New brake pads too tight...

Santapez

Well-Known Member
Team MTBNJ Halter's
I just read this. In 25+ years of mountain biking, I have never heard of anyone needing to replace a worn disc. Is that really a thing?
I have worn through multiple discs. While I can't say the braking performance was bad, they certainly were under the limit when measured and visually were really thin where the pad contacts.

I don't like a lot of free-throw before the pad contacts the rotor and new rotors definitely helped with that especially as the pads wear.
 

shrpshtr325

Infinite Source of Sarcasm
Team MTBNJ Halter's
I just read this. In 25+ years of mountain biking, I have never heard of anyone needing to replace a worn disc. Is that really a thing?

technically yes, the rotors on your bike wear just like the rotors on your car. however i have managed over 8k miles on a set of rotors and not had to change them so it is much less wear on a bike compared to the wear you put on your pads.
 

a.s.

Mr. Chainring
I have worn through multiple discs. While I can't say the braking performance was bad, they certainly were under the limit when measured and visually were really thin where the pad contacts.

I don't like a lot of free-throw before the pad contacts the rotor and new rotors definitely helped with that especially as the pads wear.
Was that with alloy rotors or steel? Or both?
 

Santapez

Well-Known Member
Team MTBNJ Halter's
Was that with alloy rotors or steel? Or both?
Do Alloy rotors exist?

Steel, and none of them were organic-pad-only rotors as I gave those away whenever I ended up with them. I can't recall specially which they were but would have been the normal Avid/Shimano mid-range ones.

I just assumed it was from wet/muddy conditions.
 

a.s.

Mr. Chainring
Do Alloy rotors exist?

Steel, and none of them were organic-pad-only rotors as I gave those away whenever I ended up with them. I can't recall specially which they were but would have been the normal Avid/Shimano mid-range ones.

I just assumed it was from wet/muddy conditions.
I guess I don't ride in enough wet and muddy conditions.
 

Cassinonorth

Well-Known Member
not sure why he has you adding water, water does NOT increase the speed at which the pads wear in, all it will do is carry the dust away (maybe).

I'd be shocked if that were true. All I've ever heard was that wet = faster wear. True in my real world experience as well. I'd love to be wrong if you have any sources that disagree...google is coming up empty.

I just read this. In 25+ years of mountain biking, I have never heard of anyone needing to replace a worn disc. Is that really a thing?

Absolutely lol. Over a long enough time period the rotor wears down under their recommended thickness which is usually posted on the rotor. I'd take a caliper to yours, you'll be surprised.
 

shrpshtr325

Infinite Source of Sarcasm
Team MTBNJ Halter's
I'd be shocked if that were true. All I've ever heard was that wet = faster wear. True in my real world experience as well. I'd love to be wrong if you have any sources that disagree...google is coming up empty.



Absolutely lol. Over a long enough time period the rotor wears down under their recommended thickness which is usually posted on the rotor. I'd take a caliper to yours, you'll be surprised.

water on its own is a mild lubricant. Its the same concept as wet sanding, wet sanding is considered a slower (finishing) process over dry sanding with the same grit paper. The reason wet weather wears pads/rotors faster is because the water carries all that mud and grit into the interface instead of the dry dirt that mostly just falls away.

 

ebarker9

Well-Known Member
I'm not sure why bedding pads with water is a thing, but I've found that it works better as well. Could be some combination of more finely finishing the surfaces of the pads, something to do with the way that material is deposited on the rotor, flushing away the grit, or some other interaction with the pad material that isn't totally comparable to wet sanding.

Also not sure what the deal is with rubbing the pads together under water to start, but I've seen multiple sources recommend this, and I've again found that it does work well. There's an initial period where a bunch of "gunk" comes off of the pads and then it stops. I'm not clear whether that is actually removing some "bad" material that shouldn't be on there, or if the water just starts to run clear because the pads become less effective at removing material as they effectively polish each other.

Regardless, pad bed in is the most finicky part of working on bikes (at least for me) and this is a process that's worked consistently for me, so it's what I'll continue to do unless a better process emerges.
 

a.s.

Mr. Chainring
I wet a paper towel with alcohol and rub the rotors clean. I then take fine sandpaper and scrub the rotors in both directions, wipe the grit off with the paper towel, and install the pads. I’ll ride around my house as well as up and down the driveway a few times and the pads are bedded (is that a word?). I’ve never had a problem doing this.

For shits and giggles, I inspected my rotors today and could not see any noticeable wear. Maybe the next time I take it to the shop the mechanics will see something different. But they won’t. Because in the bazillion times I’ve taken my bike to the shop, I have never been told I have worn rotors. :rolleyes:

Also, my new pads are no longer rubbing. I must have worn down the rotors. 😂

:banana:
 

Norm

Mayor McCheese
Team MTBNJ Halter's
I put new brake pads in at the trail head and bed them in on the first descent.

I've replaced rotors due to wear on several occasions. They don't look worn, but if you hold new rotors up to them, they are laughably thinner.

Like, did you actually laugh?
 

JimN

Captain Wildcat
Team MTBNJ Halter's
Like, did you actually laugh?

Yeah, because I would have never thought they would wear that much.

Apparently they are also more frail when they wear down.

1683162616721.jpeg
 

Santapez

Well-Known Member
Team MTBNJ Halter's
In Jim's defense, he put new brakes on his Honda Fit at 90k. Mine has 96k on the brakes and the tires the car came with are still on it.
 

Cassinonorth

Well-Known Member
I wet a paper towel with alcohol and rub the rotors clean. I then take fine sandpaper and scrub the rotors in both directions, wipe the grit off with the paper towel, and install the pads. I’ll ride around my house as well as up and down the driveway a few times and the pads are bedded (is that a word?). I’ve never had a problem doing this.

For shits and giggles, I inspected my rotors today and could not see any noticeable wear. Maybe the next time I take it to the shop the mechanics will see something different. But they won’t. Because in the bazillion times I’ve taken my bike to the shop, I have never been told I have worn rotors. :rolleyes:

Also, my new pads are no longer rubbing. I must have worn down the rotors. 😂

:banana:

Somewhere, a bike engineer's head just exploded.

Do you think they put the minimum thickness spec on the rotors for fun?
 

a.s.

Mr. Chainring
In Jim's defense, he put new brakes on his Honda Fit at 90k. Mine has 96k on the brakes and the tires the car came with are still on it.
Wait-so you’ll change your bike rotors multiple times but the car…
 
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