Originally Posted by
AzTallRider
Clearly not nutrition for that distance - it's not nearly long enough to deplete your glycogen stores. The issue is likely the duration of your commutes: they just aren't long enough to develop your endurance, so when you do a longer ride, your aerobic system and muscles give out at a point a bit longer than what you have been doing. You need longer rides to develop the endurance you need for longer rides. I faced with a similar situation. I commuted 8 miles each way for a year, but I didn't drop any appreciable amount of weight, nor did I develop what it takes to do longer group rides. I found an alternate long route to work, and also upped the intensity of those commutes. That helped me get to where I could handle the long distances better, to where I could use those long weekend rides to really improve my conditioning. You need long rides to develop/maintain the fitness required do do them.
As for (possible lack of ) nutrition not being a problem: I'm not sure that is all that clear: It depends on what state he started in (both in terms of nutrition as well as fitness) as well as how hard he was working...
If I go out without eating beforehand I start to feel the effects after 10 or 12 miles. I can't say that I am bonked -- but I do start to slow down.
I think the real, clear, defintive answer is: "Well, maybe..... Or maybe it was low tire pressure, or maybe it was a rear brake not fully releasing or maybe it was chain problem or maybe it was..."