I bike 3 or 4 times a week now, 3 times on a 4 1/2 mile strip of concrete bike trail that is mostly flat, and occasionally on the weekends on the street or on another trail.
Something I have noticed on the trail with other bikers on their 'more capable' bikes are that I know what my bike is capable of.
When I come to a bridge that slows me down to near walk speed, other bikers are fiddling with the gears.
I know how much strength it takes to get up the hill, they probably don't.
I also see bikers peddling past at twice the speed, but not exerting very much, while I am at my maximum peddling pace.
The A-bike is lite, and I am at a point I can peddle at near top speed indefinatly and not get tired, which is how I like it.
It has a speed range that someone who is in decent shape can attain, and maintain, and therefore have a reference point of how well you have been doing.
Myself, I started out barely able to go half a mile. Now I can easily go 14 miles without real fatigue.
Other people will get to the end of the track faster, but have they had a better workout than you have?