I've misplaced mine, and noticed the other caliper doesn't have the other one.

  • How important are these? I mean, do pads fail or come loose at times, without these safety feature present?
  • Is it possible to find a replacement?
  • What other components have those?

This is the back of a Deore M-535 caliper, where the pin is marked at the places it should have been secured, caliper

  • They are a fail-safe for if the threaded pin holding the pads works it's way loose. As its a part of the bike probably not checked often I'd suggest replacement with a generic part or replace the pin with a split pin.
    – DWGKNZ
    May 29, 2015 at 19:12

3 Answers 3


Usually it's called a Retaining-Ring, poodle-ring or a split-ring. They will look something like this.

enter image description here

Special pliers are made for their removal and installation, but I usually just use needle-nose pliers.

I'm not familiar with that particular model of caliper, but I do think replacing the ring is probably important. In a pinch, you can tightly wrap and twist a piece of wire in the groove usually occupied by the ring to hold you until you get the right part.

Your local bike shop may have spares specific to that part. You can also try your local hardware store. In the screws and bolts section the will usually have bins of split retaining rings because regardless of the application, when you remove one the "springiness" tends to make them fling off into the tall grass and get lost (at least whenever I do maintenance).

  • Good point. I'll put it in mind for the next visit.
    – PIXP
    May 29, 2015 at 20:14

It seems to be known as an R-Clip or an R-pin:


The pin which actually holds the pads in is threaded and on all the Shimano brakes I've ever owned with this setup (3 bikes) I have never encountered a situation where the pin has come loose and the R-clip would have been required to stop the pin coming out.

Ideally the clip should be there should the worst happen, but personally I'd have no reservations riding without it.

  • Good enough. I tell you what - if i can find something else in the bike that uses more of these i'll think about actually looking them up...
    – PIXP
    May 29, 2015 at 20:14

That is a pin (which you have) and a clip (which you don't). They are part of the brakes's Pad Retention system.

They are important because they ensure the brake pads stay in place. You can buy them online, here for example, but if your local shop is cool they should give you one from the lots of spares they have.

Take it easy using your bike while you don't get it fixed.

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