Wheelhub

Bike related price comparison site

An excellent idea in the cyclists greeting card line

Velomax

More products to buy (thanks Don White for this link )

Chain Reaction Cycles

Often cheaper than wiggle

Epic cycles

Colnago, Wilier, Orbea, Scott, Look - bike heaven

Forza cycles

Local boutique - De Rosa, Orca and Ridley

Evans cycles

Big catalogue, frequent sales, free postage

Ribble Cycles

Great prices and excellent for Italian brands

Cycle Basket

Limited stock but if they have what you want, then you wont find it cheaper. Based in Llangynidr so cycle over and collect rather than pay their high postage fee!