It's not a bad bike. The paint is new, the brakes work, and somebody obviously cares about it.
It's a badly designed bike. Step-through, solid steel, no gears, no suspension, and generator to run the front light. For a city that's so enthusiatic about bikes, why have they ignored every advance in technology since 1950?
We rattle over the cobblestones, which aren't so romantic when they're making your wrists go numb. Jumping on to and off kerbs to avoid traffic is much harder work. Still, they're not as bad as the ones in Thailand, and the traffic is much more respectful.
We see a few of the sights, but faced with the prospect of doing this for the rest of the day, Lyn's brain quite reasonably decides to "exit her skull via her right eyeball", as she put it. I ditch the bikes, put her to bed, and explore on foot.
A museum here has built scale-models of a couple of dozen of Leonardo Da Vinci's mechanical sketches. They range from simple multiple-pulley systems to an amazingly impractical "car" that's hopelessly over-engineered. It's difficult to see how the same man could have come up with both.
I duck into a cafe for a coffee. Twenty-five seconds later I'm crossing the road in search of the church that Lonely Planet says is here. I follow a couple of Spanish backpackers inside.
It's very quiet. The thick walls make the building defensible, but they also make it peaceful. I sit for a moment, and begin to feel clear-headed and energised.
The coffee's kicking in.
On the way out the priest sitting by the entrance motions me over. He's everybody's favourite grandfather, with a thumbs-up for a repeat visitor and a welcoming wave for the tourists. We can barely communicate, but I give him a few coins from my pocket for the church's restoration, and he points out that, if that's where I'm keeping my money, it's going to get stolen soon. As usual, I'm horrified when he thinks that I'm american, and he's delighted when I say I'm from Australia.
He's a lovely old man in a lovely old building created to encourage bloodthirsty intolerant delusions. On the way out I'm reaching for my ipod; suddenly I need the teachings of MC Hawking very badly indeed.