Just picked my bike up from the mechanic after having the brakes bled and we got chatting about removing the dead zone for XTs by fitting thicker rotors. I'm currently running 203mm fancy Ice Tech rotors (the triple layered ones) which have served me well but I like having a very on/off feel for my brakes so thinking about thicker rotors.
Got told about Galfer ones but they're about £80 an end.
A) is there a more cost effective option?
B) will thicker rotors retain braking performance for big Alpine descents etc?
C) anyone made the switch and any good?
Maguras are 2.0mm, thicker than Shimano at 1.8mm.
Superstar do a 2.3mm
I’m using TRP on one bike, Galfer on the other. Both keep running true and improve the brake feel. With those thinner ice tech discs, I was always getting them bent by rock strikes. Shimano should do 2.3mm versions of them… surely the sandwich design would be easier to make if thicker? Pretty sure they’d be more resilient, and feel better with most of their brakes. I wonder what the new Saint Brakes will use…?
https://www.freewheel.co.uk/aztec-stainless-steel-fixed-6b-2mm-disc-rotor-varpbr6
Aztec 2mm from £24.99 each
There'a also TRP/Tektro rotors at 2.3mm that are reasonably priced. Unsure on clearance in Shimano brakes though.
B) will thicker rotors retain braking performance for big Alpine descents etc?
Yet to test them fully (Alpine descending won't happen for me until August) but in UK riding I'm having better braking with 4pot XTs & posh XT/XTR rotors with the cooling fins, compared to Zees with RT66s/Magura Storm HC 2.0mm rotors. Much better. Last time I rode in the Alps I had heat issues with my Zee/Magura rotor combo, possibly pad related - I was using Uberbike Race Matrix then, currently I'm using finned metal Shimano pads.
Basically, I'm not convinced thicker rotors would be any better than the posh Shimano ones you currently have...
I’m using the standard GALFER rotors with XT and it works well. They didn’t cost that much. They are about £30 an end
The expensive Galfer Shark 2mm rotors are £80 - but the "Enduro" 2mm version of their regular Wave rotors are nowhere near that
https://www.bike-discount.de/en/galfer-bike-wave-fixed-e-bike/enduro-6-bolt-disc-rotor
the 203mm is listed separately for some reason
https://www.bike-discount.de/en/galfer-bike-wave-fixed-6-bolt-rotor-disc-for-e-bike
Those fixed Wave ones are what I’ve been using with Zees.
The ice tech ones I used previously cost me more, and were great when new. But not so good with worn pads… and, as said, gained wobbles/rubs I couldn’t true out.
I picked up some super cheap Magura Storm rotors.
I am on the larger size (90kg) and they work just fine. The only time I've had brake fade before was on 180/160mm worn Shimano rotors, but then I've done the same descent since getting the Magura brakes and rotors and no issue at all.
Whether that's any better than new fancy pants Shimano, I've no idea.
Thicker rotors are "better". I use Hope 2.3mm.
They are structurally stronger so less likely to warp or be bend. More material means better hear sink so lower operating temperature.
However, they are not going to chance lever feel. Your brakes are a self adjusting open system. It doesn't know the difference between thick rotors with thin pads or thin rotors with thick pads. The pistons adjust to offer the same clearance. (Until you start getting to the point if really worn pads and rotors)
However, they are not going to chance lever feel.
But, from experience, with several brake brands, they do. The difference is notable at all times, but even more obvious once your pads are no longer new.
I'm using AliExpress Galfer Shark-a-likes with my GR4s. 203x2.3mm and about £15 quid. Work mint.
I'm also using TRP R1 with my V4s. 203x2.3mm and were about £9 quid when Merlin had them in stock a couple of years ago. Work mint.
Of the 2 types, I'd rather run the R1s, but only because they were cheaper. But will happily move to the Shark-a-likes when i need to change them out.
I put some Tektro 2.3mm rotors on mrsfoos bike as she's a known brake dragger. She has not managed to overheat them so they definitely dissipate heat better but also they needed no trying they were straightest rotors I've ever fitted.
Hope vented rotors are 3.3mm but aren't cheap and possibly too thick for most brakes
Hope do 2.3mm solid rotors now as well. They were recommended for the V4 (which won't take vented rotors AIUI). RRP £57
At the end of this review there’s a detailed report on Galfer 2mm rotors vs thinner Shimano: https://www.pinkbike.com/news/review-shimano-xt-8220-brakes.html
However, they are not going to chance lever feel.
I’m another one that would dispute that. I didn’t buy them to change the feel of the brake, but the change was immediately noticeable. It doesn’t make much sense, but it happens
They are structurally stronger so less likely to warp or be bend. More material means better hear sink so lower operating temperature.
However, they are not going to chance lever feel. Your brakes are a self adjusting open system. It doesn't know the difference between thick rotors with thin pads or thin rotors with thick pads. The pistons adjust to offer the same clearance. (Until you start getting to the point if really worn pads and rotors)
Came to post basically this. Not sure how big a difference it will make to warping (if you whack a rock, I think the major difference will be that the thicker rotor is harder to straighten), but having more material will mean they take longer to heat up. Shouldn't make any difference to lever feel.
Superstar do 2.3mm rotors, I think I paid £40 for the pair. Work very well and definitely helps reduce lever throw (which I like).
I’ve run both 1.8mm and 2.3mm rotors on two different sets of brakes. The thicker rotors do change the feel.
And if you think about the complex minutiae of a bike brake (as opposed to simplifying it to its basics) you can see why. You might not notice if a bike’s brakes were operated by your feet but a human’s index fingers are incredibly sensitive to tiny changes!
Last night I adjusted the truss rod on a bass. I’d measured the action (distance from top of fret to bottom of string) as 3.5mm at the 12th fret, which is fairly high. Tightening the truss rod straightened the neck and brought the action lower and I played it and thought “wow, that’s miles lower, is it too low?” and kept playing and decided it felt good but I wouldn’t want to go any lower or it would get in the way of me digging in.
Out of curiosity I then measured (again with digital calipers) the action once more - it was now 3mm at the 12th fret. I checked a few times (I checked a few times when I measured it before too).
So a half millimetre change in action on a bass with high action felt like a BIG change. That’s the ridiculous ability of human fingers to notice tiny changes, as in brake feel!
Logic tells me that thicker rotors should be better. Simple: more material = more heat dissipation.
But my own experience so far* is I've had better performance from XT/IceTech and XTR/Freeza sandwich rotors than thicker rotors. That's having tried normal 1.8mm SLX/RT66, TRP 2.3mm, Magura Storm HC 2.0mm, XT/RT86 and XTR/MT905s.
Same findings in this test: The best MTB disc brakes – 14 MTB brakes in comparison | ENDURO Mountainbike Magazine (are their testing methods valid? I'm not clued up enough to know, but appear sound to me). "All MTB brake rotors are made of steel – at least on the friction surface. The thickness of rotors can vary depending on the models and manufacturers, and is primarily linked to heat dissipation. More material enables better heat dissipation, preventing the sensitive calliper from overheating – at least in theory. In our lab test, however, we weren’t able to confirm this theory. Shimano, on the other hand, use a sandwich design with an aluminium core on their XTR ICE-TECH rotors, which is intended to improve heat dissipation, while at the same time reducing weight. Our lab results confirmed that sandwich structure makes perfect sense, with the Shimano XTR brakes reading the lowest temperatures – an effect that is particularly noticeable with sintered pads."
* experience so far doesn't include alpine descents which have always been the hardest test of brakes for me.
Thanks for the feedback everyone. Going to have a proper test of the freshly bled brakes this weekend and may ditch the ice tech rotors for some thicker, solid ones and take both sets on my jollies. Easy enough to swap them over if needed...
Thicker rotors and new pads will initially feel different as the pistons can only retract so far. Similar to people who overfill to reduce lever throw. Once things wear enough to allow the pistons to go back into their self adjusting range, then that's what they will do. This is controlled by the roll and slip of the caliper seals against the piston and you have done nothing to influence this. However, the change from the "new" feel is very slow and gradual so much harder to notice.
Very similar to how every fork upgrade feels great, but a lot of that can be down to the fact that it was also accompanied by a lower service which possibly make the biggest difference. But no one notices the gradual decline in performance from that freshly serviced feel.
Also rotor diameter to consider. I've got 203mm XTR rotors F&R but 220mm SLX F&R might be better. Fancier rotor material vs larger rotor diameter, what wins...
primarily linked to heat dissipation. More material enables better heat dissipation, preventing the sensitive calliper from overheating – at least in theory.
i thought there was an optimum working temperature- they need to be hot enough, but not too hot. Massively powerful brakes/huge rotors/light rider/short descent might not be up to id3l working temp. I’ve definitely felt some of this effect with some brake/pad/rotor combos - my v4s definitely work better after the first few activations on a trail. (Of course quality of bleed, age of fluid, minor contamination also come into this)
Disadvantage of ice tech rotors is that if you don’t replace in good time they can fail catastrophically and also become very easy to bend as the steel layer gets thinner.
I’ve run both 1.8mm and 2.3mm rotors on two different sets of brakes. The thicker rotors do change the feel.
And if you think about the complex minutiae of a bike brake (as opposed to simplifying it to its basics) you can see why. You might not notice if a bike’s brakes were operated by your feet but a human’s index fingers are incredibly sensitive to tiny changes!
Last night I adjusted the truss rod on a bass. I’d measured the action (distance from top of fret to bottom of string) as 3.5mm at the 12th fret, which is fairly high. Tightening the truss rod straightened the neck and brought the action lower and I played it and thought “wow, that’s miles lower, is it too low?” and kept playing and decided it felt good but I wouldn’t want to go any lower or it would get in the way of me digging in.
Out of curiosity I then measured (again with digital calipers) the action once more - it was now 3mm at the 12th fret. I checked a few times (I checked a few times when I measured it before too).
So a half millimetre change in action on a bass with high action felt like a BIG change. That’s the ridiculous ability of human fingers to notice tiny changes, as in brake feel!
The problem with this is that the pads and lever in a hydro brake system aren't directly connected. First, the pistons automatically adjust to give very close to the same clearance regardless of the rotor thickness - this means that the piston travel should be very consistent, as long as you don't have sticky pistons. Then, the fluid in the system automatically adjusts to give the same lever position. The lever feel is determined by the pad clearance and that should be fairly consistent if you don't have sticky pistons and the system is fully topped up with fluid.
Swapping old, badly worn rotors and pads for new ones might change the lever feel, however, but that's not a function of the rotor thickness.
I jumped from 1.8mm - 200mm rotors to 2.0mm and 220mm rotors front and rear, it made a noticeable difference to braking feel, the modulation felt more pronounced and overall power too. I wouldn't go back down in size or thickness.
“In theory” MTB brakes self-adjust and the simplified models of a brake that are being referred to “show” that you can’t feel a difference.
In practice you can feel a difference and that’s because brakes don’t work as ideally as people like to pretend they do, and humans are incredibly sensitive to tiny changes (some actually notice, some don’t - and those that don’t like to tell those that do that they’re imagining it…)
Thicker rotors are "better". I use Hope 2.3mm.
They are structurally stronger so less likely to warp or be bend. More material means better hear sink so lower operating temperature.
However, they are not going to chance lever feel. Your brakes are a self adjusting open system. It doesn't know the difference between thick rotors with thin pads or thin rotors with thick pads. The pistons adjust to offer the same clearance. (Until you start getting to the point if really worn pads and rotors)
This and others +1
Rotor thickness isn't going to have an impact on the initial feel, just heat dissipation and cooling. I agree with that enduro test, Ice-tech rotors 'feel' different. But it's more that they remain consistent after the first couple of moments of hard braking.
New rotors probably feel better because both the braking surface is flat (so the pad isn't being squished into the concave brake track) making them feel firmer, and flat for run-out so a wobbly rotor isn't moving left/right and pushing the pads back making the free-stroke less.
Thicker rotors and new pads will initially feel different as the pistons can only retract so far. Similar to people who overfill to reduce lever throw. Once things wear enough to allow the pistons to go back into their self adjusting range, then that's what they will do. This is controlled by the roll and slip of the caliper seals against the piston and you have done nothing to influence this. However, the change from the "new" feel is very slow and gradual so much harder to notice.
Very similar to how every fork upgrade feels great, but a lot of that can be down to the fact that it was also accompanied by a lower service which possibly make the biggest difference. But no one notices the gradual decline in performance from that freshly serviced feel.
Do you use thicker rotors?
My experience hasn’t slowly changed with time, it’s a measurable difference in free stroke.
Without getting the calipers out I can easily compare difference between my thick rotor brakes and my normal rotor brakes. It’s very easy to tell that the improvement has stayed despite the 2+ years of running thicker rotors, as every time I jump on the “normal” brakes I hate the increase in free stroke. This never used to be an issue as they were fairly similar before.
That’s whey you’re seeing several people here tell you there’s a change when using thick rotors. It might not make much sense but it’s happening
Rotor thickness isn't going to have an impact on the initial feel, just heat dissipation and cooling.
I would have thought that heat dissipation was more a function of surface area, and that thicker rotors, other things being equal, have a negligible increase in surface area.
That’s whey you’re seeing several people here tell you there’s a change when using thick rotors. It might not make much sense but it’s happening
And I don't disagree, but I'd put money on the mechanism not being that thicker rotors inherently reduce free stoke. Otherwise thicker pads would do the same.
I'd suggest that new thin rotors and fresh pads would feel just as good. And then in 2 years time possibly not as good because they won't remain as straight. There might even be an issue whereby if the pistons have a groove worn in by the seals them aligned with thin rotors, the pistons would be pulled out towards a thick rotor.
The greater thermal mass of a thicker rotor (and the increased distance between the braking surfaces) will change the temperature at the surface and that will change the feel (discs will dissipate all their heat eventually but generated heat is moved via conduction as well as being dissipated by convection and radiation).
I will never cease to be amazed by the ability of educated people on forums to over-simplify complex systems to justify their opinions… Over in guitar world apparently wood makes zero difference because every armchair expert has no understanding of resonant systems.
Do you use thicker rotors?
Yep, went from Hope 1.8mm to Hope 2.3mm
Agree with TINAS, I'm not saying the change in lever feel isn't happening but I am questions the rotor thickness being the mechanism.
You get more or less the same feel whether it's from fitting a new 1.8mm, 2.0mm or 2.3mm rotor. It's the new part that counts, especially in conjunction with new pads.
New pads/old rotor or new rotor/old pads just isn't the same. I find pads go slightly convex and rotors concave as they wear, and either or both just feel not as good as new/new.
The greater thermal mass of a thicker rotor (and the increased distance between the braking surfaces) will change the temperature at the surface and that will change the feel (discs will dissipate all their heat eventually but generated heat is moved via conduction as well as being dissipated by convection and radiation).
It would be an interesting thing to model, back in the every-gram-counts days I used to run those silly alligator rotors that weighed naff all. And they were rubbish. I'd qualitatively put it that a 203mm rotor was only as powerful as a conventional 180mm rotor, and coincidentally weighed the same.
At the time I wondered if there was something going on beyond A-level physics explanation as in simple terms friction should be independent of area (friction force = coefficient of friction * perpendicular force).
What I'd really like to try is a rotor with a much more solid brake track.
I will never cease to be amazed by the ability of educated people on forums to over-simplify complex systems to justify their opinions
I also suspect manufacturers come up with post-hock justifications for how their products look and function.
e.g. thick rotors, you could add mass more effectively by making them more solid. But I hypothesize that a thin but solid rotor would warp, whereas a thick one that's more air than rotor might not as stiffness increases with the cube of thickness*.
*Sir Mix-a-lot's theorem.
I have a set of the Superstar 2.3mm rotors, they were too wide to fit in my GRX brakes so I'm not going to use them, fitted once and removed. Ping me a message if you want them for the cost of postage plus 1 beer token.
I will never cease to be amazed by the ability of educated people on forums to over-simplify complex systems to justify their opinions
It's nearly as amazing as how often educated people reach for condescending to justify their stance rather than explaining it.
“It's nearly as amazing as how often educated people reach for condescending to justify their stance rather than explaining it.”
Because it’s too damned complicated, like many real things. Who has the time to write a thesis on this? Brakes are superficially simple but the minutiae are very very complex. But at least pointing this out and allowing discussion and opinions from people who’ve tried different thickness rotors is more useful than telling all those people that they’re imagining it!
I would have thought that heat dissipation was more a function of surface area, and that thicker rotors, other things being equal, have a negligible increase in surface area.
Yes, the dissipation will depend on surface area, but a thicker rotor can absorb more energy. It effectively acts as a buffer, it will heat up more slowly because it can absorb more energy, and cool more slowly because it has more energy to dissipate but the same surface area, so you will have more consistent temperature.
But at least pointing this out and allowing discussion and opinions from people who’ve tried different thickness rotors is more useful than telling all those people that they’re imagining it!
I gave up when the same people telling me I was imagining it, then also told me I wasn’t imagining it because it was the effect of new pads and rotors… but then also told me I was imagining it because with new pads and rotors the pistons self adjust back to where they were anyway, whilst also ignoring that you’d have to reset the pistons to fit the new rotor and pads in the first place.
Just isn’t worth the effort
"What I'd really like to try is a rotor with a much more solid brake track."
With a solid brake track you don't have as much surface area or as much turbulent flow around the metal to remove the heat. This is an advertorial but I think there's some truth in the marketing:
https://www.bikeradar.com/advertising-feature/galfer-shark-evo-advertorial
"The Shark EVO’s braking track looks busy. There are small holes, larger windows, wave-like cut-outs and finned shapes. Galfer says each feature has a job.
Becchis explained the smaller holes are designed to help with heat dissipation. The larger openings contribute more to bite and help clean the brake pad surface. The wave shape helps clean across more of the pad’s height, which becomes more relevant in wet or muddy conditions.
It is a useful explanation because it shows the compromises involved.
More openings do not necessarily mean better braking, for example. Remove too much material and the rotor loses mass. That can make it less able to absorb sudden heat spikes under heavy braking.
Add more aggressive cleaning features and the disc may clear mud better, but it can also increase pad wear. "
So that's stuff about the holes (which matches what I've read elsewhere) and then some stuff about the mass vs dissipation:
"A professional downhill rider might brake extremely hard for a short period, then fully release the brake and allow the system to cool. A less experienced rider might drag the brakes for much longer, creating a lower but more constant heat load.
Both riders can overheat brakes, but they’ll get there differently.
“For a pro rider, mass is important,” Becchis said, explaining that a rotor with more mass can better absorb a sharp temperature spike before the heat has time to dissipate.
For riders who brake more continuously, dissipation becomes more important because the rotor is dealing with a steadier flow of heat."
This does make me wonder if a front rotor should be more solid and and rear rotor more full of holes?
