I have 50/34on my summer c40 but on my newly purchased winter c50 its 53/39. I am debating with myself whether to bother switching it to compact. Anyone know the actual ratio differential when comparing 34t versus 39t? I have heard that 1 tooth on a chainring = 3 on the cassette. Thus unless you put a 34teeth mtb cassette on with a 39 ring you cant even get close to the 34t ring 25tooth cassette ratio. And even this would only make it like a 36t. Anyone know if this is right??