Keep riding with them!
I was you 2-1/2 seasons ago when I started riding with a group and I was the only mountain bike trying to keep up with the road bikes!! Now I'm leading rides and passing SOME others uphill (not all by any means). Trying to keep up, not lose the group, watching them and asking questions is how you become a stronger rider. GOOD FOR YOU!!! GO GET 'EM!!!
Louise
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"You don't really ever have to fall. But kissing the ground is good because you learn you're not going to die if it happens."
-- Jacquie "Alice B. Toeclips" Phelan, former U.S. national champion cyclist