What's being discussed here has little to do with capitalism. A more properly capitalist enterprise of bike flipping would involve one person doing the work, the mechanic/driver/craigslist watcher, and another owning the means of production who pays less to the worker than is made after selling the bike, while keeping the rest.

Markets aren't unique to capitalism. All of this, the good and the bad, could happen without it.

What's at issue here is basically the tension between 2 extremes of individuals pulling a profit out of a market. The more respectable craftsman mechanic buys a neglected bike, puts considerable labor into it, adding "value," and eventually re-sells it. The second is just pulling arbitrage. Buying low, selling high.

What's interesting to me about being a mechanic and fixing up old bikes is that it's a quite opposite experience than we normally have as workers in a capitalist system. We own the means of production, add value to a product ourselves, and retain ownership at the end of the day of that product. It's more in line with the idealized owner-entrepreneur model of capitalism that's all but dead.