Brake rotors

5 replies to this topic
  • RasmusDK

Posted June 13, 2012 - 11:35 AM


Iam thinking about making some new brake rotors for my bike, I want a solid rear disc so it dont eat pads as quickly with mud on them. A friend of min has access to laser cutter and I can draw them myself. But what material should I use? And how straight do they have to be?

  • grayracer513

Posted June 13, 2012 - 11:51 AM


The OEM discs are stainless steel. Carbon steel is easier to work with, gives better braking performance, but rusts and wears faster.

Omitting the slots and holes will not solve the pad wear problem, and may in fact make matters worse, since the mud will have nowhere to escape from between the pad and rotor.

  • RasmusDK

Posted June 14, 2012 - 12:26 AM


Cheers. Solid discs help cause the mud gets scraped off when you brake, and you therefor dont keep dragging it around in all the cutouts.

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  • grayracer513

Posted June 14, 2012 - 08:14 AM


Cheers. Solid discs help cause the mud gets scraped off when you brake, and you therefor dont keep dragging it around in all the cutouts.

That's actually not the case, but carry on.

To address the question of straightness, the thickness of the rotor should vary no more than 0.05mm (.002"), and the runout, or axial deflection limit is 0.15mm (.006")

  • MaxPower

Posted June 14, 2012 - 09:40 AM


I've seen teams change rear rotors to a solid disc before in the mud.What is the reason you feel that is the wrong thing to do Gray Racer?
My personal solution to mud that bad is for me not to ride that weekend

  • grayracer513

Posted June 14, 2012 - 10:29 AM


The most effective way to address mud on the rotor is "wave" cutting both the inner and outer edges. The angled leading edges of the waves scrape away mud quite well. Solid rotors are sometimes an improvement over those with round drilled holes, but not always, or even usually. To a degree, it depends on the mud involved (size of the grit). When they are drilled, it's true that mud can hide out in the holes, and if the sand in the mud is very coarse, that can cause trouble when a good sized chunk of gravel gets caught. But with solid rotors, that same mud simply builds up on the leading edge of the brake pads and runs under the full length of the pad, with nowhere to escape to. It ends up being kind of like choosing between being shot or hung. Angled slots are preferable to holes, IMO, and running a good stiff brush against the rotor mounted on the swing arm may be the most helpful thing you can do.

To be fair, as a desert racer in SoCal, I don't really deal with this kind of thing that often. I usually use your approach. :devil:

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