Can We Melt Disc Brakes!?

Disc brakes like them or loath them, they're becoming increasingly more popular amongst road riders for their superior braking performance. But just how far can you take them? Can we melt disc brakes? Ollie and Hank are in Italy to find out!
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[@gcn]

What other challenges would you like to see Hank do?

[@TheMoodyedge]

Crack a Canyon frame................................................nar, forget that one...too easy.

[@Dabbtrabb]

What is the max weight he can carry while climbing 10k at a steady gradient

[@Black70Fastback]

apparently a hot dog eating contest seems right up his new found skills

[@PenguinIceNinja]

Try this with some entry level disc brakes and see if they glow in the tunnel!

[@YukitakaOhashi]

@@PenguinIceNinja same here!

[@bimblingalong]

If you want to do that test again with a cyclist who's starting weight is 110kg, I'm more than willing to eat focaccia & tart at the top of a mountain! 😂

[@robest334]

Better yet, attach the bike disc brake onto a truck or a car.

[@Dabbtrabb]

A year ago, I would have been your ideal candidate. Would've still eaten the focaccia and tart..

[@eleycki]

I can do that without eating. 🤣

[@QwertyUser1983]

Please do test! You may ask a Sumo Wrestler to try. (*♡∀♡)

[@123moof]

Can confirm. Took a 136kg total weight loaded cargo/bikepacking bike down a 800m 15+% descent. Brakes smelled bad, front brake was fading, and had to take pauses to cool things down. I am planning on bumping up the rotor size before I try similar again.

[@charlificity]

Hank’s extreme test represents normal life for us cyclists above 100kg. Trust me, the brakes still work 😂

[@KNURKonesur]

As a 125kg+ cyclist I agree. I just have to replace them much more often than my wife who's about 53kg :D

[@tri-seeker2753]

100+kg rider plus 25kg of recumbent trike, means that Hank's test tested absolutely nothing for me 😀 On the other hand, based on color of that disc, it had to experienced temperature around 230°C (highly unscientifical way of measuring temperature guys) and that rotor is very well cooled, inside of brake caliper had to be real inferno. On the even OTHER hand, I can repeatedly not melt, but baked my rear brake on way shorter downhill to the point it starts sqeeking terribly and when I have something in my panniers, it even stop breaking (not entirely, but significantly less), and that is 180mm rotor and Galfer sintered pads... So my point is, YES, brake fading IS a thing that you may experience on a road so if you for some reason HAVE TO drag a brake, frag the rear one. In that case, your front (AKA more powerfull) is still cool and ready to save your ass...

[@parenthlete]

@@KNURKonesur haha nice 😊

[@eleycki]

Exactly, and ally rim brakes are fine too!

[@ericvutran4140]

Hey Schotte, what brakes do you recommend for us 100kg guys?

[@motomehanicar459]

Never spil water on hot brakes! Disc can easily bend from temperature shock.

[@KNURKonesur]

It's a sponsored bike, they'll be fine :P I don't think any normal person would ever think to do that :P

[@chrisb_rc]

I'll not drive in rain anymore

[@jackiewong0806]

@@chrisb_rc Driving in the rain actually helps dissipating the heat. Pouring water is different because it changes the temperature rapidly and hence will cause bending. That's not the case with rain. Ignore though if you're just joking.

[@jim9685769]

Not true. People should realize that bikes, motorcycles and car brakes are designed to work in the rain after driving hard and breaking all day. It doesn't affect brakes to get them wet.

[@Rover200Power]

Trying braking hard and immediately going through a big puddle. Constant water presence from rain has no effect.

[@oggypip9889]

Descending in the drops would have been harsher on the brakes (less drag = more energy through the disc). Also: for steel to change color, it must have been at 250°C or more at some point. Purple starts at around 270°C, blue at 300°C.

[@mateosebastian8555]

Was thinking dragging the rear brake would get it hotter as it brakes less effectively compared to front

[@bsmith5167]

He should have been pedaling too.

[@KNURKonesur]

Shoulda, coulda, woulda.

[@danielakerman8241]

@@mateosebastian8555 It brakes less effectively because of weight transfer. The rear brake never loads as much as the front brake. It would likely still have a lower temperature than the front brake because it's dealing with less forces just through the physics of braking.

[@kidkarbon4775]

Campagno discs are made from tempered stainless steel as such the values and math being presented are not quite correct.

[@nukedathlonman]

Actually, sintered (what you called "metal" pads), or what is called semi metalic in the automotive world, don't just wear longer, but are pads that intended to operate at higher temperatures for more extreme uses (ie heavy hauling, racing, etc). They have less bite when cold then a resin ("organic") pad, but they are more resistant and hold up better at higher temperatures (what they are intended for). While yes you want to ensure the pads don't over heat as it causes them to lose effectiveness, the more terrifying thing is to ensure the brakeing fluid doesn't over heat and boil.

[@babybirdhome]

That’s for sure! I did that once in a supercharged Thunderbird on my way home late at night coming up on a tight downhill turn that was notorious for people going off over the years. I was young and stupid and had no idea you could boil brake fluid. I had been driving up to it around 135 MPH and laid into the brakes approaching that curve and started to slow down but then suddenly the pedal just went flat to the floor and I wasn’t slowing down a bit. I frantically downshifted as carefully as I could to avoid throwing it into a spin by dragging the rear wheel drive wheels too hard on a downshift but I needed to shed speed. Thankfully I kept my wits and, having had previous experience with overheated brake pads, figured it was a heat problem so counterintuitively I let off the brakes while downshifting to let them cool just a touch before laying into them one last time to try to save my dumb ass life, and thankfully that was enough to cool the fluid and the next time I stamped down the brake pedal, I had some braking again and managed to slow down enough to make the corner. I sure learned a lesson that night! Never, ever pushed anything that hard again. If it had been anyone else driving, they probably would’ve gone right over the edge and died like so many other people who missed that turn had done over the years. Terrifying doesn’t even begin to express it. Don’t be dumb like I was, people! Be safe and keep your stupidity to a minimum. Your life and the lives of others depend on it. And I actually was wondering if they were going to artificially test this because I was curious what happens at the edge of braking on a bicycle with disc brakes. How likely is it that you could ever boil that brake fluid? It did concern me when he mentioned that it isn’t regulated or controlled like automotive brake fluid is, so manufacturers could be putting who knows what into it, and every formulation could potentially have very different performance characteristics at the margins. I’m thinking it might just not be possible to do that on a bicycle, but they do have a very tiny surface area to dissipate heat from.

[@bindingcurve]

@@babybirdhome Automotive brake fluid is hygroscopic, meaning they will absorb moisture when exposed to air. Your not boiling the brake fluid, your boiling the water in the brake fluid. You need to flush your brakes every few years or sooner if you do high performance driving. Mineral oil is not hygroscopic However when water gets into the system, it will tend to pool at the caliper (very bad). So learn to bleed your brakes on your car and your bike.

[@Daivd1111]

@@babybirdhome I think bindingcurve is right, even at 135mph, an emergency brake to a full stop should not boil your brake (if so then there would be much more accidents at race tracks). It's the water that's boiling- even a bike brake can reach ~100 degree C.

[@johncarrington8612]

Adding to your answer, the sintered brakes also last longer than organic pads in wet/muddy conditions. Dot fluid will pick up water from the air and usually has a higher boiling point than mineral oil. Dot fluid is more corrosive than mineral oil and needs to be handled and disposed of more carefully when doing a bleed. These are all things that have been worked out in the mtb world of cycling.

[@Rikcey]

@@johncarrington8612 I very much so prefer DOT over Mineral. It's cheaper than proprietary mineral oil, even when you get some high performance dot 5.1. Even wet, that stuff has a boiling point of 180. Which is almost twice the boilingpoint of the water a well used (mineral oil) brake accumulates at the caliper over time in adverse conditions. (I don't shy away from rain and grime). Yes, it's more corrosive, so, I guess bleeding is more involved. But you'll do that bi-annually any way. Brakes are safety devices ultimately, so I want to know they are as reliable as they can be. I run Hope rx4 4pot calipers with SRAM masters on a Hope 180 rotor in front, 160 rear.

[@edinelsonramirez5656]

By the time he gets around to measuring the heat, the temps have probably dropped another 10°! Needs to get temp measure the moment he comes to a stop. Thanks guys!

[@aliancemd]

And IR guns are not appropriate to use on reflective surfaces, but they are not really doing a scientific experiment, it's more as an ad for Campagnolo.

[@gcn]

We need to send Ollie over to GTN for some running training!

[@arbjful]

@@aliancemd wireless temp. sensors fixed to the rotors may be more accurate

[@lesleyrobertson]

I think you should try this test with fully loaded backpacking and touring bicycles. At last weighing my touring bicycle with me on it came in at ~150kg. The discs have turned blue at one point which means a temperature of over 300C and I think warped the disc. Also you could tape the IR gun to the fork and measure the temperature continously down the hill..#realbraketest

[@4nz-nl]

If you think your brakes will overheat on a descend... simply slow down further and hold a lower speed. It might be a bit counter-intuitive that holding a lower speed will require your brakes to dissipate less energy, but it's true. If Hank would ride a 7.5 kg bike and want to ride 10 km/h down a 10% hill, that would require ~200W of constant braking energy. At 20 km/h, that's already 385 W. At 40 km/h, it's 570 W (because wind will be holding him back), and at 60 km/h, you're back at 350W again. His theoretical max coast speed is just over 70 km/h.

[@christoferstromberg6605]

Nah go even higher then, 150kg is less than my commute to work. I'm hauling ~170kg to work. A touring/bike packing setup would probably go over 200kg for me :)

[@4nz-nl]

@@christoferstromberg6605 Damn! How tall are you?

[@christoferstromberg6605]

@@4nz-nl 185cm. But I don't have the cyclist build, I'm more like a strongman.

[@kaspervestergaard2383]

So abit chubby we could say ? @@christoferstromberg6605

[@MrTegner]

I must say that i wasn’t expecting anything else from the top of the range brakes!! How about to do this test on a real entry level bike, no beginner rides a bike like that and the one that does isn’t a beginner so please do the test on a much cheaper bike. I really love how Ollie shoves the tart in Hanks mouth ❤️

[@onegrapefruitlover]

You underestimate the willingness of rich people to buy stuff regardless of their lack of knowledge or talent

[@Jean-jk4zv]

Trp Spyre cable brakes with stock trp rotors and pads are fading on small steep descents like lasting a few hundred meters ! They are equipped on a lot of gravel bikes. I will never go in the mountains with those. Someone tried ? Had zero fading problems with Shimano rotors and pads.

[@gcn]

We found that the Eurobike's budget discs didn't fare so well descending the Alto de Velefique in Spain! 👉 kzbin.info/www/bejne/pobciI2ZYsScosU

[@mikestonejyytyhyhitrws1646]

Actually there are plenty of beginner riders who hop on an expensive bike as there first bike, not me, and why? ‘cause they can!!!

[@fortinbras47]

Do this on a top the line rim brakes with super expensive carbon clincher carbon wheels, and you almost certainly would have destroyed the wheels. You possibly might have crashed catastrophically. Regardless of dura ace or whatever, there's a known issue that carbon clinchers (in contrast to tubulars or alloy) have problems dissipating all the heat energy put into them from a big descent. For rim brakes, buying "top of the line" can perversely leave you more vulnerable to this problem (alloy wheels don't have the heat issues that carbon wheels do).

[@aaronedgeart]

Hank, "I'm not gonna' lie". Ollie, "Why would you lie about it?": A GCN golden moment.

[@antoineboillet2288]

I have experienced disc brakes almost completely failing while still following a very thorough intermittent braking technique : On a fully loaded touring tandem totaling about 150kg down an alpine pass. The organic pads felt like butter with little braking power. The disc were a nice blue color at the end so reached a good 300C. If you want to put it truely to the test, retry the same experience on a tandem ! If you want glowing color, you should use metallic pads as the organic pads will melt before the 800C-900C required for steel to glow.

[@GordoGambler]

@@username8644 Who the hell would worry about that??

[@macvos]

There's a reason some tandem bikes come with 203mm rotors combined with a dedicated drag brake...

[@Jeppelelle]

​@@username8644 Yeah, i wish there was atleast 1 road bike (slight exaggeration, they do exist but are rare) out there being sold with atleast 180mm rotors, as a 110kg rider, the difference in braking power between my 203mm/180mm MTB 4-piston brakes vs my roadbike 160mm/140mm 2-piston brakes is scary, the difference is insane. But yeah, thanks to hobby riders with beer bellies thinking it would be end of the world if their bikes where 20-40gram heavier then we will be stuck with this shit, but yeah, who cares about safety when you can improve your local riders with 1s per 10k..........🤷‍♂180/160 should be standard on all road bikes, if people care about the weight penalty they could downsize

[@YuriThorpe]

@@Jeppelelle Peak Torque makes a 180mm rotor adapter for road bikes

[@Jeppelelle]

@@YuriThorpe sure but the leverage ratio for the given fork is untested, probably okay but it is not 100% guarantied

[@102112519]

Big fan of these Mythbuster-esque type videos. Looking forward to the days where if the experiment fails, the blow up the bike anyway.

[@halfblood47]

Exactly my thought!

[@Bajbajoc]

They should do the same with rim brakes

[@RevoltingRudi]

not much heat on my bike. i live in the flat so i descend like a little bitch on unknown 8% declines. i did some dragging and my aloy rim got warm but not "holy shit" warm. it was a 53mm deep section 17C Rim with 23mm Conti 4k Tires.

[@gcn]

One for the Eurobike perhaps? 😂

[@tysonmou1]

I weigh 115kg and am interested in braking performance when heated up at different temps. When heated up it usually requires more distance to stop. Descents scare me, especially when the bottom of a hill there is a main road with cross traffic, and I drag my brakes on a rim brake bike. More brake tests please.

[@fnorgen]

I've stress tested my sintered metallic pads on a brutally steep and long hill. Those things had much better heat resistance than my old semi metallic pads. Even with the front rotor roasted blue there was hardly any fade. They take forever to wear out too. Though it does sound like train is pulling into the station every time I touch the brakes. They're exactly what you're looking for as long as the noise doesn't bother you too much.

[@bikecommuter24]

As someone who just got back into cycling and a retired mechanic, I love seeing all the new tech on bicycles and seeing that the components hold up even under abuse. I would have done the test but I have lost 41kg over the last two years, I don't want them to find me and come back.😆

[@anke569]

Thank you for this video. This makes me so much more comfortable during a descent. I'm fairly new to cycling and going down steep hills still makes me feel quite anxious.

[@mildpandemic3944]

Now do it at night to see if they'll glow! Hank's befuddled "Wot?" was perfect.

[@KNURKonesur]

Hank is a good actor :)

[@3Max]

This is exactly the video I needed. Started taking some very mild descents, and have been worried about my brakes. Still going to take it easy on them, but good to know that the engineering should hold up! Thanks Hank!

[@brentlewis4570]

Love to see campagnolo represented here. As a long time campy rider, all the focus on 105 gets a little old. Campy makes some great equipment. Thx!!

[@yyattt]

Part 2 - attaching the brakes to a motor to see what it takes to make them melt.

[@macvos]

Enduro MTB magazine actually did this. While the ICE-tech rotors worked well with normal usage, the sandwiched material between the braking surfaces actually softened up and got pushed out between them. Pretty crazy.

[@pchykins6680]

Great to find out that finally there's a brake that can withstand brake feathering for 16 km! A friend's full hydro road bike brake system (the most common brand we know), brake faded in less than 12km of descent when we tried it. The bite went to zero when used with non-ice tech rotors...but with ice tech rotors though, it was just fine.

[@qingyuhu]

Hank and Ollie are hysterical and informative at the same time!

[@J0zla]

Ollie mentioned kinetic energy - it grows proportional to mass (double the mass double the energy) and with the square of the speed. In my opinion to put most energy possible in the disc they should put on the vest and let the speed build on the descent and then break hard - constantly accelerating and stopping . At 30 kph you have 9 times more kinetic energy then at 10 kph - so the amount of energy you have to dissipate is much greater.

[@cliffordromina3527]

Speeding up is just converting potential energy into kinetic energy. So they would have put the same amount of energy into the brakes as long as the ride the same elevation and mass, regardless of the speed.

[@reubydoi7111]

but the total amount of kinetic potential energy that is available to convert to heat over the whole descent is governed by only the height of decent and total mass (minus inefficiencies(aero drag, mechanical ect)). Going faster will only increase the amount of kinetic energy the rider has at a given moment, not the total energy that must be dissipated by the brake as heat. Going faster would actually decrease the energy the brake must dissipate because there would be a larger effect of aero drag, therefore less of the total kinetic potential energy the rider had at the start needs to be dissipated by the brake.

[@reubydoi7111]

you may still be correct that going fast and braking hard would make the brakes hotter by the bottom but it would be because of the rate of cooling vs heating not because the energy of the rider has been increased

[@bindingcurve]

Will not work, the brakes can cool down FAST. And the funny thing about going faster, the air not only cool down the brakes, but also provides resistance, helping the issue. Dragging is the worse thing you can do.

[@stevek8829]

Did you consider that while you are building speed, the brakes are cooling? 👀

[@yisraels4555]

Hydraulic disc brakes (not necessarily on bikes) fail because outgassing of the brake pads reduces contact with the disk or the fluid boils. The slots on the rotor prevent gas build up so brake pad outgassing is not an issue. Even the cheapest DOT3 brake fluid is required to have a boiling point over 230C. Measuring the caliper temp would have been more interesting since that would give an idea of how hot the fluid is and how far away from the boiling point they are. Not that we know exactly how Campy specs their fluid.

[@KILLTHEREDDITOR]

He was measuring the calipers though

[@nstrug]

Campy brakes use plain old mineral oil, either the official Campagnolo oil or Magura Royal Blood (both are approved).

[@macvos]

@@nstrug Magura Royal Blood has a boiling point of 120 degrees Celsius. Like Shimano, Magura and Campagnolo probably isolate the oil from the heat by using, for example, ceramic pistons. The first part to limit braking performance would probably be the organic pads glazing over.

[@nstrug]

@@macvos they use ‘Duroplastic’ aka phenolic resin. Same as Hope do.

[@macvos]

@@nstrug Shimano now uses "glass fiber phenolic" insulating pistons. I assume the Hope and Campagnolo pistons are insulating as well.

[@desmoMarco91]

My friend and i descended full speed the whole stelvio pass descent (21km), i weigh 70kg and was on alloy rim brakes....he weighs 87kg and was on carbon wheel rims and his tyre exploded!! He was lucky to not have any damage to the rim but if you are looking for such a long descent on carbon wheel rim brakes make sure to cool them down halfway at least once

[@KeithHeinrich]

Carbon rim brakes are a bad idea in the hills for us non pros. Older ones have been known to delaminate from heat build up and have been banned at one event I attended which has a long steep descent.

[@zbynekbroda4729]

"It's not magic. It's physics." That was deep not gonna lie

[@VN9001]

Now I didn't think for a minute that they would "melt" but I thought for sure that there would be some warpage of the disc. Kudos to Campy for such a well made/engineered product! 👍

[@Driver8takeabreak]

My friend is an engineer at SRAM and according to him they did basically this in the Alps with early versions of their road discs. Long, long descents in the heat of the summer trying to make them fail. Early on though they didn't test the other end of the spectrum and their brakes were not working well in cold temperatures during cyclocross season. I remember one race in Bend, OR when many of the pros just couldn't really use their brakes (because it was -10C that day). Seems they've sorted all that now.

[@peterbarr2011]

That was absolutely tremendous, the presenters in GCN are so entertaining

[@gregvassilakos]

Thank you for the video! Now I know not to worry so much on long descents. I'm impressed that the rotor didn't warp. Pouring water on the rotor while it is still hot was a good test of the rotor's ability to resist warping.

[@michaelclements4664]

For a more useful comparison, run a heat/stress test comparing caliper/rim brakes to disc brakes. Under equal descending conditions, test which fails first, and what mode of failure it is.

[@gregvassilakos]

I thought about this video during a long descent this morning from Agios Patapios to Loutraki in Greece. The video gave me a lot of confidence.

[@bobzuidema3560]

What an abuse on that poor front brake... but all in the name of science and another great video! Big hats off for Campa for delevering such outstanding quality!

[@adunnthing]

I’d be interested to see the state of the pads after that abuse

[@luukrutten1295]

Pretty much done. You would better replace them.

[@KNURKonesur]

As a 125kg+ cyclist mostly cycling on gravel hills and rural hilly roads in Scotland I replace my brake pads around 4x more often than my 53kg wife. Every couple of months they are toast basically.

[@7654321asdq]

@@KNURKonesur Cycling around rural hilly Scotland sounds pretty great

[@ymi_yugy3133]

I assume that given their massive surface and little mass they reach an equilibrium rather quickly. Something like an emergency stop at high speed on a really steep slope would probably push the brakes a lot harder.

[@l.d.t.6327]

The moment I saw you used steel Campa discs, I knew you wouldn't melt them. Try the sandwich structure alu shimano ones. They will at least be warped.

[@stuartfreedman6854]

When I first got my disk equipped bike, I touched the front rotor at a red light "just to see". Don't do this.

[@gcn]

We second this statement. Discs get HOT! 🔥

[@lunam7249]

nice tattoo...😳

[@fpeter01]

Once was the weather really humid in the Alps and I did a longer descent. I liked how the water evaporated from the disks. It had a satisfying sound effect. :D

[@coverchick]

love to see the comparison to Shimano dura ace disc! Well done, fellas

[@hollywoodundead72]

You guys are hilarious, I tell ya what a blessing to be able to just warp into this. Nothing else mattering but the here and now. Love you GCN team !

[@davidhenry5925]

Good video. Not surprised by the results. I was a little surprised by the heat on the 2nd descent (356 degrees F) is quite hot. I didn't expect to see brake fade, cars have been using disc brake technology for many years. The weight load per square inch of disc surface on a car rotor is much high than the bike. Additionally, the bike rotor is out in the wind where cooling is superior.

[@gcn]

It was a bit surprising, but it is a very long descent, and he was dragging it the whole way down - we'd definitely not recommend it!

[@simonm1447]

@@gcn I already got the brakes of my MTB blue (which means they had 300°C) on shorter, but very steep descends. Offroad you can't just let it run, on a road aerodynamics also start to consume some of the energy at 50 kph but you can't ride that offroad through forests. They are just MT 200s, but they never took any damage.

[@cliffordromina3527]

These chalenges are so ridiculous that they are down right amazing and very fun.

[@gcn]

Thanks Clifford!

[@diogorocha6311]

I love to hear people talking about stopping power of rim brakes when they clearly have no vast experience with decent rim brakes whatsoever. I often ride rim brakes on mountains and have gone through much steeper descents than this without any heat issues (130 degrees, really?) and i could any second stop the front wheel and go over the bars. Interestingly enough, people who mention rim brakes have no stopping power, will defend their statement saying that they meant there is no modulation. Either you brake too little or too much. But then again, isn't power a measurement of how much/with which intensity? Then why did you say rim brakes have no stopping power? 😀

[@crapilanofridge7745]

I remember a descent of the Col de Aubisque (in the direction where you ride the soulor first) with no guard rails and precipitous drops, sad to say, I did a lot of brake dragging. But I did get to the bottom in one piece :)

[@SniperSpec0ps]

Back in the 90's, when I was competing, I did a fun run down the mountain from Big Bear, CA. This was before disc brakes, so I was using Ultegra rim brakes on my race bike. The rim got so hot, that they popped both intertubes, front and back. Coach clocked me at over 80mph though, which was very fun.

[@robyn2791]

Ollie and Hank, my two favs at GCN. They are great together.

[@siriustraining1774]

You guys need to try Shimano Ice Rotors. We melt those on the rear of tandems all the time. We also have seen temps above 900-1000 on a 10" rear rotor (Standard size for a Santana Tandem!)

[@jedisdad2265]

Dr. Bridgewood, the warping occurs with so called shock cooling. Hot discs get splashed with very cold water. This is common even on automobiles especially in the winter time.

[@giuliobagnaresi9951]

È bellissimo che ogni GCN abbia il suo Giorgione e il suo Maranga

[@Skyflier11]

Fun & Interesting vid, would love to see a follow up vid where you see what it actually takes to melt a disc. Do manufacturers test this? Also Ollies Wild West walk to the car at the end 🤣

[@KNURKonesur]

I'd like to see the state of the brake pads after that test as well :D

[@andrifsig]

Had full confidence in the disc brakes. I go on bicycle touring trips every summer. Two summers past I weighed in at about 125 kgs at the time, had a fully loaded touring bike which weighed in at 55 kgs when fully loaded. Descended a 580 meter gravel downhill where the steepest parts were 25%. Had the wise thought to stop 3 times during the descent to let the discs cool for a bit and enjoy the scenery. 180mm front and 160mm back and from Sram.

[@mandy2tomtube]

As anyone who tempers steel would know when the steel turns gold or most people would say straw color you hit 400 Fahrenheit when the steel turns blue you have hit 550°F If you come to a complete stop while your brakes are hot, this is what causes warping the rotors will cool down to an acceptable level within a few minutes. Another words if your brakes are really hot, just like a horse let it cool off before you come to a stop.

[@paulb8587]

Great to see Campagnolo on the channel.

[@calummacarthur1149]

great video, would like to see a comparison of pads (including ones with heatsink fins)

[@888julianman]

..It removes any sense of anticipation when the words ‘Includes Paid Promotion’ appear above the video in the first few seconds. From that point , it was only ever going to be a positive test , in favor of the equipment ..

[@alfabethev2.074]

My thought excactly 👍🏻

[@solomioist]

You have tested the best of the best. On my tracking e-bike (self converted) I have some cheaper hydraulic brakes. When I have hit a hard decent and braked at 70kph, my pads have started to smoke.

[@sevenokve]

Olli and Hank are hilarious. 😂❤️

[@fortinbras47]

Luescher Teknik has a nice video on problems with carbon clincher wheels and rim brakes on big descents: basically carbon clinchers have extra problems dissipating the heat. All that heat eventually softens or even melts the resin holding the carbon fibers together and you get wheel damage or even catastrophic failure. Putting the heat generated by braking into a robust, dedicated braking metal (i.e. the disc) solves the problem.

[@grachtschrap]

This is a fun experiment! Maybe a fun idea would be testing different brakes from different manufacturers and price classes.

[@cervelo9465]

As an old timer , Campagnolo was always the no.1 equipment of choice to have. Now I am old I like to indulge myself.

[@Burkhard_Ehnes]

GCN folks: Sure - your business is entertainment disguised as information. But when it gets such into dark red in terms of hazard for the viewers, you have to be called out! Get the physics right first!. If you brake continuously with whatever weight you place on a bike you never get the energy into the brakes as with one or a couple of consecutive hairpins approached with 80 km/h! The energy or impulse is related to the square of the velocity. You get EVERY rotor, especially such small ones, with less weight on much shorter descends easily much hotter, the brakes to fade with whatever pad material and literally doing cracking noises. That leads to the next major misinformation - by the way. Rotors and spiders are separated to exactly NOT transfer the heat into the hub, or at least as few as possible - the opposite to what you claim. Just imagine what would happen otherwise...

[@tezzanewton]

I’d love to see Durianrider do this with his beloved rim brakes 🤣🤣🤣

[@johnrafael4110]

we need more hank and ollie videos i stg theyre mad funny together

[@esenel92]

Haha poor Hank better have good life insurance😁 I do sense a bit of a missed opportunity to check the temperature of the fork and hub/axle as well, as the fork might get weakened by heat radiated towards it for such a long time, so it would be nice to see if the airflow over it can prevent it from heating up too much, and to check if the temperature of the fork goes up faster if you stop right at the bottom of the hill/mountain instead of riding a little longer to get rid of the heat. For the bearings it would be fun to check if they get hot enough to affect the grease that's in there. (I doubt it would get hot enough to actually burn the grease, but it might go drip out of the bearings, which would warrant re-greasing them after doing long downhills with a lot of braking) As for melting the discs, I should hope not, as the emergency brake might actually be Hank's face instead of the rear brake if it decides to warp, or snap while using the front brake like this.

[@brianwillaman1776]

Love these tests you guys do!!

[@cervelo9465]

Campagnolo, Colnago, Assos, etc. Some of the legendary and high quality names from my cycling youth.

[@pablobriz5102]

I'm around 95kg, usually over 120kg with bike and gear, with a gravel bikepacking/touring setup, with 160mm rotors, Shimano grx brakes (and 45-50 mm tires muuuch more grippy than those road tires) I've never had any problems, even on long and fast, or sketchy descents where I have to drag brakes for a while (although not as much as this test). That said, I always try to use a good braking technique -but because I like speed, and that's the only way if you wanna go as fast a possible, "safely". Based on my experience, I didn't expect the brake to fail in this test. But I think a similar teste with 140mm rotor, with over 110-120 kg of rider+bike+gear, could really find the limits of a bike disc brake. My thoughts are the first failure point is the fluid or the pads, neither the rotor, caliper or pistons if they are in good condition. It would be great to see that test.

[@liamroche1473]

The speed of descent matters, of course. As the speed goes up, a larger fraction of the gravitational energy is being dissipated as wind resistance, but what is left is dissipated by the brakes over a shorter time. There is some speed at which the rate of dissipation is greatest (it may be dangerously fast). A complication is that the brakes also get better air-cooled as the speed rises!

[@MikeNolan1967]

great stuff. Just about to use it in one of my GCSE physics lessons.

[@peanutaxis]

"Proprietary mineral oil" = plain old random mineral oil.

[@ANTOINE62330]

I did a bike trip a few years back and the bike was heavily loaded (as was the rider). I remember that during a long descent I had to sacrifice my water to spray it on the rotors every 1km or so, so I would not lose my braking ability. The water landing on the rotors was directly turning into steam !!!

[@FlatSpinMan]

That disclaimer part was absolutely hilarious. So well done.

[@gcn]

Thank you

[@Star14trek]

I have had bad break fade with organic brake discs did Fred Whitton few years ago and coming down from hard knock rhino? Nearly over shoot a few corners Weight is always going to be main issue so think i was around 85-90kg+bike+fluids so around 100kg. Having said that after doing Helvellyn Tri and coming down kirkstone pass on rim brakes +carbon wheels you can get brake fade + bike wobble easy trying to avoid other racers/cars and avoiding the stone ways!

[@rayF4rio]

The best test would be to pit Campy vs Shimano vs Sram disc rotors & pads. But I doubt Shimano or Sram would like that.

[@andreasbayer]

Well. With steel discs I wouldn't worry too much about the disc (the water could lead to warping though...). The organic pads are more of a worry, but seemed ok. But this test would be interesting with shimanos ICE technology, since that is a sandwich of Steel/Aluminium/Steel and Aluminium is far more sensitive to heat than steel is...On the other side, alu is used in those discs specifically to transport the heat into cooling fins and better cool the discs... maybe with too small discs and or more aggressive pads one could take these to overheating... Also the rear disc could be less prone to overheating with maybe different air movement but I don't know... but more weight and smaller discs in alu would be interesting...

[@aljaliah6868]

CAMPAGNOLO ❤️❤️❤️❤️❤️……….enough said !!!! I wonder if they did the same with that cheap Japanese Dura Ace , would the result be the same ??? Material for another ten minutes episode ? TWO minutes if the discs crack 😂😂😂

[@glace5620]

Campagnolo= high quality.

[@Team5TL]

That was fun to watch, I’ll go hug my Campy brakes now

[@Metal-Possum]

The Hydraulic Press Channel did this using an inexpensive Tektro mountain bike brake and a lathe... it blew the hydraulic line before anything else happened. They repeated the test using disc brakes on a car and they got red hot before stalling immediately.

[@dakalla]

2 weeks ago i went down Passo Giau on carbon rim brakes in full on mountain rain and 6° on my wahoo. Draging the brake all the way with no stopping power hahaha! They said its fun to ride in the dolomites. Thanks GCN! ;)

[@MrGreensunray]

You survived 🎉

[@littlevo9]

Je fais 90kg et j’adore les descentes les freins à disques sont exceptionnels et permettent une précision et une force de freinage sans comparaison,le gain en sécurité et confiance est juste énorme.

[@brianboschma]

Here is a photo of what happens to Shimano Ice during a 1000 ft descent on a very steep trail in the Santa Cruz Mountains, Ca. Braking hard but pumping. Note how the stainless out shell delaminated from the inner aluminum core. Very disconcerting as the rear wheel partially locked up as the bike was nursed to a stop.

[@donaldryder5534]

Also, dragging rim brakes on descents can heat up the tire enough to blow it off the rim. I know from experience.

[@gcn]

Oof. Hope you didn't crash too hard!

[@falfield]

I too have had a similar excitement, after making the mistake of adding air to the tyres before a steep descent off Exmoor. The front cover exploded a second or two after coming to a halt. It sounded like a rifle and left a 9inch tear in the sidewall. I've since learnt that this was an illustration of Gay Lussac's law (for a constant volume, pressure increases in proportion to the Kelvin temperature). When calculated, it shows that even if there was 100degC temp rise from the braking, the pressure only went up by a third, so I was not far off blowing it up while pumping.

[@cbcampbell6959]

“When we get to the bottom of the climb.” Is that like raising the bike down off the work stand? Lol

[@whatwelearned]

Ollie went so Northern when he measured the second test that people south of the Midlands couldn't understand him

[@francoispayen]

"Yeah just smash it, it's extra weight. While you do that I'll practice my quick draw." 🤣

[@andrewmcalister3462]

Love the difference between the Campy brakes and when they made Oscar do a long descent on the Eurobike

[@thomas1644]

It would be fun to see this test again but with custom brakes that are designed to get hot (no slots). I just want to know if it's even possible for bike disk rotors to glow red. Also, this would be really unrealistic, but you could be pedaling hard down the hill (while braking) to put even more energy into the rotors

[@Showmetheevidence-]

I mean it’s a silly question, but those mountains are just incredible!

[@ViveSemelBeneVivere]

Dr. Bridgewood is on the slippery mad scientist slope with bikes! Yaay!😁

[@ASMRchildrensbookreading]

Careful Hank, not sure you want to be sledging Ollie. The man's half the reason we watch the channel. His kind natured nerdiness wins fans. Just because you thought an IR sensor was another Ollie Follie doesn't mean you can sledge our Chief Geek.

[@zakkupfer1390]

Bro they heat treated those brakes🤣🤣🤣🤣

[@jpg6482]

I have boiled road brakes before in north devon! Lots steep descents the fluid gave up and pads seemed to glaze. That happens way before anything melts. Happened when I was a lot heavier 130kgs and I hit a car on the very steep lane decent jnto wollacombe as couldn’t stop (two cars were edging past each other in narrow lane). I hit one - flew right over both and landed in road 🫣🥹trek Domane snapped in half few broken ribs

[@fernandodisola6675]

Nice video "campagnolo is of very high quality system" but I still prefer my Rim brakes they've work fine on steep descent in the last 120 + years with no problems 😁😁

[@joetaylor486]

I may be a dirty mountain biker, but while bike packing, I came down the byway from Coniston Old Man down towards the lake side and had my front, 205mm hydraulic brake go vibrant blue, and fade away totally. Scary beans. Thankfully dragging my cleats and heels on a rough tarmac track, plus rear brake gradually pulled me up.

[@Alan_Hans__]

A harsher test would be to pick a nice steep straight section where Hank could get to about 70-80kmh, have Ollie waiting out of the car just past that point and smash the speed from warp speed to nothing in as short a time as possible. With the current test the heat is basically being dissipated fairly evenly over about 1/4 of an hour. On top of the extended time is the time between when Hank stops and when Ollie got his gun out. The disks get rid of heat quite quickly so in the time between stopping and being measured there will be a fairly significant drop in temp. Doing the same test with a thermal camera in a follow car would probably show temps over 200C.

[@L0ckenmaster]

In the Industrie are temperature measuring strips often used. Low tech but very effective

[@oliverbridgewood3929]

A - we didn’t have a descent like that we could get to within the window we had to film B - we don’t have that kind of equipment unfortunately! Trying to do the best with what we have! hope you still enjoyed

[@SuperFunSuperLiz1]

Omg Ollie, Hank has skill and Campy is too of the heap. Do this again with one of the non-pros you have there, and on a china special, or a sub $700 disc bike.

[@pex3]

"why would you lie about it" 😂

[@AleksiJoensuu]

Lack of trying! Try having Hank pedal all the way down! 😄

[@pterius]

Easy modo! You could've just get a cool set of bikepacking gear and stuff it with some heavy load to build a total weight of the system up to the top level allowed by frame/bike specs. It would probably be something around 130 kg. I wonder how the brakes would handle this. I believe they will - as manufacturers usually take such scenarios into account - but still interesting

[@jpnw3272]

Isn’t there physics which may answer this? Granted. Campagnolo disk brakes are supposedly amazing. However, I think it is the amount of energy from acceleration to braking. I’m not a physicist. Please reply if I was incorrect. I saw this on Engineering Explained. Great test! Loved it! Learned a lot!