? During that moment, the chain doesn't sit flush with the pulley, which is effectively like riding with a shorter chain. We know that a longer chain wears out the cogs, but would a shorter chain not also wear out the pulley sooner than necessary?
    – Sam7919
    Oct 17, 2022 at 13:14

1 Answer 1

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I observe that the centerline for the slot is not in line with the other post. What that means I don't know, but its the only mechanical difference I can see.

The outside-shape is cosmetic as long as there is sufficient metal to hold the load.

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    I see the same for the flat top version as well. I wonder if the slot is that way so that it lines up better with the motion of the quick link pliers.
    – newroadie
    Oct 17, 2022 at 11:04

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