its my partners birthday soon and he has been talk about getting a bike for ages so I want to surprise him but have no idea what size I need or anything as I cant ask him as I dont want him to know obviously
Is it for riding on road or for doing tricks and jumps?
For simple riding then get a bigger frame - perhaps a 19" frame.
If he will want to do some 'off-roading' then a slightly smaller frame will allow him to lower the saddle so it doesn't keep hitting him in the backside. So maybe a 17" frame would be good - that way he can raise the saddle enough for riding on road, giving a good mix of on/off road.
