The wave of new London bike shops

Also recommend the service and advice that http://www.thelondoncycleworkshop.co.uk/ provides on St John's Hill Nr Clapham Junction, focusses on servicing, repairs and some commuter accessories. Same day repairs and servicing and even offers a courtesy bike. (not tried)

These guys are really very good - after mixed experiences with other LBS's in the area I have been in there about 4 times for various pieces of work and have always been satisfied - thoroughly recommended. Price to my mind is very competitive and they are happy for you to source parts and then they will do the wrenching.

Done wheel builds, complete strip downs and bits and bobs for me.