Hi guys, I've just joined i'm in Herts and have a pretty good knowledge of the green lanes in the area (and the nice wiggly black ones too) as County Rep for The Green Lane Association (GLASS) and the vehicular users rep on the Hertfordshire Local Access Forum.
Been off tarmac over the years on a R80GS, Yam TT600, R1200GS, XT600, F800GS so know all the best places to get a hernia!
Currently riding a CCM604 as the Tiger is a bit too "roadie" but then again i've been known to lane on the CCM with the Supermoto wheels fitted too.
For information Hertfordshire County Council have had a policy of resurfacing Byways with crushed/rolled concrete so most are easily ridable on the larger bike. Interestingly it's the Unclassified County Roads that are rougher.