Monday, July 16, 2012

Build a simple short wheel base recumbent bike - Part 4

You will need to create a long gooseneck that will allow your handlebars to be placed in a comfortable position that will allow room for your knees to pass underneath. Handlebar position and style are a matter of personal preference, but you will definitely need to extend a regular bicycle gooseneck in order to gain the height necessary to clear your knees.

Find, a set of handlebars you like and then sit on the bike, turning the cranks around while a helper takes a measurement from the handlebar center to the top of the head tube for you. Using this measurement, you can create the extended gooseneck, using some bicycle frame tubing or electrical conduit as shown in the photo. Cut the clamp section from the original steel gooseneck and then insert the new tube between the base and the clamp to create a new extended gooseneck. 

Remember to also consider the angle of the extension tube to position your handlebars in the most comfortable position. You may need to tack weld and test, making slight adjustments in order to get the angle just the way you want it.

Once you have tack welded your extended gooseneck together and tested it on the bike, complete all the welding, making sure to weld the entire joint on both the top and bottom. Clean up and inspect your welding to ensure that there are no gaps - you don't want your steering system to come apart during a ride!

Now that all of your frame and steering parts have been completely welded, you can prime and paint your new bike. I always use department store spray paint to complete a project, and if you take your time and follow the directions, you can achieve a very good quality paint job for only a few dollars.

Primer is first added and let to cure for a day or two so that there is a good base coat for the paint to adhere to. Only a light sanding is necessary on bare or painted metal, just to remove any welding spatter or edges of old paint that remain. It is not necessary to spend days scraping every last bit of paint from the parts to be painted. Once the primer has had a day or two to cure, apply the spray paint, and again allow a day or two of curing before assembling the bike.

The completed SWB is shown here, fully painted and ready to ride. All bearing parts get a fresh coat of grease, and the chain is given a very light rubbing of oil. At this point, the seat has not been covered, but I ended up adding another 4 inch top section as an upper back support.

A front and rear caliper brake were added, using the original parts from the donor bike. For more information on installation and adjustment of brakes and shifters, see the tutorial on our main page. Install all cables along the frame and avoid any tight bends so that the levers and shifters work with minimal friction. Brakes and derailleurs need to be aligned for optimal use, especially when taking them from one bike and putting them on another.

Besides the laid back seating position, riding a short wheelbase recumbent bike is virtually the same as any other bicycle. Get into the seat, place your best foot on the top of the cranks and then launch. If this is your first recumbent bike with pedals placed ahead of the front wheel then it may take some time to get used to the fact that your cranks stay pointing forward during a turn. You may have the “wobbles” for the first few launches and corners, but after a few hours the bike will feel completely natural.

Recumbent bicycles offer an aerodynamic advantage over upright cycles due to the reduced frontal area hitting the wind. You also have a massive strength advantage as you can now deliver the full power of your legs directly into the cranks as your back is pushed into the seat.

On an upright cycle, you can only deliver as much force as you weigh, and any more will just lift you off the seat. Having the cranks so high from the ground also means that you can blast into corners without slowing down or worrying about where your pedals are. The only limitations on the corners will be your tire traction and courage to take them at full speed.

Now that you have been bitten by the recumbent building bug, why not try a more advanced project, or try your own modifications to this one? Add an adjustable seat, a sliding bottom bracket, electric assist motor, or even a front fairing to cheat the wind. The possibilities are only limited to how much time you have to spend at your workbench!