I upgraded to sintered pads. Are my rotors going to explode?

[Semmelrocc]

I know you're supposed to swap rotors if you switch from organic to sintered brake pads – at least that's what I read everywhere. Why is that?
I took my bike with me on summer holidays and forgot a spare pair of brake pads and the inevitable happened, I had to replace one. The LBS in the area only had one pair of brake pads for my SRAM Guide RE on stock, and that was a pair of sintered pads. So I went home, cleaned the rotor and installed the new pads. Ran them in and they work great now – no noise, same braking power as before, everything seems to be fine after several 100 kms. Rotor color is as it should be and thickness is also ok.
So what's the problem? Should I have gone for a new rotor? If yes, why?

 

[Beekeeper]

I looked this up on another forum as I was wondering that myself. Apparently the resin-only rotors don’t handle heat so well. In extreme heat conditions with sintered pads the rotors are more likely to warp. No idea if this is true but I guess it makes sense.

 

[Bigfathairybiker]

organic or sintered pads can use the same rotors.
organic wear quicker, but wear the rotor slower.
sintered wear slower, but wear the rotor faster.
Organic may lose some braking efficency when wet or hot.
Sintered may stand higher heat without losing as much efficency.
Organic are made from things like rubber , resin and other organic stuff.
Sintered are made from a mixture of metal and other stuff.
Organic are usually cheaper than sintered.

In normal casual riding you probably won't notice any difference.

Brake rotors can warp with either organic or sintered pads , as it is fast increases of heat buildup or sudden changes that cause warping. Eg: using brakes heavily for a long time then suddenly immersing them in water.

 

[jbrown15]

I know you're supposed to swap rotors if you switch from organic to sintered brake pads – at least that's what I read everywhere. Why is that?
I took my bike with me on summer holidays and forgot a spare pair of brake pads and the inevitable happened, I had to replace one. The LBS in the area only had one pair of brake pads for my SRAM Guide RE on stock, and that was a pair of sintered pads. So I went home, cleaned the rotor and installed the new pads. Ran them in and they work great now – no noise, same braking power as before, everything seems to be fine after several 100 kms. Rotor color is as it should be and thickness is also ok.
So what's the problem? Should I have gone for a new rotor? If yes, why?

which rotors do you have on your bike?

 

[2WheelsNot4]

resin-only rotors

Never heard of such a thing.

Or is the latest hogwash the bike industry is going to introduce to scrape out the bottom of our wallets.

 

[RustyIron]

at least that's what I read everywhere. Why is that?

Because this is the interwebs where people click "like" and "share" without thinking. Maybe the first person to post such nonsense was the Vice-President of Rotor Marketing, Shimano U.S.A., and he was trying to bump up sales. Or maybe the first person to dream up that notion was someone whose brakes were jacked, so he threw on new pads. The performance was still not good, so he leapt to the erroneous conclusion that the brake pads were the cause of his woe.

You did the experiment of changing types of pads without changing rotors, and everything works great. You proved the internet wrong!

 

[Beekeeper]

Never heard of such a thing.

Or is the latest hogwash the bike industry is going to introduce to scrape out the bottom of our wallets.

Yeah my rotors have it clearly stamped on them “Resin pads only”

 

[Bndit]

Never heard of such a thing.

Or is the latest hogwash the bike industry is going to introduce to scrape out the bottom of our wallets.

This came surprise to me also when changing my wife`s rotor, resin only. Smaller cheap shimano disc on Her Moustache Semedy. Not that I would put metal pads for Her bike…

 

[steve_sordy]

Never heard of such a thing. (resin only rotors)

Or is the latest hogwash the bike industry is going to introduce to scrape out the bottom of our wallets.

I definitely had an mtb that to my surprise had "resin pads only" engraved on the discs. Can't remember which one it was now, but it was not recently. I have no idea if this is still "a thing" or whether the practice has died a death.

Here is an example: Just to show that I'm not making it up!

https://www.mtbr.com/threads/resin-pads-only-written-on-shimano-rotor.918947/

 

[theremotejuggernaut]

Never heard of such a thing.

Or is the latest hogwash the bike industry is going to introduce to scrape out the bottom of our wallets.

It's been a thing for years. Generally on low end discs. Definitely low end Shimano have been resin only for a long time.

Cheaper metal used in the discs doesn't like rapid increases in temperature associated with metallic pads. Metallic pads are more abrasive than resin so are better paired with discs made of harder material.

 

[Semmelrocc]

which rotors do you have on your bike?

SRAM Centerline 180mm

Anyways, thanks for all your replies! That gives me some peace of mind.

 

[jbrown15]

SRAM Centerline 180mm

Those are fine for all types of pads. Resin only rotors are a softer type of material.

 

[2WheelsNot4]

Well you learn a new thing every day.

I guess the reason I've never heard of them is I've only ever used Hope kit

 

[RustyIron]

Yeah my rotors have it clearly stamped on them “Resin pads only”

I had some rotors that were marked like that. They were on a bike that gets ridden on some pretty gnarly chunk. They might still be on that bike... I don't remember. You know what kind of pads I run on that bike? Whatever I want. There have been no negative effects of running unapproved pads.

 

[jbrown15]

I like how people try to act like resin only rotors are an industry scam…..lol

There’s a reason why they are rated for resin only pads, whether you think it’s real or not it is….lol

It’s also based on performance, if you’re not stressing the brake system cruising around flat roads on your eBike yeah for sure you’re not going to probably notice any issues. But start riding demanding terrain that requires all the stopping power your brakes can offer and you’ll see why you don’t use resin only rotors with non-resin brake pads.

 

[Manc44]

Organic wear so fast they are pointless. Sintered all the way!

 

[emtbPhil]

Yeah it's not really true that all rotors can use resin or sintered pads. Some of the base line shimano/sram rotors are really thin and quite soft. They have "resin only" clearly stamped on them. If you use sintered pads with those at best you'll be replacing them pretty damn often and at worse they'll warp.

 

[Bigfathairybiker]

So, is all this anecdotal? Or has anyone done tests?
I personally have warped motorcycle discs with organic pads.
I have also managed to heat up a set of motorcycle discs to the point of glazing over both the sintered pads and discs. (IOM TT 93)

I've had a search of the tinternet but cannot find any evidence of mtb resin only discs being damaged by sintered pads.
Could someone please provide a link as from reading several previous posts there must be tons of evidence.

 

[emtbPhil]

Yes but, and this seems to be happening in every thread, it’s not a motorbike

All motorbike and car rotors are heat treated so if you hit the warping temp they’ll warp. You can hit that with organic or race pads if you’re on it hard enough. Obviously there are better rotors with higher carbon amounts in the compound and there are vented and none vented. The dreaded drilled. etc…

The resin bike ones aren’t heat treated so warp at a lower temperature. Sintered pads bite more and create more heat. That’s why the rotors are marked resin only.
That’s why they’re silly cheap. They’re just punched steel.

In the real world if you stick sintered pads on but don’t do loads of big downhills, or weigh the same as a twig then it’s probably fine. But for the price of a set of rotors why bother? Just skip a pizza and buy a decent pair.

There are pictures and quite a few stories of resin only rotors burning out or warping. Check the last decade on singletrack forums

 

[Bigfathairybiker]

I partly agree, but not with this "warping temp".
Metals do not have a warping temperature.
Even if heat treated.
There is a critical melting temperature, but to reach that you would need a gas torch.

One possible other reason apart from the one I mentioned earlier, is bends in the disc being called warping. These can occur if the forces are greater than the metal can take.

The only reasons why I can see that cheaper discs are marked as resin only is because they are thinner or made from poor quality steel.
Also, it is very likely that the insurance claims department had a say in it, to mitigate the chances of a claim.

To be clear, I am not saying using non resin pads with resin only marked discs will not end up with knacked discs.

And yes , too thin discs will bend with both resin and sintered pads.

I am just pointing out the incorrect assumptions as to the reasons why.

No bad karma intended.

Maybe I will punch out a few discs from different metals at work and try them out.
Only hard bit will be sneaking some home work into the machine operators schedule.
Maybe several packets of chocolate biccys will help.

 

[Semmelrocc]

Well, back to the original topic: after an intense weekend riding trails in Saalbach/Austria, I can confirm my brakes have not exploded.
On one occasion I encountered extreme fading on the rears though. That was when a spoke on the rear wheel broke at the start of a trail and I tried to ride down the trail slowly to avoid any further damage. When I stopped at the bottom end, there was suddenly no more resistance on my rear brake lever – nothing! At first I thought the spoke might have damaged the braking hose, but everything went back to normal a few minutes later (when the temperature was back to normal). The morale of the story: you can switch from organic to sintered, but the best option for downhill is to not use your brakes anyway.