Rim Brakes Versus Disc
 

Having had only rim brakes on all the bikes I've had, I am interested if and when I get a new bike on having one with disc brakes.

Are they better than rim brakes as I have read that they dont last very long out of the LBS and can still squeal like mad if they arent set up properly.

Which are best?

Thanks

After spending all that effort to make the bike go forward, why stop?

If you do need to stop, how fast do you need to stop?

If you need to stop really really fast, do you want a maximum impending skid stop, or a full skid stop? (Under a full skid stop, you may lose traction with the ground and take longer to stop than a maximum impending skid stop.)

Do you have tread on your tires?

Do you have rims? What are they made of?


Multiply everything together... divide by the thickness of your wallet.

Spend until you feel justified in your purchasing power.

I have heard of others having squealing problems. I have not. Squealing will be the result of contaminated pads or rotors, or perhaps incompatible rotor and pad materials.

As for not lasting as long as rim brakes... what doesn't last as long? My experience has been that disk pads last longer, they stay in adjustment longer, and the rotors suffer less wear than rims. And if you were to ever wear out a rotor, a new one is $20 and replaced with six bolts - it takes about 15 minutes. Replacing a rim is more complicated.

If you are getting a racing bike for organized road racing then rim brakes might make for a slightly lighter bike (2 or 3 oz different). If you are not racing, disks are superior.

If properly set up they also stop better than rim brakes. And they are not susceptible to out-of-true rims, which might make a bike with rim brakes unridable.

Each one has its advantages and disadvantages.

Can they squeal? Yes. Is there something that can be done about that? Sometimes yes, sometimes no. Do they have more stopping power? Depends on what brakes you're comparing. Do they have more sensitivity? Depends. Can they be overheated to the point of fade and loss of brake power? Ohhh yes :D Do they weigh more? Again, depends on what brakes, hubs and rims you're comparing.

For myself, I have one bike with disc (XC-race mountain bike), and three with rim brakes (winter/utility commuting mountain bike, sport-touring road bike, road-racer). I'd be perfectly happy with rim brakes on all four, but the XC bike can't take rim brakes since it has no studs for them.

Why do you want discs? I don't have them, but I ride with a couple of guys who do, and I don't see any advantage in everyday road riding, certainly nothing that justifies the cost. If money's an object, there may be better places to spend it. And conventional brakes technically are disc brakes--the rim is the rotor.

I split my riding time between a disc-equipped bike, and one with rim brakes (mini-v brakes). For typical road riding, the rim brakes are just fine. For mild off-pavement use, they're also adequate. Where the discs really shine is in wet conditions. I've ridden the disc-equipped bike in torrential rain, and braking was probably 95% as good as in dry conditions. The rim-braked bike? Not so much (even with good wet-weather pads).

Rotors and pads--even "soft" organic pads--are quite durable. I have rotors/pads that have seen many thousands of miles of service, and they're still going strong.

And people who parse language in such a manner on the interwebs technically are fairly unhelpful. Short answer, if you ride in the wet a lot it might be worth it. I also think it's fair to say you can modulate them a little better. I find em indispensable on my MTB. I find rim brakes more than adequate on my road bike. If I were building a commuter I would lean towards disks, but if I got a good deal on a set of wheels or a fork that wouldn't accommodate them I would be cool with that too. Avid BB7 are certainly not expensive, and they work great, so money isn't the real issue here.

I have 5 bikes; 2 with discs. 1 FS mtb bike and 1 hardtail with slick tires used for commuting. Both have mechanical disc.

Mech Disc brakes don't necessarily stop any better than rim brakes. I had Tektro disc brakes on the hardtail and they were crap. I replaced them with BB5s. Much better.

I have BB7s on the FS mtb and they are better still than the BB5s.

I have Dura Ace dual pivot road brakes on my road bike, and they are better than the BB7s. The weigth differential is only 15 (ish) pounds.

Yes, the discs can squeal, especially when wet and this can be alleviated quite a bit by using organic or resin pads.

The discs offer better stopping ability in the wet as compared to a wet rim. Rim brakes, when riding in muck off-road, will wear down rims pretty fast.

I find discs much better in the winter, they do not ice up (never for me anyway) like a rim brake would.

For off-road, I'd recommend a good quality set of disc brakes, but you'll pay a pretty penny for 'em. Don't buy the lower end disc brakes and if you have to choose between low end discs and a set of rim brakes - go with the rim brakes.

For on-road, I see no real advantage with disc brakes with the possible exception of heavy loaded touring or mountainous regions. But I tour on rim brakes (Avid shortys with STIs) and have no stopping issues.

Agreed.

I would shy away from the BB5s, the setup is a little frustrating with only one adjustable pad. The BB7s, although a little more expensive (not alot) have far better adjustablity with both pads having the ability to be dialed in.

That said, the BB5s are good but ya gotta do the card trick:
http://www.ecovelo.info/2011/04/15/a...5-disc-brakes/

Works well.

you can't simply reduce the issue down to "which one is better, rim or disc?"

a good rim brake is better than a crappy disc brake and a good disc brake is better than a crappy rim brake (duh).

as for generalities, in dry and clean riding conditions, i'd be hard pressed to tell you that a good set of properly adjusted rim or disc brakes are noticeably better than the other. however, in wet and/or messy riding conditions (like winter commuting in chicago for me), i've found the disc brakes on my current winter bike to be superior to the rim brakes i had on my old winter bike. i also like the fact that when i'm commuting in sloppy winter conditions, my rims aren't being attacked by all of the grime and grit from the road, rather the rotor takes that abuse (rotors are relatively inexpensive). and the rotor, by virtue of its placement closer to the hub, simply picks up A LOT less grime and grit from the road than a wheel rim does.

Another reason to get the BB7s over the BB5s (if you're going disc): the BB7s use the larger, rectangular pad from the Juicy lineup, not the skimpy little round BB5 pad. And you have metal and organic pad options.

Under these conditions, ice-up can be a serious concern if you need to make a sudden stop:

http://i240.photobucket.com/albums/f...Bgon/022-1.jpg

If you have an ice-up problem, you probably know it already :thumb:

I've found no clear pattern on that one. If a customer has squeal issues, they're more likely to have organic pads than metal (Shimano organics are particularly prone to "the moans"), but it can go either way. I've also encountered a few customers whose bikes hit a vibration harmonic when braking, and the only solution is to change rotor sizes. Personally, I literally threw out my first disc brake because I couldn't get it to stop squealing and it was, frankly, embarrassing to ride in traffic like that. "What's he honking for?!"

Exactly this...I think my rotor is slightly warped because it scrubs once per rotation and only starts after I start to descend the hill from work, about 300 ft in 1/2 mi with a stop sign every 400-500 ft. It will last the rest of the ride home, but I won't hear it on the way to work the next morning. I suspect the rotor is expanding slightly just enough to cause scrubbing. My ride is all urban so I'm braking at least once every 300 ft so probably the brakes don't have sufficient time to cool and contract between stops. Just a guess though.

Magura's HS33 hydraulic rim brakes are nothing to sneeze at..

Best rim brake I've used..

Holy crap! I would've taken a picture of that as well.


This squeal with disc brakes is indeed an elusive one. Although my experience has been less squeal with organic brake pads.

Both my BB5s and BB7s will squeal a bit when wet, the BB5s more so. Both will quiet down with just some braking. Now I use XTR rotors on my BB7s, so I think the rotor quality, as well as the brake pad and caliper quality will matter quite a bit.

After having ridden on discs for awhile, I'm starting to be convinenced that the dirtier the rotor and brake pad, the less squeal.

I say that because when I first started using discs 6 years ago, I would routinely use rubbing alcohol to clean the rotor on the BB5s (my OCD). I had squealing issues like you wouldn't believe.

Then after talking to a mechanic who works at MEC, I tried just leaving the dang things alone, as he advised. You know what? The squeal was much less.

The mechanic stated that the commutting or road type bikes they sell with discs will show up back at the store within 3 months with the customer complaining about squeal. They'll rough up the brake pad and rotor, squeal goes away, only to return a few short weeks later.

Their mtb bikes, with disc brakes, do not show up back at the store nearly as often with squeal issues.

He thinks that the grit picked up when off-road cycling keeps the pads and rotors from becoming too smooth, you know that shiney look you get on brake pads (?), that is what he means and he feels that this is the cause of most of the squeal.

On road bicycles with discs, they do not pick up the same amount of grit, and those brakes will develop that issue on the pads.

So, I do not clean my rotors, and the squeal issue is mitigated considerably. Only occuring when wet, and then will dissipate quickly.

Just an observation.

I put Avid BB7 mechanical disk brakes on my Vaya. They work great! All my other bikes have rim brakes, cantis and V brakes. The rim brakes are fine in dry conditions on the road. The disks are great in the wet or in hills when loaded up. Rim brakes can over heat the rims in those conditions.

Oh, I believe it. If I clean the rotors with rubbing alcohol, I follow that by cleaning them with Clean Streak. It's a nasty chemical, but it's far less likely to leave the rotors squeaky/moany.

I've occasionally fixed brake squeal by grabbing handfuls of dry dust and rubbing it on the rotors, then riding while dragging the brakes, so I can believe that one too :D

In the bigger picture, some brake squeal will be transitory, some is caused by wetness, and some is because disc is disc... you're putting substantial force on a thin rotor with a caliper attached to a semi-rigid mount, and stuff IS likely to flex, harmonize and vibrate in some circumstances. Expect at least occasional noise if you go that route.

For situations where your disc brakes won't shut up (no matter what you do), give this stuff a try.

I may be hiring a Trek 3700 Disc MTB on Sunday for a ride, will see how disc brakes feel then.

One advantage of disk brakes is that rim material & shape no longer has to have braking properties. So that frees up rim manufacturers to use different materials and shapes for wheel performance, without the compromise of a brake track.

Does it help in the rain? That's the only time my brakes squeal.

For the most part, yes. You'll get the occasional squeal, but it's nothing like an untreated setup.

I love the disc brakes on my Vaya. I really can't think of a reason for me to ever want to go back to rim brakes.

Hired myself a Merida Juliet, a grubbier version of this one:

http://www.merida-bikes.com/p2/p2Fil...eset/bikeImage
The hire shop have put slick tyres on it so it looks like a hybrid and is really nippy.


Are the discs supposed to buzz when I press them?

Rather than any kind of rotor expansion (it'd have to expand a lot), I'd suspect vibration. I have a rotor that behaves similarly. Mine is a 203mm rotor (a giant thing) that may twist in the wind a little or just vibrate due to the road. It's constantly making the same noise movie makers use for a sword being drawn from a scabbard.

mechBgon summed it up nicely. I'll add that braking techique goes much further than the braking mechanism, even in the worst conditions. I have discs on two bikes and rims on 5. They all stop. They all stop very well. I've mountain biked...not mild stuff either...for years and years without discs and never had a time when I wished that the brakes worked better. I did a 1200 mile loaded tour in Appalachia this spring on a touring bike equipped with cantilevers including one 20 mile downhill run with speeds up to 50 mph in a driving rain and never lacked for braking ability.

Learn how to brake and the kind of brake becomes much less important.

Lovely bike and the brakes were responsive just the front making a buzzing noise when I pressed but nothing major.

Liked the feel of the discs tho the handle was low on the handlebar.

Certainly would like them on a new bike should that come about but braking style of course is important.


Funny thing about this bike was that the ride today was descending on the road fairly fast downhill round a bend.

I found when I turned the bike my foot was dragging as I leant into the turn, so much smaller than my MTB.