Originally Posted by PaulRivers

I mean it sounds like your condition is outside the range of being bike specific. I mean 50 miles vs barely able to complete a 19 mile ride?

One other thing I can think of is just if their is something wrong on your bike. My family used to take the front wheel off the bikes to put them in the car, when we put them back on sometimes we wouldn't notice the front brake rubbing. You'd go on a ride that was usually a breeze and end up huffing and puffing and exhausted halfway through. Eventually we you know...learned to check for that at the beginning of the ride lol.