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Just as the title suggests, I have one bike where I'm pretty sure I've rushed the bedding and the brakes are just not performing ... I get honking momentarily every now and then with some vibration but still enough power to otb (so i know it's not contamination).

I've read some people sand and clean the rotors ... even putting them in the dishwasher to make sure they're proper clean. Others sand down the pads also. And then re-fit and start bedding again.

Is there a confirmed process that works? what grit sandpaper is suggested for the rotors and the pads?
 

· Out spokin'
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I'm not familiar with the brakes (I use Shimanos) but I run the same brand / model rotors that you do. Maybe not the same size rotors, tho.
As for pads, I hope someone else comes along to comment -- I've only had poor experience with resin pads but this was years ago and someone on these forums recently said that newer resin pad compounds are better than old resin pads so maybe that's not it. In any case I won't be giving up my semi-metallic pads anytime soon -- I really feel they offer the most power.
What size rotors? I'm using 203-220mm.

Some people feel that the brake bedding process is important. I'm not one of them. I ride my bike, the brakes bed fine.
If I were you, I'd look at rotor diameter (I don't know what you're using now) and pad compound for overall brake performance improvement.
But maybe / certainly someone else will be along shortly to disagree. :)
=sParty
 

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+1. I put brakes on and ride, and I even gasp interchange rotors (by way of wheelset). I'm blissfully unaware (or have adapted to) any reduced performance from this practice. In what ways are the brakes underperforming? Honking is part of life in the PNW so that doesn't really get a second thought from me. The first things I'd check for vibration are: rotor true, and mounting integrity.
 

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Just as the title suggests, I have one bike where I'm pretty sure I've rushed the bedding and the brakes are just not performing ... I get honking momentarily every now and then with some vibration but still enough power to otb (so i know it's not contamination).

I've read some people sand and clean the rotors ... even putting them in the dishwasher to make sure they're proper clean. Others sand down the pads also. And then re-fit and start bedding again.

Is there a confirmed process that works? what grit sandpaper is suggested for the rotors and the pads?
I doubt the bedding process was responsible for the honking noises. Contaminated brakes can still lock up the wheels so I wouldn't rule that out.

I go through this practically every day on various bikes so I know how frustrating it can be. I would start by trying the bedding process again. A long paved downhill works best for me so I can drag the brakes multiple times without having to work too much. Doing this often cures the problems you describe.

If that fails I'd move on to cleaning the heck out of the rotors with hot, soapy water and rinsing then rinsing them thoroughly. Hit the pads with ~100 grit sandpaper and then clean them and your rotor (again) with alcohol. Also the caliper.

Bedding is important to get a smooth coating of brake material on the rotor and to avoid depositing a permanent blob of material that you can feel every rotation of the rotor. This can happen when you come to a sudden, complete stop with new rotors.
 

· Out spokin'
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I even gasp interchange rotors (by way of wheelset).
I do likewise -- have 3 bikes and 2 of these bikes each have 2 wheelsets. So 3 bikes, 5 wheelsets total. I switch 'em all the time. No braking problems from one to the next.
My brake setup priorities:
  • Known high performance brakes (personally I prefer Shimano, that's not to say other brands aren't good)
  • Larger diameter rotors (203-220mm)
  • Semi-metallic pads
My braking performance has never gone lacking with these parameters. No bedding process necessary. Maybe riding steep / fast terrain often helps, too... dunno.
=sParty
 

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I do likewise -- have 3 bikes and 2 of these bikes each have 2 wheelsets. So 3 bikes, 5 wheelsets total. I switch 'em all the time. No braking problems from one to the next.
My brake setup priorities:
  • Known high performance brakes (personally I prefer Shimano, that's not to say other brands aren't good)
  • Larger diameter rotors
  • Semi-metallic pads
My braking performance has never gone lacking with these parameters. No bedding process necessary. Maybe riding steep / fast terrain often helps, too... dunno.
=sParty
Organic pads can work great too but they don't last as long as metallic. They're easier on rotors though.

No, you don't have to do a proper bedding process but for optimal performance and reasons mentioned above it's best to do it on any new build or brake install imo. It only takes a few minutes.
 

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ahh dont use ipa on the resin pads. it can soften them and if you try bedding them in, they will instantly glaze up. let them sit overnight before using again. bestter yet just use a bit of wetsand sandpaper to remove any glaze and your good to go.
 

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yep drove me nuts till ifigured out my mistake.
Never a problem for me since the dawn of Avid Juicy. Reference please? Alcohol doesn't seem to be a solvent for pad material.

I found some small forum posts with indirect anecdotes about "soaking" resin pads in alcohol, but countered by other people that use it. And plenty of articles saying its about the best OTC option...

There are alternatives like brake cleaner / acetone but isopropyl alcohol doesn't have the same downsides and is not even a dollar a bottle.

Sent from my iPhone using Tapatalk
 

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Never a problem for me since the dawn of Avid Juicy. Reference please? Alcohol doesn't seem to be a solvent for pad material.

I found some small forum posts with indirect anecdotes about "soaking" resin pads in alcohol, but countered by other people that use it. And plenty of articles saying its about the best OTC option...

There are alternatives like brake cleaner / acetone but isopropyl alcohol doesn't have the same downsides and is not even a dollar a bottle.

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guess im wrong then. dont worry about it.
 

· Elitest thrill junkie
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Right now Kia is trying to ignore a braking problem with some of the Brembo-equipped models. They will pulse badly and eventually warp the rotors, all because of a vibration issue, just like we get with mtb disc brakes. There are cars (stingers) where they have replaced the rotors and pads 3 times. THREE TIMES in a row! The thing is you can't know exactly what will fix this issue with no testing, because you've got to change the frequency. In the automotive world, sometimes they do this by weighting the pads, sometimes by weighting the calipers. Sometimes by changing the system with new rotors or even a different kind of calipers. It's kind of crappy when you don't know. There are people trying to feed the line by Kia that it's due to "brake deposits" due to a bad bed-in procedures, but seriously, like every single car is driven and braked before you buy it, whether it's on and off the ship, on a trailer, on test-drives, etc. It simply can't be this unless there is some crazy disintegrating pad issue where the pad material is just falling apart. That DOES happen very rarely, where the pad process went bad and a bunch of flawed pads went out, but that's a pretty obvious issue and your pads are basically crumbling, not going to be happening except for some ultra-rare situations.

I mean, a bunch of bikes are going to be ridden at the shop on short test rides. Do all of those also need new pads and sanded rotors, because they weren't "bedded in right"?

When I have installed automotive brake rotors and pads, the number 1 thing I've read about break-in in the associated literature is that it is normal that you will NOT have maximum power initially until the rotors/pads are bed in. This means you can NOT count on full power, which could be potentially dangerous. This is why it's saying to go out and do the bed-in process, because it makes the availability of full-power faster. Going out on say a race-course could be disastrous with brand new brakes and pads, with no bed-in.

All that said, I'd dump resin pads fast. I have a few applications where I use them, but I'd get ride of them quick if I was experiencing that problem. Metal sintered pads just work better more of the time. They wear rotors a little faster, but it's worth it IME.
 
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I thought I had performed a bad bleed on my rear XT a couple of days ago. Power just wasn't there anymore, but the lever felt good. Before barking up the re-bleed tree, I removed the pads, and cleaned both them and the rotors with 91% isopropyl alcohol until no more crud on the paper towels, re-assembled, re-bedded. Everything works great now, so clearly I had contaminated the pads. Worth a try anyway.
 

· high pivot witchcraft
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I thought I had performed a bad bleed on my rear XT a couple of days ago. Power just wasn't there anymore, but the lever felt good. Before barking up the re-bleed tree, I removed the pads, and cleaned both them and the rotors with 91% isopropyl alcohol until no more crud on the paper towels, re-assembled, re-bedded. Everything works great now, so clearly I had contaminated the pads. Worth a try anyway.
I did something similar yesterday. My brakes were squealing a little so I hit the rotors only with IPA and a paper towel pre-ride. It only took a couple of minutes, and things were quiet as a mouse as as I plummeted off this:
Tire Bicycle Wheel Cloud Bicycle wheel

Never organic pads for me.
 
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