Most riders are familiar with the concept that larger diameter rotors help improve braking performance, especially during hard, sustained braking. That's why we're starting to see more and more 220mm rotors on downhill and enduro bikes, and on eMTBs. Those larger rotors offer more surface area, which improves heat dissipation, and require less force at the lever to slow things down.
There's another way to improve heat dissipation – increase the rotor's thickness, and that's exactly what SRAM has done with the new HS2 rotors. The rotors are 2.0mm thick, compared to the 1.85mm thickness of the previous Centerline rotors. That may not seem like much, but that difference, along with a new brake track pattern, is claimed to deliver a 7% increase in power.
HS2 Rotor Details• Thickness: 2.0mm
• Material: steel
• Sizes: 160, 180, 200, 220mm
• 6-bolt or Centerlock
• Weight: 204 grams (200mm, 6-bolt)
• MSRP: $50 - $65 USD
•
sram.com The new brake pattern also has less material removed and a different orientation of the cutouts, which provides more surface for the brake pad to grab onto. Towards the center of the rotor are spokes that have been painted with a thermal dissipating paint, another step that was taken to keep things as cool as possible.
There are 160, 180, 200, and 220mm versions of the new rotors, with 6-bolt and Centerlock options available. On my scale, a 200mm HS2 rotor weighed in at 204 grams, 14 grams more than a 200mm Centerline rotor. Prices range from $50 to $65 depending on the size and mounting style.
This graph from SRAM illustrates the temperature difference between a Centerline rotor and the new HS2 rotor.
PerformanceI've been trying out the new rotors over the last month on several different bikes, all equipped with SRAM's Code brakes: a 160mm enduro bike, a 120mm trail bike, and a full-power eMTB. In all instances, the rotors are noticeably better than the Centerline rotors they replaced. By 'better', I mean that they give the brakes an overall firmer bite, and maintain that solid feel even on long, steeps sections of trail.
It's on the heavy e-bike that the improvement was especially apparent. On that bike I'd previously had several moments where I found myself wishing for more braking power. Hot, dry conditions, a 50-pound bike, and an extra-steep track meant that I had to pull extra hard on the levers to control my speed, even with a 220mm rotor on the front. With the HS2 rotors there was less fade, and it took less effort to manage my pace.
In wet conditions the rotors still make some noise initially, but they seem to clear water and quiet down more quickly than the Centerline rotors did. They'll also howl a bit on very steep, very sustained trails, the type where hard braking for minutes at a time is required. I still think there's room in SRAM's lineup for brakes that are even more powerful than the Codes, but that's a different topic. I've managed to avoid falling off any skinnies lately, so I can't comment on how well the rotors resist bending; if anything the extra thickness should make them less likely to fold over from an impact.
Now, the thicker rotors do mean that there could potentially be less pad clearance, although I haven't run into any unwanted rubbing. I've successfully run thicker rotors from other companies with SRAM's calipers before, and as long as you take the time to clean and reset the pistons the extra .15 millimeters shouldn't cause any issues.
New rotors may not be as exciting as a wireless drivetrain, or a fancy shock that has adjustable everything, but the HS2 rotors offer a clear performance benefit with only a minuscule weight penalty - that's a win in my book.
"Fade into you"
One of my buddies is newer to riding and has them on his bike. On night rides we know he's still alive because we can hear him still coming down the trail above us. That howl/gobble/squeal is a safety feature! When things go quiet we start to worry...
@VtVolk be a mate and teach him how to set up his brakes.
Shimano rotor min thickness is 1.5mm (1.8mm original thickness)
0.3mm of wear still spec'd. You lose the braking power increase from rotor thickness as it wears down, as implied by this article. There's also the trade-off of lower rotor/pad clearance when new to consider (from sticking a wider rotor in the same size caliper).
Interesting that SRAM describes the grey arms as a coating. Looks similar to IceTech, with a different material used as cladding over a base material. Stainless on non-stainless steel, in this case? Do you think you can wear it down further?
I speculate that the braking power could partly be from the lever's higher leverage due to swing-link, from tuning brake to bite earlier in lever stroke (cutting out more of the modulation zone). Otherwise, IceTech's heat management (and the improved braking) shouldn't lose out to this, considering the extra surface area it has.
Shimano RT-MT905 6-Bolt Rotors:
An extra layer of heat protection, ICE TECHNOLOGIES FREEZA rotor construction uses a proprietary three-layer sandwich design with exposed radiator fin. Together with the heat dissipating paint, FREEZA rotors deliver supercooling forces for even more reliable braking performance and lighter operation in all riding conditions. ICE TECHNOLOGIES FREEZA rotors provide consistent braking performance with longer pad life, less brake fade and noise.
race car rotors are worth almost 10k usd.
you can buy normal bike rotors for 8 usd on ebay.
They're expensive because supply/demand pretty much.
I upgraded my rotors on my 161 to Galfer with MT5s massive improvement.
I am running 223 front and back with 2.2 thick brakestuff 130€ rotors
I never thought I buy a rotor who is that expensive, well it matches the Direttissima. I have almost no space for that thickness. Only a fraction of light is shining through now.
My front an rear adapter is the same Galver adapter. Same disc size, same PM mount on the frame and Fork. Yet the rear needs a washer. How can that be?
What rear caliper, rotor and type of mount do you have ?
I actually could not get any other +43mm adapters when I got my Discs.
Now the Trickstuff adapter is on the shelf again and yeah that is 30 € for one adapter. By the way the brakes without the cheap adapters will be more then 1000USD by now with those discs.
However I dont think that Galfer did a bad job with it that.
Cheers
I've been thinking of swapping mine for mt7's for a while, though tbh the sram brakes work well enough most of the time, so while not perfect, its hard to justify.
From Shimano themselves (so not independently verified) but seems to run 150C cooler than SRAM.
Two piece rotors are also popular, and not that much more $ than single stamped steel. Surely those could be made such that the steel/aluminum interface has more overlap and thermal conductivity?
Using the aluminum spider instead of fins is a great idea, but there's no way to transfer heat to it since the steel/aluminum interface has to be loose enough to account for the different thermal expansions of both materials. If it was tight enough to allow for good heat flow, then the rotor would warp excessively when heated.
Vapor chambers!
I would be happy if my next bike came with ice tech, but I’m not sure I would buy them when I can get a 220/3 rotor that performs better than an ice tech 200/3. An ice tech 220/3, now that would be of interest for me. I would be running a galfer 246mm disc on my long travel bike if it wasn’t so ridiculously expensive.
It increases thermal mass, yes - but cooling? negligible surely..
I guess the question is, is that what you want from your rotor? There is a balance between thermal mass and cooling efficiency to be struck. Is it better to have a disc that heats up slower but also cools slower, or a disc that will still stop you for a big stop, will get hotter but will also cool faster between stops. It's a balance car manufacturers have been tweaking for years.
Hence it will be only matter of time for SRAM and Shimano to move to 2mm on teh lower cost single piece rotors . I suspect that floating rotors have higher rigidity of the inside holding "star" but ta the end of the day they shall be unified to 2mm as well.
From what is recommended by Galfer you can run even 2.3mm thick rotors
galferusa.com/bike/products/rotors?vtype=bicycle&vmake=shimano&vmodel=saint-br-m820&vyear=all
cheers
Also, new thicker rotors will make me buy new calipers when the time comes, or older brakes will handle these thicker rotors?
Can I install these 2mm thick rotors on my deore brakes?
www.youtube.com/watch?v=8_s89mGxn_E&ab_channel=GalferUSA
www.aliexpress.com/item/32966272096.html
All start quiet then start to squeal after some hard breaking events that heat the rotor up changing color. Warping never seamed to cause squeal (just brake rub when brakes not applied - PITA) - always the case hardened rotor.
I always take a flapper wheel on a dremel & clean off the blue crust to shiny metal. Also sand the pads down. Always quiet again after.
Should mention I never have run composite pads - only sintered metal.
But everything else about Code RSCs is primo! And they COULD use more power… they don’t necessarily need more. But I’d take it. That being said, solid power, great adjustability, easy to bleed. They are sweet!
"Please baby, just give me another chance! I promise it'll be different this time!"
some weak tektro at first, then juices, then formulas.. and then I discovered the Saints.. I had them on all my bikes for 5-6 years now, even on the cross-country one where they are paired with 2x160mm rotors.
tried the mt7s.. fell even more powerfull then the saints but I did not liked the lever, then code RSCs an Hope V4s...similar feel for both but, surprisingly, I liked the v4s more. For the moment, I'll keep my Saints and will add a 220 mm rotor on the front of the big bike.. not that I really need it but, if I can, then why not?
what I am really curious is Shigura set-up. The nice Shimano levers with the hulk stoping power of Magura's calipers.