The dirty little secret that I have never seen discussed on these forums is the pennies per mile to ride a bike. Take everything bike related (including shop repairs, special underpants, shoes, parts, tools, upgrades, whole bikes, tires, etc) you ever bought over a certain time period, and divide by the number of miles you rode.

Many beginners no doubt have a $700 bike with 100 miles on it and are in the dollars per mile category.
Many others ride cheap bikes into the ground and are probably at $0.10 per mile. Even then, a 20 mile ride costs a couple of bucks worth of bike wear.

I would guess that many here are around $0.50 per mile, but I have no actual data.