Yeah; it's a steel frame... scary though... what if it doesn't bend straight? I suppose 4mm isn't anything huge though.

I'll have to go measure it.

The question though: If I spend the money on a wheel, STI shifters, new cassette, and rear derailleur, it'd be probably half or two-thirds the price of a used but good condition Tiagra or 105-equipped bike... Hmmm.... things to ponder. And thanks to Acorn_user for the Ribble suggestion. Nice prices there. I could get a pair of Tiagra wheels for £50.