I presume you're talking about these:
You're right. Cars will always hit them, whether with just two wheels or four. We have some around where I live, and actually it can be less stress on the car to only go over the hump with one side of the wheels.
My main problem with them however is that they are not central to the lane, so when two cars are coming towards eachother adament that they want to straddle their hump equally, it is often an extremely close call for collision.
I hate these things very much, but I much prefer the full width speed hump/bumps.. These do not encourage cars to weave in and out (in order to hit the hump square) and proudly drive on the wrong side of the road when 'their' speed bump has cars parked on it. As for the bike, I like these little bumps.. I can sew quite nicely through them..
You should see these. They're just a few miles from where I live and often frequent the road.. 'fake' speed bumps
https://www.walesonline.co.uk/news/wale ... d-16619511It was a 40, but was reduced to 30MPH and these things painted on the road.
As for the sight of these bumps, you're right, they're a lot more agressive than traditional full width speed humps. And the white paint does go. They're also slicker because they're not tarmaced, and also the angles themselves are straight lines with no natural curves up or over or down. They are however.... red.