Sqeaking brakes

Triple

Finding my (electric) wheels
May 1, 2019
12
5
It's beyond amusing to read the jealous/nutter/ignoramus style comments, keep them coming, if for no other reason to provide more chuckles in another place! Especially so where those reading know of the tens of thousands of miles I've covered, frequently on heavily-laden wheels.

Worth pointing out my points are concerning rim vs disc brakes. Hydraulic over cable activation is always a good thing for ease of use and 'feel' whether on a bike or in an aircraft, not something I'm questioning (although it is questionable whether the extra complexity and cost is necessary on a bicycle, even with a small electric motor assisting).

The quoted statements above are beliefs, expectations and general sales talk rather than empirical arguments, except for the wet weather response. It's interesting to compare with the following from named individuals working for bike brake component manufrs.

Stefan Paul, Magura Bicycle Products Manager (Germany)
Joel Richardson, Hayes Brakes Product Manager (U.S.)

Magura: "Fade on disc brakes is caused either by glazing pads (the friction coefficient is decreasing, requiring much more hand force to achieve the same brake force) and/or by overheating/boiling of hydraulic fluid, no matter if DOT or mineral oil, leading to spongy feeling and even to the possibility of a full loss of brake power.

Boiling oil is even worse, because the brake can fail completely. This can be caused by constant dragging and/or steep gradients... DOT fluid has a higher boiling point than mineral oil, but mineral oil will keep the boiling point for ever, whereas DOT attracts water over time, even through seals (and its boiling point) will decrease over time and will be worse than with mineral oil.

Having big heat dissipating surfaces is good. Small compact surfaces generate heat build up.

Hydraulic rim brakes are lighter than disc brakes if you look at the complete system. The brakes itself might be equal, but forks and frames for disc brakes have to be beefier and made stiffer to take the loads from disc brakes with their asymmetrical force input. The system of road frame and fork for discs is minimum 500gr heavier than for rim brakes. Weight on disc brakes depends also a lot on the rotor size, the bigger the rotor, the more weight.

In order to achieve high heat loads on disc brakes, especially on longer, steeper descents, bigger rotors are neccessary, increasing the weight additionally. Rim brakes are more aerodynamic than disc brakes, they can be hidden in the same shape as frame and fork, Disc brake calipers and rotors always protrude the shape of frame and fork.

With rim brakes you already have the biggest possible rotor on a wheel: the rim!
Rim brakes don’t suffer from heat build up/overheating on the hydraulic system, as the distance friction partners (rim/pad) is really far away from the hydraulic piston, so no expansion chamber is even neccessary."


Hayes: "What we found with road bikes was that you can generate incredible heat and forces... You have tiny little calipers with very little thermal mass. And they have tiny little pistons that require very little fluid volume. Then you have tiny rotors with virtually no mass that can’t dissipate heat. When you whittle everything down to a super lightweight package, the only place for all that heat to go is the hydraulic fluid, and you can boil it in no time at all. When the fluid boils, it happens instantaneously and it happens right behind the brake pads. As soon as that happens, it introduces air into the system."
 
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vfr400

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Picking on a single failure mode, which is somewhat less likely to happen than getting run over by a bus doesn't add any strength to your argument.

Hydraulic disk brakes are not more complicated, nor more failure prone than rim brakes. They have fewer moving parts and are virtually maintenance free. My own experience of using several types on several bikes over 20,000 miles is that I never needed to do any adjustment nor other maintenance other than replacing two sets of pads that wore down.
 
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Triple

Finding my (electric) wheels
May 1, 2019
12
5
These guys weren't 'picking on' anything, simply running through one of the main problems with hub disc brakes for bikes, as they exist. This is the brake component industry, remember, who stand to make a lot of extra money from the rollout of disc brakes - which I agree is largely inevitable if you look at the extra money to be made in conjunction with the 'cool' look so many associate with

What I've been pointing out is that these hub mounted disc brakes are not a panacea compared with rim brakes, and that as a technology developed for use offroad they have significant weaknesses used on the road, made all the more dangerous by users who don't have a clue about the danger. Something I considered well worth raising on a cycling forum where there appears to be little understanding that a brake which feels so amazing to someone who has come from a bike with weak centre pivoting calipers and old Fibrax brake blocks can, without warning, fail on a long or steep hill while the bike is at speed.

This false feeling of security is made all the more dangerous by some of the crazy exaggerations posted on the Internet by those unable to question their entrenched opinions, and in believing sales talk verbatim.

I know of two cyclists who experienced brake failure half way down a local hill with disc brakes, people who had long ridden down it with rim brakes with no hint of failure. They also believed discs were way superior and had a very scary wake up to just how quickly they can fail completely, without warning.

I fully get how relatively sharp discs can be in the wet and how much this can be a good thing in aggressive traffic, although the nature of the brain is that we have a tendency to drive/ride up to a certain level of risk which means that when an accident does occur it's worse than it otherwise would've been. If a cyclist is frequently having close calls with motor vehicles, there's a very strong likelihood that sooner or later even the most amazing braking system will have no chance of helping avoid a serious collision.

Talk of snatching and grabbing rim brakes suggest either really cheap and nasty bikes which you wouldn't want to trust your life on anyway, poorly setup brakes and damaged components. Far more likely is finding brakes which are a bit lazy through years (sometimes decades) of zero maintenance, such is their inherent longevity and reliability.
 
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Triple

Finding my (electric) wheels
May 1, 2019
12
5
You sure it's not a lot to do with hydraulic actuation? I've used hub discs with cables and they've usually been pretty ho-hum. Whereas hydraulics transform them, with the caveats I've mentioned.

Provided the pads are correctly installed etc, hydraulic rim brakes are terrific (plus there's not the potential to boil the fluid in a descent) and far better than what's needed for 99% of applications - as someone above says, side-actuated cantilevered rim brakes are very effective and ideal for most people.

They just don't look sexy and high tech like a hub disc does, to many. And after all, appearance is what has always mattered hugely to the cyclist, right from the early years.
 
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mike killay

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I have finally decided to fit hydraulic disc brakes to my bike.
Not as simple as I thought. Looking on ebay I see dozens of different Shimano sets, only designated by numbers and letters with no indication as to their merits etc.
Further, on looking at the photographs, some seem to be post mount and others lug mount.
My bike has lug mounts.
Any recommendations?
 

vfr400

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They're all good. You can get adapters from one type to the other, but probably easiest to get some that have the same type of mount as your present ones. Do your present brakes bolt directly to the mount or do you already have an adapter of some sort because I thought BB7s are all post-mount with a side-mount adapter?
 

Nealh

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Shimano m315 to m525 use the same generic twin pot calliper the only difference other wise are brake levers.
 

mike killay

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They're all good. You can get adapters from one type to the other, but probably easiest to get some that have the same type of mount as your present ones. Do your present brakes bolt directly to the mount or do you already have an adapter of some sort because I thought BB7s are all post-mount with a side-mount adapter?
I have flat lugs and the BB7s came with different adaptors, for front and rear
 

Nealh

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Difference in levers is in the price and styling of the ranges, the cheaper m315 levers feel and look flimsy in their design compared to the others in that range. M525 give them a miss they aren't in my view as good as the m395/445/6 levers.
 

soundwave

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May 23, 2015
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Difference in levers is in the price and styling of the ranges, the cheaper m315 levers feel and look flimsy in their design compared to the others in that range. M525 give them a miss they aren't in my view as good as the m395/445/6 levers.
my brake levers have size adjust and bite point adjust ;)
 

jarob10

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Jan 22, 2017
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I’ve finally got a method to resolve squeaky disc brakes (hydraulic)

- remove pads, scrub with soap / nail brush. Blast it dry with heat gun until it stops smoking
- brake cleaner & rag on rotors
- 200 yard full power brake drag to bed the pads in, get em smokin’ :)

Metallic pads & m315 callipers preferred. Rotor spec not relevant, although I avoid ‘resin only’ rotors. G04S bite v nicely on the front, but are a bit too much on the back, I go for vrs841 on the back

Also, brake callipers pistons tend to stick - I find white silicon grease works well, after cleaning with cotton wool buds
 
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KirstinS

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Apr 5, 2011
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I’ve finally got a method to resolve squeaky disc brakes (hydraulic)

- remove pads, scrub with soap / nail brush. Blast it dry with heat gun until it stops smoking
- brake cleaner & rag on rotors
- 200 yard full power brake drag to bed the pads in, get em smokin’ :)

Metallic pads & m315 callipers preferred. Rotor spec not relevant, although I avoid ‘resin only’ rotors. G04S bite v nicely on the front, but are a bit too much on the back, I go for vrs841 on the back

Also, brake callipers pistons tend to stick - I find white silicon grease works well, after cleaning with cotton wool buds
Sounds like a lot of effort!

I use a single alternative method. Just ride till it goes away. It always does!
 
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Deleted member 25121

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I fixed my squeaking brakes by mounting my saddle to face backwards.

(Only joking, I was thinking of some earlier posts in this thread.... ;) ;) )