# How do I know when pads are worn out?



## Debian (3 Feb 2010)

As per heading.

I've only recently acquired a bike with discs. Without dismantling them how do I know if the pads need changing? I don't want to find myself out on a long ride and half way through it my pads give up.

Carrying a spare set just in case isn't really an option as I don't relish trying to change pads on a mud encrusted caliper mid-trail.


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## GrumpyGregry (3 Feb 2010)

how you tell varies from manufacturer to manufacturer and from brake to brake. The maker's website will usually have a document somewhere like this which explains how you measure wear. e.g. _Avid brake pads should be replaced when the total thickness of the backing plate and pad friction material is less than 3mm._

But you check 'em before you go on the long ride and avoid the problem I guess.

I always carry a spare set, just in case, though I've only changed them on trail once when on hols in the Alps because the old pads, whilst within wear tolerance, were making a horrible noise which got right on my wick.


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## Cubist (3 Feb 2010)

Debian said:


> As per heading.
> 
> I've only recently acquired a bike with discs. Without dismantling them how do I know if the pads need changing? I don't want to find myself out on a long ride and half way through it my pads give up.
> 
> Carrying a spare set just in case isn't really an option as I don't relish trying to change pads on a mud encrusted caliper mid-trail.



Check them in the workshop/garage/kitchen/lounge before you ride. It takes a couple of minutes to take the wheel off and look at the pads to check for wear. Every week or so you need to take the pads out of the calipers and check to see that they still have plenty of meat on them. They reckon 1mm of material as a minimum. 

Don't be scared of them, they are far easier to maintain and change than rimbrake pads. I reckon I could change front and rear of my Hayes Strokers in about 20 minutes, and that would include cleaning the calipers and rotors, and centring them afterwards. .


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## CyenceSycle (4 Feb 2010)

I just wait till they stop working! Seriously. 

You can tell when they're about to go because you have to pull further on the lever and they quite rapidly deteriorate from there. I'm hardly ever more than 10 miles from my house or a bike shop and they're really easy to change so I wouldn't worry about it too much. 

PS I only ever deal with mechanical brakes, wouldn't know if that is the case on hydraulics


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## GrumpyGregry (4 Feb 2010)

Try finding out at Les Gets or Leogang or on 'severed dick' and do let me know the outcome


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## MacB (4 Feb 2010)

Cubist said:


> Don't be scared of them, they are far easier to maintain and change than rimbrake pads. I reckon I could change front and rear of my Hayes Strokers in about 20 minutes, and that would include cleaning the calipers and rotors, and centring them afterwards. .



I find v-brake pads with v's or cantis pretty easy to change


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## Debian (5 Feb 2010)

Thanks for the replies everyone.

I've never had to deal with hydraulic discs before and I've read many horror stories of people taking hours to replace a set of pads. OTOH others have written that it's pretty easy, I guess I won't know till I try so I'd better pick up a set this weekend and then have a look at my existing ones.

I've never had a problem with V brakes either, I can change those and set them up in a few minutes. I've always found V-brakes perfectly OK for the sort of riding I do (mainly XC), the only thing I dislike about them is the godawful noise they make when they get wet and muddy!

Any tips or tricks about changing Avid Juicy pads? I've read the theory and it sounds like they should be changeable in a couple of minutes but I bet that's not the way it'll work out for me.


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## summerdays (5 Feb 2010)

Don't let your child help you when you are doing it... mine pulled the brakes on whilst the wheel was out.


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## Steve Austin (5 Feb 2010)

Avid Juicy pads a right pain to change. Wait till they wear out completely would be my advice, the pad is only wafer thin, so you can't really tell when they are about to wear out.

To change them. You need to push the pistons back in, if you don't you won't get the new pads in. I use a large flat bladed screwdriver. insert screwdriver in between old pads, and slowly twist it until the pistons are fully back in. pop old pads out, insert new pads.
There I made it sound easy! its not

You shouldn't need to bleed


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## Cubist (6 Feb 2010)

MacB said:


> I find v-brake pads with v's or cantis pretty easy to change


Bravo!


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## Debian (6 Feb 2010)

Steve Austin said:


> Avid Juicy pads a right pain to change. Wait till they wear out completely would be my advice, the pad is only wafer thin, so you can't really tell when they are about to wear out.
> 
> To change them. You need to push the pistons back in, if you don't you won't get the new pads in. I use a large flat bladed screwdriver. insert screwdriver in between old pads, and slowly twist it until the pistons are fully back in. pop old pads out, insert new pads.
> *There I made it sound easy! its not*
> ...



This is what I've heard and it's why I'm dreading having to change them.


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## Cubist (6 Feb 2010)

Steve Austin said:


> Avid Juicy pads a right pain to change. Wait till they wear out completely would be my advice, the pad is only wafer thin, so you can't really tell when they are about to wear out.
> 
> To change them. You need to push the pistons back in, if you don't you won't get the new pads in. I use a large flat bladed screwdriver. insert screwdriver in between old pads, and slowly twist it until the pistons are fully back in. pop old pads out, insert new pads.
> There I made it sound easy! its not
> ...


What make s Avids so hard to change? The Hayes are a piece of the proverbial on my Cube, but will eventually have to change the Elixirs on the Boardman, what have I got in store? The Hayes sequence is:
Remove wheel, using flat bladed screwdriver or other proprietory wedge force old pads as far open as possible, undo small allen bolt, use it to push old pads out, quick squirt of brake cleaner on caliper body, wipe with rag, place new pads into caliper body, replace allen bolt, brake cleaner on old rotor, thorough wipe, replace wheel, centre brakes, choose steep hill to bed pads in, recentre, get on with life. About ten minutes all in at last count.


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## Debian (6 Feb 2010)

Cubist said:


> *What make s Avids so hard to change*? The Hayes are a piece of the proverbial on my Cube, but will eventually have to change the Elixirs on the Boardman, what have I got in store? The Hayes



This what I'd like to know.

I read so many times that Avid pads are the devils work to change but I'm not sure why.

Can any Juicy user enlighten me?

Anyone have an idiots guide to changing them?


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## summerdays (7 Feb 2010)

For Mr Summerdays (see I didn't even do it myself), it was that little bit of metal hinge that the pads sit in - trying to get the pads into it then onto the bike seems to result in a bit of swearing...


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## Steve Austin (7 Feb 2010)

There is no idiots guide. They are a pain to change.

As i said, just try to make sure you have pushed the pistons back in, before you try to insert the new pads. I use a large flat bladed screwdriver to wiggle in between the old pads, then insert a 5mm piece of petal in between them, to slowly lever them apart as far as i think they can go, then, remove the old pads, and try to insert the new ones.

I know people who have worked on bikes for years and this is their least favourite job. I regard building wheels, setting mechs, bleedings brakes, stripping forks as easier


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## Debian (7 Feb 2010)

Thanks! (I think)


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## GrumpyGregry (7 Feb 2010)

push the pistons back, all the way back, with a twist of a screw driver or other lever, whilst the old pads are still in situ

not as hard as changing brembo goldline pads on a laverda


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## Cubist (7 Feb 2010)

GregCollins said:


> push the pistons back, all the way back, with a twist of a screw driver or other lever, whilst the old pads are still in situ
> 
> *not as hard as changing brembo goldline pads on a laverda*


My Lemon had Brembos. Twats.


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## rusky (7 Feb 2010)

Whenever I recentre the calipers on my Hayes (using the method they describe) I always end up with the caliper too far away from the moving pad.

Changing the pads is quick & easy as long as I don't set them up the way Hayes suggest.


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## 2Loose (7 Feb 2010)

Did my Juicy 3's last weekend - a bit fiddly but a doddle in the end. 

Once everything is out, then it is easy to see how everything goes back together and then you wonder why it doesn't. When I figured out that the pads were the wrong way round, it was all done 1 minute later. Pads have been in and out 3 more times since, each time takes less than 5 minutes but after the first half hour faff I wanted to get it ingrained on my brain.

Top tip, when trying to get pads back in, look through the hole in the top of the caliper, it will help check if the h-clip is in the right position. If it isn't, slide the pads out again and turn them around...


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## 2Loose (7 Feb 2010)

summerdays said:


> Don't let your child help you when you are doing it... mine pulled the brakes on whilst the wheel was out.



LoL, at least your child didn't undo the banjo bolt like a 'helpful' friend did. 
£35 quid bleed kit and new pads and all is well now :'(


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## Valy (13 Feb 2010)

I changed the pads on my BB5s and it even though it was a bit fiddly, I got them in okay. 
With hydraulic brakes do the pistons always try to push out, so you have to hold them apart all the itme while trying to change the pads?


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## Debian (13 Feb 2010)

Valy said:


> I changed the pads on my BB5s and it even though it was a bit fiddly, I got them in okay.
> With hydraulic brakes *do the pistons always try to push out, so you have to hold them apart all the itme while trying to change the pads*?



I wouldn't have thought so. They don't on a car. And if they did this normally the brakes would be applying themselves all the time.

The only way the pistons will push out is if there's some force acting on the brake fluid.


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## Valy (13 Feb 2010)

Debian said:


> I wouldn't have thought so. They don't on a car. And if they did this normally the brakes would be applying themselves all the time.
> 
> The only way the pistons will push out is if there's some force acting on the brake fluid.



So the pistons don't push out more when trying to change the pads? I mean not to the point where they would be touching the rotor, just pushing out because presumably the retainer/spring would need to be removed than pushes the pads away after braking? Is there such a device on hydraulic brakes even... ?


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## Debian (13 Feb 2010)

Valy said:


> So the pistons don't push out more when trying to change the pads? I mean not to the point where they would be touching the rotor, just pushing out because presumably the retainer/spring would need to be removed than pushes the pads away after braking? Is there such a device on hydraulic brakes even... ?



It's a good question.

All I can say is that the pistons on car brakes don't move out under there own steam, they just stay wherever they're pushed to. I haven't (yet) changed bike hydraulic brake pads but I can't see why the pistons should push out.


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## Valy (14 Feb 2010)

Debian said:


> It's a good question.
> 
> All I can say is that the pistons on car brakes don't move out under there own steam, they just stay wherever they're pushed to. I haven't (yet) changed bike hydraulic brake pads but I can't see why the pistons should push out.



Yeah that would be reasonable. It's just there is all this talk about putting something between the pistons... and doing this and that....

All I had to do was take the retainer out, fiddle the new pads into position and put the retainer back in. As well as adjust for new pads of course.


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## arallsopp (15 Feb 2010)

BB7s (mechanical) are pretty easy too. Mine ran fine for a good 5000 miles of hilly commute in all weather before becoming increasingly gritty, grindy, whirry, slack, and generally annoying. Dead pads diagnosed (and confirmed by looking through the little hole at the top).

Remove wheel, slacken off adjusters, pinch the pads, pull them out... pull them out...C'mon frickin things... Pinch the pads, pull them out... Find the manual.. Pinch. The. Pads. Pull. Them. Out. Aaaarrrrgh! 

£45 and two days later, new brake arrives with new rotor, new pads, new body. Loosen off bolts, fit new one. Centre it. La! 

Put old one in the box for spares. Pinch the pads. Frick. They came out! Worn pretty much flat too. 

Now I have a spare. Which is nice, as I have a total of 4 of these on 2 bikes, and there's no differentiation between front and rear.

I like them.


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## Valy (15 Feb 2010)

Did you buy a whole new brake instead of replacing the pads? :S 

My rear pads lasted only about 1000Kms and the front ones area gonna be replaces pretty soon as well by the looks of things.


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## arallsopp (15 Feb 2010)

Valy said:


> Did you buy a whole new brake instead of replacing the pads? :S



Yup. I'm not proud of it, but it worked. 

After bikefix diagnosed an 'unrepairable issue' and swapped out a prior BB7, I'd been running 3 x BB7s and 1 x shimano odd thing. They also put a pretty crap rotor on the SON wheel, so faced with £17 pads + £20 rotor to get things shiny and new, chucking in less than a tenner to get all my bikes running on the same kit was well worth it.

No idea what the shimano one was, but it only managed a third of the distance of the bb7s before getting quite nasty.


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## GrumpyGregry (15 Feb 2010)

Cubist said:


> My Lemon had Brembos. Twats.



so did mine. and my beemer.

what mk was your lemon?


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## Cubist (15 Feb 2010)

GregCollins said:


> so did mine. and my beemer.
> 
> what mk was your lemon?


You had to ask? MkII, red and black V regger!


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## GrumpyGregry (15 Feb 2010)

Cubist said:


> You had to ask? MkII, red and black V regger!



sir knap! 'cept mine was on a W plate. MK II was the best sort I reckon. I don't have it any more but see her on the roads around Worthing and Dorking from time to time. No more motor bikies for me since b-i-l had a huge accident on his.


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## Cubist (15 Feb 2010)

Sold mine when the insurers wanted £1500 from me in the late eighties, and had to drop down to a 500cc. Mind you, the little Kwak I got then performed as well as the Guzzi and the Japs had finally got the idea of going round corners by then! (edit, and I could shave my beard off and wear a full face helmet as well!) 

I eventually got totalled on a ZXR750 back in 1993. Lucky to keep my leg, and Mrs Cube pointed out that she'd like kids before I killed myself completely, so it was time to move on


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## GrumpyGregry (15 Feb 2010)

Cubist said:


> Sold mine when the insurers wanted £1500 from me in the late eighties, and had to drop down to a 500cc. Mind you, the little Kwak I got then performed as well as the Guzzi and the Japs had finally got the idea of going round corners by then! (edit, and I could shave my beard off and wear a full face helmet as well!)
> 
> I eventually got totalled on a ZXR750 back in 1993. Lucky to keep my leg, and Mrs Cube pointed out that she'd like kids before I killed myself completely, so it was time to move on



had a Guzzi V50MkII, great bike, before the lemon and owned the Monza variant some years later. Don't really know why, given the hugely superior technology of Japanese bikes from the mid 80's onwards, but having passed my test in '77 on a Honda CB200 I never owned another riceburner. Worst bike I ever had was a Meriden-era Bonneville which broke down on the way home from the dealership...


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## Cubist (15 Feb 2010)

I had a V50 Mk II as well. Lovely bike, superb handling, sold it to a girl in Leeds who had it stolen a week later. 

There was a definite shift in bike handling from the Japanese stuff around the time I had the Lemon. My mate had a Duke 900 SS Desmo. A lot of the guys in the village had big Jap muscle things like Kettles, a Honda 900, a CBX etc yawn, yawn, but we used to blow them all into the weeds as soon as the roads got twisty.

That all changed with the Ninjas and Katanas etc. My last bike was a ZXR 750, an unashamed hooligan tool. It broke the speed limit on the sidestand, and just used to whisper "cane me, cane me". It did absolutely ridiculous speeds, and was a scratcher's dream. Ironically I was written off the day I stayed behind a pick up truck doing 60 in a 60 limit!


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## GrumpyGregry (15 Feb 2010)

I rode a CBR600 for a bit, company pool bike, back in the early 90's, and almost bought a Pan-European (ironically the type of bike b-i-l nearly died on as a 'bike paramedic) shortly after but went for an pre-owned R100RS instead - I was commuting the entire length of the M4 every weekend. And a mate leant me his VFR750 for a weekend on my RGS Jota.

Jap bikes are hugely HUGELY competent but a teeny bit soulless imo. Bit like Shimano vs Campag maybe 

All a bit academic now; I drive a cinquecento anti-car now when I'm not cycling.


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## Bodhbh (5 Mar 2010)

Related question: How do you know when the discs themselves are worn out? I imagine as they wear down too much there is a chance of mechanical failure on them?


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## arallsopp (5 Mar 2010)

Bodhbh said:


> Related question: How do you know when the discs themselves are worn out? I imagine as they wear down too much there is a chance of mechanical failure on them?



The rule I follow is that if there's something noticeably wrong with the rotor, you should replace it. Is it drumming under braking? Deep gouges in it? Scored all the way round? Concaved? Pitted? Near impossible to adjust the pads to?

Rotors do go out of true, and the application of a strong pair of thumbs (a fork, or (if you're into it) the two pronged park rotor tool equivalent) will restore them. I tune mine maybe twice before discarding them. Maybe once every 5000 miles or so, on a road bike.


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