I'm in the same position as the thread starter, choosing between 56 and 58 on a 2010 Cervelo R3. Im 186cm tall with a 88cm inseam. I know the optimal thing would be to have a lbs measure and decide this but this frame is nearly 30% more expensive at my lbs compared to online shops in the UK, so I really can´t afford buying it there. Any advice and experience would be greatly appreciated!