All of the Tern folding bicycles are built around a sturdy aluminum frame. For such a solid folding bike, these bikes are light weight and portable enough when folded to transport easily during your commute. Each bike rolls along on sturdy 20" wheels, which are more than capable of handling any city street, back country roads and scenic bike paths for weekend rides.
When comparing the different models, it's best to figure out what type of riding you'll be doing. If you're in a hilly area, you might want a bike with multiple speeds, but if your commute is flat, the Link Uno with its single speed might suffice. If you're planning on commuting back and fourth to work, you might want a bike with fenders and rack already installed, but if you're just doing some weekend riding, you might not need them.
The Link C7 is an entry level folding bike. It's a 7-speed bike, with shifting duties handled by a Shimano RD-FT30 derailleur. In order to make the Link C7 the most affordable of the Tern bikes, it comes equipped with a Hi-tensile steel fork and plastic pedals. This folding bike comes with different hinges than you'll find on all the other Tern folding bikes. They are a bit more basic - yet still strong - in order to keep the cost of the Link C7 down.
The Link D8 is an 8-speed bike, a step up from the Link C7 in terms of equipment and add-ons. This folding bike comes with Schwalbe Citizen tires, which provides excellent protection against flat tires. An installed rear rack can be helpful for carrying groceries. The included fenders help keep your feet and back dry when riding in the occasional rain shower. The Tern D8 is the least expensive Tern bicycle which still uses the specialty Tern bike hinges.
As we look at the Link Uno, you'll notice it's a very minimally equipped folding bicycle for the price. The Link Uno is a single speed bike with a tucked-away coaster brake, leaving no cables or levers anywhere on the bike. With no added gears for extra speeds and no externally mounted brakes, the Link Uno bike is a breeze to maintain, and the weight savings are notable when you've folded the bike and are carrying onto the subway or bus.
The Link D7i model is the most affordable model that comes equipped with a multi-speed hub. While other geared bikes have derailleurs that need occasional adjustment and cogs that need cleaning, the Shimano Nexus 7 freewheel provides seven speeds and requires practically no maintenance. This folding bike also comes with a BioLogic Portage rack for carrying small loads and front and rear fenders for keeping you dry.
Moving up to the Link P9, this folding bike is as light as the Link Uno. With nine speeds and a Kinetix Supra crankset, you'll fly along on any street, and the Aluminium frame and fork and will provide a solid and responsive ride along the way. After you gain all that speed, the Kinetix SpeedStop V-brakes, combined with the Schwalbe Marathon Supreme tires will ensure quick and responsive stops every time.
Finally, the Tern Link P7i. It's the ultimate blend of high end components and the accessories that you'll use everyday. It comes equipped with a Shimano Nexus 7 internal hub, so you'll have seven speeds of virtually maintenance free gearing. The Link P7i comes with front and read fenders, coupled nicely with front and read LED lights. Combine that with a rear rack for hauling small loads, durable alloy pedals, Schwalbe Marathon Supreme tires and dependable Kinetix SpeedStop V-brakes. The Link P7i also comes with a BioLogic PostPump 2.0, which comes in handy for adding some extra air to your tires when you need it!
If Link folding bike's aren't really meeting your needs you may want to look at the entire Tern folding bicycle lineup.