maf

I have a fairly new (~7 weeks) commuter bike that's just been in for its first service. As soon as I rode it home I noticed a problem with the front brake where it would make a horrible scraping sound and jerk around. It seemed to still work, albeit with reduced performance but I've been relying on the back brake since for fear of causing damage. I took the front wheel off tonight to see if I could find the cause of the problem and found a chunk of the brake pad missing (see attatchment 1). I decided I'd ring the shop tomorrow and see if they will replace it gratis and in the meantime I'd swap the rear and front pads because the front brake is more important. Well, as soon as I take the rear wheel off and attempt to pull the pad out, I find there are bits of the pad resting loose within the brake housing. This pad had fallen to bits without me even touching it (see attachment 2).

What has happened here? How could two brake pads on two separate wheels break like this? Another, more chilling question is if I'd had left the brakes as they are and continued just using the back brake could it have failed while I was out riding, leaving me without an effective brake just as I'm heading towards something at 30mph?

I haven't mis-treated this bike but even if I had, what could cause both brake pads to fail so soon?

spare_wheel

I would never ride 30 mph with one functioning brake and defective pads. I have had cheap after-market pads that flaked like this. I have also had problems with ultralight drilled-out mud-clearing rotors catching pads and chewing them up.

Your experience with mechanicals is one of the reasons I use hydraulics. Even if the entire pad gets chewed off my hydraulics will stop fine with only metal backing (albeit with a heck of a lot of noise).

maf

Perhaps I've used a bit of dramatic effect - I've been more cautious since the front brake stopped working properly but usually that's how fast I'd be. What do you think is the problem here? This bike is almost new so do you think I have a defective batch or perhaps the bike shop skimped on quality pads? What's rather concerning is that other people with the same bike or same pads could be sitting on a ticking time bomb. Surely it's more than coincidence that both pads fail within a few days of each other?

What's strange is before I took the rear wheel off its brake worked fine (slightly noisy when braking but nothing you'd hear if you weren't listening) but clearly it was just about to fail if taking the wheel off tore it apart. I'm thinking these are dodgy pads as in the second photo you can see the pad simply crumbling to pieces -- rolling a piece in between my fingers makes bits flake off like it was made of dust.

acidfast7

I think that you've overheated that pad material by repeated 30mph-0mph stops. The heat produced while stopping 30mph to 0mph is significantly more than 18mph, 20mph or 23mph to 0mph stops. Perhaps you should dial the wattage back a bit?

Burton

Warranty issue - take it back where you bought it and let them deal with it.

fietsbob

Un Said, so I have to guess: Brake "Pro Max"? Koolstop makes these replacement disc Pads

https://www.sjscycles.co.uk/koolstop-...ads-prod21046/

a cost conscious build, brake choice .. by my estimate..

less likely https://www.sjscycles.co.uk/koolstop-...ads-prod21040/
being a German hydraulic brake.. not made in a dozen years.. years..

hueyhoolihan

i second this... there is no acceptable reason for a disc brake pad on a BICYCLE, for crying out loud , to deteriorate like that.

350htrr

No way in hell that should have happened. I have had my hydraulic disk brake pads for over 10 years without changing them. When I finally did they both seemed OK except for being almost worn away... I usually ride 1,800 KMs a year...

maf

So disc brakes aren't designed to go from 30mph to 0 without risking failure? I'm not sure if I've actually had to stop dead from 30 before but even if I did it every day how could it cause such failure within 7 weeks? 7 years perhaps but not 7 weeks.

I've spoken to the shop and this is the first case they've heard of where the pad has come loose from its backing and they're going to take a look at it. They're going to check with their head office in case this is an issue other stores have found. I'm not sure which is worse actually, the idea that otherwise good quality pads can fail like this or the idea that many people could be using brakes that are just waiting to fall apart.

acidfast7

I pointing out your hyperbole as you're probably not doing 30mph every time you use the brakes, unless you ride here:



and, if you do shoot me a PM, because i'd to have a local show me around next month.

maf

If I were to ride down that I'd probably need this:



Where one lever controls the disc brake and the other controls a backup v-brake

acidfast7

sweet!

good luck with the pads

you may want to the check the rotors are well, maybe someone squirted them with solvent while parked outside as a crappy joke (or someone strange cleaned them with solvent to make them shine when the bike was being displayed for sale).

dynaryder

FYI,those levers are interrupter/cross levers. They work with the brifters,not on a separate brake.

Also doubt you're doing 30mph,but regardless the pads should not have failed like that. What brakes do you have? Def a warranty issue.

You said this happened after the bike was serviced. Were there any issues prior to this? Noise or strange feel through the lever? I could possibly see if the caliper was mounted crooked and the pads were low end the torque cracking them,but they never should have been set up that way.

Get the shop to replace the pads,check the brakes to make sure everything was set up properly,and have them check with the manufacturer to see if there's maybe a recall notice of something. Plenty of expensive car companies have had issues with critical systems on their vehicles.

MichaelW

You should bed in the new pads by repeatedly riding and braking to generate heat. I find that 5-6 stabs at the brake on a steep hill do the job. Break as hard as you can short of skidding.

Check the rotor for rough bits and the caliper for alignment.

contango 

Hard to know but I'd be wanting them changed under warranty and the system fully checked out.

Brand new brake pads don't have a lot of stopping power at first but after a few iterations of getting up a bit of speed and stopping they soon start to bite. I wore a pair of brake pads right down to the metal and it made a nasty noise as the rotor kept clipping the spring attachment that separates the pads. It took me a lot more than 7 weeks to do it though.

Frankly you're a fool if you let the bike get to that sort of speed knowing you've got at least one defective brake. But the answer is pretty obvious, if your brakes fail at speed you're more likely to run into something at speed.

Hard to say, it could be they were just defective pads but if the bike has been left unattended in a public place it's possible some prankster thought it would be funny to tamper with them in some way.

spare_wheel

and i wear through at least 1 pair of semi-metallics each year. when i used organics i used to wear through 2-3 pairs each year.

350htrr

Sounds like you ride your bike like I drive my car, 1 or 2 sets of BREMBO brake pads a year on my car, unlike the average car of about 1 set for 4 or 5 years...

maf

I took my bike to the shop and they replaced the two pads under warranty. They also had to replace the front rotor because me trying to brake with half a pad caused it to get scratched up. They've never seen this before so they thought it must have just been a faulty batch. Fingers crossed for the new set!

no motor?

Did they put the same brand of pads in for the replacements? I'd keep an eye on them whatever they installed, but be really cautious at first if they put the same pads in the second time.

TiHabanero

I have only seen that happen once on a newer bike. Replace with quality pads. We did that on a Giant bike and they reimbursed us for the cost. Problem solved and it likely will not return!

maf

I don't think they used the same brand but I'll definitely be keeping an ear out for any sudden scraping that starts.

This whole fiasco has shaken my trust on disc brakes a little. Someone tell me a story of when they saved your bacon and are thankful you had them

dynaryder

My first winter commuting,my V-brakes packed up with snow and I wound up glancing off the fender of a car. Never had an issue with my discs.

Burton

Bocycle parts are like bicycles - they vary widely in price and quality. You can buy mechanical disc brakes for as little as $15 and hydraulic disc brakes for over $800. The low end no-name brakes and pads are iust excuses to take your money. Stick with recognized brands and genuine replacement parts and you won't have any issues.

contango 

Most of my cycling is on my tricross which has cantilever brakes. When I ride the MTB (with hydraulic disc brakes) I need to remember the brakes are vastly better than on the 'cross. They're great for scrubbing off lots of speed in a hurry, which can be handy on fast descents.