I have a hybrid "comfort bike" (Trek Navigator 100) that just sits in my garage. I've been thinking about setting it up as my trainer bike. I have a kurt kinetic fluid trainer. The position on the bike is fairly upright and I'm planning on switching the tires to a 1.5 inch slick or city tire (currently has 2 inch hybrid tire with nobby on the edges.) The bike itself is in good shape, but I only like putzing around the neighborhood on it. I'm just wondering if it makes any difference in "training" as to the position I am sitting in while I am on the trainer. I think the main purpose is to get a cardio work out on the trainer... any drawbacks to riding on the trainer in this position with this bike?