PhotoJoe 

......and I don't mean the pro racers. I have a friend who is shopping for her first real road bike. I have to give her credit, she's doing her homework and really researching things so she knows that what she buys is what she really wants. After quite a few test rides, I think she's narrowed it down to a Roubaix or a Defy Advanced. With the 2015 Defy lineup being all disc brakes, she's wanting to make sure that's not a mistake.

She's asking me if by nature, mechanical brakes have issues, are noisy or are high maintenance? I've searched and everything I found comes down to "pros don't ride it so neither will I" to "It's God's gift to cycling". I'm not looking for more of that, so I turn to the mechanics forum. She won't ride in the rain, or mud. She won't be doing any loaded touring. She's in good shape, so if she goes and climbs a mountain, it's not like me trying to control 240lbs. on a decent. Essentially, she wants to pick the most comfortable bike possible, however, if it's the Defy, but the brakes are going to be a nuisance, I think she'd look to second choice.

Thanks for the insights from a mechanics perspective.

corrado33

What do you mean "mechanical brakes." Do you mean non-hydraulic disk brakes, or normal rim brakes?

Non-hydraulic disk brakes have the same maintenance as any normal rim brake. Both are cable actuated and every once in long while it'll need replacing. It will need adjusting however.

I've ridden both hydraulic disk brakes and cable actuated disk brakes. You get a more "stopping power" with the hydraulic brakes (stiffer brake lever.) (However, you can easily lock up the rear wheel with both, so that's a moot point.) It's also easier with hydraulic brakes to apply the pressure you need to stop the bike. (Admittedly, it's not much with hydraulic or non hydraulic brakes.) With hydraulic brakes I noticed it's more black and white. You squeeze the lever a bit, then a bit more, then there's a very sharp cut off where it'll just lock everything up. To go from "light braking" to "emergency stop" it's a very short distance. Where as with cable actuated brakes you get cable stretch, so you have to squeeze harder and longer. (I don't mind squeezing harder, as I don't find it hard to use my brakes.)

I just realize that's not the question you asked.

I don't think she'd have any maintenance trouble with either type of brake and if that's the bike she wants then she should get it. Remember though, fit rules all.

FBinNY 

The opinions you'll get pro or con about disc brakes represent differences in outlook more than a serious positive or negative. Everything is tradeoffs, so user priorities and biases will determine the decision.

Caliper brakes are light, simple, easy to service & proven on road bikes for a century. OTOH- for those who ride in all weather, and tend to keep wheels for 20-25,000 miles or so, caliper brake effectiveness falls off in the rain, and in harsh conditions the brake track wear can limit the wheel life (it's still long).

Discs tend to offer greater ability to lock wheels, which is important on dirt bikes who's lugged tires are engaged to the earth. This is more of a mixed bag on the road, because road tire traction is limited, so there's no need for braking power beyond what the traction can handle. OTOH- discs are heavier, tend to be more finicky and expensive to operate, and call for stronger stiffer forks.

So decide how and where you ride, order your priorities and decide which makes sense for you. Rainy day commuter, maybe discs --- good weather sport road rider, stay with calipers.

Wilfred Laurier

Fit rules all. Even if discs were more maintenance, but the disc equipped bike fit better, then the disc equipped bike would be the better choice. Generally, however, disc brakes are not more maintenance than rim brakes, and in many cases require less maintenance and are more robust and tolerate other problems on the bike better than rim brakes.

HillRider

You are going to get the same spectrum from wild enthusiasm to outright disgust here too. Bring popcorn and prepare for a lot of postings.

MY take: disks main advantages are they are better in really wet and sloppy conditions and they don't wear rims. Their disadvantages are increased weight and fussier adjustment. As a generality hydraulics work better but are significantly more expensive and require more mechanical ability to set up and keep in adjustment.

I also think discs for road bikes are still very much a work in progress and the changes over the next few years are likely to be dramatic and obsolete anything now available. Rim brakes have been pretty much the same for decades, work very well and are unlikely to disappear anytime soon.

PhotoJoe 

Sorry - Mechanical Discs. Forgot to clarify.

And thank you everyone for the insights while keeping the original question in mind. I know she's reading, and will appreciate any valid thoughts above and beyond the original question, but her main concern is by nature, mechanical disc brakes have issues, are noisy or are high maintenance?

And yes, fit (and by extension "comfort") trump everything else.

FBinNY 

Since we're talking about a woman, hand strength may be a consideration. When I said that most people can't benefit from the added stopping power of discs, that was based on typical male hand strength. However many women have problems with stopping power, and cannot lock up the rear wheel even with high pressure narrow tires (which should be easy to skid). If that fits your friend, then disc brakes may make more sense than they might for you or me.

RatMudd

Rumor has it that Cannondale will completely use 100% disc brakes on every bike by 2016. We all know how Cannondale is at "firsts." I feel that Cannondale's trend will leak into other manufacturer's bike design. It's one reason why I'm looking at the CAAD10 disc, versus the rim brake version.


With that said, I would only assume rim brakes are phasing out. So, you're down to mechanical disc and hydraulic disc brakes. Mechanical's are getting lighter and better every year -- The Avid BB7 are excellent. They're stock on Catrike recumbents and Surly Disc Truckers. That's something to be said. I'm not too familiar with hydraulics so her homework is to be done. Whatever she does pick, I would probably go with at least mechanical discs. For weight saving, perhaps hydraulic. Either way, pick fantastic brakes that will last and won't squeal. Homework is virtue, with lots of asking forums and reading reviews and watching YouTube vids.

jsdavis

I have cable actuated Avid BB7 and they are not noisy unless they are maladjusted or contaminated. Once they are installed and aligned, they are not high maintenance. Every few weeks I have to turn the dial on the caliper one click to push the pads out a bit, but that's it as far as ongoing adjustment. I suppose this is more maintenance than rim brakes but on those you have to adjust the barrel adjuster as the pads wear too. When the the pads wear out, I use the dials to retract the pads completely, pull the pads out, insert new pads and spring, turn dials to put pads in position, and done. It's a 5 minute job, no tools required, but pliers do help.

Rotors do wear out and they get dirty just like rim brakes and this can cause them to become noisy but the noise usually goes away on its own. I have found that they become more noisy when people keep running them after they're worn out and, perhaps, become easier to warp. I've replaced rotors maybe with every 6 sets of pads on my commute bike.

I only have experience with Shimano Deore hydraulic brakes and I will say that the maintenance on this one is lower than cable actuated brakes. When the pads wear out, remove the cotter pin that retains the pads, pull the pads out, use a wrench to push the pistons back, insert new pads & spring, replace cotter pin, pop the wheel in place, squeeze the lever a few times to set the pads and that's it. Pads are self adjusting as they wear so there is no need to dial them out periodically. Bleeding is perhaps more intense maintenance, but it's not something that's frequently required.

hueyhoolihan

IMO, brakes are brakes. people learn to brake safely with all of them. the only problem is when they don't work as expected. and reliability has never been a problem IME.

rydabent

Bikes with disc brakes can have rims that are designed for better strength, and aero considerations. Also IMO now that we have disc brakes it is really dumb to have brakes that in time will ruin rims. New rims and a rebuild of wheel is expensive, and probably needs to be done by a professional. OTOH anyone with basic tools and knowledge can change out a disc or disc pads.

JimmyH

I can see how far behind the times I am ...... I didn't even know there were disc brakes for road bikes. I've got them on my off road bikes and they are better, IMHO, if it is raining. Caliper brakes lose a lot of efficiency if your rims are wet IME. Never have seen them on a road bike. Just like to mention that I had one bike with 'juicy' disc brakes, A.K.A. hydraulic. AFAIC they are a PITA to maintain, especially if you want to change stems, requiring more cable and like that. Not that big a deal with mechanical brakes. Just more 'stuff.'

speedy25

I have a 29er with cable brakes. I think they are great. After they are adjusted correctly like sated in an earlier reply, minor adjustments are all thats needed. I have found out that in dusty/muddy conditions they do need to be disassembled and cleaned of debris, BUT its an easy job, even simpler than a flat repair.

-SP

jsdavis

Trek put discs on road bikes all the way back in 2006 and Cannondale made a disc brake cyclocross bike as far back as 2003!

2006 Trek Portland - BikePedia
2003 Cannondale Cyclocross Disc - BikePedia
https://www.konaworld.co/bike.cfm?content=*****inc

MichaelW

Disk brakes have an advantage in wet conditions and on big descents with a load. Otherwise, a good road caliper is fine. I use both and they are trouble-free.
Disk wheels can be built any rim. Disk rims have no braking surface so can be lighter; they are not stronger . Carbon rims are not famous for effective braking so make sense on Disk wheels.
Disk brakes need a stiffer fork, which is not so comfortable.

dabac

By nature - No.
All that I have encountered have been really easy to deal with.
Not as easy to strip to their component pieces as caliper brakes, but so far, less/no need to.

Minor observations:
-If you get brake squeal on a rim brake, a trusty fix is to adjust pads for toe-in. And once it's gone it tends to stays gone.
Some discs will "always" squeal in wet weather.
OTOH, they still brake almost as well when soaked, which can't be said for rim brakes.
-there are more types of different disc brake pads than there are rim brake pads. There's a higher risk that a randomly chosen bike shop won't have "your" disc brake pad, should you need one during a longer ride. Rim brakes, you'll always be able to pick up something that'd work.

OTOH, disc brake pads are really tiny. If the scenario above worries you, tape a pair discretely to a saddle rail or something.

Willbird

One rim I was recently looking at was 14g heavier without a machined brake track surface. So 14g of material is removed to machine the brake track, probably that 14g of material would make the rim fractionally stronger/weaker ?? That rim is the BHS C31w.

Bill

asmac

Could we please stop it with the brakes=locking up the wheels. Brakes exist to absorb kinetic energy (by turning it into heat) and thereby slow you down. If you lock the brakes the brakes have failed.

It's very hard to generalize about discs because every model/brand has its own characteristics. I had Avid BB5s mechanicals and they were a pain to set up. BB7s are highly regarded.

I had Avid Elixir hydraulics and they failed too soon and suffered from pad-rub. I replaced them with Shimano XT hydraulics and they are fantastic - quiet, no rub, no adjustments needed, easy to bleed (though never required) and use mineral oil (not caustic brake fluid).

They all offer excellent braking in all weather and the hydros especially require very little hand force (i.e. one finger braking). The hydros have excellent modulation (XTs are the best I've experienced ) meaning that it's possible to easily and predictably change the braking force with minimum grip.

I like discs but others don't. Take your pick.

FBinNY 

Yes and no. If the same extrusion is used for both machined and non-machined rims, then the non-machined would be stronger. But in reality, it'll be overweight.

The needed flange strength was engineered when the extrusion was designed. There was an allowance for machining, and for about 1mm of brake wear. So if that same extusion were to be used on a disc rim, there would be unnecessary added weight, with no benefit.

FBinNY 

I agree that locking the wheel isn't the objective, but it's the benchmark for brake design. That's because the MOST a brake can do is lock the wheel. So the only way to compare maximum braking power is to measure the amount of hand strength needed to lock the wheel.

krobinson103

I love my Deore Hyrdos. Super easy to maintain, one pinky finger stopping if you feel like it. Riding my roadie down a hill leaves with hands like crab claws. Riding my tourer? Night and day.

trailangel

What a minute. The rim is already a disc. Why add another?
If you don't have enough hand strength... HTFU

rydabent

You dont need too much common sense to see that the brake circle on a caliper brake rim runs 90 degrees to the wheel. That means that tire pressure has a surface to bow the rim out. A disc brake rim would be more aero, and run to the edge of the rim at an angle. There for the rim would contain the air pressure better and be stronger.

It still remains now that we have disc brakes, it is just plain stupid to wear out a rim with caliper brakes. There are many instances of reports of cross country cyclist braking a rim due to wear. Broken rim equals cyclist on foot. OTOH if something went wrong with a disc brake, they could keep riding since they would still have a functioning brake..

Willbird

Isn't it sort of a blanket statement that adding material will never add strength ?? "Sufficient" is often a compromise....when the 1mm of wear is factored in then the non machined rim over the lifespan of the machined rim probably has even more material. Again assuming they use the same extrusion for both rims.

In some applications, say forget steel gasoline engine connecting rods operations like beam polishing remove material, and remove stress risers too, making the end result lighter and stronger both. But an aluminum bicycle rim extrusion should not have stress risers in the rim track area as extruded ??



Bill

cyccommute 

If the strength of the pressure vessel were in question, you might have a point although any noncylindrical pressure vessel isn't a good pressure vessel. But rim "strength" doesn't concern holding the pressure of the air in the tire. Even when pumped to really stupid pressures, rims seldom fail due to overpressuring. The rims that have had brake tracks fail on me...and there have only been a couple out of dozens of wheels... have all been low pressure mountain bike rims.

Rim "strength" is usually talked about in terms of weight carrying capacity. Hub mounted disc and rim brake rims are about the same strength there...not that the rim has all that much to do with wheel strength in the first place.


If something goes wrong enough with any brake...hub mounted disc or rim... to make the brake nonfunctional, the brake is non-functional. I think you mean if anything goes wrong with a disc brake rim, you'd still have a functioning brake. But if anything goes wrong with the rim, you usually don't have a functional wheel which means a functioning brake is useless.