What is this on my back rim?

[badyellowvette]

It has to be brake dust don't it? Couldn't be anything else. Left side in the center of the rim. First time I didn't notice it for awhile and it etched the aluminum had a hell of a time polishing it out. Now I clean it off after every ride. Any thoughts?



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[Utopiapga]

Oil coming from the over flow hose...............

small leak maybe..............

 

[rasdes]

Brake dust, looks like black powder....mine has it after ride, it's normal if you use the rear brake a lot or have to brake hard.

 

[BBChopper]

Brake dust, looks like black powder....mine has it after ride, it's normal if you use the rear brake a lot or have to brake hard.

X2

 

[aspen874]

It is brake dust, you need to wipe it off after every ride or it WILL eat into your wheel

 

[jjarkys]

Brake dust, looks like black powder....mine has it after ride, it's normal if you use the rear brake a lot or have to brake hard.

X3

 

[ringo]

never seen it like that, its typically a fine dust evenly distributed around the rim thats hardly noticeable until you wipe it off

 

[Nukeranger]

Yep, it's brake dust.

 

[kickstart]

Is it just dust or is it also gummy like it has some oil mixed in it?

Most wheels will have some brake dust evenly distributed and your pic appears to have a concentration in one area. Making me think you maybe have some oil mixed in, does your drain hose have a clean filter on it?

 

[krkostecki]

Yes, brake dust. I get it all the time and it wipes right off.

 

[badyellowvette]

It's never gummy blows right off. Funny how it gets concentrated in one or two spots.

 

[bearman]

I vote brake dust, oil won't eat your rim

 

[ksmike]

Its on my wheel also after each long ride but it blows right off. You would think there would be enough air turbulence to blow it off naturally, but maybe the wheels builds up some static and attracts the brake dust.

 

[Tomtang aka Reptilejim]

Brake Dust

 

[sky soldier]

It could be tire rubbing against drive belt. Recently, I found out my rear axle wasn't seating correctly. Causing the rear axle to loosen while cornering. The rubbing sprayed tire rubber on my rear rim. Looked something like your pic. Sky Soldier

 

[BWG56]

I think its road dust kicked up by the front tire, and the longer the ride the more road dust. Reason I say this is because 99% of the time when I'm out for a ride, I don't even use the back brake and it has this dust on it and it gathers on the wheel exactly the way your's does. I'm not a Joe Racer when I ride, and the only time I use the back break is when I need to slow down/stop fast for a red light that just turned or some other reason.

My vote:----road dust Wax on, wax off is your biggest defense

 

[Slick-Dog]

X2

X3 I get that sometimes...

 

[Knuckles]

dirt