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Disk Brakes

Old 06-01-21, 10:17 AM
  #1  
alloo
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Disk Brakes

On Disk Brakes how do you know when to change the brake pads? Does it make a sound like cars do? I know the brake levers get closer to the bars, but how do you know if it needs adjustment or new pads? Is they're a mileage standard? Thank You very mucy for your input.
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Old 06-01-21, 10:38 AM
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The pads and rotors are rated for a minimum thickness
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Old 06-01-21, 11:05 AM
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You go for an Oil change, and the Stealership recommends replacement when they are only 50% worn.



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Old 06-01-21, 11:24 AM
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The pad manufacturer specifies the minimum thickness. I just eyeball it. If they start making a clunking sound against the rotor, then they're past due for replacement. And no, the level travel won't change if they're hydraulic, only mechanical ones would.
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Old 06-01-21, 11:40 AM
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When they don't work anymore. It's a process that sees them not working as well, having to apply more and more pressure until there is nothing left in the lever.

That is when I replace the pads.

.... or if they get fouled with oil or grease or some other material
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Old 06-01-21, 11:42 AM
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I simply peek down regularly to see how much is left. When it looks thin, I replace them.
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Old 06-01-21, 11:45 AM
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Originally Posted by dabac View Post
I simply peek down regularly to see how much is left. When it looks thin, I replace them.
Family forum, pal! Reported!
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Old 06-01-21, 01:44 PM
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Originally Posted by alloo View Post
On Disk Brakes how do you know when to change the brake pads? Does it make a sound like cars do? I know the brake levers get closer to the bars, but how do you know if it needs adjustment or new pads? Is they're a mileage standard? Thank You very mucy for your input.
How about you tell us what kind of brakes you have? Disregard all advice til you've posted brand/model.
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Old 06-01-21, 03:01 PM
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Originally Posted by cxwrench View Post
How about you tell us what kind of brakes you have? Disregard all advice til you've posted brand/model.
Cable Disk Brakes on a Blix Aveny. About 3500 miles front brakes/

Tektro Aquila Mechanical Disc Brake, 160mm Rotor
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Old 06-01-21, 03:36 PM
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I give my brakes a visual inspection...After so many years of riding I have a pretty good feel when to replace them....When to change brake pads is really just common sense.
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Old 06-01-21, 04:17 PM
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if they go from braking speed to me breaking skin, that's usually a good indicator that they're spent. looking up the specs & tolerances from the OEM is another method.
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Old 06-01-21, 04:26 PM
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Originally Posted by alloo View Post
Cable Disk Brakes on a Blix Aveny. About 3500 miles front brakes/

Tektro Aquila Mechanical Disc Brake, 160mm Rotor
There is absolutely NO mileage number at which you should replace your pads. It is totally dependent on your individual riding style, your body weight, and how you maintain your bike. Some people tear through rear pads because they're afraid to use the front brake. Some people tear through pads because they live in a wet climate and that wears pads much quicker than a dry climate. Look at a photo of some brake pads...you'll see the backing plate and the friction material. It starts out about 3mm thick. When the friction material gets down to 1mm you should start thinking about replacing them soon. You could have this much wear in a 1 hour wet/muddy CX race or if you live in AZ they could last a year. Check them often. You can look through the caliper or you can look through the opening in the top of the caliper.

When you adjust for wear do NOT use the barrel adjusters, ONLY adjust with the adjustable inner piston and adjusting the caliper position.
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Old 06-01-21, 05:19 PM
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I just changed the front rotor and pads. The rotors have the minimum thickness. The torque specs for the mounting bolts. The diameter, the brand and the direction of rotation printed to the side that faces out between the bolt holes. The rotor I removed had a minimum thickness of 1.5mm and squalled when it wormed up going down a steep grade. The replacement rotor has a minimum thickness of 1.8mm. The pads I replaced were not worn out all the way. The new pads are Kool Stop ceramic instead of the sintered.
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Old 06-01-21, 06:32 PM
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You can usually see how thick they are, just looking between the calipers.

You can take pads out and look at them, which is not really difficult.
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Old 06-01-21, 06:52 PM
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Originally Posted by Rick View Post
I just changed the front rotor and pads. The rotors have the minimum thickness. The torque specs for the mounting bolts. The diameter, the brand and the direction of rotation printed to the side that faces out between the bolt holes. The rotor I removed had a minimum thickness of 1.5mm and squalled when it wormed up going down a steep grade. The replacement rotor has a minimum thickness of 1.8mm. The pads I replaced were not worn out all the way. The new pads are Kool Stop ceramic instead of the sintered.
Minimum thickness of 1.8mm? You sure?
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Old 06-01-21, 07:19 PM
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Minimum thickness of 1.8mm? You sure?
Yes it is a Magura ebike rotor. It can handle the heat better and hopefully wont setup a vibration when it heats up. Magura doesn't state the new thickness. Some of the other brands are 2.3mm thick. There are also less cut outs in it. I'm going to bed it in tomorrow.
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Old 06-01-21, 10:23 PM
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Originally Posted by cxwrench View Post
Minimum thickness of 1.8mm? You sure?
My Magura rotors are 2mm new with a 1.8mm minimum.
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Old 06-01-21, 10:25 PM
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Originally Posted by cxwrench View Post
How about you tell us what kind of brakes you have? Disregard all advice til you've posted brand/model.
Just curious... for what model brakes would “Look to see how much pad is left and replace before it is gone” not apply?
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Old 06-02-21, 12:49 AM
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Originally Posted by Kapusta View Post
for what model brakes would “Look to see how much pad is left and replace before it is gone”
Many of them. You can just squeeze the brakes and look between the calipers.
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Old 06-02-21, 07:48 AM
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Visually just look? We are talking tenths of a millimeter. That will make a difference. I know I'm not good enough to visually look and decide about something that is less than .004 inches (1/256 ths of an inch).

I also will imagine... since mine aren't worn halfway to the recommended replace, that replacing as soon as or even earlier than recommended will help to keep disc brakes from having issues with pistons getting a little askew in the cylinder causing rub and other issues.

Harbor Freight has very cheap digital calipers that are accurate enough for the job. Pads on my brakes come out easily for inspection. And the disc itself needs to be checked to the manufacturers spec. An under spec disc with under spec pads might be even worse on the piston. And which is in the expensive part of the brake to replace.

As to the OP's question, I can only ask why don't they do what the manufacturer of their brakes say to do for that model. Shimano, SRAM and others have documents online that tell exactly when to replace.

Last edited by Iride01; 06-02-21 at 07:52 AM.
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Old 06-02-21, 08:15 AM
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On my Shimano brake pads, I replace them whenever the pad is flush with the separator spring.
I measure the thickness of the rotors and replace them when they reach the minimum thickness - 1.5mm
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Old 06-02-21, 09:03 AM
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Originally Posted by alo View Post
Many of them. You can just squeeze the brakes and look between the calipers.
Actually, it is probably all of them - which was my point (which you misquoted).
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Old 06-02-21, 09:07 AM
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Just to be clear, the OP is asking about pads, not the rotor. It is pretty easy to see if you are running out of pad.

But yes, you need calipers to measure a rotor.
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Old 06-02-21, 09:22 AM
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I know its not the pads, but what happens if you wear the rotor past the minimum thickness.
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Old 06-02-21, 09:28 AM
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Originally Posted by Rick View Post
I know its not the pads, but what happens if you wear the rotor past the minimum thickness.
My assumption is that when the rotor gets too thin, combined with the pads getting too worn, the pistons have to extend farther than intended.
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