Confusion

This is a weird sign.

For one, the yellow, but that could be for reasons.

Then we have the "no tracktors, mopeds or bikes", which is kinda odd. Especially the no bikes part, on a path specifically for bikes.

And finally, it says "alleen jeugdverkeersproef" which translates roughly as "only youth traffic test".

This could either mean that no, you can't enter unless you're participating in that test, or it could mean that "mind you, this sign is only for participants of the test". Either way, it's totally confusing to me, even apart from the fact that I'm not sure that signs that need an explanation are a good thing.

I ignored the sign of course, as any dutch cyclist would, and figured later that it probably meant that it was only forbidden to enter for participants of the test.