When I was a much faster rider my friend said that if I traded in my beloved steel for a carbon fibre bike he'd have no hope of keeping up with me... and he was a cat 3 rider.

My reply was, "you can't keep up with me now".

He has gotten faster and now I can't keep up with him.

It is all about the engine... mine has gotten older and biggest issue is that the enmgine has a piston that misfires while he's is still a fairly new model with fewer creaks in the chassis.