sputniky

Just the facts.

Why the smarmy emoticon?

sputniky

Uh, you replied to my post with the smarmy emoticon, hence my question. You really should pay attention.

Not looking for an argument, nor getting worked up, just pointing out that levers to the bar aren't caused "pad/rotor overheat to the point of failure." This is basic stuff.

Followup question. If you learned about pumping the brakes in driver's ed, were you on the ball enough to do that when your levers allegedly pulled all the way to the bar?

Bryan C. 

Ok, definitely guilty of not reading who I was replying to. My apologies, to you and @redlude97

I survived using that very same training. Never had any air form in the system which will accompany a boiled fluid condition. The rotor was definitely blue afterwards.

u235

I've had brakes fail to the point they were almost useless after a steep downhill and about 50% effective for the rest of the ride well after they cooled down. It was isolated to my off brand pads. Tossed them and never had the problem again on the same rotors (Shimano RT66 at the time). I'll still stand by my statement that pads are much more a factor and difference than rotors are.

sputniky

You didn't have any air in the system because what happens with bad fluid is that it absorbs water (most brake fluid is hygroscopic), which turns to water vapor when the caliper gets hot enough, which causes a gas bubble in the caliper, which causes your brake levers to go to the bar, and which requires pumping to maintain any clamping force.

Once the brake fluid cools, the water is reabsorbed and when you pop the reservoir open everything can look fine, except the fluid is usually darker because it's been contaminated.

Wilmingtech

Rotors are a pretty simple mechanical device. As already mentioned, spend the money on the pads.

The performance difference between a single stamped metal rotor for 15$ and a stamped metal rotor for 50$ is going to be minimal.

You are paying for artistic design more than functionality. Take a look at this and you can see that the SRAM Guide disc brakes with a stamped disc rotor can take a ton of abuse before failing and even when they do fail, its because they ran out of pads. The rotor itself has mostly held together and does it's job.

Typically the more expensive rotors will be the two part "floating" rotors (Not true floating in the sense of cars and motorcycles) with 2 parts riveted together. Because of the aluminum carrier these are less likely to go out of true than a single stamped rotor. These also will have a point of failure in the rivet that holds the 2 pieces together. Design in the 2 piece rotors can also include different metals sandwiched together to save weight and fins to increase cooling.

As far as performance in a rotor, spending 30-40$ more on a one piece steel stamped rotor won't increase your bikes braking performance.

For the 2 piece rotors there are many more factors to look at in the design to see what the benefits are. That being said, I'd take a guess that 75% or more of the people on this site are not doing mountainous climbs with 5, 10, 15 minute descents nor are they taking a chairlift up a mountain to do some serious downhill. I'll even throw in that on my regular rides I have 2-3 mile descents in the 5-7% average and get up to speeds of 45mph but rarely do I need to brake to the point that they would actually get hot enough to burn you.

I do have lots of climbing and descending where I live and I do need the braking power but spending upwards of 100$ per rotor doesn't equate to the performance gains I need to be a better descender nor does it equal a safer braking system. The gains are minimal enough that the dollar amount just doesn't justify the spend. And I am not counting pennies on a budget.

-Sean

sputniky

I ran Hope floating rotors for years. I trashed one on a road trip and swapped it out to a solid Avid rotor. No difference in performance.

Where are folks selling floating rotors for upwards of $100 per rotor? The Hopes are about $60, depending on size.

DrIsotope

AFAIC, there's Shimano IceTech, and then there's everything else.

Wilmingtech

Shimano RT 900 Rotors

Competitive Cyclist

Google Search

Seems like 80+ and tax/shipping is about normal for these.

-Sean

DrIsotope

Kinda misleading though, going straight for DuraAce. Ultegra R8000 rotors are about $50, XT are $30-40-- and those are all IceTech.

Name-brand floating rotors like Hope are ~$60, knockoffs dip under $20. If there's a $100 bicycle rotor out there, I haven't seen it.

redlude97

https://www.competitivecyclist.com/s...ck?ti=OjoxOjE6

DrIsotope

Oof. The roadie tax is particularly strong with that one, seeing that the SRAM Centerline R is 50 bucks and the stamped Centerline is $30.

But hey, "designed for road use" and $105 a pop doesn't even include lockrings. I used to think my RT86 180/160 set were expensive at about $75 for the pair. No more!

Bryan C. 

$65 at Jensen. Deals can be found if you look around.

The XTR Rt M900 rotors are $80, but discount codes come into play sometimes. I got 20% off when I ordered them.

Bryan C. 

Disc brakes are pretty well sorted out these days. It's only when you start to really work the parts hard that the improved performance comes into play. The average cyclist doesn't push their equipment to the limit so for most people the basic parts will work very well for them.

sputniky

Yeah, the solid rotors got worked plenty hard, including two solid days of lift-served DH, but it's pretty cool by normal standards in the Northern Latitudes, even at the height of Summer.

The long term advantage of floating discs is that when they are repeatedly "worked hard" they don't need to be trued as often as solid rotors.

And bling, if that's your thing.

Seattle Forrest

That seems like a pretty convincing argument. But pros probably have better braking technique that a lot of recreational cyclists, and better roads to race on. And lower weight, you have to be pretty light for the job.

I overheated my brakes to the point of needing a bleed, coming down the gravel route from Loup Loup Pass. I'd get a mile or two of good hard pack, then suddenly it's washboards so bad I can barely see. There not visible at speed before you hit them, and there's nothing to do but grab a fist full of brakes when you hit them. I could be wrong, but doubt roads like that are involved in the races you're speaking of.

u235

When you brake.. You are 100% converting momentum to heat. When and if the heating stops, the braking action stops or on the flip side, when your brakes stop working, there is no more heat being generated. At a certain velocity and a certain weight and certain time = a specific amount of heat. There is no way around that. The thing that varies is where and what that heat is dissipated too and how even it is spread around. Ideally it is spread around in some ratio to prevent fade or failure from either the disc, pads, calipers, or fluid. You can have rotors and pads that in theory can dissipate heat better or worse to the surrounding air which is a positive and pads and rotors that conduct more or less heat to other things like your calipers (which then goes to your fluid), your hubs etc.. The less a pad conducts, transfers, or moves heat results in a rotor that gets hotter but a caliper that stays cooler. A pad that conducts a lot of heat means a cooler rotor but a hotter caliper. You can say the same comparing a rotor that conduct better or worse. You do not get something for nothing. There isn't much mass in the system to absorb great amounts of heat so drastic changes in temperature can happen very fast.

gus6464

160mm XT icetech rotors are 30 bucks at Jenson. What's the point of spending $20 on a no-name?

https://www.jensonusa.com/Shimano-XT...t+rotor+180+mm

redlude97

you'd have to convince me those actually provide a benefit, they are very different than the finned icetech rotors. They weight more than sram centerlines for example

redlude97

Thats not how it usually works, after the brakes cool down then they should return to normal. If it needed a bleed after then it needed a bleed before and you didn't realize it. Did you actually lose complete braking during the descent?

Seattle Forrest

I think I overheated the fluid on the way down. Don't remember losing braking power completely, it could be that I'm not as young as I used to be, but I think I'd remember that.

Basically lost all modulation until they were bleed. They'd go from nothing at all to lock the wheels with almost nothing in between.

DrIsotope

Pros are a horrible example, because they only need the bike and all of it's components to last for a few hours. My current set of IceTech rotors have north of 15,000 miles on them. I don't buy anything marketed or aimed specifically at "racers."

jfranci3

Only two thoughts - Campy H11 rotors made a lot of air noises (thumping) with my SRAM road setup. Rounded edge rotors go into the caliper easier when changing wheels, keeping your paint nice.

RocThrower

I recently purchased the 6 bolt Ice Tech rotors from Jenson, $60 for the pair. I have Ice Techs on my road bike, but stamped rotors on my gravel bike. Both bikes have Shimano hydraulic brakes, but the Domane's always felt more powerful; less lever force needed. After bedding in the new rotors on the gravel bikes, my brakes feel more like the Domane's, so for me there is definitely a difference. This is not to say that the stamped steel rotors didn't work well or were really lacking, but there is an improvement in performance.

u235

Agree, I have a set of RT86 too no problems. End of thread
Back to my way original first post in this thread... A crappy set of pads will always suck regardless of the rotor. A good set of pads will perform good on just about any rotor and possibly better on a better rotor.