First Look: SRAM Guide Ultimate Brakes

Mar 31, 2015
by Mike Kazimer  
SRAM
SRAM

SRAM's recently launched Guide brakes have been well received, possessing performance and reliability that are a marked improvement from the previous Elixir line. By ditching their TaperBore master cylinder and going with a cam activated cup seal and port system, SRAM was able to create a brake that has earned praise for its excellent modulation and lever feel. Now, just over a year after the Guide brakes were first announced, SRAM has a new addition to the line, the Guide Ultimate.

The Guide Ultimate's lever body internals are the same as on the standard Guide but the blade is made of carbon fiber, and titanium hardware is used for further weight savings. The use of carbon and Ti isn't the real story though – it's the new caliper, which received a complete overhaul as part of SRAM's goal to develop a brake with an extremely high level of consistency, one that maintained the same lever feel throughout a run, no matter how long or steep the trail.




Guide Ultimate Brake Details

• Intended use: all-mountain / trail
• New S4 four piston caliper
• Heat shield in caliper for reduced fluid temperature
• Titanium lever hardware
• Increased pad pocket
• Uses same pad shape as standard Guide and Trail brakes
• Weight: 360 grams (front brake, includes rotor, hose, clamp, adapter and all bolts)
• MSRP: $288 USD per wheel
• Available May 2015
www.sram.com




SRAM Guide Ultimate
The Guide Ultimates feature aluminum pistons with a phenolic insert in the middle to reduce heat build up.
SRAM Guide Ultimate
A cutaway view of the caliper that shows the horseshoe shaped heat sink.

Updated Pistons: To help achieve their goal of creating a brake with even better consistency, SRAM uses four aluminum pistons in each caliper. This reduces the likelihood that a misaligned piston will apply uneven pressure to a brake pad, and helps reduce seal wear. Instead of being completely machined from aluminum, there's an insulator in the center of each piston to help dissipate heat, while the surface of each piston is also covered with tiny grooves that are meant to help improve rollback, the speed that they return to their original position after the lever is released.

Improved Heat Management: Excessive heat buildup is the enemy of disc brakes, and companies go to great lengths to try and keep temperatures in check for as long as possible. To that end, SRAM has come up with a simple yet supposedly very effective heat sink that is located just in front of the brake pads. The horseshoe shaped piece of stainless steel channels heat away from the pads, and SRAM's in-house testing found that this created a 20°C reduction in running temperature. The shape of the caliper itself has been altered as well – the pad pocket (the portion of the caliper where the pads sit) has been widened in order to increase the amount of airflow between the rotor and the pads for additional cooling.

SRAM Guide Ultimate
The Centerline X rotor's two piece design shaves up to 20 grams off the weight of a standard Centerline rotor.
SRAM Guide Ultimate
The new bleed adaptor pushes into a port in the caliper and doesn't require the complete removal of the screw at the caliper, although the bleed setup at the lever remains the same.

New Rotors:The Guide Ultimates come with new Centerline X rotors that are up to 20 grams lighter than the standard Centerline rotors. The use of a two piece design is the reason for this weight reduction, with the seven arms of the rotor mounted to an internal carrier. Two piece designs can occasionally develop play over time, leading to an annoying 'kathunk' that feels like a loose headset when the brakes are applied, but SRAM say that they took special care when designing the interface between the outer and inner portion of the rotor to keep this from happening.


Simplified Bleeding Procedure: It's fair to say that nearly anyone who's ever bled a set of brakes has one time or another dropped a miniscule bleed screw and watched it immediately roll under a bench, an event that's usually followed by a good amount of cursing and maybe some hair pulling. To help prevent temper tantrums, SRAM has developed a trick new bleed adaptor that should make brake maintenance much easier. The adaptor pushes into a port on the caliper, and then the anodized knob is back off slightly, allowing fluid to be pushed from the syringe through the caliper to the lever. Bleeding the Guide Ultimates is extremely simple, and requires fewer steps than what was required for any of SRAM's previous brakes. The new adaptor will be included with every Guide Ultimate brake set.


Riding Impressions
bigquotesI was able to get out for a short ride on the new Guide Ultimates, but as fun as the rolling, berm filled trails of Rotorua were, there wasn't enough sustained braking to determine whether or not the new features make a difference in the consistency department. They did work well throughout the entire ride, with the excellent balance of power and modulation that the Guide brakes have become known for, but there wasn't a noticeable difference in lever feel or performance from the standard version. That's certainly not a bad thing, and once they're available we'll get a set in for review, at which time I'll be able to take them on steeper trails with enough vertical to give them a proper evaluation, including giving the simplified bleed procedure a try. - Mike Kazimer


Guide



153 Comments

  • + 116
 I want brakes that run on ice cream and only make noise to the tune of queen songs. Can these do this?
  • + 168
 Avid did that years ago with the Elixirs, unfortunately the only song they knew was Flash... AAARRRRGGGHHH!!!!
  • + 40
 I thought Avid's Mission statement was "we're going to make a supersonic man out of you".

It would make sense with their history of unsatisfactory brakes!

However I've only heard good things about them in the past year or so. Maybe (hopefully) they've stepped up they're game.
  • + 39
 I think it was more like ''Don't stop me now'' because you planned to go to Mars after that jump, right?
  • + 7
 So it looks like I was wrong, they could in fact sing two songs!
  • + 19
 Don't forget turkey gobble, 2 songs 1 animal
  • + 4
 I rode my buddy's trail bike with guides on them on some pretty gnarly steep trails and they were AWESOME. I was tentative at first knowing they wer SRAMs , but they perform fled great the whole day.
  • + 5
 My Elixir have just died, these were the warranty replacement for the previous warranty replacement. could not bothered with all that again..

the obvious choice was Shimano SLX. Inexpensive, extremely effective, very reliable.

The general consensus here in the UK is that if your new bike comes with Avid's then ok, you'll put up with them

As soon as you get a problem you dump them for Shimano brakes.

And if paying out of your own pocket for new brakes, its gonna be Shimano?

Avid always seem (as an aftermarket brake purchase) - overpriced, overcomplicated, unreliable

As a mechanic I've dealt with way too many warranty claims on Elixirs to ever buy them out of my pocket - you get good warranty support from SRAM which is important because you will need it.

I am sure the new Guide brakes have merit but its gonna take a lot of work to earn the trust of consumers burned by the Elixir experience?
  • + 12
 Well anyone that gets guides on a new bike won't be complaining, I love my set of rsc better then xt.
  • + 2
 guides seem to have awesome performance based on the reviews. Whether they will stand the test of time is still up in the air, though a rebuilds should be easier without the taper-bore system.
  • + 2
 taper bore, low fluid volume and poor QC ruined the previous generation of their brakes. Hopefully Guide will last the test of time
  • + 10
 Your awesome not buying into the yuppy shimano bull I agree my codes are still the best brakes ive ever ridden not one complaint. It sucks seeing so many people having issues with sram/avid brakes. It makes me wonder am I just the lucky one or is there something more to it like poor mechanic skill well setting them up or not bleeding properly. Ive run juiceys, elixirs, old code 5s, db1s and the new codes and ive yet to have an issue with any of them
  • + 1
 as long as they're nor bipolar like my elixir 3s I'm cool with it
  • + 0
 @mhoshal Hopefully your skills as a mechanic are better than your writing!
  • + 0
 is it me or the set is still heavy for carbons? well its a 2 piston so yeah but still its 2015
  • - 1
 Who hid my keys, pissed the seat, and swapped my saints for these!? Fuuuuuuuckkkkkk!
  • + 2
 @Novic look around more carefully. Maybe you are just at the wrong house?
  • + 2
 I didn't realize this was a spelling contest. But you can make fun of my writing all you want I understand with the shitty bikes you ride you probably are a miserable bastard
  • + 1
 The good thing about avids is when you have a problem (blown seals, air bubble that doesnt want to come out, etc.) you can fix it bc their bleed procedure allows suction and they have replacement parts where as shimano you basically have to buy a whole new caliper/lever. In addition, they have a pad contact adjustment that actually works. Yes shimanos will probably work, but when they don't, god help you.
  • + 1
 @hatton

for the average consumer, by the time you've paid for the replacement parts and the labour time for a wrench to do the work, its costing as much or more than just buying a new MC (master cylinder i.e. brake lever) or caliper from Shimano and then you have a whole fresh end of the brake.
  • + 2
 for the average consumer...but for the guy that likes to work on his bike to save a bit, it's not. As big and evil of a company as SRAM is, they've got the best, most accessible service manuals and readily available service parts and kits of just about any company out there and I respect the hell out of them for that.
  • + 0
 Still you're bether off by buying new brake system than bleed kit, and new rear mech than jockey wheels
  • + 3
 And a new family if your baby cries Wink

The lack of rebuild kits for sheemano is troubling. The fact that they don't need them for years is nice. It is like old Chevy vs old Toyota. Used to be harder to find import parts for cars, but old Japanese cars took you 300,000 miles almost trouble free when american was lucky to go 100,000.
  • + 1
 @hatton

average consumer is not rebuilding hydraulic brake systems. They just want a mechanic to fix their bike for them. This costs time and money.

I've been a workshop manager for some of the leading bike shops in the UK, and have dealt with 100's of warranty claims on Avid brakes, very few on Shimano

yes Shimano have nothing like the levels of OE penetration that Avid have (due to SRAM's low OE pricing) but Shimano brakes seem to run and run until they fail, whereas Avid develop issues either out of the box, or degrade in a season
  • + 52
 When my XO trails finally die I will be replacing them with this. Say what you want but those have been one of the best brakes I've used.
  • + 11
 I'm with you on that!
  • + 7
 Mine occasionally have a different feel at the lever. This usually happens with a combination of high elevation and long descents. I've never felt any loss of power, but the different feel at the lever can be distracting. And the contact point adjustment doesn't do anything. Literally, nothing.
  • + 4
 I haven't noticed changing lever feel, but I am on the lighter side. Also my contact adjustment definitely works as advertised.
  • + 4
 My code and code r brakes that I had used in the past were both more consistant performers than my current zees
  • + 4
 My Saints were horrible. I have had no issues with my Avids in the past and my current Guide RS's are great. I must be lucky. You can manually adjust the pad contact to your liking as well without shelling out the extra coin for the adjustment. Bleed the brakes with the bleed block that comes stock with the kit. If you want the contact a bit closer, shave a bit of the bleed block down, very little at a time. Allows slightly more fluid in there pushing the pistons outboard closer to the rotor. Glad to be back on a Sram drivetrain after nothing but issues with my Shimano Zee and Saint stuff. Just sucks I got my Guides brand new and they already re-designed the caliper!!
  • + 5
 If you got a pair of XO brakes that worked, they were the best ever. I had a pair that was amazing! But I also had a pair that couldn't hold pressure (warranty seal issue), and went from awesome to zero pressure over the course of a ride. Reliability is *king* on brakes. SRAM will need to prove itself over a few seasons to get back into the game.
  • + 3
 the elixer cr's that worked were sweet too. Better than the modulation on my deores. I am still sticking with mineral oil until I see these things last a few years. Hopefully these will push a bunch of used xt's onto the market cheap.
  • + 0
 the elixer cr's that worked were sweet too. Better than the modulation on my deores. I am still sticking with mineral oil until I see these things last a few years. Hopefully these will push a bunch of used xt's onto the market cheap.
  • + 2
 @krashDH85 You mention shaving down the bleed block to get the pads closer to the rotor, but isn't that the purpose of the "Contact Point Adjustment"?
  • + 2
 I'd like to add that the zees are great but if left unused for a while they feel like they're bedding in again when I start riding at first
  • + 2
 @skell...I mentioned this if you don't want to pay the extra money for the contact adjustment. Just mentioning you can manually fine tune the contact point if you don't have or want to buy the guides with it
  • + 32
 Let's come to a screeching stop before we all get heated up about this
  • - 3
 I see what you did there
  • + 3
 This guy Rolleyes
  • + 3
 always appreciate a good avid burn - much like how their brakes smell after maybe 1.5sec of actuation
  • + 5
 turkey gobble in the dry, and screaming kittens in the wet
  • - 3
 I burned through 2 new sets of pads (front and back) and warped my 180mm SRAM rotors halfway down a 3000' decent with my Elixers... It smelt like death!!
  • + 25
 Oh boy, here we go...
  • + 10
 You said it! Let the know it all wars begin!
  • + 9
 Hate comments starting in 3..2..
  • + 8
 Okay here's the plan, I run into a tree and brake my nose bone, blame it on my brakes, convince my parents to give me $300 for new brakes, and buy these in may. Yup. Worth it.
  • + 23
 That only gets you one brake though...@smillertime531
  • + 12
 May get you a full face helmet too.
  • + 6
 CRAP. Sell a kidney?
  • + 23
 @BenPea What a coincidence.... That's what I say every time I pull avids/sram brakes
  • + 3
 am i too late for the poop on sram party
  • + 0
 Poop away. Apparently these brakes are good though so your feces maybe miss placed.
  • + 1
 @thestigmk1 - thanks, I LOL'd
  • + 14
 Great incremental improvement, but lets get away from DOT and on mineral oil! No more burning hands! No more burning eyes!
  • + 24
 I think having DOT fluid available pretty much anywhere is a lot nicer than possibly getting lucky and finding Shimano mineral oil in stock at a bike shop.
  • + 1
 Baby oil. People in other forms of biking have been using it for years.
  • + 2
 @wetbed0 - you serious? Baby oil? I'd be quite curious to know if my XTRs could run on that =)
  • + 60
 Um, if you're getting brake fluid in your eyes, you are doing something wrong. I don't see many blind automotive or motorcycle mechanics either.....
  • + 13
 You need the same safety procedures for mineral oil. Neither one to put in the eyes..(0;
  • + 7
 DOT 5.1: $10 for a quart, enough to bleed a whole stable of bikes. Shimano liquid gold, I mean mineral oil- $20 for a few mL, can do one set of brakes if you don't spill.

DOT: better performance at high temps, doesn't have that inconsistent feel resulting from water pockets in the mineral oil.

I'll stick with DOT thanks.
  • + 4
 I use butcher block oil, which is just highly purified mineral oil. 8 bucks for a decent amount at the hardware store
  • + 6
 standard mineral oil(including what Magura uses) has a much lower boiling point than DOT. If you want numbers, google it, as people have tested the boiling point claims. The only mineral oil that kept up with DOT was the Shimano, which is the first time I've ever encountered a company saying "our version of this common material is better than everybody else's... because reasons!" being actually true.
  • + 4
 Currently rocking Guides RSC and think they're on par with my XTs, but saying DOT is better than mineral is total BS. Both have their plus and minus. In the link below the Shimano oil actually have the highest boiling point.....Plus bleeding Shimano is way easier compared to bleeding SRAM.

www.bikerumor.com/2013/04/11/tech-speak-brake-fluid-break-down-and-implications-for-road-disc-updated
  • + 2
 @chrisingrassia check out trials forums. They you just about anything but magura blood, mineral oil, in their magura, I'd think shimano would be the same.
www.rotorburn.com/forums/showthread.php?13473-Magura-oil-substitute
  • + 2
 Never in these tests do they do use some form of compression test, where they use a specific amount of weight and compress the fluid and see which one compresses less. That's the info I want and feel like they are missing half the point of a comparison test. Boiling point... sure it's a good number to know, but I would like to know how many people truly have boiled their fluid whether DOT or mineral. I never have on my bike, that's something that happens on race cars. Also a note on the boiling points in the Shimano test. The ones listed for DOT fluid are the minimum boiling points to meet DOT specifications. Many companies boiling points far exceed those minimum requirements. There are DOT 4's that go up to 680 degrees F before boiling.
  • + 0
 you can run DOT 5 instead of expensive mineral oil in shimano brakes, as long as its Silicone based only. has a 500F temp rating, wont breakdown like the mineral oil sh*t. been running it for 10yrs now. best thing about DOT 5, you can get it anywhere AND its non corrosive
  • + 2
 @mtaero a more apt test would be an expansion comparison between caliber, hose, and pressurized portion of the brake lever assembly between the different models of brakes. While fluid is technically compressible to varying degrees, the compressibility of the volume of fluid actually in a brake system would have a negligible effect on brake feel and efficiency. The biggest culprit for lousy brake feel is the quality and length of brake hose. Poor brake design of course being an issue as well.
  • + 1
 @Jhou check out Maxima DOT 4 racing fluid at 600F boiling

www.maximausa.com/product/brake-fluid
  • - 3
 Dot fluid is hydrophilic you dope. Mineral oil is hydrophobic. Ergo avid sram maguara etc actively suck water into the system. Shimano's oil however resists water. Plus the extra casing around a shimano hose resists swelling more and gives a more consistent feel especially to the rear.
  • + 5
 Do you understand why DOT fluid is hygroscopic? Water will get into any brake system, that's just the nature of the game. In, say, a mineral oil system that water will not mix with the brake fluid and you'll get pockets of fluid that have different boiling points. When you heat up the fluid under hard braking, those pockets of water flash boil into steam, then compress. That leads to a inconsistent and vague feel. DOT fluid absorbs water so the fluid retains a constant boiling point and you get consistent results under hard braking. If mineral oil was better and more consistent under hard braking, motorsports would use it. But they use DOT instead.

Also- brake line casings are not brand specific. You can run Shimano hose on a SRAM system and vice versa, so not sure what you're trying to point out there.
  • + 10
 Dropped a bleed screw?!??????!!!

Seriously? !?!?!

Whoa.


I run hopes. None of this dropping parts and special bleed adapter trash. Turn the screw, bleed it, tighten and done.
  • + 1
 same with shimano. gravity bleed. turn hose, done.
  • + 6
 HOPE.
  • + 11
 *waits for recall*
  • + 6
 A 20C reduction in running temperature?! That's a skeptically large drop...
  • + 1
 Depends what normal is? Contact surface temperature is well into the hundreds generally which depending where they a re measuring that drop could mean that they were measuring a quite high temperature on long descents.
  • + 3
 Always makes me laugh how most people on here with their opinion of guide brakes have never actually owned them. I own them and I can say they are the best brakes I have ever used. My previous brakes where SLX and XT and I'm sorry Shimano fan boys and girls Guide brakes are far superior in every way. I have had zero issues with them in 6 months of all weather use.
  • + 2
 Wow. A calliper as heavy as a Code? Seeing as the weight-quoted 180mm rotor, with Ti bolts instead of steel, saves 20g (but you probably use Ti rotor bolts already so you'll miss out on most of that saving) and a full 180mm front brake is quoted as 21g lighter than Guide RSC, that means that all but 1g of the weight saving from carbon lever and Ti hardware is counteracted by a heavier calliper. Now, I inherited Avid brakes at day 1, have stuck with them and learned to get on with them well and am a satisfied customer. Better the devil I know. But surely the biggest issue is the lever bite point coming closer to the bars as the pads wear down??? - so you have to progressively wind out the lever reach to a less and less convenient/ideal point. OK, so Guide levers are a little better than previous Taperbore versions due to more (read; heavier) fluid content (I assume). I can counteract that by messing with pad advancement and/or re-bleed, but I don't call that user-friendly and neither are trail-side fixes.
  • + 2
 I have had the Guide RS brakes on my bike for 6 months and I have to say "meh". The modulation is good and they do well on long descents coping with heat. However, I've already had them bled several times because of such a long pull before engagement. They start out really well from the shop but after a handful of rides they go back to "normal." As a result I have them setup to be far away from the bar and my hand.

As a side note I was watching On Track with Curtis Keene and he has his tech bleed his brakes after every day to alleviate this dead spot.
  • + 4
 Most pro racers get fresh brake bleeds every day, regardless of what brand they run, that's kinda normal.
  • + 3
 I ran one on my DH bike for a bit before I sold it and have been running them on my Reign for a few months now. Getting the first bleed done on them this week. Im half way through my second set of pads now and have noticed that after about 3/4 of the pad is used the lever feel and consistency really starts to drop and feel like a poorly bled brake. First thing to check is definitely your pads!
  • + 2
 yeah, don't base your maintenance on what the pro's do. they sometimes switch pads 2 or 3 times for an event, they burn them in, use them, then switch. they also use different grease/lubes so it'll be more efficient on the pivots and bearings, but will diminish bearing life, but what do they care, they switch them out often. they also run higher pressure on EVERYTHING and get things done that seem kinda useless to us. but they have their mechanics work their bikes like an F1 car.
  • + 1
 During the race season I bled my Hopes after every race. Some weekends I would bleed them before also depending on how much riding I did prior. It sounds obsessive but it makes a difference. The dark, dirty fluid was always a sign I was doing my bike right.
As for fade due to temperature I ended up making my own custom screw on extension for my master cylinders which basically doubled the amount of fluid. I also ordered new (dry) lines and seals and switched to 5.1 fluid. No more fade. (On my older brakes).
  • + 1
 So a piece of stainless steel, which by the way is a far worse heat conductor than the aluminum caliper body, is somehow going to cool the pads by 20°C? If it were copper I might believe it, but in stainless steel it's unlikely to do much other than keep the pads from chewing into the caliper body. The improved cooling comes from the rotor & caliper shaping, not that piece of steel.
  • + 20
 Is copper what you used when you designed your brakes with your degree in engineering while working for one of the largest manufacturers of bicycle components?
  • + 4
 Sorry Sram, but my set of XTR m9000's with rotors cost 100 dollars less than a set of those and they weigh 200g less...
  • + 2
 SRAM brakes: Becoming more Shimano every year.

Also: Positioning the RSC as the top model last season, only to come out with a "completely new" version comes across a bit 650B.
  • + 1
 Seriously! So do the non-ultimate brakes not have all these features???!!
  • + 4
 Do any of you actually ride??? or do you just discuss complete BS on here ??
  • + 1
 All I will say is if you live in the UK then hope are the best bet they were designed and built for the UK conditions. Avid's take one look at the lovely British mud and run away sqealing back to the dry dusty conditions they can cope with....just!!!
Back up support and spares are brilliant in the UK for Hope.
The power and lever feel have always been excellent all the way back to the old O2 and C2 units and they have simply got better as time goes on.
Working as a bike mechanic I get to play with all sorts of different setups and the one thing I will say is that as yet NO Avid (lets face it that's what these are) have as yet been able to hold a candle to a set of Hopes.
However to be fair I will reserve judgement on these units for when I get a set through my doors.
  • + 3
 i wonder why not comparing them to xtr or xt or something else brilliant on the market to have some reference to write about ??
  • + 4
 Also, define running temperature and what the reduction is actually coming from. The previous model?
  • + 0
 hmm i like sram... i have a pair of elixir 3's on my hard tail xc bike and can honestly say they blow my formula rx brakes on my full sus out the water.
But they took so long to get right ...... like 5 bleeds ?? All downtime on riding...

hopefully this wont be the case with these ..... or the standard version.

i felt some at the London bike show and in terms or build quality id say they are poor. the lever feels tacky cheaply made. (standard guides)

if i had the money and need to buy new brakes id have 2 options really.

Hope tech 3 levers with v4 calipers or shimano slx both have good build quality and reliability on the sides not to mention a lot easier to bleed and get right.
  • + 2
 IMHO, that "new" rotor seems like the XX and the inspiration is from the Hope.
In other words, that rotor is.....................
  • + 14
 like a session.
  • + 0
 I think they should have stayed with HS1, Centerline is just ugly
  • + 1
 does anybody make new lever blades for the guide style levers? been thinking about some DB5s for my hardtail, but I like the one-finger-friendly lever shape of the shimanos I've been running recently.
  • + 3
 Have been running Guide RSC's for over six months now. Modulated power that makes me happy each and every ride. Job done....
  • + 2
 I don't care how great they are, not putting that shiny crap all over my bike. The end.
  • + 2
 Would like to give these a go, but I still love my XTR trails. Guess I'll wait for these to blow up...,
  • + 4
 They aren't going to blow up.
  • + 2
 I have a bike shop and a mountain bike track were we do testing and I give this brake 5 stars best brake in years.
  • + 1
 Those are nice things to have, but they do not qualify your opinion. What kind of testing have you done?
  • + 1
 Avid: blah blah blah new blah amazing blah power blah blah blah.
Shimano: shut it Avid. You're drunk. Go home.
  • + 1
 i laughed
  • + 0
 Two specialized riders and Jerome Clementz broke their brake lever. This doesn't happen to Saint Brakes. It survives from abuses.
  • + 1
 They're still sticking with that conical auto caliper centering rubbish, are they?
  • + 3
 Nope, not on the guides. See the picture.
  • - 2
 $576 for the pair?!! SRAM milking cash out of you for substandard products again. No thanks. I already got SLX, I had Elixir they sucked, bleeding was a chore and they howled and gave me a migraine.

Shove them up your ass AVID.
  • + 1
 Wait, so do the regular non-ultimate Guides not have all these features??!!?!
  • + 1
 I bet the rotors are the biggest influence on performance. Cooling leads to consistency after all.
  • - 19
flag gabriel-mission9 (Mar 31, 2015 at 7:41) (Below Threshold)
 huh? how are the rotors gonna affect cooling?
  • + 6
 Because the rotor is the biggest heat sync of the entire braking system. Friction from the brake pads and the rotor generates heat which will eventually cause brake fade. This is why a 200mm rotor has better long term braking performance than a 160mm rotor. It can dissipate heat much better from the system.
  • + 2
 Yep, I get that.

My question is, how are these rotors going to cool any more efectively than the old ones?
  • + 1
 It's probably not much performance gain over the old rotor, but Kazimer said, "The shape of the caliper itself has been altered as well – the pad pocket (the portion of the caliper where the pads sit) has been widened in order to increase the amount of airflow between the rotor and the pads for additional cooling."

So that's how.

The biggest performance gain will be the horseshoe heat sync inside the caliper body near the pads.
  • - 2
 Yeah.... Thats why I asked, how are these new rotors going to dissipate heat any faster than the old ones. The answer is they aren't. So I still don't understand taletotells comment.....
  • + 5
 Aluminum dissipates heat much better than steel. Also an aluminum carrier dissipates heat better than fins on pads cause it rotates and creates an air flow around the disc.
  • + 3
 Shimano goes to great lengths to remove heat from the rotor by adding cooling fins. This isn't that by any means, it's just more surface and bigger air holes. I see what you are saying and agree that the change in rotor will have a minor affect on the cooling of the system as a whole. But even a little gain is better than none at all. If I was buying these brakes going from the original guides, I probably wouldn't change rotors until the old ones were completely worn.
  • + 2
 Gabriel, the rotors are designed to push out and remove gasses that build inside of the caliper/pad/rotor interface. The quicker these gases can be expunged, the quicker it will cool. Look up vented rotors on cars. Similar concepts.
  • + 2
 The calipers have a liquid which holds heat inside, and has less surface area on what is essentially a fancy chunk of aluminum. The rotor, with large surface area and aluminium, plus the holds that cycle hot air out of the contact area. Rotors are pretty good heat sinks really. They even sink further into the hub. The caliper really only has its fluid and mounts as a sink.
  • + 2
 The old guide rotor had the same drilling. The only difference really is the aluminium spider. The amount of heat that makes it down this far without being radiated out into the air is going to be insignificant to the performance of the brake if you ask me.
  • + 1
 Even if it's only a few %, it counts. Look at shimano or hope, they put fins or machine the caliper to increase the surface area, they use aluminum core or vented discs, aluminum plate on pads for better heat transfer, etc.... every detail is important.
  • + 1
 Yep. All this is going on within 1cm of the areas that get hot. Adding an ali spider with a fairly poor thermal coupling to the hot rotor isn't going to help much. In fact I wonder if the full steel one actually radiates heat to the spider more effectively despite steels poor heat transfer properties, as the heat doesnt have to go from steel rotor, to steel rivet, to ali spider.
  • + 2
 That is a good point @gabriel-mission9
It is a wonder you don't see cooling fins on high end steel rotors instead of alu spiders. Cooking finds all over the whole apaeatus might make the most a sense, unless it needs to get to a optimal heat to work properly.
  • + 2
 They still weigh more than shimano xts...
  • + 3
 Mmmm. Juicy!
  • + 2
 I thought screech went to jail?
  • + 1
 Just put guide rs on my dh bike with the existing icetech rotors. Can't wait to try them out. Previously had xt's on.
  • + 1
 I feel a bit Disc'd by this, I will need to refer to the Guide!
  • + 1
 I don't usually like the look of Scram brakes, but I really like these!
  • - 4
flag Larkey1 (Mar 31, 2015 at 8:16) (Below Threshold)
 I don't know why everyone is - proping this guy. It's a valid opinion.
  • + 0
 When i made this comment, your previous comment was severely neg propped.
  • + 2
 Oh right ahaha
  • + 1
 In order of Best to worst HOPE SHIMANO AVID
  • + 1
 100% agree
  • + 1
 my juicys are good enough
  • - 1
 Sram Guide!, lets pretend there not avid and see if anyone notices! Ah shit we failed! oh so did the breaks, suprise!, bleed kit out again!
  • + 1
 Nice of you to let him finish
  • + 1
 I've got the rsc on my Spartan and they r awesome
  • + 0
 I can save 20 grams a rotor! No way!
  • + 1
 Hope's... Maybe!?
  • - 1
 The Ultimate guide to your next bleeding nightmare?
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