79pmooney

On dry roads and aluminum rims, very good braking with rim brakes is easily done. (Not saying everything out there is good, but many systems are. Mafac front brakes, Weiman/Diacompe rear brakes and Tektro levers, SunTour Superbe sidepulls with Tektro levers, Shimanl OEM cantis with (I think) SunTour levers and Shimano dual pivots with V-brake levers all give me real stopping power. All capable of lifting the rear wheel on dry road in a controlled stop.)

And, just for fun, the el cheapo bike I threw together a fer years ago had Tektro levers and no-name very used mismatching sidepulls and real stopping power. Whole setup - $40 plus cables. The levers were new and not discounted.

So "Rim brakes are not the best, but they are ok as long as you understand their limitations." Yeah. Poor brakes are poor. All rim brakes have limitations in the rain. And there is not a direct correlation between price and stopping power. There are some very expensive poor stoppers out there and some gems out there to be had that cost very little. And they all require maintenance and an eye on cables, housings and pads. But that is not difficult.

Ben

smarkinson

I believe it is because they have a longer travel in the lever, the so called modulation. With rim brakes the lever travel between off and fully on is shorter so it is easier to accidentally apply full brake. With discs you have to pull the lever over a greater range which provides the rider with more control over the amount of brake pressure applied.

woodcraft

If the pads are new, braking may improve

after they wear in a bit- more rubber on the rim.

SkepticalOne

This is a decent explanation, except I wouldn't say its 'longer travel' for the lever per se...but with respect to the engagement of the bake, a caliper brake has a more punctuated 'On-Off' feel to it, whereas the hydraulic disc provides more graduated control in between full-off and full-on, theoretically giving a rider the ability to find and ride a finer line prior to full lock-up.

I ride hydraulic discs as of late season, and this is my experience. Not necessarily more or better braking, but rather better fine adjustment. And of course, more consistent performance in all weather conditions.

Trakhak

Three other contributors to the difference in braking feel among the OP's bikes: wheelbase (probably shortest on the Trek road bike), amount of rubber on the road (probably wider tires and thus bigger contact patch on the hybrid and folder), and rider position (probably drop bars on the Trek versus flat or riser bars on the hybrid and folder).

All three factors make braking on any road bike, regardless of whether the bike has disc brakes or rim brakes, feel substandard to riders who are not used to road bikes.

gregf83 

Something is not setup properly if you have to pull the lever any distance before braking starts. Modulation refers to the stopping power being linearly proportional to the pressure applied to the lever. With good hydraulic brakes there shouldn't be much movement of the lever before braking starts and once it starts the lever shouldn't move unless your lines are expanding which is something you don't want.

LUW

It's very simple: you have to apply less force on the levers. Let me use an analogy. Let's say you have to hammer a nail into a board, and it's an easy job to get the nail all the way in, even if you use a small hammer, but you DON'T want to mark the board. When would you be more subtle, using a small hammer or a big mallet? Both the mallet and the small hammer will do the job, but since you can use less force with the small hammer, you'll end up doing a more delicate job with less chance of marking the board.

The same goes with disks, specially if you're talking about hydraulic units. As you need less pressure on the levers for the pads to compress the disk, you can be more subtle about it, and there you have the famed "modulation" that is gospel for disk lovers. If you have to apply less force it's easier to perceive the point just before wheel lockout, that is the point where you're getting your maximum brake efficiency.

Though rim brakes are in reality a big disk brake, where the disk is the wheel, because of the system of levers used on the cantilevers you won't get that finesse in modulating the force you apply to the lever, and it's easier to skip that optimal point and lockout the wheel.

For experienced riders this advantage is "less necessary", but specially when conditions are harsh or in an emergency any help to stop will be more then welcome.

Bike Gremlin

I've had no problems, riding both wet and dry, with road rim brakes, V-brakes and disc brakes.

Max braking power: disc, V-brake, road brake.
Modulation: disc, then road and v-brake come hand in hand.

Modulation being what makes the difference, both disks and road brakes have more than enough power.

But they are all good enough for panic stops and for locking wheels if you want. So, I'd never call a road 105 rim brake a poor brake. Just that quality hydraulic disks are exceptionally good.

San Pedro

I saw some GCN video that said using both brakes stop fastest. Only rear is the worst.

On my road bike I am very confident using mostly the front at all speeds I do. On my hybrid, with V-brakes, I am much more weary to brake hard with only the front. The wheel locks up much more easily with the v-brakes and combined with higher center of gravity it is very easy to go over the bars. On a drop bar bike it seems way easier to avoid this with the lower center of gravity and the easier to "modulate" the braking.

shelbyfv

Thanks, folks. I can understand modulation and can see that a hydraulic system could enhance this over a cable system. I thought people were saying that the disc could stop quicker than the caliper and i didn't understand that. I see now that is not what was meant.

LUW

Well, since you can better modulate the power being applied to the disk, you will stop sooner. Not by a huge difference but a disk brake gets the job done a little sooner.
That's why I said disk brakes are better then rim brakes. Traditional cantis are not bad, but disks are better.

Maelochs

I still think tire traction is the deciding factor. Since you can't lock the front brake anyway, and modulating the rear brake is easy and also not particularly important to stopping .... On the other hand, a disc system weighs more which increases stopping distances.



If the difference cannot be measured with complex scientific instruments .....

Sy Reene

It seems that with either caliper or disc brakes, you still need an ability to perceive that point right before the wheel locks up as to when to stop exerting more braking power with your hand. How does a disc brake communicate that feel back to the rider better than a caliper brake?

I'd also ask (you might be able to tell, i've never tried disc brakes), how well one system (caliper vs disc) compares to other braking on slick surfaces.. meaning maybe damp roads or light snow..? With a car, pumping the brakes (now done with modern electronic ABS) is what's done. A further-traveling hand movement for disc brakes(?) would seem to make it hard to do fast repeating multiple quick sharp brake pumps.

LUW

You're missing the point. Literally . Once the wheel stops turning (= lockup) what is slowing you down is the friction between the rubber and pavement. But that method is less efficient and less controllable then keeping the wheel turning as slowly as possible. And the weight factor is a bit exaggerated because with disks you have the weight lower, so it's not exactly gram vs gram.

Hard to put in words, but because you need less force on the levers you can better feel the wheels before they lockup. The same way you would feel that your wheels are almost locking up with cantilevers, but with disks it's like you have more warning AND it's easier to control.

It's all in how much pressure you apply to the levers, there's a sweet spot where you have maximum force on the levers (the pads are almost locking the disks) but not enough to completely jam the disks. There's no such thing as pumping the brakes on a bike because the system is absurdly smaller/shorter then what you have in cars, so things are much more instantaneous.

With all that said, do not fool yourselves: if you grab a handful of brake lever in a panic situation you will lock up your wheels and sphincters, be it rim or disk brakes. Braking is an art, you have a very narrow margin between a smooth stop and skidding down the road - highside or lowside. With disks (specially hydraulics) you get a little more leniency.

Sy Reene

Maybe not called "pumping" but I've certainly heard folks recommend on rides situations calling for "feathering" of the brakes.

LUW

AFAIK feathering would be to have a light touch on the levers, compressing easily and gradually .

shelbyfv

On a long descent you might apply the brakes, then release, apply and release and so on to prevent overheating. I guess that could be considered pumping. Is this necessary with discs? Yes, I admit to braking on descents.

TimothyH

Whether you call it feathering or something else, very rapid changes in pressure applied to the brake levers is a useful technique, especially in the wet. It isn't jamming on the brakes repeatedly but more subtle and most useful if one is braking near the limit of adhesion.

It is best to practice threshold braking or braking as late and hard into a turn as possible before trying to learn feathering (or whatever anyone want to call it). Most riders who are not racers or not very aggressive tend to brake too soon or ride the brakes down hills anyway and so threshold braking would be a useful thing to learn apart from feathering.

Another use case for feathering is for the rear, to feed in some rear brake without locking it up on a long downhill curve, again especially in the wet.


-Tim-

Maelochs

No, I fully understand that rolling friction is greater than sliding friction. And I know from panic stops (which I sometimes practice, because better to be prepared) that it is really easy to lock the back brake (I usually set mine looser therefore) and that in a true panic stop the time involved is so short---you either stop or hit something in a second or two---you might have the time to pump the brakes two, three, maybe four times.

Gradually squeezing until they lock or almost lock Sounds good ... but in that half-second between when the car runs the stop sign and your brain tells your body to react, you have already covered a fair bit of distance, and in the next split-second it is likely you grabbed Both brakes really hard---the adrenaline dump of an actual impending-death situation tends to do that.

Yeah, you can modulate---but i find it isn't easy because while your left hand (if you use normal brake routing) needs to squeeze as hard as possible, your right hand can't .... but all the while you are also watching the oncoming car, looking to see if there is head-on traffic which will flatten you if you lean left, trying to calculate if you could possibly let off the brakes and turn enough to avoid the impending wreck, and by the time you have read five words the whole thing is all over, one way or another ... so the rest becomes academic.

Something like 70 percent of your stopping power (maybe more, I am too lazy to Google it) comes from the front ... the back is there basically to let you do the classic slide/release/pump maneuver, where you lock up, skid half sideways, then release the brakes and jab the pedals and shoot off in a (hopefully) safer direction.

(That is actually what happened at my last near-wreck---I overcooked it on a short downhill into an uphill corner and found myself heading head-on into the oncoming traffic lane which was unfortunately occupied by a couple SUVs ... I did a brakeslide and pedaled once and shot back into my lane like I had planned the whole thing. See ... disc brakes might have killed me. )

If you are going to pedantic you should also be precise and observant. You seem to have overlooked the smiley face along with the weight comment. (Oh ... and if they are hydraulic, the fluid reservoir is usually up high. )

Of course ... we actually agree when it matters ....

And the less you have to move the lever to lock up ... the greater chance you will lock up, with all the adrenaline coursing through you. Fine motor control is Not enhanced by adrenaline amplification of muscle power.

Which is why I practice. I am not sure how much extra benefit discs would be in a panic stop on slick tires on pavement---I only have discs on my MTB. For me the greatest benefit of discs is all-weather operation--if I need brakes i have them, when I need them. Rim brakes in a hard rain have brought me some interesting moments--even if it only takes a fraction of a second for the shoes to squeegee away enough water to grip, until it happens, the brain wonders "Will it happen in time?"

Anyway ... I have never done a Serious panic stop (I mean a stop in a life-threatening situation) on pavement on slicks with discs ... and I hope I never do, even if all the rest of my road bikes have discs. So ... this is all conjecture, and I hope it remains so.

shelbyfv

+1

gsa103

As for the OP, the primary issue is riding position, and contact patch. His other bikes will have weight further back, and larger contact patches, where it's more difficult to get OTB, and more traction before skidding.
Also, the earlier generation of Ultegra (pre-6700) had bad ergonomics for braking from the hoods. You pull hard, but don't get good leverage, so you have to pull much harder than you would think.

As for disc brakes, the main factor is that they use a flat steel disc rather than an aluminum rim. The rim has all sorts of imperfections and non-idealities that discs simply don't have. If the rim has bulge (pot-hole), it will tend to grab every revolution (even a micro bulge). The bead joint can cause rim brakes to grab. If the rim isn't perfectly true you'll get uneven braking. All of those things make rim brakes more prone to grabbing. With disc brakes, the disc is made out of solid steel, so is much more durable and less likely to get damaged. Since the braking force is very consistent, you can run very close to the traction limit. With a rim brake, you have to back down a little more, just because there's more variation in the braking force during one revolution.

ColonelSanders

Has anyone here ever heated up their rims enough to blow a tube?

Bike Gremlin

I explained proper braking technique here, with pics. Works on road and MTB bikes. Also explained special conditions (ice, mud...):

Braking technique - Cycle Gremlin

Bike Gremlin

And it has worked for me on several occasions.

Situation one, motorcycle, with my girlfriend. Car turns left across our path, then stops! Effectively blocking the whole lane. Cliff to the right, oncoming traffic to the left. Holding with my legs onto the fuel tank, to keep her weight from overwhelming me to, loose hold on the bars, feathering the rear and squeezing the front brake. Just to the point of slipping. On a motorbike with good brakes and tyres, a slip point can actually be felt before it happens. My calculation is we won't stop in time, but it was better to hit the car staying upright, slowing down as much as possible, than sliding down, slowing down less, and going beneath the car's wheels. The oncoming lane got cleared, so I did a last second swerve around the car. Had I not been able to swerve, I would have hit the car with some 20 km/h speed left. I did, however, do lots of panic stop practice, along with the girlfriend I often ride with (she needs to know how to hold onto the bike, not making things worse than they need be).

Second time: a car pulls across my lane, on a bicycle this time. Slowing down as much as possible without risking going down. Hitting the hood with the front wheel, rolling over the bars onto the hood. No injury.

Good practice makes it possible not to panic too much and do all you can for a safe stop. You don't have to lock the wheels in panic. But without practice, you probably will.

Another situation, also on a small and light 125 cc motorcycle, was car to my right doing a u-turn, while I was on their left (blind spot, I should have known better). On that occasion, using a bit of front brake, I deliberately locked the rear wheel, sliding the rear end to the right, hitting the car sideways. No injury or damage to anyone. Just a "Are you OK?! Sorry, I didn't see you. Fare well". I had practiced sliding the rear end just for fun, never even considering I'd ever use it for anything practical.

LUW

I find it interesting that on EVERY rim Χ disk discussion people end their point of views with something like "in a panic stop you will skid the wheels, so disks are not a plus". Really ?

If out of nowhere suddenly comes a semi barreling on the wrong side of the road towards you at over 100+ you will die, regardless of you having disk, rim brakes, a CF frame or matching socks and riding shoes. That's not the point. Disks are more useful on an everyday basis, on normal situations, because you can stop a little easier. That guy that went over the mountain on the video some posts back would have done the same even with disks because he was way too fast, he overcooked the turn. Why do cars use disk brakes instead of drum brakes? Why do motorcycles (city and race bikes) use disk brakes? Because they work better then other alternatives. The same applies to bikes. For the last time, rim brakes are NOT worthless, far from it, but adding all the pros and cons, disk brakes work a little better.