A unique highway lowracer

A big wheel forkless lowracer

 

Even though my bike building has come to a bit of a halt this year, that doesn’t mean I’m not coming up with new ideas on a daily basis.  A few times a day, I like to find a quiet place to relax with a notebook and sketch up new project ideas. I have really missed my Marauder. I think it may be time to make another long wheelbase lowracer so I can get out once in awhile to feel that burn as I push both machine and engine to the limits. The terrain out here is not the same as the city, so my lowracer will need to have suspension to take me down the gravel road out to the highway. There isn’t much traffic on the paved highway around here and the ride would certainly be challenging thanks to hills and tight corners.

Another option is to transport it to a nice stretch of country road about 15 minutes from here where there is very little traffic and fairly smooth straight terrain. There are many cyclists using this stretch. I can just see myself eating roadies up once again as I slip under the wind and pass them one by one!

 

Some forkless bike examples

 

This time though, I want a very unique lowracer that has 700cc or 26 inch wheels on the front and back, a rear suspension, over seat steering, and no front forks. Yep, you read that right, no front forks! I have two designs for a forkless bike: one with a hinged triangle and the other with a wrap around frame that allows the front wheel to pivot much like the front wheels of a quad or tadpole trike.

Having no fork over the front wheel would mean that a larger wheel could be used without obstructing the pilot’s view. This will also smooth out the ride, so it would be a decent chassis for an aerodynamic fairing, allowing the rear suspension and long frame take up the bumps. Suspension is a must on a faired lowracer since these things can easily reach automobile speeds, making the smallest bump feel like a pothole. The forkless design and long wheelbase configuration also keep the front of the fairing low so that you can see the road ahead rather than having to peer around the body. This type of streamliner would not be all that great for pack racing on a track, but out on the open road, it would be a real blast!

 

A crazy pivot fork bike

 

The easiest forkless design is shown in my sketch and in these cool examples, where the hub pivots on a kingpin held in place by a single tube that wraps around the wheel, leaving space for the turn. I would run a connecting rod up to a control arm just behind the front wheel and then use dual cable steering to get around the curved tube so that there would be less flex in the system and tighter side tolerances for a fitting into a full fairing.

My other version involves a hinged triangle with the pivot very low behind the wheel to keep the tiller effect minimal. I have tried this in the past on this crazy ride called “Tour De Hell”, but the result was a bike that had serious bad attitude and took a lot of practice to ride smoothly.

Of course, having a short wheelbase and a huge amount of tiller, this bike steered like a front end loader, swinging from side to side and causing serious steering feedback. I think this system would work out on a long wheelbase recumbent if the pivot had more caster and was placed much lower to get it closer to the axle. I am not sure if I will actually try the pivot fork design since the other method would defiantly work as expected.

Perhaps this winter I may cut some tubing and lay out my new forkless highway lowracer. I always wanted to build a long wheelbase lowracer and then go all the way on a fiberglass fairing so I can get out and push the limits of what is considered possible under human power. I certainly won’t be heading to Battle Mountain to race with the big boys of speed, but I would certainly have fun smoking past road bikes doing 50 MPH on a faired lowracer down our country roads!

~ Brad

Build a simple short wheel base recumbent bike – Part 3

The goal is to position the cranks over the front wheel in such a way so they there is no pedal or crank arm interference with the front wheel as it turns. If the crank arm were to hit the front wheel, the steering would lock up, resulting in a loss of control.  So, basically, you want to position the bottom bracket as far ahead and as low as possible, while at the same time ensuring that the cranks do not interfere with the front wheel and so that they are placed the optimal distance from the seat for your leg length.

To find the best bottom bracket position, sit on your seat (with shoes on), and extend your leg while a helper holds the crank arm with pedal installed. Your helper can then take a measurement from the head tube to the bottom bracket or crank center so you know the correct distance from the head tube to install the bottom bracket. The lower front boom tube can then be cut and tack welded to the head tube as shown in the photo so that you can test the crank position for both your leg length and clearance over the front tire. You may need to make fine adjustments to meet both requirements, so take your time and get it right.

Once you have the lower front boom tube solidly tack welded in the correct position, you can measure the distance from the bottom bracket joint to the top of the head tube and cut the upper boom tube that will form a triangle between the bottom bracket and head tube. This tube is also fishmouthed to fit the bottom bracket joint and the head tube to create a good joint for welding.  The resulting triangulated front boom will be extremely strong, able to withstand any amount of pedaling forces.

With the front boom installed, you can now install the cranks and rear derailleur in order to make up the long chain needed.  You will need a chain about twice as long as a normal bicycle chain, but this is no problem, since you can simply join together two chains to make a new one.

For information on chain joining and sizing, see the tutorials section on our main web site. When sizing the new chain, set it on the largest front chain ring and on the middle rear chain ring and then make it long enough to pull the derailleur into the position shown in the photo, with the top idler wheel just over top of the lower idler wheel. You will also notice that the chain is in the way of the front wheel, but this will be fixed with the installation of the idler pulley.

An idler pulley designed for a 1/2 inch v-belt can be used to reroute the lower side of the chain over the front wheel as shown in the photo. There is never any tension on the lower (return side) of the chain, so it can be routed behind the top (drive side) of the chain, out of the way of the front wheel. Place the idler pulley on the lower front boom tube so that the lower chain will clear the front wheel and not rub on the top side of the chain. Any steel or nylon 2.5 inch to 5 inch diameter idler pulley that includes a ball bearing will work. You can purchase a suitable idler pulley at most yard and garden supply stores.

Once you have found the optimal place for your return chain guide pulley, weld the bolt to the boom tube as shown in the photo. Also shown is the completed welding on all front boom tubing joints.

Complete any leftover welding, and then clean up the welded areas. Your short wheelbase frame is now completed, and only needs a steering system to be installed for test riding.

Part 4 in tomorrow’s blog

 

AtomicZombie.com

Black Lightning recumbent, Illinois

“Hi. I am sending a picture of my son Ray Schwartz on our latest bike, the Black Lightning. It is based on the Meridian, but lower.

 

He wanted the twin hand shifters so that the handlebars would be clear for the throttle of the next improvement, an electric motor. This has been a great hobby shared by my son, my best friend, and I. We can’t wait to start the next one!

Thanks, Rob Schwartz”
Zion, IL, USA

http://rcm.amazon.com/e/cm?t=atomzombextrm-20&o=1&p=48&l=st1&mode=tools&search=welder&fc1=000000&lt1=_blank&lc1=3366FF&bg1=FFFFFF&f=ifr