And that's how you get better. Keep riding with the group. You already know you can conquer the biggest hill and you weren't far behind, either. Subsequent rides will find you farther and farther along, acclimation will get you even farther. One day in the not too distant future you could be the one waiting for the new rider at the top of the hill.

My arms and shoulders will get that way when I'm working hard to keep up with someone(s) new or in a new situation, sometimes I really tense up. I'd be better off relaxed but have to remind myself to stay loose. Once I get comfortable with the group/ride it's not a problem. Don't know if that's your case...



PS. I'm sure you don't qualifiy for 'suck' after a ride like that!