Costochondritis (got me down)
Wheel the bike out. Close the garage door. Ouch. That's not right. Help? Off to A&E. Lots of sticky ECG monitors. A chest x-ray. Oh, pretty sure you've got costochondritis, sir. Take these tablets (seemingly named after a bad hand on Countdown), rest a bit, and you'll be fine.
It still hurts, though...
(With apologies for the piss-poor Ween reference.)