bedding brakes in for a commuter: why bother?

[Sunyata]

I never remember to bed in my brakes when I get new pads and I have never had a problem. But… all my disc brakes are hydraulic. Not sure if that makes much difference, though.

[huskerdont]

I bedded in BB7s the fist time, but have not since, for those or Shimano hydraulics. I just let the first ride be the bedding in and haven’t noticed a difference. I suppose that as long as the levers don’t immediately start going all the way in to the handlebars it’s okay, and of course if one brake does, you still have the other.

[Crickey7]

I’m with Sunyata. Many, many pad replacements without bedding, but all hydraulic (about half Tektros, the rest a mix).

[ginacico]

I’ve replaced the pads on BB7s many times, and didn’t know bedding was a thing.

[honestmachinery]

I had a similar noisy experience with new pads and rotors on used BB7s this weekend. I didn’t touch the rotor faces while installing, but I didn’t degrease them either. Probably should have. Will try that before testing again.

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[bentbike33]

Seems to me the whole pad bedding recommendation is a way to get you to practice some panic stops in a non-panic situation to: (1) make sure everything is still working correctly after the installation (e.g., no misplaced lubricant) and (2) give you advance warning of any change in braking characteristics caused by the new equipment.

[hozn]

I generally bed in new pads. I don’t think that there is a noticeable performance difference, but bedding them in leaves me confident that my brakes will stop the way I expect them to. (Brake strength improves noticeably after a bunch of those bedding in slow-downs.)

As for the squealing …. I would guess a contaminated rotor, though I have had some pads (jagwire scintered come to mind) that are just noisy pads. I switched back to organic on my commuter so I don’t scare peds when it is wet out.

[peterw_diy]

@hozn 182554 wrote:

I generally bed in new pads.

What’s your preferred technique?

As for the squealing …. I would guess a contaminated rotor, though I have had some pads (jagwire scintered come to mind) that are just noisy pads. I switched back to organic on my commuter so I don’t scare peds when it is wet out.

Yeah, I’ve rubbed the rotor down with isopropyl alcohol, which helped only for a bit. I think I might pull and lightly sand the pads next. Supposedly the brakes ship with organic pads, but I wonder if they’re more metallic than my resin-only Shimano rotor likes.

[hozn]

@peterw_diy 182581 wrote:

What’s your preferred technique?

I think I use the same technique: accelerate to 15-18mph then brake smoothly back down to walking speed and do that a dozen or so times.

[peterw_diy]

@hozn 182582 wrote:

I think I use the same technique: accelerate to 15-18mph then brake smoothly back down to walking speed and do that a dozen or so times.

Thanks. And I just noticed on my old invoice that my rotor is an RT66, which should work with and pads.

Time to clean, sand, and try again…

[peterw_diy]

Status update: rotors matter!

Cleaning the rotor with alcohol only bought me a little time – the squealing returned. So I tried cleaning the rotor and installing new pads. I think the old/original pads might be metallic: all the way through, their color is dark, like black coffee, while the new, organic pads are the color of pate.

Within a few urban miles, I heard awful pinging sounds under moderately hard braking, as of something were plucking spokes. Six pings per wheel revolution. Why? The Shimano RT66 rotor’s brake track is a few mm narrower than, say, a SRAM Clean Sweep G2 that I had purchased for a new wheel. Here’s a photo of the old Shimano rotor laying on a SRAM rotor; you can clearly see on the Shimano arms that the SRAM pads extended closer to the hub than did the brake track. Six times per wheel revolution, the bottom of the pads hit a rotor arm. Ping ping ping. I think this is also evidence that the original pads were not organic, but some harder compound that didn’t compress as much.

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I’ll see how it goes tomorrow, with the SRAM rotor in place, cleaned well, and a brand new set of organic pads. If this sucks badly I might just go back to the front canti brake! 😉

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