Do drilled rotors stop better in the wet?

I have recently switched from old style magura marta drilled rotors to the newer undrilled wavy rotors. Having done the ‘puffer 24hr I reckon that those with drilled rotors had less pad wear. Also out yesterday and it was really wet and I thought that the braking was a bit weaker than usual.

Anyone else agree, might switch back to drilled until summer!

I’m currently using Hope sawtooth floating rotors with XTR calipers and I’m sure the pads last longer than they did when I was using Shimano rotors, I put it down to the larger holes in the Hope rotors clearing the grit away from the pad surface quicker.

Me too, went from drilled Hope rotors to undrilled wavey ones. Not as grabby as the Hope ones, but not as much stopping power either. Now gone back to drilled Hope ones for the winter, better wet weather performanc.

Years ago when I was studying mechanical engineering at university, I was stold that there was theory that drilled brakes were worse in the wet because water got into the holes and was draggged on onto the disc as the pad went past. Your mileage may vary or wibble flip doo as they say on ukrm

The first drilled disks I had was on motorbikes and the holes were introduced to improve wet-weather braking.

I was always under the impression the holes where to aid in cooling and reduce weight? The none drilled wavy rotors achieve this by having an inconsistent air flow from the wavyness and causing it to cool down that way…

But then I’m no engineer.

Back in the 80s, WhichBerk? had an article on drillled vs non-drilled motorbike discs and interviewed various pros and manufacturers. The conclusion IIRC was that for your average road user undrilled discs were better because they cleared the water quicker – precisely because of the issue Nicknoxx refers to.

But all the fancy road bikes had drilled discs because that’s what the punters expected. Nothing new there then.

Early motorcycle discs were stainless steel with IIRC organic pads – very poor in the wet. Drillings were introduced to provide better wet weather performance as it broke up the film of water quicker. Materials science moved on tho and better disc and pad materials were developed so poor wet weather performance was not an issue

Brake pads in the 60’s used to produce a gas during use. This gas could build a layer between pad and disk, reducing performance. The holes allow somewhere for the gas to escape.
Modern brake pads dont do this so much but cross drilling does help prevent a film of water doing the same thing and aids heat dissapation.

Brake pads still produce gas [especially new pads] the holes in a drilled disc help to disperse it
Gas build up between pad & disc is known as green fade

More details here

I was stold that there was theory that drilled brakes were worse in the wet because water got into the holes and was draggged on onto the disc

a theory is just a conjecture and may have no basis in fact