My position depends both on my absolute speed (higher = farther from curb) and on my speed relative to motor traffic (greater differential = closer to curb). (Yes, I see the inherent potential conflict; read on.)
For a concrete (asphalt, actually
) example, consider La Costa Av. just west of Rancho Santa Fe Rd. On this stretch of road, there is a several-percent grade with 1.5m/5-foot bike lanes on both sides, and a posted 45mph/72kph speed limit. Going east/uphill, I grind up in the bike lane at about 7mph/11kph, and have no desire to experiment with dynamic lane positioning. However, when descending westbound at 25mph/40kph, I find staying in the bike lane extremely uncomfortable and disconcerting, particularly,
but not only, when I approach a side street intersection. I don't grab the center of the right lane, but I am probably on that lane's right tire tracks.