i have 2 bikes, my good one and my spare. i always ride my new one unless somethings wrong with it, but my pedals messed up so i'm riding the spare. i was riding around and for some reason it is way easier to spin on my old one, but it doesn't feel as controlled as on my good one. the only big differences between them are the tt and chainstays, both are smaller on my spare, but is it something else that makes it feel so easy? i do have much lighter tires on my old one, so is it rotational weight?