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This article was shared and discussed in the Red Hydraulic section. I will leave it as, the guy was a moron, used the wrong equipment, mismatched parts and admitted this. Even admitted user error.

How about the insights from OEM on cable failures? :rolleyes:
 

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Scott in Maryland
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Wow ... I thought this was pretty objective ... didn't interpret that author blamed his accident on his brakes ... presented a pretty straightforward state of the current technology, IMO.

I sure don't think the guy was a moron. ...
 

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titanium junkie
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Article written by experienced cyclist with insight from major OEMs ..... after a severe crash on road bike hydraulic disc failure! Objective and enlightening ... as close to a "must read" as I can offer my RBR bike buddies....



Road Bike Disc Brakes Are Coming, But Will They Work? - Bike Rumor
It seems a little scary to read the article for a rider transiting to disc brakes on a road bike. Not sure what is to blame for such accident. The accident could easily be caused by rim brakes as well, as there have been many similar accidents over the years with rim brakes. I personally have a couple of close calls desending a steep hill with rim brakes. Disc brakes in general should work great for road bikes. Cars and motorcycles have been using disc brakes for ages.
 

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It's objective and informative, but it's also a "duh" article. Yeah, he used a brake setup not optimized for CX and not road and ran minimalist Ashima rotors at that. Then the major lesson of using bigger rotors to address heating issues...literally discussed the obvious albeit with the major manufacturers to get the point across thoroughly.
 

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Some things become obvious in hindsight. Painfully so, in this case. Glad the author is ok (5 broken ribs!) and took the time to post an informative article that includes manufacturer perspectives.
 

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I ride in circles..
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Interesting write up.. It's a bigger issue moving forward to disks than I thought.
 

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Horsepoo.

My wife and I have a tandem with disc brakes (BB7 Road). Even loaded touring in very hilly terrain has never produced brake failure. Using disc brakes on the road isn't new, applying the weight weenie approach to road discs is.

The guy put lightweight rotors onto his bike and then dragged them down a hill. Surprise! It produced brake fade and failure. I am shocked. Too bad he didn't have dual pivot brakes and the lightest carbon wheels and tubulars he could find.

I am glad he is OK, but this is user error.
 

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Horsepoo.

My wife and I have a tandem with disc brakes (BB7 Road). Even loaded touring in very hilly terrain has never produced brake failure. Using disc brakes on the road isn't new, applying the weight weenie approach to road discs is.

The guy put lightweight rotors onto his bike and then dragged them down a hill. Surprise! It produced brake fade and failure. I am shocked. Too bad he didn't have dual pivot brakes and the lightest carbon wheels and tubulars he could find.

I am glad he is OK, but this is user error.
Thank you and well said! This guys write in horse manure! No wonder SRAM or others OEN ignored him.
 

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Burnum Upus Quadricepus
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Horsepoo.
Agreed.

My daily commuter, a 2006 Trek Portland, came with BB7s and 160mm rotors front and rear. While it's not the world's best climbing bike, I took it on vacation to Colorado's Front Range in 2008 precisely for the road disk brakes on the mountain descents.

I'm a lifelong flatlander so I'm not embarrassed to say I'm an inexperienced descender.

My very first mountain descent was Mt. Evans. It was wickedly windy that day, the road is in poor shape, and it has no guard rails. I rode the brakes pretty heavy on the descent from 14,130 feet. (Which is more altitude than I've skydived from.)



They sure didn't like it. They were howling like a banshee towards the bottom, and the rotors were warping from the heat. But they never faded and certainly never failed. After they cooled, the rotors straightened out by themselves and I checked the pads for glazing. There was none.

I put the pads back in and rode up to Peak-to-Peak Scenic Byway two days later, and back down the the plains again. A little less on the brakes this time, but still a lot more than the locals.

I agree that the Bike Rumour guy's problem was rotors. Look a those things. They're about 85%, maybe 90% air. Decorator rotors are for show bikes.

My bike came with Avid Roundagons, and that's what we rode in Colorado. Since then, I got new wheels and treated myself to Avid G3 rotors. The G3's have much better braking performance than the Roundagons, even when using the same pads. Rotors matter.
 

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Happily absent RBR Member
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People in long mountainous descents can suffer brake fade on even relatively large rotors. Road descents use more braking energy than even the downhill bikes they borrow brakes from (that also get brake fade on occasion).

The author isn't a moron - he says right out that what happened to him caused the article to get written, and he absolutely doesn't blame discs in general. Any other reading is frankly.... moronic.

Three very heavy bike component makes say in the article that heat is a problem in any normal sized rotor. I'm not sure how much clearer that could be.

And they also make mention of the difficulties in designing forks and wheels that can take disc braking and still ride like supple road bikes. The road market is driven by weight and ride quality - two things that are major problems for disc brake design.

There was a much more reasoned and thoughtful discussion of this article last week on the Paceline (formerly Serotta) forum. I'd recommend reading that for more insights than name calling and article skimming.
 

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I see it time and time again coming down the canyon (vertical drop 3000+ feet) from skiing at Alta each weekend ... it's the people that ride the brake continuously that burn their brakes up. Once it was so bad that the mini van looked like a James Bond smoke screen everytime he applied his brakes.

The author states "I kept light pressure on the levers, dragging my brakes to keep my speed around 30mph on a very curvy, steep road." That's exactly not how to use your brakes. While I'm unable to exactly describe exact thermal dynamics involved in overheating your brakes, it has something to do with heat flux and saturating the pad to disc interface, plus not having enough heatsink to absorb the kinetic energy. Modulating the bakes would allow the pad to rotor interface to cool and energy to spread throughout the rotor.
 
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I see it time and time again coming down the canyon (vertical drop 3000+ feet) from skiing at Alta each weekend ... it's the people that ride the brake continuously that burn their brakes up. Once it was so bad that the mini van looked like a James Bond smoke screen everytime he applied his brakes.

The author states "I kept light pressure on the levers, dragging my brakes to keep my speed around 30mph on a very curvy, steep road." That's exactly not how to use your brakes. While I'm unable to exactly describe exact thermal dynamics involved in overheating your brakes, it has something to do with heat flux and saturating the pad to disc interface, plus not having enough heatsink to absorb the kinetic energy. Modulating the bakes would allow the pad to rotor interface to cool and energy to spread throughout the rotor.
This is probably very oversimplified, but more heat will transfer from an interface such as brake rotor to the air when there bigger temperature differential between them. Lets say someone wants to maintain a certain average speed down a hill -- they can "ride" the brakes and maintain that average speed by apply a small amount of brake pressure continually, or they can modulate the brakes and dump a bunch of energy in periodic short bursts.

Bleeding the same amount of energy by hitting the brakes in short bursts should cause the temperature at the very surface of the pad to get significantly higher, since a lot more braking power (energy/time) is being applied. As a result of the high temperature difference between the rotor and air, more of this energy should get carried away by the air compared to dumping the same amount of energy into the brakes more slowly.

On the other hand, riding the brakes continuously will cause the energy to heat up the pad more gradually. Because the instantaneous temperature on the surface will be lower, heat will be more likely to remain and "soak" into the rotors and brake pads. If the entire rotor gets hot throughout, vs just the surface, that's when warping etc. may occur.

Another issue is that even if average speed is the same modulating vs. riding the brakes, power lost due to air resistance is proportional to the cube of air speed, so more energy will be lost to simple air resistance (rather than being bled off by the brakes) when varying speed more drastically vs going at the same average speed continuously down the hill.
 

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On the other hand, riding the brakes continuously will cause the energy to heat up the pad more gradually. Because the instantaneous temperature on the surface will be lower, heat will be more likely to remain and "soak" into the rotors and brake pads. If the entire rotor gets hot throughout, vs just the surface, that's when warping etc. may occur.
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Riding the brake will cause the brake pad to get saturated with energy, as it is always in contact with the rotor. The rotor on the other hand is only intermittently in contact with the pad. Applying and releasing the brakes will allow the pad interface surface to cool. The area of most concern is the pad to rotor interface as that's where the real friction action is. Loose the friction, loose your braking.
 

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titanium junkie
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Thanks. Not bad for a lifelong lowlander and flatlander, eh? And on his everyday commuter besides.

Next time I'm out there, I'm taking my Litespeed. :thumbsup:
hey brucew, I have just noticed the rack on your bike, is it a Tubus Logo Titan? I am looking into getting one soon and wondering if you can shed some insight about it. How about the trunk bag shown? Thanks!
 

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Happily absent RBR Member
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Riding the brake will cause the brake pad to get saturated with energy, as it is always in contact with the rotor. The rotor on the other hand is only intermittently in contact with the pad. Applying and releasing the brakes will allow the pad interface surface to cool. The area of most concern is the pad to rotor interface as that's where the real friction action is. Loose the friction, loose your braking.
Articles I've seen about car racing raise doubts with this theory. In the end, energy is energy, and expecting a braking program to prevent fade for average consumers is not a solution - the variable rate of cooling does not mean that the total thermal threshold for fade isn't going to be exceeded whether you maintain a speed or accelerate and crash brake repeatedly. Once you go above that number, no brakes.

Compared to the thermal load of a rim (the biggest rotor) and a sacrificial pad, brake fade on discs is a bigger problem.
 

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Seriously?

Who would use those rotors? :confused: They look more like a strip of wire than a brake rotor.



Makes me think of someone cutting their Record brake pads in half to make them lighter and then whining about Campagnolo having poor braking.
 

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Great link. Thank you,

I've been spending the last couple years thinking carefully about what I wanted in a new bike. I'm convinced that electronic derailleurs and disk brakes are definitely the future for road bikes. But while the former are here, the latter are not. This article lays out all the reasons I ended up deciding that if I wanted a road bike with disk brakes, I'd have to wait another two years or so. At 61, I don't really want to do that.
 
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