I'm essentially 28 years old, fat, and basically out of shape. My question is this. Everything I've read is that beginners should try to ride at 80rpm cadence and try to do long "slow" rides to build up some aerobic endurance.
What I'm experiencing is that (before I got a computer that tracked cadence) I can ride in my neighborhood (which is hilly) for about 30 minutes and average maybe 8mph for about 30 minutes. When I ride along our city's nice flat bike/pedestrian trail, I was able to average 10-12mph and go for an hour the first time out. But, when I switched out my computer for one that has cadence, I was only pedaling at 60rmp (which is probably akin to how I rode when I was a kid and could ride all day long)
Once I started trying to pedal at 80rpm, I seem to wear out pretty quickly. I haven't tried it on the nice bike trail, but I tried it on a trainer at low resistance and was only able to last 18 minutes. When I rode around the neighborhood, I was (to my suprise) able to go for about 30 minutes aiming for 80rpm, but I wound up averaging 70rpm when I looked at the computer at the end. I'm pretty sure I couldn't go for an hour.
So, here's my question. At this point should I just suck it up and go at 80rpm as long as I can stand it or should I go out there at whatever cadence I do for 60 minutes and as I get in better shape, add rpm's instead of bumping up gears? I still have the platform pedals that came with my bike, so I know there's a limit to how much I can do until I can save up to upgrade those.
I should probably also mention I (possibly foolishly) signed up to ride for a local 20 mile fun ride (which seemed realistic at the time since I was able to do 12 miles on day 1 when I was just riding and not worrying about anything). The ride is in early October. I basically am just doing it to hang out with friends and hopefully get a T-Shirt.
And I thinking about this too much given where I'm at or do I need to just suck it up and it'll start to be more fun once I'm a little stronger? I used to LOVE riding when I was a kid and was in high school.