American Euchre

I've seen this video referenced many times as "proof" that discs are better stoppers.

One thing that those who advocate discs NEVER mention is that the rim brakes are operating with CARBON rims. It is well known that carbon rims offer inferior braking surfaces, and that aluminum is far superior.

Obviously, GCN is infatuated with the "latest and greatest" but I'd like see someone with more scruples offer up a fairer test with a comparison between disc brakes (both hydraulic and mechanical) vs. rim brakes on ALUMINUM rims.

If anyone finds such a video or has their own informal comparison to offer, post it here.

https://www.youtube.com/watch?v=uHFSSXOSnxs

PepeM

A refreshing topic for once.

Dan333SP

Those GCN guys are such poseurs.

redfooj

how might this improve your life?

Elvo

Aren't the discs made out of aluminium?

smarkinson

No, disks are stainless steel. Which is heavier than aluminium. And we all know heavier=better.

****

Dan333SP

Race cars have carbon-ceramic disc brakes. Why can't they give bikes the same? That would make them stop more betterer.

WalksOn2Wheels

While we're at it, let's put wings on the aero bikes like them fancy MotoGP racers.

Seattle Forrest

Carbon makes a fine rim, when you don't try to also use it as a brake.

Campag4life

I found the GCN video both entertaining and factual and I really like those guys and think they do a good job and keep it fun.
To me, what they disclose is pretty common knowledge in the industry. Disk brakes may offer fractionally improved brake performance. Question remains...is better brake performance a good thing when racing wheel to wheel in the peloton? No.
So no dispute that disk brakes are excellent for stopping. Caliper brakes do a pretty good job as well and don't keep the top ten riders in the world from beating also rans on disk brake bikes.

Then what's the beef? Sharp edges on rotors is the issue. Cost aka potential for lacerating a rider in a crash which happen like clockwork in the peloton versus a fractional improvement of braking being the benefit. A net benefit? My personal opinion is as soon as a couple of pro riders get chopped by disks, the plug will be pulled 'again'. Maybe this time, an effort will be made to protect the edge of disks.

For average riders...like the video explained, those living in mountainous country may prefer a bike with disk brakes. Makes sense. Not essential as top riders don't use them for much higher speed than we mortals ride but if average Joe prefers disk, why not?

StanSeven

I posted my actual test results on two different threads. I used a new disc equipped bike and two older bikes with carbon wheels and rim brakes - older DA mechnical with Kool Stop pads and newer Di2 with Shimano. From 15 mph on dry roads, they all stopped the same. On a wet surface, the disc stopped about five feet quicker the first time. After that when I altered the rim braking action, it was between 1.5 to 3 feet difference.

Someone posted about the GCN video. I went back and looked and my results would be similar I think - no difference on dry but two meters better for disc on moderately wet roads if I was doing 25 mph like they did instead of my 15 mph.

Since I don't ride in mountains and don't intentionally ride often in the rain, I don't see any advantages.

Banzai

Anecdotally, with a sample size of one (me): Calipers on Alu rims v discs with sintered metal pads in DRY conditions; no difference that I can perceive at all. WET conditions, edge to the discs.

ReneV

For my money, dry rim braking: no problem; wet rim braking: often scary (big guy, world-tour-grade downhills). Have only tried disc brakes a bit but they strike me as exactly the right incremental improvement to braking technology, with details still to be pinned down.

Luis G.

Good hydraulic disk brakes are many times more powerful than rim brakes this has been proved time and time again in mountain bikes.
Now if road bikes will ever receive or need this type of braking power is up for debate.
Rotors are steel. Usually stainless.
The only real benefit I see from disc brakes is the hydraulic modulation you can get. Not so much braking power.

The reason why race cars use ceramic is due to heat build up. Race cars can in extreme situations heat up steel rotors to temperatures that would ruin heat treatment and but more commonly they just greatly reduce performance as they heat up.

WalksOn2Wheels

Because heavy is the new light, we might as well have steel rims and use the disc brake pad material on the rim brakes. We could make billions.

Maelochs

Care to post the numbers?

Good hydraulic discs are only better off-road because they work instantly in severe conditions---conditions which most road riders would never see (ride a lot in two-inch-deep mud on the road?)

I have a disc-equipped MTB, and road one with canti brakes for many miles. I have decades of road-riding experience. I am not just making stuff up to win an Internet debate. "Many times more powerful" is gross hyperbole. If it "has been proved time and time again" I'd like to see the "proof."

Yup ... pretty much widely understood.
Ceramic and also carbon fiber, which dissipates heat even more quickly ... and also need to be heated to very high temperatures to even Start working. Auto racing fans have seen lots of cars go off because cold brakes couldn't haul the car down enough after a start or restart.

Bikes have more of an issue with fluid heat, not rotor heat .... because bike rotors are right out in the air, and not anywhere near mechanical components which themselves generate enormous heat.

Bike rotors are steel because aluminum in those dimensions wouldn't be sufficiently rigid, which would cause the brakes to drag on the pads. heat build-up is not ever a performance issue.

Really though, the whole debate comes down to this:
Right now there is no evidence that discs will cause more injuries, but that is the only real sticking point.

The tiny amounts of added drag and weight are insignificant if every bike has the same brake system and is at the same minimum weight. The difficulty of wheel changes could be addressed through UCI rules determining universality among systems in UCI competition.

The real issue isn’t stopping power. Discs are so marginally better right now that it is like the debate over removing the weight of three atoms from your bike to go faster. Discs are only an issue because the manufacturers want to sell them on commercial bikes.

Potential injury is the only reason not to use discs ... and only real-world testing will establish whether or not the dangers are real.

Seattle Forrest

Scary scary discs! Close your eyes, luddites!

CliffordK

Look at how much bigger one can make the rim logos with those discs and no brake track.

Luis G.

https://www.youtube.com/watch?v=AxmzlGeKPRY

What type of disc brakes do you have? What size rotors also. I have a 160mm front rotors on mechanical disk brakes, braking power is similar to rim brakes. However on my buddies Orbea with hydraulic the power is absolutely bonkers. Enough to lock up front wheel going downhill. That's a 200mm rotor up front, I do not remember which hydraulic I want to say it was Hope.

Maelochs

Dude, that is a test with two wildly dissimilar bikes on pavement. And good canti brakes can lock a front wheel too ... particularly depending on the terrain.

That is the thing with MTB brakes---they need to work on gravel, packed earth, sand, roots and rocks, wet leaves, every kind of ground cover ... so max braking is nothing like road bikes, which are on the road (and roads can vary a lot but ... ) The brakes on my Cannondale are amazing .... The brakes on my old Univega were amazing too. but so much depends on what you are riding on .... generally it is a low-traction surface so knobs make a huge difference (aggressive knobs? Low pressure? less aggressive knobs?) and tire pressure .... which can change for each ride, sometimes (I tried high pressure and aggressive knobs on Utah slickrock .... hmmmm.)

I am sure a 200 mm rotor stops harder than a 160 ... but again, it is about usable traction, which depends on more than the rotor size or even brake type.

I am not all-knowing, but as far as i do know, offroaders adopted discs because rim brakes are more likely to fail or at least hesitate when wet, and also rims wear really badly when riding in mud and grit using rim brakes.

I want to say Avid hydraulics .. but ai am too lazy to walk into the other room to look. I know they are 160 mm rotors. Maybe I should upgrade, ...

Seattle Forrest

And how much lighter the rims can be when they don't need to deal with heat build up or being squeezed.

Luis G.

It's hard to explain in words but without proper braking technique you won't make use of high end hydraulic braking. Provided terrain and tires are reasonable technique will matter a lot.
Never seen a rim bike lock the front wheel when going 15mph, and trust me I've ridden with quite a few people. I've seen this happen multiple times when riding, usually people panic and go over the handlebars. In fact in road cycling I've been told you should NOT be able to lock out your front wheels unless you love shattering collar bones.

If you notice the guy kept a lot of his weight forward instead of back, and that was not a high end MTB. He could of stopped way sooner if he was in a braking position before he grabbed a handful.

There's a reason I have mechanical disk brakes on my MTB, and it's because I am not yet skilled enough to be using monstrous hydraulic brakes.

deapee

If you can lock your wheel up, I think your brake is sufficient.

Maelochs

Hmmmm ....yeah Under most circumstances one should shift one's weight to the rear when braking ... unless one is trail-braking through a corner, perhaps. But it is not hard to lock a front wheel --- that is what causes people to go over the bars, or more frequently just to crash because the front wheel flops sideways when it stops rolling. There is a reason why even with canti brakes, smart riders keep only one or two fingers on the levers.


On a road bike yes ... it is not that it is not possible to lock the front wheel, it is unwise. Generally it is always unwise to lock the front brake because it causes crashes.
I am pretty much not sure that there is such a huge difference between mechanical and hydraulic that you could ride one and not the other.

I went from cantis to hydraulic and it took a few minutes ot get the feel of the brakes. I am sure you could manage hydraulics. I also think that either will provide all the braking one needs.

Anyway, I don't race (and only did very, very briefly very very many years ago .... using canti brakes.) I ride for fun and pleasure and the attendant fitness gains, but mostly to enjoy riding. People who push harder might need better gear.

American Euchre

Rim brakes on a 55 lb. beach cruiser, eh?

That's an even more idiotic "compare" than the GCN video.

How about you do a braking test next time with a sumo wrestler on one bike and a 6 year old kid on the other. That would be just as fair.