I was smooth on the ride in. Like buttah...

I did overtake a guy on a mtn bike. He was spinning at what I'd guess was 100 rpm. I hesitated - should I pass him before the corner? Well, it was either going to be then or in another 50m, so I went by. I had to stop at an intersection, and he actually skidded his back tire as he came up to me. I made the turn and that was the last I saw of him. We were on a one-way street with no traffic, so I didn't cut him off. Maybe I should have just sat on his tail for the rest of the block?