Det

Hello guys, I'm wondering if you could help me.

I am in the process of overhauling my permanently squealing hydraulic brakes, apart from the levers (RS505). That includes the rotors, pads, the calipers and even the hose.

Old setup:
- Caliper: RS785
- Hose: BH59

New system:
- Caliper: R8070
- Hose: BH90

I have internal cables, so am probably going to use something like: youtube.com/watch?v=QZaGL83RMFI (with e.g.: parktool.com/product/internal-cable-routing-kit-ir-1-2)

According to the Shimano Compatibility Chart: productinfo.shimano.com/#/com/2.4?acid=C-499 and this thread: weightweenies.starbike.com/forum/viewtopic.php?t=147493, ST-RS505/R8070 should work just fine using a BH90 straight-straight kit.

My questions:
1) Does a BH90-SB/-SBS kit imply BH90-SS (+extra parts)?
2) Is there anything else I should be aware of?

davidallenxyz

I think you should be aware that replacing the internally routed hydraulic cable will be a time consuming job that is very unlikely to solve the squeaky brakes.

If the brakes work well, then try to overlook the squeak. It is common in disc brakes. Squeaking will have far more to do with the pads and the discs than anything else. As long as you are l not losing fluid, I would leave the rest of the hydraulic system alone.

Det

No, it's of course not the cable (I don't think) that's causing it. It's just what the new calipers require.

However, I've already replaced both my pads and rotors before, rebled the system a couple of times, and the squeak keeps coming back again and again (dirt layer on top of pads).

At this point I can only assume it's the calipers.

Andrew R Stewart 

Det- If you can tell us and the bike industry how to rid brakes (I don't care if they're rim, disk, drum, roller...) of squeals let me be the first in line to invest many $ in your consulting company.

Having said that there's every chance in the world that changing calipers will change/stop your squealing. But how to transfer this to other set ups is the challenge that we have lived with since bikes first had a brake of any form. Andy

Det

Not sure what that last sentence means, but certainly if my new R8070 with resin pads would start squealing, like someone was yelling in metal, after just a few uses of the brake, then I will stand corrected.

Andrew R Stewart 

What I was trying to say is that bikes have had squealing brakes for decades across all types of brake designs. Thousands of very smart (and frustrated) people have spent many hours trying to eliminate squeals. That we are still having squeals and find the need to ask about it might suggest that it's a not fully understood issue. What works for one bike doesn't transfer over to another bike, even with the exact same specs. Yes, there are techniques (toe in of rim pads is very commonly done, at the loss of braking effectiveness, replacing the pads is another) but these are not a guaranty or even a stable and forever fix.

Spend some time in the trenches (a LBS) and you'll see what I speak of. Andy

fietsbob

It's a Feature , if they get out of your way quickly..

TimothyH

Mine squeal like a pig.

Just like @Det, I have replaced pads and rotors + cleaned the calipers with little improvement and it always starts squealing again.

So yeah, I'm interested in hearing how things turn out.

-Tim-

Det

Answering my original questions:

No. A specific BH90-SS kit is needed.

This won't be possible (flat-mount calipers on a post-mount frame/fork).

Anyways, unimaginably, a quick test of 1/5th the price resin pads instead of finned sintered ones completely muted the brakes (exact same method of bedding in - brake firmly from good speed without locking wheels about 10-15 times).

However, one of the pistons in the other caliper doesn't move at even speeds even after cleaning and numerous bleeds, which keeps bending the rotor. They don't sell those separately, so gonna have to replace the whole caliper.

Otherwise, everything's nice apart from few things nothing to do with brakes. Completely fixable as well tho.