likewater

What are your opinions on disc brakes and their future on road bikes? If buying new would you go discs?

What are the downsides to them? Any problems with having so much more stopping forces being exerted on the bike?

CliffordK

I don't know. I think there would be quite a few variables.

I would look at weights very carefully.

If the goal was a simple upper mid-range bike, aluminium rims, then I'd probably go with rim brakes.

On the other hand, if I was going for 100% Carbon Fiber rims, then I would certainly consider disc brakes.

Would there ever be a need to run both 650b and 700c wheels on the same bike? Disc brakes would be natural for a quick change.

One point about individual racing. Disc wheels haven't been fully standardized yet. It will likely come to a large extent in a couple of years, but it might be a lot easier to expect to borrow a rim brake wheel than a disc brake wheel.

CrowSeph

Personally i hate disks on roadbikes.

likewater

Why good sir?

2 Piece

Personally, I would not buy a new bicycle be it road, mountain or a commuter unless it had hydraulic disc brakes. Hydraulic disc are sooooo nice. They stop great, they feel "right" and rain and wet conditions do not bother them. If you are worried about weight, buy lighter weight shoes.

Psyclist01

Just to add a note that disc brakes on road bikes are the way to go IMHO. I bought my first endurance road bike couple of months back (Specialized Diverge Aluminium DSW comp) which came with Shimano BR785 hydraulic disc brakes, the stopping power is just fantastic.
Haven't tested the brakes in wet condition yet but from what I have been told, it should not have any impact on the stopping power.
Amazingly, it is quiet when you apply the brakes on a downhill at full speed.
It is a personal preference I guess. If you want lightweight go for rim brakes otherwise disc brakes are simply fantastic.

Garfield Cat

If buying new, the disc would be on a gravel bike.

dabac

It'd have to be a helluva deal before I'd ever consider buying a rim brake bike again. More consistent braking in all weathers, less hand effort needed, no rim wear. I'll happily accept the associated challenges of the very occasional bleeds, how to make several wheelsets interchange etc.

tedder987

Well I pick up my new bike (2017 Roubaix) next week, and it has discs...

Honestly though they do not apply 'more' stopping force though they do apply it at a different point on the wheel (if you can lock up a wheel with rim brakes you have maxed out on stopping force). The wheels are build differently to take this though and tend to have higher spoke counts which is good for a clyde like me.

The brake modulation and lack of fade in the wet are the key improvements. You can also add greater resistance to overheating if you live somewhere mountainous(though not impervious).

rydabent

I would absolutely go with discs. The main reason is disc brakes dont destroy rims over time. With discs the rim can be made lighter stronger and more aero. And lastly on really fast down hills you dont have to worry about over heated rims blowing out the tire. Disc brakes are the new click shifting, and clipless pedals. Due to economies of scale, in 5 years or less there will be few bikes produced that dont have disc brakes.

1989Pre 

Who needs the extra price, weight, loss of aerodynamics and shift in balance? My brakes are fine and always have been. Campy Veloce. (Even I can afford a new rim every five years).

sdmc530

no doubt! disc is the way to go. No rim decay over years, lifespan is longer and brake force is better in wet conditions. Not saying they are the beat all brake system but they are just better IMO. The last two bikes I purchased a mountain bike 4 years ago and road bike 2 years ago both had disc. Got them on the mountain bike first, loved them and wont ride anything else not. 5 years from now roadbikes will have them anyways and pro's will have them.....

WarrenR

No, all pain for very little gain, if any. haha

AlmostTrick

Yes. I detest that grinding sound of rim brakes once they get some grit it the pads. That being said, on a bike that is only used in dry conditions on paved roads, rim brakes can go a long time before this happens.

And "loss of Aerodynamics" with discs? You've got to be kidding. I challenge any rider (who wasn't allowed to look down) to tell the aero difference between disc and rim brakes. You can't.

BobbyG

I commute and I bought a bike last year with cable-actuated disc brakes, but continue to ride my other rim-brake bikes, especially my winter bike. In my case, with my bikes, I find stopping power to be about the same. I can see where hydraulic discs would work much better than cable discs.

For me the big difference seems to be in the rain and wet. The discs seem to work better. The pads seem to need more adjusting as they wear, but that may be a function of the softer, grippier pads I like. I understand that hydraulic discs are self-adjusting.

Obviously if you are off-roading in dirt, muck and grime, discs are better as the braking surface sits higher off the ground and stays cleaner.

However, I did manage to get a drop of oil on my discs last year. That necessitated a cleaning of the disc and a change of pads.

If I were not off-roading, and riding in mostly dry conditions, and had metallic rims, and not riding long downhills with lots of intense braking, knowing what I know now, I wouldn't care too much about whether a bike had rim brakes or cable actuated discs. Hydraulic discs, though, are starting to sound good to me.

Robert C

I use my bikes for daily transportation. As such, I wouldn't consider anything without disc brakes.

Garfield Cat

Isn't the aero difference better evaluated, at least initially, in a wind tunnel test environment? Then after that, by experienced riders' input.

FullGas

for my riding, rim brakes have performed admirably for over 100K miles.

have never had to retire a rim due to excessive brake track wear.

see no need and have no desire for discs.

ymmv.

Scarbo

I just have road bikes. My next bike will be something that I can ride on gravel comfortably as well. So, my next bike will have disc brakes on it (I already have them on my MTB).

I do a ton of really long climbs and technical descents. I like rim brakes just fine and I've never had a problem with my rims overheating; but I just like the added security of knowing absolutely that they never would with disc brakes.

jon c. 

I ride strictly road with nothing but rolling hills. Rim brakes work just fine for me and my 35 year old rims aren't worn out yet. I can see that disc brakes could be advantageous in some environments, but I'm unlikely to ever encounter them.

thin_concrete

I don't really ride in the rain and don't have huge descents, so I don't need discs. My rim brakes are quite fine and easy to maintain.

Scarbo

I love rim brakes for this, certainly. I said, in a similar thread, that their simplicity is underappreciated.

_ForceD_

I would say that it really depends on the conditions you ride in mostly. If you're frequently in wet conditions, doing lots of hi-speed descents, and/or any other situations that require lots of braking...then I guess disc brakes are the way to go. For me, properly functioning rim brakes have always been sufficient. I've never really been unable to lock up the wheel in an emergency situation. And so if you can lock up the wheel I guess your stopping distance literally comes down to where (and the amount of) the rubber meets the road.

I did a large event ride last weekend (Hilly Hundred in Indiana) and saw a few bikes with disc-rim brake combinations. Some with disc on front, rim in rear...and vice versa. I don't understand the disc in front combination.

Dan

cyccommute 

This is a common assumption that simply isn't true. Hub mounted disc brakes don't have "much more stopping force" than rim mounted brakes...which also happen to be a disc brake. The braking force you can use is limited not by the braking mechanism but by...well...where the rubber meets the road. There is only so much friction that any bike can develop before the rider is thrown over the bars. Having disc rotors mounted on the hub doesn't change that equation.

I have noticed the same thing about disc vs rim. I have both and neither is head and shoulders over the other. I even have one bike that has mechanical discs on the front and rim brakes on the back. From a brake lever feel, there is no difference between them.

I also feel that hydraulics aren't any better than a cable disc brake. In fact, I took the hydraulics off on bike and replaced them with mechanicals. The problem I've had with hydraulics is that they aren't what I would call "modulated" as everyone else gushes about them. To me that were extremely grabby and difficult to "modulate". They were either on or off which is the exact opposite of "modulation".

I'm not alone in this. My daughter noticed the same thing on her mountain bike with hydraulic brakes. Once we both made the change to mechanical disc, the brakes are actually easier to modulate.

Here's another of those things that people say all the time but don't seem to understand that the limitation isn't the brake mechanism but the surface the tires are rolling on. The hydraulic brake bike I had was scary to ride on wet surfaces. A slight tap on the brakes, the tires stopped rolling and I was picking myself up off the ground.

I'm also not convinced that the lag people experience with wet rim brakes is any less with a disc brake. I've experienced the same thing with wet discs

If the dirt is dry, there really isn't much difference between discs and rims. If trails are muddy, there's a difference but, as a responsible mountain bike rider, I stay off the trails when that are muddy. I don't need to be leaving a permanent reminder that I've gone for a ride.

This is one of the real problems with discs. Rubber pads wear oil off quickly while the sintered nature of disc pads suck the oil deeper into the pads and leave a lasting reminder. Contamination of the pads is a very real problem.

One of the other failings that I have with discs is the need for hyper-trueness. A rim brake can be adjusted far enough away from the "rotor" of the rim so that a rim that is slightly out of true aren't a problem. A hub mounted rotor has to be extremely true or it will drag. Being a millimeter out of true means that the rotor will drag severely on the pads. A millimeter is an extremely small amount of distance.

People have been riding down hills with lot of intense braking for a very long time before modern hub mounted discs came along. I know that overheating of the wheels is a concern but it is a lot less of a concern than people make it out to be. If you are riding a bike with tires at 100psi and at 70°F, you'd have to heat the tires to 230°F to raise the pressure by 30 psi. That's probably not enough of a pressure increase to cause a blow off. If you raise the pressure to 160 psi which is much more likely to cause a blow off, the temperature has to increase to 390°F. It could happen but the rider would have drag the brakes for a very long way to get that kind of temperature increase.

The problem here is that the hub mounted discs heat up too. In fact because they are much, much smaller and you are putting the same heat into them as you would into a rim brake without the thermal mass and surface area of the rim and tires, it's much easy to overheat hub mounted disc brakes. Bad things happen when any brake over heats.

Scarbo

This makes a lot of sense to me. I wonder if it would be possible to create some sort of test between rim brakes and a collection of discs on some long, steep descent. As I said earlier, I've always been fine with rim brakes on gnarly descents. My perception is that disc brakes provide extra security; but I am more than willing to be persuaded otherwise--especially since rim brakes have always worked really well for me in the past and because they are so easy to maintain.