Bicycle Mechanics - Chain rubbing against large front plate

I have Lemond Versailles 2008 with mostly 105 components; 10 gears on the back and 2 plates on the front (39/53).

When I use the 2 outest gears(small ones) in the rear, and I use the small plate on the front, the chain rubs against the large plate. It does not rub against the derailleur, only the front plate. I took the front plate off and saw the marks left by the chain over the last year.

I didn't have this problem when I first got the bicycle or at least I did not hear it then. I have had the bicyle tuned up 3 times in the last 2 years hoping that they can fix the issue but with no luck.

Could you give me some ideas?

Thanks

It is called cross-chaining. Don't do it. When you need those gear ranges, shift to the large chainring and a larger cog to get the same ratios.

It's called cross-chaining. There really isn't a mechanical fix to it, other than don't do it. Using the small-small combination will prematurely wear out your chain and (as you found out) can mark up the large chainring. I doubt it'll hurt the chainring, but it can't be good for the chain.

And it's totally unnecessary since there are equivalent ratios using the big chainring and the middle sprockets. For example the 39/12 (small-small) is 85.4 gear inches; 53/16 is 87.1 gear inches. The latter will give you a much straighter chainline and will use a lot more teeth which saves wear on your chain and cassette.

See http://www.sheldonbrown.com/gears/

Have you had both the large and small chainring checked to see if they may be bent? it doesn't make any sense that it wasn't rubbing and now it does. Something has to be out of alignment and or bent did you have the rear derailleur hanger checked as well for alignment. Good-luck :)