Sounds like my father-in-law came in to buy a fixie, sorta.

Father-in-law: So when am I gonna get to race you there boy - I can walk fasta than ya can run - trust me you'll lose
Me: Um, Dad, dude - you haven't 'ran' in 20 years, and I've been training for 6 months now for another marathon in October.
Father-in-law: Don't underestimate me...
Me: What-the-****-ever, dude.

I ran my 20 mile training run @9 minutes a mile. He went back inside after he walked the first 2 miles in 45 minutes complaining about how I cheated him.

Maybe he's out to make me beat his ass in cycling too?

(I actually like the man a lot, he's just not smart when it comes to where he's at physically these days apparently)