Is it normal for resin brake pads to contain small amounts of metal?

Question

I just bought these brake pads from amazon (the resin variant, NOT the semi-metallic variant, see picture), and even though they are supposed (?) to be non-metallic, I can see small amounts of a glossy substance that very much looks like metal. Color wise I'd say it's closest to copper.

I'm asking because the semi-metallic pads I used previously shredded my last pair of rotors which, as I only found out afterwards, was only meant for resin pads. I replaced the rotors now with another very cheap pair that is also for resin pads only, and I would like to make sure I don't shred it again.

Answer 1

Yes, it's perfectly normal. For example, see the ubiquitous Shimano B01S resin brake pads, which are/were supplied as the stock pads for many hundreds of thousands of hydraulic-braked bikes with resin-only rotors:

As you can see, even with an OEM Shimano pad, the material is full of little metallic shavings. It may look like a lot, but they really only account for a small percentage of the surface area in contact with the rotor. There's still a lot of organic material surrounding the metal. I'd expect there's a good reason the metal is present, likely for some performance reason or another.

Another thing you may consider is upgrading to hardened rotors capable of handling metallic pads. While they are more expensive, yes, they also last significantly longer, and I find they brake better. Perhaps it's just a better-designed hole setup, but I also think there's some friction aspect which works better with the harder rotors.

Answer 2

Yes, it's probably copper. Wouldn't even be surprised if it's bronze.

"Metallic pads", actually which is "sintered metal pads", contains much harder metals, including iron. There is no DIN or ISO approved percentages to denote which one includes what material to which degree, manufacturers are free to make whatever they want, and call it whatever they like.

This is same with car or motorbike brake pads.

With absolute zero metal in a pad material, it would be too soft, heat resistance will be too low, and not grippy enough. Don't bother about them much. Disc brakes in bikes is an abomination of engineering anyway...