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With Shimano disc brakes, there are two options for types of brake pads: resin or metallic. My understanding is that the metallic brakes generally have more stopping power while resin are more modulated and squeal less.

With that said, as far as I have seen, some use a split-pin to stay in place, while others use a bolt.

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A split pin used on both organic-resin and sintered-metallic pads

This is strange to me: I feel less comfortable knowing my ability to stop is based on a bent split-pin rather than a screwed-in bolt! Is there some explanation for this?

My best guess is that the metallic pads create more heat, which could warp threads, but that's just a guess.

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    Not sure if its wording or something else, but your picture shows two split-pins, two spring-retainers, and no bolts ? – Criggie Jun 7 at 23:42
  • @Criggie: wow, you are completely correct. At first glance it looked like bolt to me with the head and the bottom looked like threads. And now looking back at all of the resins, it appears my whole statement was flawed. Should I retract the question? – Cliff AB Jun 8 at 0:14
  • no there's a good question here - I've taken the liberty of editing the question to focus more on the fastener than the pad compound, because that matches how Nathan answered. If you feel this could be better, either use "revert" in the edit history or just edit onward. – Criggie Jun 8 at 1:17
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Some caliper models use the threaded style pin and some use the bent cotter pin type one. Several of the pad shapes are used in calipers of either type. Every Shimano replacement pad that is compatible with a caliper that uses the bent pin type retention pins will come with any replacement pin or pins that may be needed, plural because there are actually 3 length/profile variations of bent pin across Shimano calipers. There is no metallic versus organic distinction involved.

For the most part the calipers that have the threads are the more expensive ones, or at least that's how they've been doing it recently. To date I believe all the road calipers are threaded, but that's subject to change. On all these calipers the pin is considered part of the caliper and is re-used. If they're lost or damaged, a specific replacement has to be obtained; there is some overlap but it's not dimensioned the same across all the Shimano calipers that use threaded retention pins. If the threaded pin is lost or damaged, a bent cotter type one of appropriate length can be substituted without issue.

Neither style is subjected to braking loads in any way. The pin is a loose fit in the hole of the pads. Braking loads from the pad are entirely pushing on the lips of the caliper that the pads rest against. The pins are there solely to prevent the pads from falling out when you're not braking.

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  • Right, if the pin sustained braking loads it would snap immediately. But I'd still prefer the object preventing my brake pads from falling out when not braking was extra secure! – Cliff AB Jun 8 at 0:28
  • Minor point - the bolt/pin is to retain the pad when its not actively being compressed. So there are no real braking forces affecting the retainer. Also, the retainer can't be too tight because then it could interfere with actuating the brake properly. – Criggie Jun 8 at 1:20
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    Try pulling a bent cotter pin out of its station. Use pliers big as you can find. One will find it quite impossible even with the additional power of a hand tool to even come close to getting a bent cotter pin out. It must first be straightened-- and near perfectly so if the pin is the appropriate size. The straightening process can be tricky as well since the pin will tend to spin away from the straightening force and stay bent and in place. Even a few degrees from straight, unassisted human force is still inadequate to remove it. It is quite safe in this application. – Jeff Jun 8 at 3:01
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    @CliffAB For the reasons Jeff indicates there is zero cause for concern with the bent type. They're overbuilt and never fail. In fact if anything the threaded type are the more likely to fail from coming loose. Most make the contrivance of a circlip at the end to prevent this, and all require loctite. That's not the mark of a more foolproof design. – Nathan Knutson Jun 8 at 3:43
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    In addition, you can't strip the head of a split pin. Which I've now manged to have happen due to poorly fitting allen-keys on both front and rear pad bolts. – Kialandei Jun 8 at 10:43

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