On a trip I'd describe as purely academic, I traveled east from Amsterdam to scope the Czech Republic cycling scene. Results were terrifying.
The image in the post isn't necessarily of any significance, except that in four days, that was the only on-street marking that designated a space for bikes on the road — that I saw. (To be fair, there was a designated bike lane on the river path.) ((To be even more fair, I didn't see a single bike rack in those four days either!))
If you tried to ride on street pictured, cars would be passing you upwards of 40 MPH. And the dangers of getting "right-hooked" is higher than and tourist in an Amsterdam coffeeshop.
Although cyclists in Prague are rare, they're quite visible. Most of them appear dressed for combat, save for their reflective gear. The overwhelming majority of bikes are mountain bikes, with fat tires and shocks. Necessary for navigating the city's storm drain-laden cobblestone streets. Most people on bikes wear helmets, and its not uncommon to see gloves, eye protection, even knee protection.
The traffic is much like any large city. One-laned roads are extremely common in the city center with cars seemingly approaching in every direction. And I'm not sure what you'd call it, but their street system is laid out in exactly the opposite of a grid.
One of the safest places to bike, which I observed from other riders, was in the middle of rail lines. That opens up the opportunity for a lot of other problems, but it provided a slight bit of levity.
All together, riding a bike in Prague is great if your looking for an adrenaline rush, and not much else. I would guess that renting a bike for a day was probably the most dangerous thing I've done in Europe since I've been here.