Bicycle Mechanics - nasty scrape on my alloy Trek
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06-06-03, 12:30 AM
OK, so now you know what frame I ride. "SOMEONE" (not me) who lives where I do, has put a MASSIVE big scrape down the side of the top tube of my otherwise quite tidy alloy frame.:( It looks like it was done against one of the brick columns in the garage. The paint is wrinkled and bunched up at the edges of the scrape, not simply chipped off.
Should I trim or lightly sand the edges and then apply undercoat and touch up paint? I am concerned as much about the potential for rust as the cosmetics. So far, the bare alloy does not show signs of rusting (after several months). It's about a third of the way along from the seat tube end, so it dosn't get a lot of sweat on it, tho I do brush it with my knee occasionally.
I'm pretty pissed...it's the biggest ugliest scrape I've ever had on a bike....after years of training, racing, crashing, travelling in a bag through airports. It happened in my own garage, at the hands of a 'relative'. Ya gotta laugh (don't ya?, I can't really kill them, can I?)
06-06-03, 04:59 AM
If the frame is Aluminium alloy, then it wont rust. The oxide will seal the surface and no further corrosion will take place.
That depends whether the top aluminum layer was taken out or not. The Alclad layer (1100 series) is the oxide coat and that'll usually corrode, protecting the inner alloy. However, if the top Alclad layer was taken out, then the inner alloy could be in danger of corrosion. Problem is, aluminum corrodes very slowly, so it's very difficult to tell whether it's corroding or not. Best safe bet: clean it out, get some scotchbrite (don't use sandpaper) and scrub it down, and paint it with touch up.
Sorry to hear about that.
06-06-03, 04:52 PM
Thanks for the tip. I never thought of it having a protective outer layer of alloy. It is a 2300 series frame. Now that you mention it, the exposed alloy surface is still very smooth and undisturbed looking. I'll try to keep it that way when preparing the surface for a touch up.
06-09-03, 08:15 PM
oh, please, who cares about a scratch. Just sand it a little and throw some clear nail plish on it to seal it up if it cut too deep, and keep riding, that is originally why you bought the bike right?
06-10-03, 04:02 AM
Correct Jcivic00. All the talk about fancy gear and 'pretty' bikes gets a bit much for me sometimes too. Chassis work is boring. I'm still looking for a thread on supercharging the engine
... something legal and non-lifethreatening.
06-10-03, 01:32 PM
You can sand down/remove the crinkled up paint and then apply a coat of clear nail polish over the area. If you've got some time, you can get a nail polish to match almost any frame color because of the assortment of different shades. You don't have much to worry about on a Aluminum bike, but I always do it. If you ever have the same problem on a steel framed bike, you are definitely going to want to do this or apply a coat of touch up paint pretty fast after it happens.
06-10-03, 05:23 PM
Being naturally lazy I'm tempted to not bother. I had a small chain drop/jam incident between the chainstay and rings several years ago...the bare patch of alloy left has not visably deteriorated any further.
I think the only problem is when a different alloy or steel is in direct contact with the bare frame at that point (plus electron conducting sweat), like at the cable holder support on the frame. That seems to be an area that can get really ugly all by itself.
06-10-03, 05:51 PM
Originally posted by jcivic00
oh, please, who cares about a scratch.
From what we were told, it wasnt just a tiny scratch. It was a very good question so settle down.
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