Mechanical Disc breaks saga - episode 1

The other thing to add is about squeal. It is down to vibration at an audible frequency.

It tends to be caused by an imperfect setup (which I posted in the previous response) or through contamination.

If you cleaned the rotors before operating the brakes FOR THE FIRST TIME and have not got any cleaner, lube, gt85 spray etc on the rotors since and cleaned them with isopropyl alcohol on a regular basis, then the pads shouldn't be contaminated. If you didn't do this, then despite cleaning the rotors you may have contaminated pads. They could have become contaminated whilst riding, say through an oily puddle, from road spray etc. This can affect braking performance and cause squealing under braking.

It can be other reasons too - on cool, damp days you can get squeal which once the discs are warmed up disappears but can then return after they cool down again! I've had this but on a dry, warmer day, without cleaning or touching the rotors in between, had no squealing at all.

Trying a different compound can help assuming everything is set up correctly. I used to buy Uberbike sintered pads for my BB5s which I found great and they hardly squealed at all.

So, setup and cleaning with isopropyl alcohol are the key to stopping brake squeal, and ongoing maintenance and avoidance of contamination with bike cleaners, chain lube etc etc.

Hope this helps.

PP

I had BB5s for a number of years and to be honest they were a bit of a pain in the arse, but did work correctly when set up.

It is possible to feel a bit of the 'holes in the disk' under braking in my experience. But ensure they are set up correctly.

1. the calipers must be positioned perfectly perpendicular to the disc rotor - you might need the caliper mounts faced to ensure this.

2. the adjustable pad needs to be proud of the caliper body (you need to keep an eye on this or you will end up braking on one pad and the caliper body!). It needs to be very close to, but not touching the disc rotor. If the caliper is not perpendicular as in point 1 above you may not get full pad contact under braking.

3. the BB5 works by one pad moving towards the disc rotor, bending it to come into contact with the adjustable pad (fixed in effect when riding). The rotor needs to be true with no 'buckles' otherwise in order to stop it rubbing, the fixed pad may be too far away causing excessive lever pull to take up the extra travel.

4. the pad that moves needs to be set quite close to the rotor as well. The lever operates on a cam which pushes the pad inwards to contact and bend the rotor so it comes into contact with the fixed pad thus sandwiching the rotor between the lads and creating the braking force.

5. the moveable pad adjustment can be a little fiddly as you have to pull the operating cable tight, pull the lever around so that all the excess play is taken up, then clamp the cable on the lever. The cable adjuster (if previously set to a mid position) can the pin be used to fine tune the 'off' position of that pad, ensuring it is very close to but not touching the rotor. Again, the rotor must be true or the pads will be too far apart to prevent rubbing and need excessive lever pull to get full braking.

Its all a bit fiddly and of course will require constant adjustments of the fixed pad as it wears down and the cable pull as the pads wear and the cable stretches slightly over time. When set up they work fine, but performance drops away and adjustments are required. I also found that when used on winter roads the calipers would corrode and the adjustable pad would get stuck and eventually they became shot.

I upgraded to hydraulic 105 just over a year ago on my winter ride. So much better.