Do my rotors get to hot?

Sander23

Active member
Aug 28, 2020
700
433
Belgium
I've had some rt64 for the past 5700 km, I recently switched to some ice tech rotor in 203mm(same size as before).
I noticed these rotors gets a little black. Is this due to to much heat?.

My riding has stayed the same . Only changed pads to some swisstech ebike pads.

I did notice when the pads and disc gets a little wet that they scream like a pig

20240313_143736.jpg
 

VWsurfbum

🤴King of Bling🌠
Jan 11, 2021
1,371
2,028
England
I've had some rt64 for the past 5700 km, I recently switched to some ice tech rotor in 203mm(same size as before).
I noticed these rotors gets a little black. Is this due to to much heat?.

My riding has stayed the same . Only changed pads to some swisstech ebike pads.

I did notice when the pads and disc gets a little wet that they scream like a pig

View attachment 136227
Out of interest, have you got a picture looking at the calliper from the top? it looks like your pads are sitting too far out of the disc?
If that's the case you wouldn't be getting full power, and then having to use more force to get the same amount of braking force, leading to over heated discs?
then again, they could be absolutely fine ;)
 

Sander23

Active member
Aug 28, 2020
700
433
Belgium
Out of interest, have you got a picture looking at the calliper from the top? it looks like your pads are sitting too far out of the disc?
If that's the case you wouldn't be getting full power, and then having to use more force to get the same amount of braking force, leading to over heated discs?
then again, they could be absolutely fine ;)
20240313_170020.jpg
20240313_170013.jpg
20240313_170206.jpg
 

Dax

E*POWAH Elite World Champion
May 25, 2018
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Are you noticing any issue with the feel of the brake? Sponginess, pushing back against your finger when you pull the lever, pulling to the bar? Is the rotor glowing or turning blue? If not, your brakes aren’t getting too hot.

For comparison, this is how my front rotor looks:
IMG_4102.jpeg


I would worry more about the wear pattern, think you may have the caliper slightly spaced off the rotor.
 

Sander23

Active member
Aug 28, 2020
700
433
Belgium
Are you noticing any issue with the feel of the brake? Sponginess, pushing back against your finger when you pull the lever, pulling to the bar? Is the rotor glowing or turning blue? If not, your brakes aren’t getting too hot.

For comparison, this is how my front rotor looks:
View attachment 136265

I would worry more about the wear pattern, think you may have the caliper slightly spaced off the rotor.
No sponginess,rotors won't get red or blue ish, only only thing I have is my rear brakes lever returns slower ( did a bleed and cleaned lubed the pistons still remains.


I noticed the edge to. It uses the original caliper mount that was used with the same 203 rt 64 rotor. I don't have any spacer under it.
 
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Mikerb

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May 16, 2019
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Weymouth
I dont know what compound those pads are! Never seen pad material that black...is that how they were when new?

I would clean the rotors thoroughly using brake cleaner and if necessary a light grade wet and dry.............and personally I would dump those pads. One possible scenario is that the pads were not run in well and the sacrifice layer was overheated. That contaminated the rotor which in turn will have contaminated the pads. Giving the pads the same treatment may work.

An overheating rotor goes blue not black so it is not overheating, although I doubt you are getting full potential from the brake with the rotor covered in that black deposit.
 

Sander23

Active member
Aug 28, 2020
700
433
Belgium
I dont know what compound those pads are! Never seen pad material that black...is that how they were when new?

I would clean the rotors thoroughly using brake cleaner and if necessary a light grade wet and dry.............and personally I would dump those pads. One possible scenario is that the pads were not run in well and the sacrifice layer was overheated. That contaminated the rotor which in turn will have contaminated the pads. Giving the pads the same treatment may work.

An overheating rotor goes blue not black so it is not overheating, although I doubt you are getting full potential from the brake with the rotor covered in that black deposit.
These are the pads.
I light sanded the pads wich w was fairly easy, I will do the rotors also and try to bed them in.
 

Sander23

Active member
Aug 28, 2020
700
433
Belgium
1stpic is swisttop 2nd are shimano resin. Thats probably why they dont use all the contact. The are round off at the top
20240313_170519.jpg

20240314_084039.jpg
 

Dax

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May 25, 2018
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Don’t use car brake cleaner, apparently it leaves oil on the surface. I usually use IPA.
 

Planemo

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Mar 12, 2021
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Essex UK
Don’t use car brake cleaner, apparently it leaves oil on the surface. I usually use IPA.
Brake cleaner should leave zero lubrication residue as clearly we dont want any oils around brakes. If it does, bin it as its clearly not doing the job its labeled for.
Brake cleaner will also get rid of contaminants that IPA wont touch. IPA is great for general cleaning of 'delicate' surfaces (some plastics will melt from brake cleaner) but brake cleaner will always do a better job at cleaning provided the item can tolerate it. Brake discs and pads can.
 

Dax

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Brake cleaner should leave zero lubrication residue as clearly we dont want any oils around brakes. If it does, bin it as its clearly not doing the job its labeled for.
Brake cleaner will also get rid of contaminants that IPA wont touch. IPA is great for general cleaning of 'delicate' surfaces (some plastics will melt from brake cleaner) but brake cleaner will always do a better job at cleaning provided the item can tolerate it. Brake discs and pads can.

Maybe it’s an old wives story, been told many times over the years not to use car brake cleaner because it will contaminate the surface.
 

Dax

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Been told by whom?

Bike friends, bike mechanics, bike forums. Looking around there’s a lot of threads arguing both ways on this, I’m happy to call this an old wives tail…and I’m going to keep using ipa on mine
 

Dax

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I've been using brake cleaner for 30 odd years in the motor trade without any issues.

The theory is that car brake cleaner is fine on car brakes (which I’ve used it on for years) but it contains oil to stop cast iron brake components rusting, which car brakes get hot enough to burn off the discs, but bike brakes do not. Never been 100% on that as I’ve had mtb rotors quite hot.
 

p3eps

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Dec 14, 2019
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I have a 20litre drum of Wurth Brake Cleaner, works fine on both motorcycles and eMTBs
I use Wurth Brake Cleaner too - but aerosol tins. Funnily enough, we use EXACTLY the same ones at work 😂

Been using it for 15+ years with no issues. It removes any oil / contaminate and dries in within seconds. If you spray it on your hands, your fingers start going white as it sucks the moisture out of them!. I spent many years as an instrument tech with hacks all over my hands. Now, the techs wear nitrile gloves all the time, and I sit in an office with baby soft hands!!
 

RustyIron

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Jun 5, 2021
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The theory is that car brake cleaner is fine on car brakes (which I’ve used it on for years) but it contains oil to stop cast iron brake components rusting, which car brakes get hot enough to burn off the discs, but bike brakes do not.

That's absurd.
MSDS sheets are available for about any product imaginable.
Please support these ludicrous claims with some data.
 

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