Bugger and damn! I think all such changes in height should be marked with white lines, they are bad at the worst of times, killers on a bike!
There is a series of new'ish roundabouts at the new'ish entrances to Aldermaston bomb works, two of which I use every couple of days. They are 'mini' roundabouts, bigger than paint spots, with a high kerb, but they have an area of brick setts about 3 feet wide surrounding them and that has a totally flat kerb edge to it and then there is the tarmac. The road is not too wide and this makes it really easy for cars and trucks and a lovely 'cut' for bikes.
However, much to my chagrin, last year I went along the road the other side of the site which leads down to Aldermaston village; two more roundabouts, but this time they had RAISED brick setts with about a 3" kerb. I almost pitched in too fast but spotted a white van taking the long way round (most unusual for such a creature) and banged on the brakes. Absolutely ridiculous especially when the 'bouts the other side have flat sett areas.
Had a right whinge at the council but all to no avail, obviously.
Brian (who has no idea why it is always the front that climbs the kerb and the rear that doesn't, when his 'logic' says it should be t'other way round)