Brake rotors, how thin is too thin?

[ALdad 06]

The pads on my 2000 sport need replacing. Rotors are about 3.4-3.5mm. What risks or issues am I taking in running one more set of pads maybe about 15k miles? I commute daily the bike stops just fine. But the pads are really thin. Will one more set of pads 15kmi. I am guessing will shave another .2 or .3 mm off rotors. Tell me if I am stupid in pushing it .

[john zibell]

According to the manual, wear limit is 3.9mm. Not very much wear allowed as new is 4.1mm and thin to begin with.

[GuzziMoto]

How many miles total and what kind of pads have you used to wear the rotors down that much?
Yes, I would say you are pushing it already.

[ALdad 06]

How many of you have actually measured your rotors? The manual says replace at 3.9, that’s .2 mm wear from new. .2mm is 2 sheets of paper. Could someone tell me how this small amount could make a difference in performance or safety? I am sure there is a reason. I would sure like to know. The bike has 34k mi. this is the second set of pads. The first were stock and the last ones were the Kevlar organic. I commute stop and go traffic and I hardly use any rear brake so I would assume the wear is normal. I don’t have a problem replacing the rotors, other than I am a cheap bastard. But I would like to know what the issues are with thinning discs from one who really knows brakes. I am guessing thin rotors are more susceptible to warping and eventually the calipers won’t grab, but .2mm, please. I have the same thoughts with our car when I am told I need new rotors every time it goes in for brakes .

[john zibell]

How many of you have actually measured your rotors? The manual says replace at 3.9, that’s .2 mm wear from new. .2mm is 2 sheets of paper. Could someone tell me how this small amount could make a difference in performance or safety? I am sure there is a reason. I would sure like to know. The bike has 34k mi. this is the second set of pads. The first were stock and the last ones were the Kevlar organic. I commute stop and go traffic and I hardly use any rear brake so I would assume the wear is normal. I don’t have a problem replacing the rotors, other than I am a cheap bastard. But I would like to know what the issues are with thinning discs from one who really knows brakes. I am guessing thin rotors are more susceptible to warping and eventually the calipers won’t grab, but .2mm, please. I have the same thoughts with our car when I am told I need new rotors every time it goes in for brakes .

I believe the thickness is for hear dissipation and strength. I'm not a fan of the original rotors. Get some good 5mm thick Brembo rotors and you won't have to worry about replacing them for a long time. Todd can help you out with that. Once the rotors get thin, I get concerned over their strength.