The Importance of Base Training for Cyclists makes some really good points I should take to heart.

The most important phase of our training is the base period. For most cyclists, since we plan to peak in the spring or summer, fall is traditionally the time when we focus on endurance/base-building rides. Also known as LSD (long, slow distance), these rides are high in volume (time), but low in intensity (heart rate). This can be a challenge on the road, because an endurance pace for most riders is pretty darn slow and doesn’t allow for much climbing (a challenge in choosing routes here in Northern California). It’s just so tempting to hammer, catch a rabbit on the road, or join in a fast-paced group ride. But to truly build base, it’s necessary to be extremely disciplined and spend most of our time on the bike at a lower (read slower) intensity.