I have just got my new Brompton and decided to change the 'H' style handlebar from Silver to Black. How do I open the Handlebar clamp to insert the new bars?? I have done this on other cycles in the past but as the Brompton is the most expensive cycle I have ever brought... I don't want to mess things up by levering the clamp jaws with a rough old screw driver like I would with a ordinary cycle!