No more then five miles, try starting your watch and then put it in your pocket and try to run "easy" but do it by feel. we need to build an way for telling from your body when we are running hard and when your not. But no more then five miles, four if you want.
They do a nice bright orange BMC CX, or go for a road Caad 10 frm. Cannondale and fit with 28" knobbly tyres, it's one of the best value alloy frames on the market and I use mine as a CX/winter hack fitted with 105 it's virtually bombproof