Tldr: current rotors (203mm magura storm) overheat and get noisy. Looking for recommendations on new rotors that handle heat better. Also considering upgrading from 203mm to 220mm if it helps performance and heat management.
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Hope y'all are doing well, I just wanted to ask for some of your thoughts on rotors. I currently have some Magura 203mm HC storm rotors on my SL ebike. The bike has some deore calipers and the thicker 2mm rotors give them a nice feel compared to my old Shimanos,, but the issue I'm running into is that they are terrible for overheating, the rear rotor gets hot and screams like a banshee.
So I am wanting to pick up some different rotors that dissipate heat better. I recently learned that with some finesse, these deore calipers can run 2.3mm thick rotors which opens up many more options. I'm curious what rotors have worked best for you guys, and is it worth up sizing to some 220mm rotors? I don't think I want to spend a fortune on galfer or hope rotors, so mainly looking at mid-range type stuff. I found a solid deal on some lewis rotors but I'm not sure if they are decent. Also see lots of trp options out there.
Galfer.
TRP S05e rotors (2.3mm thick). They're like Galfer Sharks, but thicker and cost half as much. Also have better hole pattern (doesn't leave ridges in pads) and tend to be pretty damn straight out of the box.
But do they come in pretty colors??😉
Anther vote for the TRP RS05E rotors. They are great.
They cost almost as much as the brakes themselves haha
Sick I will try and hunt them down. Will be so nice having silent braking again and not feeling self conscious on group rides.
Would you say going to the 220's worth it? Id have to get adapters but they are only like $15 I think.
I am running Magura MDR-S and MDR-P rotors on my bikes. The Storm are definitely more of an XC/AM rotor, great rotors, but not up to the task at hand for you. Thicker rotors can help with heat but is not always the full story. Material in the friction ring and spider can has as much or more impact on dealing with heat. Correction: Thicker rotors won't change your power but will add some heat management for sure.
- I work for Magura - full disclosure
Yeah I got em because they were 2mm thickness which at the time I thought was the max size my calipers could handle - and i wanted a bit stiffer of a feel in my brakes, which they do achieve. But on a hot summer day they just get so hot haha - could cook a meal on em after a proper ride.
Ended up grabbing some of those TRP downhill rotors in 220mm. Did some research and it seems like the extra size helps with heat slightly, but more so makes the brakes more sensitive - so you dont need to squeeze em as hard, and that sounds amazing for helping arm pump.
"220mm rotors won't change your power" In the world where physic's Dont exist huh?
I’ve had great results with Intend rotors, and counterintuitively they’re some of the cheapest on the market.
Also consider your pads - some pads really don’t seem to cope with heat well. Galfer pads are great, and if you pick the compound for e-bikes they’ll cope with heat better.
Good catch, I am fighting a headcold and have had a few brain blunders the last few days. I meant to put that thicker rotors will not add power, but are better at heat management. Yes, 220mm rotors will have more power than a 200/203mm.
If someone in here wants to go down a whole new dimension of rabbit hole regarding power optimizazion and heat management through "rotor and pad optimization" I recommend this thread in a german emtb forum. Tirolbiker63 has gone to absolutely incredible lengths to compile what is probably the most comprehensive database of just about every brake disc and pad combination. Hats off to him!
Just check all the links in his signature of his posts and use a translator.
Here's an example of a test with 8 different discs in combination with "Sinter green" pads.
https://www.emtb-news.de/forum/threads/bremsscheiben-design-vs-funktion.11971/post-338905
This thread is pure gold in terms of knowledge, data collection and experience.
I heard they more so add sensitivity over power, like power is more easily accessable, you don't need to squeeze the levers as much. Good for arm pump apparently
It's physics. The braking torque applied increases linearly with the radius of the brake disc.
Torque = Force × radius
Ignoring other variables (like brake setup, applied force on the lever, same disc design, equally bed in brake pads and discs), increasing the brake disc diameter from 200 mm to 220 mm corresponds to a 10% increase in braking torque.
This, in fact, feels for the user like "power is more easily accessible" and "you don't need to squeeze the levers as much".
It's actually 10% less squeezing 😄
Then there are other benefits like a generally cooler disc and cooler brake pads, which obviously helps with fading.
Bigger discs mean more power for longer if the disc design isn't crap.
the new thick rotors are so much more resistant to heat buildup that I felt my first F1 moment on 220/200mm on my large eeb: depending on the pad and conditions, I was having to drag brake at the start of trails to get the mofos up to temp! Made me feel like Han Solo. A small price to pay for pretty much eliminating brake fade over long runs.
Brakes feel solved.
So stoked to put them on my bike, i think its gonna be a great upgrade. Gotta head to the LBS to fit some caliper spacers and then im off to the trails to bed em in. Was able to get two for cheaper than a single Galfer shark, from amazon of all places... They were selling them in pairs for $165 CAD.
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