I've bought a couple of kids bikes from these guys. They're always helpful, friendly and know their stuff. They have a good selection of kids bikes and the quality of the bikes is much better than anything else locally. They also do mini micro scooters and all the paraphernalia that goes with them.
185 Seven Sisters Rd (a couple of blocks west of the railway bridge at the station).
I would wholeheartedly support this recommendation for Finsbury Cycles. They are great for adults too.
i have used them for the last few years and bought both my bikes from them. yes they are good, know their stuff and if your not happy they will sort it- as they know me very well they do go out of their way to help, often turning my bike round in an hour whilst i get a coffee- and as im rather accident prone and have tendency to buy new things I buy there, they have replaced them for me- totally unexpected
prob jon at the castle is still better and better value for fixing bikes, but this is more convenient as you can also get all the extras you need