Well i have just spent three hours reading on the internet and i have learnt a lot of does and don'ts but haven't learnt were to actually measure from. It seems to be the consensus the saddle needs to be level. Were do i measure this from? Because the top of my saddle is curved and i cant get a solid reference. Do i measure it from the rails? This tips the top of my seat slightly forward. Is this correct or am i miles off, thanks.