I ride with a group twice my age...So yeah I can keep up but I get pretty tired towards the end. I did one ride with a 52/17 and that had me in pain.

I can actually climb faster in 42/17 than I can on my geared bike. It seems hammering on the pedals and the fixed assist really helps.

The lighter composite bicycles are stiff and compliant like no other. They are lighter and more efficient than old steel. Not to say that steel is inferior but carbon bikes with tightly spaced gear ratios are a helluva lot faster than my fixie or 5 speed cluster.