any one any idea what is meant by the drop for the brakes on a road frame ?

i think am being a total ass asking but thought i would

cheers WW

It's the reach from centre of the caliper bolt to the rim braking surface. Most modern road frames have very similar reach, but they're not all the same; they can vary a few mm, both front and rear. You might've noticed when swapping brakes from one bike to another, that the pads have to be adjusted. Some older steel frames have larger drop, to the point where long-reach calipers are required