Originally Posted by
OakLeaf
For one thing, when you're climbing, even strong riders are going so slow that the advantage from drafting is minimal.
For another, flatland pacelining is a way for riders of comparable but not identical abilities to stay together; stronger riders take longer pulls, less strong riders take short ones or even peel off as soon as they reach the front. Strength and weight differences are greatly magnified once you get into the hills.
But mainly, even with only two riders, one of you may want to stand up when the other wants to stay in the saddle.
Personally I don't have the skills to micro-control my bike's front-to-back movement when I stand up, even though I'm perfectly comfortable in a flatland paceline. Other riders, who spin perfectly smoothly, get into a big side-to-side sway whenever they're standing up. There's just a whole 'nother level of bike control involved when you're standing.
With all these disadvantages, and with the advantage of drafting being so small, the groups I ride with in hilly country never stay that close together.