I was wondering how to tell when your disk brake pads need replacing. My front brake seems to be not stopping as quickly as it used to, or as quickly as I would like. I know this could be due to road grime build up, but I am unsure if this would be a reason to replace the pads. What would be the indicators be that would call for replacement of the pads?
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When brakes are worn to metal, they emit the loud squealing and screeching sound when applied but it is not time, it is too late.– nightriderCommented Nov 13, 2023 at 17:39
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5 Answers
I change mine as soon as they don't work as expected. You usually notices this when you have to apply an unusual amount of force on he levers to make the bike brake. It really depends on how much you use the bike, it can be enough to go out in the rain and brake hard a couple of times to destroy a set of break pads.
answered Aug 26, 2010 at 3:02
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1Thanks, I thought it might be just that, but wondered if there were other indicators, like car brakes will squeak when they get low. Looks like I'm going shopping for some brake pads. Commented Aug 26, 2010 at 22:50
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3Thus is dangerous advise. When you notice it while braking it may be quite a bit too late.– gschenkCommented Apr 24, 2019 at 14:41
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4@gschenk Concur. Pads should be replaced when they pad material wears down to the minumum specified by the manufacturer. Commented Apr 24, 2019 at 22:48
You should just pull the pads out and see how worn down they are - or if they are really dirty. Sometimes it helps to get some rubbing alcohol and clean the pads and rotors.
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3+1 because this method is quite objective i.e. you can see how far down is the resin worn off, is there only half a milimeter to the steel bed.– VoracCommented Jul 5, 2012 at 7:26
Shimano and SRAM specify minumum pad thickness, which you can look up. Park Tool suggest at least 1mm, which you can measure with 3 business cards.
answered Apr 24, 2019 at 13:09
I've had disc brake pads become poor performing well before they are worn out, with no recovery possible, so I now keep a small stock of relatively cheap pads to swap out when I start to get performance issues.
Causes of poor performance? Hydraulic fluid leaking from brake cylinders (even tiny amounts you cannot see) or burning of pads by over-exuberant use before they are bedded-in. I'm getting better at both these issues!
I never change mine until I hit metal on part of the pad. Hitting metal is probably the only indicator that accurately predicts the true state of wear on the pad. All the other "feelings" that maybe the brakes aren't performing as well as they used to are generally just based on the conditions they've been subjected to over the past few days (as OP noted). I've had pads that worked like complete garbage in the rain, and after I took them on a gentle downhill in the sunshine, worked amazing in all conditions afterwards. Side note - that's also how I get the screaming banshee sound to go away on a loud set of pads.
Basically, if you're noticing a difference in braking quality at the top of the pad vs the bottom, you should be very concerned about the manufacturing process that the pad manufacturer is using. There should be no difference between the top of a sintered pad (I assume the same goes for organic) and the bottom. As long as you have some pad material left over the entire area of the pad, you're good.
And yes, I assume that the OP has replaced pads by now :)
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2I imagine having no pad material left to brake with to be a somewhat inconvenient thing to notice while riding your bike at speed down a hill.– gschenkCommented Apr 24, 2019 at 8:49
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5-1 for a dangerous suggestion, all manufacturers specify a minumum pad thickness. Wearing pad down to the metal backing plate can severely degrade it's performance and damage the rotor. Commented Apr 24, 2019 at 13:05
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1@ArgentiApparatus concur - as the pad thins there's a chance entire chunks will come off, leading to a sudden decrease/stepdown in braking effectiveness– Criggie ♦Commented Apr 24, 2019 at 22:10