I'm crazy psyched when I get down into the 5:20~5:30 range for a 5k these days -- 4:45 is awesome. I would suggest that you can, with confidence, define yourself as fast. It's interesting that you're considering dialing the bike training back, while I"m just getting excited about ramping up (though, the mileage you've done historically in your training is on a different scale).
I'm hoping to get some speed back myself, so I may actually attempt to structure my training a bit in the near term. I did a 10k a few years back in ~48:30 and I'd be fired up to get near that again.
Thanks for that Mark...Still want to keep the bike training but no Ironman races on the horizon so don't need to be putting in huge kilometers in. Still looking for that magic formula, but look like it needs to be hard work.