I hope this page will answer that question.
In the last ten years the popularity of recumbent bicycles has soared, and as with all things, popularity has brought a great deal of standardization. The recumbent rider of today has many models of bikes to choose from, many more than the upright biker. But when all the hoopla is cleared away there are only two basic designs that are commercially available, the long-wheelbase (LWB) and the short-wheelbase (SWB). There are many variations on these designs but basically that is it.
The long-wheelbased bikes have the pedals behind the front wheel, and the short-wheelbased bikes have theirs ahead of the front wheel. These bikes look and handle quite differently. Each type has good and bad points. And each also has a devoted following claiming the superiority of one design over the other. What both designs have in common is the need for miles of chain to drive the rear wheel.
There is another type of recumbent bike and that is the front wheel drive (FWD). Front wheel drive means that you are going to use the front wheel to propel the bike as well as steer it. There are two ways of doing this.
One is to build a bike that looks like a SWB with the bottom bracket (BB) out in front connected to the main frame, but instead of routing the chain to the rear wheel it goes to the front wheel. This is accomplished by running the chain to a pair of idlers mounted on the head tube and then down to a freewheel on the front wheel. The chain is thus twisted when the wheel is steered. While this design works it has all the drawbacks of a regular SWB, plus a more complicated drive system.
|
|
A far simpler way of building a FWD bike is to mount the bottom bracket in front of the front wheel but have it attached to the fork instead of to the frame. This type is known as a pivoting bottom bracket, or swivel nose FWD. This type has some unique advantages over both SWB and LWB bikes.
First of all, it needs less chain than even a standard upright bicycle. That alone is a weight savings of about 20-24 ounces, or more, over most other recumbents. The riders feet become part of the steering process, and with a little practice the rider can steer with their feet. This makes this the only recumbent that can be ridden hands-off. There is no problem if the feet overlap the front wheel because the feet turn with the wheel. This makes the designer's job much easier. The designer can put the BB and the seat where they want it instead of where it has to be to keep the feet away from the wheel. There is no need for those little oddball sized front wheels. This type of FWD bike can accommodate anything from a 20" to a 26" front wheel. The result of all this means a properly designed FWD bike is a very good-looking bike.
Another advantage in having the BB mounted on the steering unit is that the forces between the arms and legs are balanced out. This allows the rider to use his or her arms and back for extra leverage, much like a standard bike when you you are out of the saddle. This makes this FWD bike a very good hill climber and sprinter.
The bike has the stability of a LWB and the wheelbase of a SWB. This design also lends itself to modular construction. It can easily be made in sections to take apart, or be converted into a folding design.
I built my first FWD bike in 1979. It was made from two old bike frames I had around the house. It only took a couple of weekends and was an immediate success. (I don't have many of those!) It only took a few refinements to the steering geometry and I had a first-rate bike. I had many requests from people who wanted me to build one for them. I figured the easiest thing to do was to draw up plans and let them build their own bikes. I visited a lawyer to get the plans copyrighted and he persuaded me to also take out a patent. I was issued the patent in 1982. This was years before Flevo or anyone else came out with a FWD design.
Want more information? See my Bike Plans page for contact information.
