Try it at home: hold the bike by the saddle and spin up the wheel on 44/11 then slam on the rear brake - the rear of the bike rises right!

There is a video somewhere of one of the Kona boffins demonstrating this with a frame with two rear mounted disc brakes ;one with the extra caliper lever and one without.

I know a lot of guys here with Lapierres (at least 6 of us) and I have to say only I've managed to crack a frame which was replaced no questions asked by my dealer.  The new part was dispatched and fitted within a week (plus the colour matched).

Now Trek which I also broke a rear triangle for quibbled a bit though they did honor the warranty but as nick said the new rear triangle was black instead of the grey of the original.

Stevey

 Has your inner chain ring rubbed the bb shell? what was your solution or have you just left it?