Want to get some bad service? Try james' or Langsetts while your up that way. Decathlon is probably the best though, as cheep as buying online, as convenient as an LBS.
Langsetts have always been good when I've been in. Good work on my bike last time it needed doing, and priced well too.
18 is a good little shop imho, not too keen on James' though. They don't seem to like customers.