I've decided I need to get fit so I'm going to start riding a bike to work. Problem is I don't really know much about them and I don't want to get ripped off. Can anyone offer any good tips and pointers that I should consider when buying a bike? I was planning on spending around £400, and I don't mind buying a second hand one if it means I get a much better bike for my money. I mainly want to ride on the road, but I'd also like the option of riding it off-road if I want to. I am 6 foot tall (182cm) and weigh about 96 kg (if that makes a difference?). Cheers in advance for any help!