Hi, this will be my first folding bike, I would like a folding bike because I can't keep a full size non folder at work, and my area is pretty bad for thief's. Also I have been looking for cheap road bikes for months now to no avail, and I don't fancy spending all my time shopping for cheap bikes should one I buy be stolen.

I aim to use it to commute 9 mile round trip in a reasonable time (30 mins each way) without working up too much of a sweat, as for terrain its central London so pretty flat and mainly smooth. I have been looking at full size folders such as the Tern Joe C21 (no more in large size and discontinued) and the Joe P24 at a bit higher cost, however after doing more research I'm starting to think a 20" wheel will suffice for my commute. So about the C7 and D8 models, for this price it seems logical to get the D8 as if I were to purchase the C7 I would require some mud guards for the wet months, I am also aware the tyres are better on the D8 and the hinge system. However I'm not sure if there is much difference in the frames from 2012 to 2013, or any other differences between the bikes. Any advice on these bikes at these prices, or recommendations for other folding bikes would be more than welcome.

Edit: The Turn Link D7i (2014) has also come to my attention for £500, I really like the internal geared hub, is the bike worth the extra £125?

Cheers