These ideas aren't by any means complete but are in the dream stage and may appear on some of my cycles in the future.
This idea would work best on a tandem with this mechanism in front and the rear rider doing the steering. Using a shaft drive system instead of a chain would mean the drive could pivot around the bevel gear.
If this system was used on a single rider trike some sort of supplementary steering and feet rest would need to be made. The best I guess would be to steer with the feet.
A problem that annoys me a lot on a trike is riding on an angle most of the time due to the camber of the road. This arrangement is setup using a tadpole style trike with the boom passing through a tube so the rear frame incl seat as well as the pedal system pivots inside the tube mounted to the cross beam. Some sort of dampening, a locking screw and a spring to centre action may be needed. The weight of the rider should then pivot the frame straight when the trike is leaning with the camber of the road.
A clockwork spring mechanism is set up so that when a lever is pressed the spring is wound up. That action slows the cycle and when the lever is let go the spring stays taught. A gearing system is inside the spring coil so that when another lever is pressed the spring goes through a reverse gear so that power is applied to the wheel. There is obviously limited amounts of storage depending on the capacity of the spring and it needs provision so that the spring cannot be overwound, maybe with a torque clutch. This system may give quick acceleration after each braking.
When a child's bike trailer (with a single rear wheel) is connected behind a trike the action of the child pedalling tends to destabilise the trike up front. See this page. The idea here is to make a 2 wheeler trailer using an existing bike frame which the child can help with the pedalling and braking.
This design wouldn't be completely stable but should work. A container could be placed in the area between the 2 rear wheels to carry things. The wheel behind the rider is the only one planned to be driven and fixed handlebars should be fitted to the frame.
Why not have 2 connected behind.
A recumbent bike frame that has built in the ability to convert from long wheel base to short easily. In SWB mode the forks and front wheel are mounted in the head tube just in front of the seat. The front head tube has just a fork head tube in to fill the space and gives a place to mount things like lights etc. This tube will need to have a bracket on it for the steering rod in LWB mode and will be able to pivot so may need some sort of fixing, especially if lights are mounted. In fact the LWB steering rod could be placed on it even in SWB mode so the lights turn with the steering. In long wheel base mode the 2 forks are reversed and a control rod added between them. The above seat steering is always placed in the tube closest to the seat.
built HPV's have an intermediate cog mounted on what was the
old bottom bracket. (main pedal axle) Recently what I've found is
the cone nut that holds a pedal axle in place is the same thread
and size as a rear cassette. (set of cogs mounted on the rear
hub) The idea then is to use a rear cassette as an intermediate.
The ratchet part inside the cassette needs to be removed so that
it will freewheel both ways with all the bearings etc left in
place. The BB then has only the right cone nut screwed in half
way and the cassette screwed onto that nut. The rear chain then
could go to one cog and the front to another. With a bit of
creative arrangement a derailleur can be added to give some
gearing as well and the cogs may be able to be rearranged in the
order you want. I would expect the 2 chains to clash when on
side-by-side cogs with the existing cog spacing on a cassette so
this may need to be made a little wider at that part. This
shouldn't be hard as they usually have spacers between each cog
anyway but it may mean you lose a cog in the group to make this
Thinking about the strength of this arrangement, both the pulling motion at the front will be mostly compensated by the pulling from the rear so I would expect it to be strong enough. As the 2 chains get moved apart there is a twisting force but I don't think this is strong enough to cause problems.
Now there's one problem with all of this. The right hand thread on a BB is usually on the left which means the cassette won't screw on so you will need to improvise. You could either re-fit the BB the other way round, re-thread the tube or weld a right hand thread cone to the outside of the right one.
|2 bike frames are needed. Join the top
part of the frame and add a tube between the bottom
A double chainring is added to the rear pedal assembly and a 2nd set of handlebars fixed to the front seat tube.
Simple as that!
I could imagine this design could be used to make a tandem with a large 27" frame and a smaller 20" rear to cater for an adult and child.
You may also like to check out another web site How to build an inexpensive tandem
|At first thought the normal bike bottom
bracket would be the obvious choice for a suspension
pivot. The difficulty I have with it is I haven't found
an easy way to make it so the bearings can be serviced
and the rear forks removed.
Here is a simple to build suspension joint that can easily be removed for bearing adjustment and is made with normal bike steering head parts. To get a symetrical joint 2 threaded fork stems will need to be butt welded together if you can't thread the tubing.
2 bike steering head stems are cut down so both sides can fit inside the pivot. A washer is welded to the end of the head stems for the bolt to pass through.
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Last updated Friday, January 30, 2009