Langston Hughes has that famous poem entitled "I've Known Rivers," and I think I could write one on bikes.
I prefer to bike to work when I can. I love being in shape to ride 3-4 hours at a steady pace on my road bike in countryside surrounding Athens. I like to ride to the farmers market and load up the bike with healthy provisions for the week. Getting around campus by bike beats every other mode of travel: 7 minutes from my office to the Ramsey Center for a mid-day workout. Bikes are just cool.
And when I travel, I look for bikes: Copenhagen, Amsterdam, Germany, Austria, Uganda, Portland. In Uganda, a bike can be the difference in having a livilhood or not (which reminds me of the centrality of the bike in the old Italian film "The Bicycle Thief"--no bike, no job). Or it meant the difference between a health care worker seeing just a few patients a day to seeing a dozen or more. I think that if I were to start a country, I would have a bicycle on the national flag.
So I zeroed in on bikes as soon as we landed in Cuba. Like the cars, the bikes of Cuba are mostly old.
And they are utilitarian. The first one below is serves as a mobile cart for the predominant kind of onion that was available. But there were a wide range of utility bikes such as the three-wheeler below it. Last in this set is the mobile bakery. Older gentlemen would wheel their bikes through the streets of Gibrara crying out "PAN!" and people would step out their front doors that open on the sidewalk and buy the cheap white loaves that constituted the only kind of bread I encountered during the week.
The best bikes seemed to be the ones that had been built over time from parts the home mechanics could procure. Roberto, seen here on his way to the market with his wife, built this sturdy, ridable bike with the best components that I saw in all of Gibrara, and he was diligent in taking care of it. I was suprised to see the northern European-style bike complete with fancy kickstand and padded seat on the rack. While not as common as in Uganda, folks in Cuba will still hitch a ride on a bike rack sitting side saddle.
Adaptations and retrofitting are always interesting too. Here's a bike that I encountered out in the country when we were visiting the more far-flung missions. While I doubt it was functional, this bike is an example of the ingenuity and inventiveness of Cubans to make something out of what is available.
And as Holly and I wandered the streets of Gibara one afternoon, we happened upon this handcycle. As we were admiring it, a gentlemen with an obvious disability walked out of his "flat" and graciously posed with his government-issue bike. He was proud of it and spoke of his plans to repaint it. 
But always, the proof is in the riding. I asked a gentleman out in the country if I could ride his bike and he obliged. Evidently, I rode a bit farther than he expected and he expressed concern about me stealing it. Me: un ladron de la bicicleta. And at the Gibrara library, in the back courtyard, there was this bicycle go cart that just begged for me to play in. Note the old school-type seat backs, the bread rack on the back, and the "front lights" made from old speakers.
I think I spotted one "road cyclist" while I was travelling about. The roads aren't exactly conducive for road cycling even if bikes were affordable for such a frivolous activity. But perhaps one of the real limiting factors in cycling for exercise is the lack of calories. Last year, one of the group members had the opportunity to visit a home gym that consisted of weight equipment made from old car parts and engines: Cubans do repeat sets of transmission lifts. When he asked about cardiovascular exercise, the reply was that nobody in Cuba runs; there aren't enough calories for that kind of exercise.
