Shimano road disc braking question

[NHAero]

My new Habanero is built with R8020 hydro mech shifter/brake lever and a BR8070 Ultegra front caliper and BR7070 rear caliper. The pads that came with them are L05A RF. I don't have the braking power I expected from this setup after using 9100 series Dura Ace shifters/calipers with K02Ti pads on my Bingham (or for that matter, the RS685/BR785 non-series set-up I had on my Litespeed, or the 10 year old XT brakeset on my Pivot FS29er.) The DA and XT setups will pretty much let me do stoppies or skid the front wheel. Not happening with the new Ultegra brakes.

First I had some air issues in the system but those appear solved. Bleeding was done with pads and wheels out of the bike, so not contaminated from that process. I have cleaned the TRP rotors multiple times with alcohol, and heated the pads and sanded them, twice. I've gone through the bedding in process each time I sanded them.

I swapped in a Fulcrum front wheel and no difference.

Suggestions? Is it the pads?

[eddief]

sounds as if the ones you're using have been...used.

[NHAero]

Originally Posted by eddief

sounds as if the ones you're using have been...used.

Brakes are new on this bike, they have 70 miles on them.

[fa63]

Could it be the TRP rotors? I like to stick with matching rotors if at all possible.

[MikeD]

You have 160mm rotors?

[EB]

Have you looked at the pads to see if the surface appears glazed? This can happen with brand new pads if you overheat the brakes while bedding them in.

If they appear glazed, sand off the glazed surface and re-do the bedding process, with no hard stops or hard braking.

[prototoast]

I would try 1) swapping pads and rotors with your other bike. That way you should be able to identify whether this issue is with the lever/caliper. 2) swap in original pads to see if they're the issues. 3) swap in original rotors to see if they're the issues.

[eddief]

if the bike is just sitting there, you not on it, and you apply the levers, what do they feel like? does it feel solid like a brick or spongy? If there is any sponge feel then I'd guess still have air in the system. If solid like a brick and no squeak even when riding, then maybe it is non-matching rotors. Interesting problem.

[NHAero]

Originally Posted by Eli Bingham

Have you looked at the pads to see if the surface appears glazed? This can happen with brand new pads if you overheat the brakes while bedding them in.

If they appear glazed, sand off the glazed surface and re-do the bedding process, with no hard stops or hard braking.

They definitely appear glazed after bedding. And interestingly, not over the entire pad surface, it's as if less than 100% is making contact. On one pad, the glazed area is a strip maybe 60-65% of pad face.

All rotors are 160mm front. The Fulcrums have very little usage so rotors are close to new. I switched to SwissStop rotors on the Bingham before my trip to VT last June to avoid the Shimano heat warping issue so I'm guessing those rotors have 1,500 miles on them, and the pads are original with about 5,000 miles. I pulled them today to see what they are and they are near the end of service life so I swapped new pads in. They are MTX Red Label and I hope they are as good as people say, I got them last year when I couldn’t find OEM pads.

[NHAero]

Originally Posted by prototoast

I would try 1) swapping pads and rotors with your other bike. That way you should be able to identify whether this issue is with the lever/caliper. 2) swap in original pads to see if they're the issues. 3) swap in original rotors to see if they're the issues.

I think what I might do tomorrow is start with using the Bingham front wheel with the SwissStop rotor and the new MTX pads, in the Bingham. Then assuming that goes well, swap in the re-sanded Ultegra pads in the Bingham calipers. I know the Bingham brakes are bled right so that may help me figure out if the issue is that there is still air in the new system, despite a full initial bleed and then follow on burping of the lever, and letting some fluid out of the caliper too while the Shimano bleed cup was on the lever.

[EB]

Originally Posted by NHAero

They definitely appear glazed after bedding. And interestingly, not over the entire pad surface, it's as if less than 100% is making contact. On one pad, the glazed area is a strip maybe 60-65% of pad face.

All rotors are 160mm front. The Fulcrums have very little usage so rotors are close to new. I switched to SwissStop rotors on the Bingham before my trip to VT last June to avoid the Shimano heat warping issue so I'm guessing those rotors have 1,500 miles on them, and the pads are original with about 5,000 miles. I pulled them today to see what they are and they are near the end of service life so I swapped new pads in. They are MTX Red Label and I hope they are as good as people say, I got them last year when I couldn’t find OEM pads.

MTX reds are great with proper bedding. It sounds like your pads are indeed glazed. Try sanding off the glazed material and re-bedding using the MTX guidelines. Don’t overheat the brakes while bedding!

[NHAero]

Originally Posted by Eli Bingham

MTX reds are great with proper bedding. It sounds like your pads are indeed glazed. Try sanding off the glazed material and re-bedding using the MTX guidelines. Don’t overheat the brakes while bedding!

According to the MTX guidelines I've been bedding the pads too vigorously. Will sand the OEM pads and try to bed again.

[peanutgallery]

There is that bike shop on the island...that guy can help the OP

Brickyard Bikes if I recall

[NHAero]

Originally Posted by peanutgallery

There is that bike shop on the island...that guy can help the OP

Brickyard Bikes if I recall

That's the name. Great place. I've been buying some of my consumables there to support having a good shop here. Still want to do my own wrenching though. Between Paceline and Youtube that is continuing.

I had a heck of a time getting some slight rubbing eliminated and this afternoon looked carefully and it looked as though the caliper was very slightly out of parallel with the rotor. Pulled the caliper and noticed slight paint build-up on one edge of the flat mount. A few light passes with the file and a single rotor truing and that was solved.

Why not try to become a better mechanic instead of running to the shop?

[peanutgallery]

At a certain point, value of time....you always have lots of questions. Dude seems that he would have all the answers. Hook him up. Become an apprentice

Originally Posted by NHAero

That's the name. Great place. I've been buying some of my consumables there to support having a good shop here. Still want to do my own wrenching though. Between Paceline and Youtube that is continuing.

I had a heck of a time getting some slight rubbing eliminated and this afternoon looked carefully and it looked as though the caliper was very slightly out of parallel with the rotor. Pulled the caliper and noticed slight paint build-up on one edge of the flat mount. A few light passes with the file and a single rotor truing and that was solved.

Why not try to become a better mechanic instead of running to the shop?