HammerHead Trike - Page 1 of 7


Figure 1

This fun and easy to build DIY project is designed to inspire you to build a bike that can conquer a typical winter climate with snow, ice and slush. The Hammerhead is a two-headed monster that eats snow and ice for breakfast, and has no fear of Old Man Winter's icy wrath.

I designed this two headed bike to give myself a way of staying in shape during the winter months, when it is just too dangerous to ride a two wheeler. I used to take my fancy, overpriced mountain bike out for winter rides, but soon realized that it wasn't suitable in deep snow or around icy corners.

Obviously, a three-wheeled bike was necessary to maintain balance, so I rebuilt one of those old-style trikes (the kind with two wheels and a big basket in back) and tried to make it as light as possible by removing all parts that weren't needed, finally switching those road tires to knobby tires for better traction. The results were very disappointing; not only was this bike as heavy as a tank, but it also had no traction at all. Because delta style trikes (2 wheels in the rear) only drive one of the rear wheels, it mainly just spun around on most surfaces except bare pavement. Adding a differential (a gear system to spin both wheels and transfer power between them) was just too complicated, and would have added even more weight, so I decided to scrap this type of approach.

My new plan was to have two front wheels for stability, and one rear driving wheel for traction. This two wheels up front (tadpole style) design is popular on low-slung recumbent trikes, making them very fast and comfortable, but these lowracer style trikes are not really a suitable design for winter riding for several reasons.

First, you don't want to be slung two inches from the slushy ground while winter riding because you will get very wet from the front wheel spray.

Second, people in cars will not be expecting to see bicycles in the winter months, so you want to be as visible as possible. A low recumbent trike is not very visible to drivers of motorized vehicles.

Third, is road salt. If you live in a community that routinely uses salt on roads and sidewalks, then this is a problem because salt will corrode metal. Why spend so much and money on something that will require many custom-made parts, and will end up rusted at the end of the year?

Hammerhead is not only as high as a regular bike, and to build it requires only regular bike parts and a little welding here and there. The design uses a regular mountain bike with two head tubes welded on each side of the frame in order to support two sets of front forks and wheels. Both wheels steer at the same time just like the skis on a snow machine. In fact, the steering linkage I used here is scavenged from a snow machine!

This capable winter trike is called The Hammerhead because the finished frame looked something like a hammerhead shark as you will see when the trike is completed.

Figure 2

Now that you have a plan and a desire to conquer winter, let's start by gathering some parts. As shown in this photo, you will need a complete mountain bike (stripped down to the frame), two front wheels, two head tubes (ground clean) and a matching pair of front forks. The critical requirement here is that both head tubes, forks, and front wheels be identical or very close in size. Even the tires should be the same, as any mismatch will cause the final bike to be uneven and wobbly.

The first step is to create the two head tube extensions. Each head tube is welded to a pair of 12-inch lengths of one inch diameter thin walled electrical conduit, or similar bicycle frame tubing. These two tubes are then welded to each side of the original head tube on the frame. Both tubes are welded at exactly 90 degrees to the head tube, as shown at the top of the next photo.

If the original head tube is not as tall as the two new head tubes, make sure you position the new extension tubes so that they are able to mate to the original head tube. To make a good weldable joint, fish-mouth the ends of the tubing to conform to the round edge of the head tube as shown in the lower part of the next photo.

Weld carefully, tack welding only at first to ensure that the two tubes end up at 90 degrees to the head tube. Any error here will result in a front wheel misalignment, so check the angles with a 90 degree square as you work. Look ahead to see how the extension tubes will position the two new head tubes at the same angle as the original head tube and at 90 degrees to the frame tubing.

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You can build it yourself from our easy to follow DIY plans!