Replacement disc brake pads

VonLuck

I recently purchased a Giant Rapid 3 bike (about 6 months ago) and this is the first time I've had a bike with mechanical disc brakes. They are beginning to screech a little and are not stopping as quickly as normally so I'm guessing it's time to replace the pads.

The simplest option would be for me to drop the bike into a shop and get them to do it for me, but seeing as they charge €10 per disc, plus the price of the pads, it's going to cost a decent amount.

I'm sure I'd be up for the task of replacing them myself to save a bit of money, but I'm a bit lost in the amount of pads to choose from. Is there a particular type that I need to get for my Giant bike, or is the same as buying pads for V-brakes - a one size fits all? I don't want to end up buying pads that I won't be able to use!

Thanks.

H.E. Pennypacker

You're looking for these ones: https://www.bike24.com/p212048.html

Your pads/discs may be contaminated rather than worn. Or perhaps they're glazed. It might be worth checking the existing ones for wear before spending any money

magicbastarder

how much mileage have you done? six months seems a little short for pads - i replace my front pads one year, 4,000km, ago and they're still alright (though i must check them now that i think of it!)

iamtony

There should be some kind of wear indicator that will show if they are worn.
In a car if brakes are squealing it's down to a build up of brake dust. Power hosing them usually cures it. If they are worn out they will grind from metal on metal contact. Also when fitting pads in a car applying a layer of copper grease to the back of the pads stops squealing down the line. The brake dust sticks to this instead i believe.
Glazing I'd suspect is very hard to do on a bike, I could be wrong but in a car you'd have to rally it to achieve the temp needed to cause glazing.

Macy0161

I'm doing mainly rural spins, but the amount of sh!te on the roads has my mechanical discs screeching a bit. Generally ok while pads and rotors are clean, but don't have to go too far for them to get a bit squealy!

Lemming

You say you've got mechanical discs; that implies cable rather than hydraulic operated. Regards your decreased braking performance, have you checked the cable for wear (granted, six months seem a bit off ... ) and/or dirt ingress that might be impeding cable operation? If you've got hydraulics, ignore that last question and check whether or not you've got a fluid leak ... which brings me onto:

... the squeal; contamination of some sort. If it's just dust or general road crap, it'll clear in short order - helped on with a blast of compressed air. But if the squeal persists and can wake the dead, you've probably got pad contamination that requires replacement. Please clean your rotors (plenty of youtube videos on the subject) before slapping the new pads in or else you'll likely just transfer whatever messed up the old pads over.

iamtony

Lemming wrote: »

You say you've got mechanical discs; that implies cable rather than hydraulic operated. Regards your decreased braking performance, have you checked the cable for wear (granted, six months seem a bit off ... ) and/or dirt ingress that might be impeding cable operation? If you've got hydraulics, ignore that last question and check whether or not you've got a fluid leak ... which brings me onto:

... the squeal; contamination of some sort. If it's just dust or general road crap, it'll clear in short order - helped on with a blast of compressed air. But if the squeal persists and can wake the dead, you've probably got pad contamination that requires replacement. Please clean your rotors (plenty of youtube videos on the subject) before slapping the new pads in or else you'll likely just transfer whatever messed up the old pads over.

brake cleaner on the discs would help before fitting new pads. Use original pads if possible.

Lemming

iamtony wrote: »

brake cleaner on the discs would help before fitting new pads. Use original pads if possible.

I use muc-off disc-brake cleaner; does the job most of the time. Comes with a handy directional nozzle/funnel thingy so you don't spray it everywhere else too.

rubadub

Lemming wrote: »

t if the squeal persists and can wake the dead, you've probably got pad contamination that requires replacement.

The squeal from mine is like something out of the exorcist, but I have grown to love it, at times. It is a million times better than a bell when some idiot struts out onto the cycletrack, it utterly scares the shite out of them.

Even better is with cars nudging out of roads and onto cycletracks. It sounds absolutely horrendous when I brake, you can see the drivers completely wincing at the sound and putting apologetic hands up. It really sounds like I am jamming on the brakes last second and that it is a total near miss, and that my braking is totally extreme and should be unnecessary and that it is a very abnormal sound.

magicbastarder

magicbastarder wrote: »

how much mileage have you done? six months seems a little short for pads - i replaced my front pads one year, 4,000km, ago and they're still alright (though i must check them now that i think of it!)

took them off while cleaning the bike today, still plenty of meat on them.

speaking of squeal - mine are fine in the dry but squeal in the wet. i'm wary about using copper grease on the back of them - i believe that can help reduce the squeal - because the notion of going near the pads with grease seems to be tempting fate a little.

Leaksireland

Disc brakes will always squeal it’s just dirt and grime build up.
For me I clean the disc with fairy liquid.
Take out the 2 pads, put a drop of fairy liquid on one and rub them together, repeat until clean. That will fix it unless oil has soaked into the pads.

youtheman

My discs squeal from time to time.  In fact I can actually play a tune on them when they get really loud !.  Doesn't really bother me, in fact it's quite reassuring.  I cleaned them (once) in the dishwasher after seeing that tip online.

magicbastarder

i once soaked mine in white spirits and blasted them afterwards with a heat gun.
a cheapo domestic heat gun should be able to get to at least 400C. not that i know what temps i took the brake pads to.

cdaly_

Lemming wrote: »

You say you've got mechanical discs; that implies cable rather than hydraulic operated. Regards your decreased braking performance, have you checked the cable for wear (granted, six months seem a bit off ... ) and/or dirt ingress that might be impeding cable operation? If you've got hydraulics, ignore that last question and check whether or not you've got a fluid leak ... which brings me onto:

Be careful here. Adjusting the brake cable for mechanical disc brakes should only be done to deal with cable stretch, not pad wear. The calipers have adjusters to use for pad wear. Basically you wind them in until the wheel locks then back them off 1/4 turn or so so the wheel spins freely.

Lemming

cdaly_ wrote: »

Be careful here. Adjusting the brake cable for mechanical disc brakes should only be done to deal with cable stretch, not pad wear. The calipers have adjusters to use for pad wear. Basically you wind them in until the wheel locks then back them off 1/4 turn or so so the wheel spins freely.

My comment regards the cable was to address the possible cause behind the complaint of lower performance, not contamination of the pads/waking-of-the-dead noises.

VonLuck

Thanks for all the advice. I will try to take the pads out and give them a quick scrub, see if that improves things.

I do think they are somewhat worn though as I do need to pull further on the brake handles to come to a stop. I cycle in the city so there is a lot of brake usage! Is there a minimum depth of pad I should be checking for or how do you know when it's time to replace them?

And is it possible that the cables have loosened and need to be adjusted as suggested? I park my bike in a narrow rack and it does tend to get a lot of knocks or cable snagging from other bikes.

Lemming

VonLuck wrote: »

Thanks for all the advice. I will try to take the pads out and give them a quick scrub, see if that improves things.

I do think they are somewhat worn though as I do need to pull further on the brake handles to come to a stop. I cycle in the city so there is a lot of brake usage! Is there a minimum depth of pad I should be checking for or how do you know when it's time to replace them?

And is it possible that the cables have loosened and need to be adjusted as suggested? I park my bike in a narrow rack and it does tend to get a lot of knocks or cable snagging from other bikes.

TBH, your problem is probably just pad wear for the most part from what you've described. If you put in new pads and still feel like you need to haul the levers into the bars to get anywhere then I'd look at pad-tweaking such as might be available from your calipers as suggested by others already, then consider investigating the cable-housing for any obstructions (i.e. mud & grime caked into the ends), then the cable in that order.

One other thing that sprung to my mind whilst writing that last sentence: do your brake levers have any travel adjustment? I ask because it is not uncommon (at all) for mtb brake levers to come with adjustment mechanisms on the levers (be they tool or thumb operated) for on-the-fly 'feel' adjustments). For example, my Hope Stealth X2 levers have an adjuster that is an allen key on the inside of the lever/mount area, but my Shimano XT levers have a thumb adjuster on the outside of the levers that allow for the lever travel to be adjusted as you see fit.

Edit: on reflection, I can't speak for MTB mechanical brakes because both of mine are hydraulic brakes which might be a factor regards lever adjustment. I stand open to correction on that.