Two Wheels Good (CE)

Two Wheels Good Crouch End; probably the closest bike shop to me, and my first port of call for spares, service and advice.
A very helpful bunch of chaps (and a chapess as I recall)
If you live nearby pop in and have a browse and a chat. Don't expect a warehouse crammed full of bike bling, but a quintessential independant local bike shop, the cornerstone of cycling communities the whole country over. They have a sister shop in Stoke Newington too.
In short, highly recommended.

These folks are local to me and quite a few times have sorted out my bike for me or have supplied much needed bits and bobs for me to keep her running at little to no notice. Advice they give freely and is dead useful and they really care you are going to enjoy your ride. They focus mostly on the commuter and road rider and only tiny criticism is the quality of the repairs is variable. They are great friends to the free local mountain bike club The Trax and sponsor their races with prizes..