I can probably only justify one – the commuter. It replaced the car, it saves train fares, it was the bike that got me back into cycling and it still keeps me smiling. And in the past I used it for what I now use the hardtail and the road bike for before I got them.
But then it’s no stretch of the conscience to justify a spare, back-up bike. Probably the MTB as they’re different enough.
Having had five bikes and now down to these three (sold the singlecross and snapped the winter road bike), I don’t think I could get rid of any more. I have a real hankering for another cyclocrosser, but I’d really have to sell the road bike to properly justify it.