This might be a question which is impossible to answer for certain.
Basically, my story is I'm a tubby guy who has taken up riding in the last few months.
Because of where I live (the only roads leading away from my house are highways where people drive pretty fast) and because I was/am out of shape i decided to ride on a trainer rather on the road until I got into better shape and lost a lot of weight.
I read in a Chris Carmichael book recently that a very simple way to very roughly gauge one's fitness is to ride 3 miles and see how long it takes you to do it. 12 minutes up and you're in terrible shape, 8-12 and you're in moderate shape and under 8 you're in pretty good shape.
On the trainer I have ridden it in 7:40. But I know that even on a flat surface there must be a difference between the trainer and the road because on the trainer i don't have to haul my considerable bulk around.
Does anyone know if there's a formula which says that for every X pound over some set weight you need to add X seconds to the ride to translate from trainer to road? Obviously, this would not be exact.
Failing that, how fast do people who are in good shape ride 3 miles on a trainer?
As I said up front, I'm new to cycling, so if this is a moronic question, sorry.
I'm 50, also, if that makes any difference.