Poor braking and rim residue after every ride

steadyrollingman

A few weeks ago I suddenly noticed a load of hard black deposits on the rim of my rear wheel (aluminium) - instantly thought it must be due to brake pads overheating as I'd been doing more climbing/descending than usual in the previous week. Cleaned them off (eventually) with white spirit and realised that the rear pads were approaching the wear limit so replaced them all round with some SwissStop greens. Yet after one ride, the marks were back - though quite easy to remove with just a wet thumb if I do it after every ride.

So a few rides ago, I made sure the chain and cassette were forensically clean in case that was the source of the dirt, and used a degreaser to properly remove the residue on the rims, but it still happens after every ride (just 2x13 miles on most days, with only a handful of braking moments). It's on either side of the rim, and I also cleaned the braking surface of the pads in case that was the source of the contamination). The brakes aren't biting so well either and there's a bit of squeaking now too.

I've googled this quite a bit and though there are posts on removing residue, from what I can tell it's not something that people are experiencing after every ride. There doesn't appear to be a problem with incorrect toe-in either. I then started to worry that grease was being flung out from the hub during rides, but there's no evidence of dirt on the hub itself, or on the rim below the braking surface, and the rims are still fairly new (DuraAce C24).

So any ideas? Is this definitely from the brake pads and how do I stop it?

ugo.santalucia

What is the problem exactly?

Take a piece of rubber, like an eraser and rub it on a metal surface, you will notice it leaves a residue... it's the result of friction, which prevented you from clearing a red light at 20 mph and in turn saved your life.

Pads wear and the residue is to be found on the rim, get over it. Besides, if you keep cleaning them with spirit, you might as well bin those pads, they are probably soaked in spirit and no longer work

steadyrollingman

The problem is it's only just started happening - and the front wheel is totally unaffected, both when it was on the previous set of pads as well as the current ones. So something has definitely changed in the last month, and I'm sure there must be more to it than ordinary pad wear.

Jon_1976

My preferred method of pad maintenance is to pick the bits of metal out and then roughen/clean any crap/glazing off the pad with a file. As for rims, you'll always get stuff embedded into them. The pad material has to go somewhere, and its bound to stick on a hot surface with imperfections, ridges, valleys, etc. Just clean as much off as you like with a green pan scouring pad.

The back wheel will also appear worse as its having gunk and allsorts of stuff chucked at it by the drivetrain.

I've used swissstop and koolstop pads, but I really like the pads that shimano supply as standard on 6800 callipers. Seem much smoother (less grabby) than swissstops. I've only toed in one set of pads (swissstop blues) due to them making a horrendous racket.

ai_1

ugo.santalucia wrote:

What is the problem exactly?

Take a piece of rubber, like an eraser and rub it on a metal surface, you will notice it leaves a residue... it's the result of friction, which prevented you from clearing a red light at 20 mph and in turn saved your life.

Pads wear and the residue is to be found on the rim, get over it. Besides, if you keep cleaning them with spirit, you might as well bin those pads, they are probably soaked in spirit and no longer work

Since you mention it, what is the best way to clean the rims? I usually just give them a wipe with a dry paper towel. I've occasionally used soapy water and then a good rinse but it's messier and not sure it's any better.

steadyrollingman

Well I probably haven't done more than 200 miles on the new SwissStops so I'm not sure how much metal would be in there, but maybe a quick file wouldn't hurt. I've only cleaned them once with a biodegradable degreaser so it's possible that wasn't harsh enough to remove any contamination. But they seemed to work ok for the first grab or two after that cleaning, before getting squeaky - and as you say, Jon, 'grabby'. But not sure whether I can put that down to pads entirely, as I'd also just fitted new Jagwire cables, inner and outer at the same time.

I have just taken delivery of some 35mm Fulcrum Racing Quattros actually which I'll stick on next week and see if the problem persists - like I say, can't understand why only the rear wheel is affected. And as mentioned, I did clean the drivetrain up before the last outing so think dirt from that will have had little effect on the rim.

Oh yeah, I was hoping we'd all be mature enough to leave the 'rim residue' alone though

cougie

Are you braking harder on the rear wheel ? You must be if that is wearing down quicker.

TBH I dont see the problem with residue. The blocks need to go somewhere.

steadyrollingman

No, my braking has predominantly been on the front wheel - and now even more so now due to the reduced performance. So it's just a handful of grabs per ride to complement the front when necessary.
If you're used to residue then, presumably you still get decent braking - and no squeaking? I do - and that is a problem!

homers_double

I have the answer to preventing rim residue and worn pads, it's a bit bravado and I've not yet tried it myself...

steadyrollingman

Everything's worth trying once (except incest and morris dancing). You probably wouldn't get the chance to try it again though...

tootsie323

steadyrollingman wrote:

Everything's worth trying once (except incest and morris dancing). You probably wouldn't get the chance to try it again though...

If I were threatened with morris dancing I think I'd start viewing my sister in a different light...

fossyant

Ride the bike in the rain, there will be crap everywhere.

Stay away from white spirit and degreaser. Just wash with soapy water. Simple. You are probably looking at new pads as they could be contaminated with all that crap you sprayed it with.

Secteur

too much oil on the chain (or oil being applied too soon before riding so it hasnt penetrated properly) - it sprays off onto the rim, usually just/more on the drive side.