Originally Posted by
mike
I think the two biggest factors are stiff bearings and the wind resistance of bulky clothes.
You can immediately feel the stiffness of a cold bike as you kick-off on your early winter morning ride. the bike doesn't even coast as easily as it did in summer. Theoretically, the ride will improve as the bearings and grease warm up, but I don't think that happens effectively in below freezing temperatures, especially with the hub flange and spokes to act as cooling fins.
Grease in rotating bearings at very low temperatures turns the grease to a consistancy of soap or spun honey.
Also, clothing makes a HUGE difference in wind resistance. We are essentially kites on our bikes. The bigger the kite, well you get the idea.
I think the stiff tire hypothesis is off-mark because hard tires are supposed to give less rolling resistance and make for a faster ride.
I had an 87 Nissan with a 5 speed manual transmission. When it was really cold it took a significant amount of effort to move the shifter. Newer cars seem better because I think they use a lower weight oil in the transmissions that don't thicken as much.
So I think you're right that the wheels don't turn as easy and neither do the cranks. Compared to a car's transmission, they don't generate as much friction and they're more exposed so the lubricant won't warm up as much.
I don't think tires roll as easy however. It's just a hunch more than anything I can explain. Yes they're harder and they don't flex as easily, but they don't unflex as easily either. I just feel as if they aren't rolling in an optimum way.