Disc brakes - Cycling Mob: Road Cycling, Mountain Biking and More

02-07-2007, 08:08 PM

I have XTR disc brakes 160mm. 3 years and several sets of pads later,
it just occured to me.....

Should I be replacing the rotors? When does one do so other than when
one is bent?

Ideas, comments and flames begin here.......

02-07-2007, 08:25 PM

CB wrote:
> I have XTR disc brakes 160mm. 3 years and several sets of pads later,
> it just occured to me.....
>
> Should I be replacing the rotors? When does one do so other than when
> one is bent?
>
> Ideas, comments and flames begin here.......

For MTBs, it's hard to wear down a SS rotor down to the minimum wear limit.
I did a quick search and was unable to find any values for minimum
thickness. There's a chance, however, that it may be printed on the rotor
itself, as they are on motorcycle disc brakes. Examine it closely for such
information.

--
Phil

02-08-2007, 10:59 AM

On Feb 7, 10:08 pm, "CB" <[Only registered and activated users can see links. ]> wrote:
> I have XTR disc brakes 160mm. 3 years and several sets of pads later,
> it just occured to me.....
>
> Should I be replacing the rotors? When does one do so other than when
> one is bent?
>
> Ideas, comments and flames begin here.......

I posted this sometime last summer. ...

One of the former Shimano USA tech reps gave out the the number of .
20
mm from the nominal width I believe.

This is based on the rotor not being out of true or scored, both of
which tend to end the life of a rotor long before a reduction in
thickness.

Also consider that, given the semi-industrial standard (there was
one?)
of 2 mm, various rotors seem to run nominal widths of between 1.80 mm
and 2.2 mm. So knowing what the nomial width that you started with
would be key. Current Shimano rotors seem to be coming in at 2.0 mm,
but the older RT75's that I have listed were coming in at the low end
....1.8 mm.

Just for the fun of it here are a few numbers that we came up with
while doing some brake trials. small n ... 4 rotors measured for each
average.

Avid Stainless 1.9 mm
Aztec Stainless 2.0 mm
Shinamo SM-RT61 1.8 mm
Shimano SM-RT75 1.8 mm
Shimano SM-RT77 1.8 mm
Shimano SM-RT96 1.8 mm
Shakamuri Ti 2.0 mm
Stan's Al 2.1

R
What was once old is new again.