Although I don't often ride in a paceline, I have a good understanding of the concept. But, here's a specific question/scenario that I need some advice for...I'm 65 about 10 lbs over my cycling weight and just starting to "get my legs" on the bike. I'm a fairly slow climber but recently did a 35 mi. ride that included some significant elevation at 15 mph. average. Wish I could give some accurate stats but I can only say the route was pretty hill with a 2.5 mi. climb at the end. I probably average 5 mph on the steeper parts of that section of the ride. A 25 yr. old mechanic at my LBS keeps bugging me (in a friendly way) to join him on our clubs' Weds. night ride. He's more overweight than I am and hasn't been riding more than me but, as I said, he's 25 or so. Anyway, this Weds. night ride is 54 mi. in a paceline at about 18 mph over a pretty flat route. There are basically no "climbs" but maybe a few "sprinter's hills." My problem is that I don't know how to judge whether my current fitness will allow me to do the ride at that pace. Any guesses or info on how to judge my solo rides vs. paceline rides?