Short answer: twelve.
Last week someone asked me how many bikes I own and have owned. I couldn’t give a straight answer. So I made a spreadsheet.
I’ve never owned more than four bikes at once.
The average bike spends 3.6 years in my possession. At any given time since college I’m likely to have 2.7 bikes in my quiver.
Unlike a lot of bikey people, I don’t collect bikes. Among my bikey friends, four is a pretty small number. My habit since about 2003 was to own two-plus bikes; the “two” is usually a commuter and a faster road bike; the “plus” is usually a mountain bike and/or beater that I seldom ride. Usually the “plus” bike was really cheap; perhaps as cheap as “free.” Free bikes always seem like a good idea but I never ride them.
My bikes are well-loved. I rode in a charity century this weekend; every time I do this I’m impressed at how nice many enthusiasts’ bikes are. Clean chains, no scratches or chips or cable rub, shiny saddles that aren’t peeling. I think some people have very nice carbon fiber bikes that they only ride on special occasions. I’m not like that. My bikes either get ridden several times a week in all weather or, apparently, not at all.