Wiggins uses O-Symmetric chainrings on both his tt and road bikes. They make the gear he pedals larger between 2 and 5 o’clock in the pedal stroke and smaller in the weaker sections. They also make shifting a little difficult. To help this, O-Symmetric supplies an adapter for the front derailleur (the silver aluminum piece betweent the frame braze-on and derailleur) that raises and shifts the derailleur aft on the bike. A K-Edge helps avoid dropped chains.