Hi Jonoj, are you saying an 18 at strubens (according to the topos) is a generally accepted 19 or the other way around? So far I have only climbed at Strubens so I am keen to know.
Thanks for point out my mistake.... actually meant to say OVERgraded - have now corrected it in the my original post.
What I mean by this is as follows. A route at Strubens, lets say that 21 cracky handjammy one with the little roof on the righthand side of the carg, may have grade 21 moves on it.... but when you compare it (at less than 10m in length) to a longer Boven or Montague route of the same grade (and closer to 30m in length), you'll probably find the longer routes feel a lot harder. This is purely because you have many more sets of grade 21 moves to go through to complete the climb.
So, if you have only climbed at Strubens thus far, be wary of jumping on to longer routes of the grades you currently climb. First test yourself on a long route, a few grades below your top grade, and see how you feel.
I s'pose you could train at Strubens for longer routes, by only claiming a redpoint once you ascended, and then downclimbed the route without falling or resting!