I am not road bike fit

I like to think i'm reasonably fit for my age, my peers from school mostly seem to be fat and look at least 10 years older than they are but i certainly not road bike fit.
today was the first Cycle Studio Redditch social ride with Alex, Dan and Mark two of our customers. Alex is the one we all tried to hang on the back wheel of, but he is 22 years younger than me! more worrying is that Mark is 9 years older than me and he kept up with Alex the whole ride, he does however have a carbon fibre wonder bike and i'm using that as an excuse. i was barely able to hang on to Dan's wheel though and he's hardly ridden lately due to a back injury. so not a very good performance. I will say i rode 30 miles on a fat bike into a bloody great headwind 16 hours earlier and my legs were showing signs that they needed a break.
It was though, great fun.
ride 19
18 miles
total 398