I'm not sure if this is the correct name for them but many of the
cycle paths I encounter have these things laid into them, particularly
on segregated cycle/pedestrian ones. The tiles are laid with the
grooves parallel to the path on the cycle side, and at 90 degress on
the pedestrian one. The path designers obviously think this will
encourage cyclists to stick to their own side.
However, running over the tiles in line with the grooves is decidedly
unpleasant. When your tyre is on a ridge it tends to thud down into a
groove. When it's in a groove, the groove tends to [censored] the wheel.
One path I have been using has a line of these tiles every 25 metres
or so. Assuming it is pedestrian free I move over to the wrong side
just long enough to negotiate the tiles. Because the grooves are at 90
degrees to the path and close together the tyre cannot fall into them.
There's just a gentle thrumming vibration as you pass over them.
Either these things have not been researched or they've all been laid
the wrong way. Or possibly I'm insane; it sometimes seems as though
I'm the only one marching in step.
--
Dave...
P.S. I also hate those knobbly tiles you get at pedestrian crossings.
They play havoc with in-line skates.