I had my local bike shop, Campus Wheel Works, do a major overhaul on my road bike. They added another sprocket? to the front and two to the back, changing my 10 speed into a 21 speed. New front and back derailleurs, a new crank set and a new front wheel rounded out the upgrade. In addition, they realigned my brakes (my son had crashed my prized bike). I rode it for the first time yesterday. Until now the mountain bike was used. Accepting that a bike ridden in the snow/slop would get beaten up, the road bike had stayed dry and inside until all muck was off the roads. I had added a rack to the mountain bike so I could still grocery shop.
The transformation of the road bike was amazing. For $350 the bike rode like new. This does seem like a lot of money, but in the long run, when you have a comfortable bike with features you like, it is much less expensive to upgrade/update it if possible. A new comparable bike would have cost me $650. The biggest problem with my road bike was the lack of a "granny" gear. Very happy.