I’ve had a Canyon ultimate AL for 8 months, not been used over winter but the paint developed a strange defect along the top tube only on both sides:

It’s only affecting the anodised area and I can’t shift it with mild degreasers. I have 3 other bikes in the garage which are fine. Any idea what this is and if/how I can get rid of it?

What was it lent against?
Could it be a cloth with something in/on it that stripped some of the anodizing off?

Could be from your sweat being transferred there from your shorts during riding, and left there all winter?

Bike Aids?

Looks like a sticker….

Nothing left on the frame at all, or stuck to it.

Although I sweat a fair bit, it evapourates and I’ve never had any dripping off of me but I did think it looks like some manky bars someone has had on their turbo bike.

Aids? I’m certain the bike has had no unprotected contact with other bikes but will make it watch Philidelphia just to put the point home.

sort of effect muc-off used to have – I’d go with sweat damage to the anodising.

I would guess it’s a combination of shorts rubbing and sweat affecting the annodising.

Salt damage to the anodising (from sweaty shorts) would be my guess – I’ve had similar (but a lot worse) from poorly anodised cranks after road salt exposure.

Birth mark

Bike AIDS. The bad kind.

Rub with T-Cut, polish off then use car wax + buff to it’s former glory.
Job done.

Eh? More rubbing will probably just remove all the annodising in that spot.

Faulty / cheap manufacturing finish ?

Thanks for the replies. I’m not convinced it’s sweat damage though, I never make contact with the frame when pedalling and never stop mid ride so unlikely I’ve made much contact with my shorts.

I certainly won’t be attacking it with stronger cleaning products and polish just isn’t going to work on this finish. The paint is looking slightly thin/faded in places so I’m wondering if there is a defect with the paint. I’ve sent pics to Canyon so will see what they say (they’ve suggested Muc Off so far) Will update with any progress.

Do you live on the coast? Reminds me of what happened to older cars in my old home town on North West coast, the sea air would speed up any corrosion