I read this thread slightly concerned! Myself and 14 yr old son are cycling (touring) Calais - Paris in a week, he on a sub £100 full suspension mtb! I've tried to get him to swap to a hardtail we have laying around, but he wont be parted from it.
He has been out at sparrow fart most mornings in the last week doing 25 mile runs... with his rear panniers on and all his camping kit (not the tent)!! Doesnt even break a sweat. I've mentioned the 'pro' talk on here even, but...
I've replaced brake cables etc and am now resigned to it. Will let you know how it goes.
If something breaks that i cant fix, every village in France is full of bike techies... i believe!