Every time I think I've seen every possible type of bicycle here in the Netherlands - regular two-wheeler, bakfiets, tandem, side-by-side tandem trike, bar-on-wheels, even a brass band on a bike - I see another new and intriguing type of bike.
But it's also been interesting to see how the Dutch switch to different bikes and other modes of transportation as they get older. First, well after they've turned 70 and their hair has gone silver, they might get an assisted-power bicycle that they can still pedal but with a little extra help. And/or they'll switch to a tricycle like my own Nana used to pedal around in Florida. Then, when pedaling is no longer an option, they'll get a Rascal scooter and drive down the street following the same rules as the cyclists.
But today was the best so far! It's the start of the local Fiets4Daagse (four day cycling event), and there are LOTS of extra people on bikes in Diever. I came home from the grocery store to find an elderly man with a bike at the foot of the driveway. He appeared to be resting or waiting for someone, and as I approached I noticed that he had medical tubing running to his nostrils and oxygen tanks strapped to the pannier racks on the back. Clearly age and health were not going to hold him back from cycling!