My 14/12 SLX RT66 rotors (resin pads) are worn again.

New they are 1.8mm, Shimano advise replacing @ 1.5mm, my front is at 1mm….

Is this “normal” wear for a trail bike MTB?

Would i benefit from greater longevity with a 203mm?

Any other recommendations?

Probably depends on how long you have ridden them, the conditions and the pads your using? Are you a brake dragger? Ride in the Peak a lot?

14 months for some people is about 4 rides, others will be 14,000km

Yea, i know, its very much a personal thing. I’ll just suck it up, they’re not pricey to replace.

How many sets of pads are you going through in that time?

Dunno about pads, i don’t count them, a few, always replaced before the spring sets off alarms.

I’m going to replace with the same, just kinda pondering if a 203 /160 combo would be a bit shonky……..

My fronts definitely worn more than the rear.

Gone RT66 180mm.

I’ve never ever needed to replace a rotor.   What am I doing wrong?

Nothing, brakes are for wusses.

maybe you’re dragging them :/

I go through rear discs and pads quite quickly as I’m out a lot and in all weathers.  Add in the gritty trail surfaces I ride mostly and I can easily go through a rear disc in 8-9 months.  The front doesn’t suffer anywhere near as much wear as it generally stays grit-free due to me manualling most puddles even though I use the front brake more than the rear.  Also in the winter the crud gets channelled down the seatstays by my mudhugger so that doesn’t help pad or disc life!

Off the brakes lad. Time is meaningless. Decent distance would be more an accurate indication. But like you say, they are cheap, so don’t worry about it.

admittedly it’s a/ not used as much as before and b/ it is quite thin, but still got my Hope wavy rotor on my M2 SS hardtail. Think that was back in 2001/2  😉

Distance isn’t either, it depends on the type of riding too.  The brakes on my main bike (was on my 5, now on the Rocket) are Hope E4’s and they spend all their life on steep stuff and uplift days so get a hammering.  The brakes on the other bike, Deore’s on a Trek Fuel EX, do general stuff like trail centres and XC rides so have a much, much easier life.  The mileages they both cover are similar (or were when the Trek was running, waiting to get the pivot bearings, BB and suspension serviced plus some new wheels) but the wear on the brakes and other bits are completely different.  The Deore’s actually wear the same front to back and the discs are still the originals from 3 years ago but when I had the 5 it got babied by not being used most of the winter as replacing two pivot bearings with a 5mm allen key and a hammer is 10x simpler and cheaper than the 10 bearings on the Trek.  Hence why the brakes got an even easier life as they didn’t generally get covered in grit.

At the end of the day they’re brakes on a mountain bike that gets used in all weathers.  I look after them by keeping them clean after a ride and replacing parts as they wear but they’re not some precious thing to be kept behind bulletproof glass.  There’s nothing sadder than a mountain bike that doesn’t get used as it was designed to be.

When I lived in Sheffield, yes.

Now I live in Berskhire, no.

Its entirely down to the fact the the Peak is made from material called millstone grit. Its a sedimentary rock made up of particles that are incredibly hard, so it breaks down and turns into liquid sandpaper! <span style=”font-size: 0.8rem;”>Chains, brake disks, chainstays, cranks, everything would wear down if it wasn’t protected.</span>

Mileage plays a part too but you still need miles + the right (or wrong) sort of conditions. Steel has a Mohs hardness of about 6-7.5 depending on type, millstone grit is something like 8.5. A material has to be harder than another to wear it away (so diamond is 10 on that scale). Riding somewhere with chalk you wouldn’t have the same problem as its hardness is 1!

Millstone grit is predominantly quartz particles I believe. Moh’s scale hardness of 7.

Never changed, never checked. I suppose I should. Oldest set are approaching 20 years now though to be fair that bike doesn’t get ridden much these days.

I brake with my face. Or hand if I get it down in time.

Millstone grit is predominantly quartz particles I believe. Moh’s scale hardness of 7.

I’m not a geologist, just half remembering a tribology poster in the engineering department.

Decent distance would be more an accurate indication. But like you say, they are cheap, so don’t worry about it.

Yes. My XC hardtail still has the original disc rotors. Old bike and still use it quite often.

My 8 months old 150/150 all mountain bike is “eating (resin) brake pads”, disc rotor (rear) is down to 1.5 mm. Will get a new rotor end of the year?

But the amount of energy which goes into the brakes of this bike is very high.

So yes: “decent distance” is key? And 14 months o.k. for your riding?

I only ever change the discs on changing brakes where I’ve been upgrading and maybe changed the size.

Never replaced due to wear.