Further enhancements

As mentioned below, the suggestions for a passage with a more open feel were taken into account. On top of that, I was thinking of some modifications to keep out bikes more effectively. I came up with two:

• An extra turn would not only make it even harder for bikes, but would also make the users leave the same direction as they came in.
• As a last resort, if real life usage shows the inadequacy to block bikes out, one or two turnpike could be added as shown below. This will definitely tackle the problem completely, however it does also erase the original elegance.

This setup is even more simple in construction, while preserving all advantages of the one sketched above: