Choosing just one shop in london for a week-end trip

Online shop make it harder for small businesses to continued.

I try and shop at actual brick and mortar building as I possibly can (especially local independent shop), even though I would save something like £5-10.

It depends which online shops though, wiggle and parker for example have a stupidly low prices, and work on low profit margins but a high turnover of sales.
Hubjub for example though sell things for a fair price however, and for many who live outside london a site like hubjub is the only place where they can purchase fixed gear componants.
After all even tokyo fixed have an online shop, i see an online shop as a way to open your shop to others who otherwise would not be able to visit.