As I remember it (I'm pissed on G&T at the mo) your 71 is 12mm wider at the hubs all ready (over a drum brake model) so if the the 70 > beam is 10mm narrower then it stands at -22mm so I'm guessing that (by the way I'm tying my Nappa in knots right now) they are working on 4.5 narrower than a...