Seriously does it matter if you're going 10 mph or 20 mph if the traffic's going 45? Either way you are WAY slower. Ride what you've got. You've got just as much right to the road as anyone else out there. Even Lance on a 5-lb racer will be going 10 mph up a large enough hill, and the drivers will still be going over the speed limit (that 400-hp motor doesn't even notice mountains)... My point is that you're fine.

Don't worry about clogging up the bike lanes, if any other bikers are actually faster than you and are competent VCers they'll take the vehicle lane and pass you on the left like they should .