Can't bed in my hydraulic brake pads

Question

I washed my bike with Rhino Goo fast action cleaner and fairy liquid in a spray bottle mixed with water. I used a hose pump with no pressure, so no liquid will go into my bearings etc. After I washed it, I dried it up and after a couple of hours applied lube on a chain with a slow method (1 drop of lube on every chain element). I applied it on lower part of it so it will not drip on anything except the floor.

Couple the days after I went out to bed the brakes in. They were horrible at the beginning: squealing, no force at all, stopping after a mile etc. I went up and down the hill for like 20 times, feeling that breaks were at their 70-75% of original state (front wheel was on its way to lock up and the back one skidded a few times). I had no time to continue with a thought that I do the same tomorrow.

Next day I went to the same hill, same bike, nothing happened to the bike at all, but all the stopping power was gone. It felt like I needed to do the bedding process all over again, but after 2-3 rides down the hill, I felt the force coming back and eventually, the same 70-75% of the original stopping power occurred.

Is it the liquid I'm using to clean the bike, because its not the first time this thing happened (I cleaned after not using for 3-4 months due to injury and bike becoming a bit dusty) or the way I clean the bike, or because I didn't finish the process of bedding in? I'm just about to give up and I'm ready to use the bike as it is and make the bedding in process on the way.

Answer 1

There is a good chance that mix of soaps is leaving a residue on the rotors and that is collecting on the pads and fouling them. If that soap residue is your problem, then it's also possible that the heat from use is helping performance, but it's not burning the soap away completely.

Whenever you're having a problem with brake power or excessive noise, the first troubleshooting step should always be to remove the wheel and the pads, clean the rotor and pads with brake cleaner or alcohol, and to then sand the pads with a fine sand paper just enough to take the very surface off. Don't sand the rotor (ever).

If that doesn't fix your problem, the pads might be fouled and contaminated by some kind of gunk, or an oil from chain or bleeding could have soaked into them. Sometimes this can be fixed by boiling out the contaminant with a small torch, then sanding the surface again, but most of the time, new pads are needed.

Bedding: the process of "bedding in" your brakes really only applies to when the pads and the rotor don't know each other, so to speak. New pads, new rotor, new both, the surfaces aren't worn into each other to make the maximum contact surface. What happens in bedding, is the differences in surface between the two wear in and become a match to each other. Washing your bike doesn't un-bed them. Removing your pads and re-installing the same ones doesn't un-bed them. Removing the pads and sanding them does un-bed them. I wouldn't worry about there being some complicated process to bedding, it's just a matter of knowing that for the first bit of your ride, the pads are wearing in to fit your rotor and the power comes up a little more with every use of the brake. You can do that in a parking lot or a special hill if you like. I just hit the trail and take it easy for the first half hour or so, or until I like how the brakes are working.

So go through those steps to try to revive the pads and clean the rotors, then maybe change up your cleaning process. If you like that mix of soap, be sure to rinse that soap off fully from the brake calipers and rotors. I personally recommend straight water if you want to use the hose. I clean with Windex or Simple Green and a rag and I only spray alcohol on rotors.

Answer 2

Although this question is the first I've heard of Rhino Goo, upon doing a little online research it seems anyone who uses the stuff simply raves at it's power and looks of their ride after using it. Apparently it's Earth friendly and will not harm paint. Anecdotal reports of it's use on hydraulic brake calipers mention only it's outstanding performance and were silent regarding any issues with pad contamination after using. I did not see where anyone mentioned the "fairy spray" aspect, and I've took that part of your question as the complete title of the Rhino Goo product you were using. If fairy spray is a different product, that may need some looking into regarding whether it's safe for brake pads/rotors. Rhino Goo fast action cleaner does not seem to be the source of pad contamination, if that's the source of your brake troubles. Here's a link to an online forum conversation that addresses the performance and safe-for-use on brakes within the discussion.

It's possible your pads or rotors became contaminated from lubing the chain, despite the proper technique you describe. I've had instances where brake performance fell off suddenly and in such a time frame that lubing the chain could be the only explanation. When my brake pads or rotors get contaminated, the first thing I notice is the bite point becoming softer or less dramatic, if that makes sense. I use metal pads with Shimano hydraulic brakes so the diminished grab at the bite point is quite noticable. Other symptoms of contamination include increased stopping distance and inability to lock up the rear wheel when getting on the lever. Despite the metal pads, noisy braking isn't usually evident except in wet conditions, where it happens whether there is oil contamination or not.

My contamination fix is removal of the pads. I'll note the glassy, darkly stained surface of the pads. I first spray 90% isopropyl alcohol (IPA) on them let it soak a bit and wipe with a clean rag. Several swipes with a clean area of the rag each time. I spray them several times with the nozzle very close to the brake pad surface--kind of a jet wash. Use care as this can cause the alcohol to fly all over and into eyes or onto something not tolerant of it. I jet spray each pad several squirts in a row and let them sit. Spray again after several minutes and wipe with clean rag. I do a few reps past the point where the rag comes away clean after wiping. Next I use sandpaper--80 or a 100 grit to roughen up the pads and remove the surface layer. The rotors get the alcohol treatment as well (while still in place on the wheel). I spray a liberal amount and wipe clean and spray again, this time leaving the alcohol a few minutes on the rotor. I wipe before the alcohol has dried. I do this 3 to 4 reps.

Occasionally after cleaning the pads with alcohol, I'll use a mini butane torch and fire the brake pad surface for several seconds with a constantly moving flame. I may repeat this one or two more times letting the pad cool enough to wash with alcohol in between. IPA is flammable so use care here. Firing of the brake pads is pointless after the point you notice doing so yields no smoke. A contaminated pad will smoke under the heat of the flame almost immediately. It ceases to smoke rather quickly as well. That's a good stop point several seconds after the last wisp of smoke is noted. Continued firing of resin pads will cook off the resin and make the metal coagulate into sand-like grains. These can be removed with the swipe of a rag or sandpaper and the pad will function properly still, but in doing so you've unnecessarily introduced a fair amount of wear to the pad, decreasing it's life expectancy.

The key after decontamination of the pads and rotors is to take some time and bed the clean pads and rotors in as if they were new. Several repetitions of controlled but firm braking from a decent speed will make them come alive again. Avoid locking the wheels. You want to create heat from the friction of pad on rotor, which must be turning to accomplish. After 3-5 reps, you should notice a change in the braking quality. By or many times before the 10th rep, it's likely you've achieved the max performance benefit the bedding process will give you. Other sources of poor braking performance should be examined if proper bedding-in of new or reconditioned brakes has failed to satisfy the way you want your brakes to feel.