Weight Weenies

There is no way in hell I will ever ride a road bike with discs, I experienced brake fade while riding one of my disc MTBs on the road and for those who have never experienced it, it is truly terrifying. I had no brake power at all and was flying down a hill going 45mph, only way I was able to stop was by putting my feet on the ground to slow myself a bit and eventually hopping over a curb to crash into some bushes (neither of which I could have done on a road bike with cleats on). Sure, if you know how to ride them you won't likely experience brake fade, but whos telling buyers not to pad their brakes during long descents? I knew about the issue before it happened to me anyways, even experienced riders who know can have careless moments.

If you want to descent totaly safe on a long descent, you'll definitely need rim brakes!
Like this: https://www.youtube.com/watch?v=haEbtHiUcBc

Roel W wrote: ↑

Mon May 27, 2019 11:21 am

If you want to descent totaly safe on a long descent, you'll definitely need rim brakes!
Like this: https://www.youtube.com/watch?v=haEbtHiUcBc

I watched that crash when it happened 2003 TDF
I always thought that crash by Beloki was caused mainly by the melting tarmac.

That aside thinking of the many,many years of rim brakes racing down the Alps,Pyrenees etc I think while nothing is "totally safe"
They have a great record

Beloki meanwhile was surrounded by team mates, unable to move. It later emerged that he broken his right femur, elbow and wrist, and was forced to leave the Tour. It seemed that the crash had been caused by melting tarmac.

“All the corners were melting, there was asphalt but it was bubbling. He (Beloki) was racing the race, and racing aggressively,” said Armstrong afterwards

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^ Beloki's tubular glue was probably starting to melt due to the heat, you can see his rear tyre roll off the rim during the crash. Needless to say, he would've crashed whether he was on rim brakes or disc brakes, tubs or clinchers.

mattr wrote: ↑

Mon May 27, 2019 11:12 am

This whole DoT/mineral oil argument is hilarious.

In a well maintained system there is nothing between them.
In a workshop environment, service/bleed/looking after and so on, there is nothing between them. (You need to be careful/methodical and clean up after yourself properly either way.)

The differences only come to light when you treat them badly, or don't maintain them. Or are incapable of weilding a spanner and a rag with the requisite level of skill (quite low really).

20+ years of working on and/or designing/analysing hydraulic systems, mineral and DoT filled (and other stuff you *really* don't want to service youself!).

Yes, although DOT systems are more likely to have more problems if ignored and not maintained. But it's not like they're going to suddenly go from 100% to zero, there's quite a bit of warning...and when it comes down to it, it's your fault.

TobinHatesYou wrote: ↑

Mon May 27, 2019 6:48 am

You haven't given us any other information. How do we know if the following are true or false?

1) Your brakes are bled properly.
2) Your pads are in good shape.
3) You descend without excessively dragging your brakes.
4) Any number of other things.

We can all make rim brakes fail too.

They were top of the line shimano xtr hydraulic brakes and were only a few months old. After that had happened I took my bike to the shop I bought them from, a very reputable local mtb shop that specializes in high end mtb products and they took a look at the breaks and said nothing was wrong with them. The cause was #3 "excessive" brake dragging, but it happened near the top of the hill so it didn't take long for them to fail and IMO brakes should not fail cause you use them to much. This seems like a bad design. Yeah sure if you know how to ride them properly and don’t ride long descents this shouldn't be an issue, but most riders probably don’t know this. Anyways I ride in the mountains, basically all of my riding is either going uphill or downhill and I take lots of long descents where I need to maintain a controlled speed, I don’t want to be periodically slowing down and speeding up in intervals to keep my brakes from failing, I find that really annoying, I’d rather just ride at the speed traffic is moving/the speed I’m comfortable at. I have never had any trouble with my rim brake tubeless alloy fulcrums or carbon tubular zipps on long descents at a steady 45mph+. That being said I know carbon rims have their fair share of issues related to delamination but I have not experienced any of these issues and I tend to ride alloys most of the time anyways. Overall rim breaks are way more reliable and you would pretty much have to be trying to make them fail.

On any road that allows you to go a steady 45+ mph, you're not braking much at all...independent of the brake technology on the bike.

Thats an odd assumption to make, on a lot of hills I could easily go faster than 45 but I dont want to, thats why I'm using my brakes.

If you cooked XTR brakes on the same road you don't manage to melt Zipps on then there's something more too it...

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Honestly I was probably a bit more gentle when it came to riding my zipps but I still gave them a beating many times over and never had any issues, I believe the resin they use doesn't begin to soften till temps reach close to 300 C which is pretty dang hot. As for the alloys, I can and have cooked the crap out of them dragging brake with zero stopping power issues. I shouldn't argue that carbon rim brake wheels are more reliable as there's lots of variation between wheelsets, I bought my zips cause they had the best overall reviews when it came to durability and safety and they lived up to that but at the end of the day I still ride aloys 4/5 rides. The way I look at it is you put carbon rims on a bike mainly to save weight and if you are then throwing heavy disc setups on there to counteract the braking issues that's kind of defeating the purpose with an overly complex solution, not to mention the breaking issues that come along with discs.

I’ve reached and exceeded the max working temperature of Magura HS33 rim brakes. Completely ineffective after a certain amount of braking.

All hydraulic brakes will fade if they're over-used - it's why car/bikes that are raced use ceramic/carbon discs. Brake fade is common on track days.

Excessive dragging on a descent suggests poor technique more than anything.

guyc wrote:All hydraulic brakes will fade if they're over-used - it's why car/bikes that are raced use ceramic/carbon discs. Brake fade is common on track days.

Excessive dragging on a descent suggests poor technique more than anything.

We often see under skilled drivers burning their brakes coming down the passes near us.

I genuinely wonder if they understand that their car has a transmission with multiple gears. And that it, too, can be used to slow them down.

Gunnar, helpful hint: If you are going fast enough to run out of skill, sit up and let wind resistance slow you down.


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guyc wrote: Excessive dragging on a descent suggests poor technique more than anything.

No, can very well be:
- traffic that doesn’t allow you go as fast as you would like.
- people on the side roads
- wait for other group members that you dropped in the climbs
- just you don’t want to go too quick cause you don’t know the descent

In all the places I ride, you can’t use the the full speed of the descent for many reasons that are not related to the guy behind the handlebar.

Now the problem may be impacting both type of braking system, I only experimented minor brake performance degradation (slaughtering pig noise with some carbon rim brake wheels and a bit more spongeous (?) feeling and rubbing noises with disc).

Curious to have pro mechanics feedback after the giro. During last tdf, mech were changing many disc after one (!) mountain stage, several of them not being true any longer.


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C36 wrote: ↑

Tue May 28, 2019 2:29 pm

guyc wrote: Excessive dragging on a descent suggests poor technique more than anything.

No, can very well be:
- traffic that doesn’t allow you go as fast as you would like.
- people on the side roads
- wait for other group members that you dropped in the climbs
- just you don’t want to go too quick cause you don’t know the descent

In all the places I ride, you can’t use the the full speed of the descent for many reasons that are not related to the guy behind the handlebar.

Now the problem may be impacting both type of braking system, I only experimented minor brake performance degradation (slaughtering pig noise with some carbon rim brake wheels and a bit more spongeous (?) feeling and rubbing noises with disc).

Curious to have pro mechanics feedback after the giro. During last tdf, mech were changing many disc after one (!) mountain stage, several of them not being true any longer.


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We were stuck behind an ambulance after watching the Mt. Hamilton stage of the ToC. I could smell its brake dust. Brakes didn’t fade after 8min of constant dragging. Some carbon rim brake riders pulled off when the shoulder got sufficiently wide to give the ambulance a bigger gap. That is an option.

I did sit up and puff my elbows and knees out to help slow me down.

I have never had a disc rotor go severely out of true from warping. I have seen maybe .1mm of warping on my rotors after truing them to almost perfect condition.

Why wouldn’t you regroup with dropped riders at the top of the climb?