Tandem Tom

I had the opportunity to ride a mountain bike last week that was equipped with hydraulic disc brakes. As this was the first time riding with this these type of brakes I have a question.With other types of brakes I could "feather" them these seemed to be full on locked when I just touched the levers! Is this typical?
Thanks!

habilis

I have no personal experience with hydraulic disc brakes on bikes, but another recent thread reported a front-wheel collapse when the brake was applied hard during an emergency stop. Could these brakes be overkill for bikes?

jimc101

What brakes were you trying? different brands, and even different models within those brands can have different feel.

dabac

You need to realize that what has driven the functional part of disc brake development the last years have largely been a desire to get full stopping power with only one, or possibly two fingers on the levers.
And to get full, modulated braking ability from only one finger on the lever, the brakes do need to be rather powerful. No surprise if it take an unwary rider by surprise.

And disc brakes have overstressed other parts before. In the early days of discs being used on roads there was a bunch of bent forks and even downtubes.
IMO, that's a sign of other parts being under-engineered, and not brakes being over engineered.
We wouldn't accept brake lines or caliper mounts on cars breaking on account of too hard breaking, would we?
Available friction, that's the sensible design limit for how much force a brake, wheel, fork, frame should be able to take.

rmfnla

That's why I still prefer rim brakes; the braking force is channeled through as few components as possible...

Bike Gremlin

+1

I'm yet to find a situation where (good quality) rim brakes can't brake as hard as the wheels can hold traction - with good modulation as well.

Canker

no

also no

corrado33

I used to think the EXACT same thing as you. The first few times I rode a disk brake equipped bike I thought "Dang, these have no modulation."

Then I rode them down a steep mountain bike trail.

My mind changed rather quickly.

I would say that rim brakes can be adjusted to give the same braking performance, but disk brakes give you lighter lever pressure, which is great for LONG downhills.

dabac

No, that's not typical.
But good hydros give the most braking power WRT pinch force than any other brake system. You might need some time to recalibrate.

dabac

Figuring out the exact chain of events of a wheel collapse is tricky. Correctly aligned, they're usually very strong. OTOH, get it sideways, and it'll fold easily.
A little bit of a skid, a little wobble, the wheel goes sideways and folds. All in the snap of a second. W/o video, differentiating this from a "pure" overload sequence would be quite difficult.

fietsbob

Magura Hydro rim brakes work better than tom's mystery set.
brakes that dont do that * posters think are not Good enough, from what they write.

* stop like someone stuck a Broom-handle in your spokes.

Colorado MTB riders are the market for those big disc 8 piston hydraulics that stop like hitting a stone Wall.

gsa103

Hydraulic disks allow you to run much closer to the traction edge than rim brakes. The brakes respond faster and with less force, so properly modulated you can stop significantly shorter in tricky situations, like wet and loose dirt. That's the reason that mountain bikes have moved exclusively to hydraulic discs. Disc brakes are also less sensitive to rim damage which can cause grabbing.

GCN recently did a direct comparison between rim & hydraulic discs for road/gravel bikes. In dry conditions, the performance was identical, disc showed an advantage in the rain and huge advantage in loose gravel. If your experience is mostly routine riding on paved roads, the differences are marginal.

Bike Gremlin

Paved roads all year long - no problems.

Off road - dry, or slightly damp - no deep mud and not often in the rain.


Hydraulic disc brakes are the best there are. However- they add weight, complicated servicing, cost more, put stress on the rest of the bike, front one has a tendency to pull the wheel out of the fork.

So when I add pros and cons, I stick with V-brakes for MTB and regular rim brake calipers for road bike. They have given me good enough stopping power. If I rode a lot of off road hilly terrain in the rain, I'd go for hydraulic disc. Perhaps even for a lot of paved hills in the rain and poor weather.

corrado33

This is the important part, the servicing generally requires special tools (I'm talking about bleeding.) The tools vary from one brand/family to another brand/family.

If I had to guess though, I'd say disk brakes last longer. I took a bike with almost brand new rim pads on a 30 mile off mountain bike trail. By the time I finished the pads were 3/4 gone. Sure, I was on them a lot of the time, but still, that's a lot of wear. On the other hand I've ridden my disk brake bike multiple times on that trail (and for the rest of the summer) and the pads are still fine with plenty of wear.

Bike Gremlin

Plus rim brakes often have to be adjusted to wear, while hydraulic disc brakes self-adjust as pads wear. Though rim brakes wear excessively in the wet, dry conditions don't wear them as fast. Also, pads are rather cheap and easy to replace.

Wilfred Laurier

Can you provide a link to this thread?

Thx.
WL

habilis

Here it is:
[h=1]Crashed bike and now front disc brakes are pulsating[/h]

jimc101

Far too little info was supplied by the OP in that post, going downhill at a pretty slow speed, and applying brakes hard makes with the end result in wheel failure makes little sense. The only way can see this happening is due to either prior wheel failure, or just a bad build, neither which had any relation to the brakes.

dksix

Is bleeding a bicycles hydraulic brake system different than bleeding all other hydraulic brake systems? Just generally, hydraulic systems are set up and forget. Where is all the air coming from that's requiring the constant bleeding/maintenance? I've never had as much trouble bleeding a hydraulic system as I have getting a front DR to shift properly.

From people who has owned hydraulic brake bikes do they require more attention than is needed to keep wheels trued, tires inflated to correct pressures or derailleurs shifting properly? This isn't intended to start a debate, legitimate question for those who are actually using the systems.

Bike Gremlin

Brakes using DOT fluid need bleeding every year or two - since DOT fluid absorbs moisture and will tend to overheat during hard braking if not changed regularly.

Brakes using mineral oil don't have this problem, but for all I know (correct me if I'm wrong) to be on the safe side (dirt contamination, oil changing property and viscosity from heating-cooling) - 2 year service interval is advisable.


Air can come in if there's air left in handlebar container and the bike is turned upside down, but that is not the main reason for bleeding.


Bleeding bicycle brakes often requires special adapters/tools. Having bled a number of race motorcycle brakes, I find the bicycle hydraulics more tricky to work on!


One more thing: servicing also includes occasional (once a year at least) brake calliper piston cleaning.


Despite me finding disc brakes more trouble than gain for the way I (and most people I know) cycle, hydraulic disc brakes are the best brakes made. There's no question about that. Stopping power, modulation, wet and mud performance - number one, hands down!

Canker

The methods you have to use to bleed hydraulic brakes can vary greatly from brand to brand. Some like Shimano's, mineral oil based, are super simple and can just be gravity bleed without any special tools, though they do make special tools. Some like Avid/Sram, dot based, require special tools, chicken sacrifices to the God of hydraulics, and are a huge PITA. There are a lot of how too videos on youtube. My hands end up killing me by the time I'm done bleeding my Avid brakes pushing and pulling on the stupid syringes. My newer shimano's have been going strong for 2 years without being bleed and my front is just starting to get a little spongy feeling and should be bleed just to replace the old fluid if nothing else.

I don't do squat to mine other than bleed them when they need it and check pad wear every now and again. Well I did just install a new/used set of rotors and one was very slightly bent and rubbing so with my bare hands I tweaked it. I can and have ridden all my local trails with v-brakes but I'm really glad I don't have too anymore. My road bike still has rim brakes and while I'm sure I'd like discs on it too the pros are way smaller and not worth buying a whole new bike to get.

dabac

Well, once a good hydro brake does need to be servicing, it MIGHT take some more effort.
OTOH, a good brake can be bolted on and ignored for years w/o any noticeable deterioration in performance.
IME, bleeding a set of hydros is DIFFERENT rather than worse compared to recabling a set of rim brakes.
And, once you've done a few, usually faster.

It hasn't been about absolute stopping power in years, brake force vs lever effort ratio is the big thing for the immediate ride situation.

calimtb

That GCN comparo was horrible. So many uncontrolled variables.

At the very least, test with alu not carbon rims.

Bike Gremlin

This is my opinion and experience. Some might find it other way round, can't argue with that:

Bleeding (servicing) hydraulic brakes takes more time and experience than changing cables and setting up cable actuated rim brakes. In addition to that, servicing hydraulic brakes also means cleaning brake pistons as well.

habilis

I agree (always) that one anecdote proves nothing. Two or more? Still proves nothing, but it starts to make me wonder....

@dabac writes: "And disc brakes have overstressed other parts before. In the early days of discs being used on roads there was a bunch of bent forks and even downtubes.
IMO, that's a sign of other parts being under-engineered, and not brakes being over engineered.
We wouldn't accept brake lines or caliper mounts on cars breaking on account of too hard breaking, would we?
Available friction, that's the sensible design limit for how much force a brake, wheel, fork, frame should be able to take. "

Hydraulic brakes are a great improvement in motor vehicle applications. However, wheel lock-up in a car is dangerous, so the industry invented ABS. Front-wheel lock-up on a bike can cause a broken neck. I wonder if the engineers could come up with a simple way of limiting the max stopping power, before someone gets pitched over the bars. I DO NOT mean ABS for bicycles! Maybe a simple detent in the caliper. Otherwise, more riders may find that their bike (or they) were "underdesigned" for their brakes. (God, I love to start a good argument!)