Recumbant DIY Trike Project Part 3/The Chains to Long/Jackshaft Using Pedal CHainwheels

18 Apr

Animation of a spinning bicycle pedal

Animation of a spinning bicycle pedal (Photo credit: Wikipedia)

holga | 35mm | sprockets #3

holga | 35mm | sprockets #3 (Photo credit: slimmer_jimmer)

My latest change to my bolt together trike[I don’t have excess to welding equipment yet]is to increase the torque to the rear wheel.This feature may slow down the trikes speed going uphill while compensating for not being able to standup on pedals like a conventional bike.Its really going to be easier to just stop and sit awhile in my “ez-boy recliner”type tadpole while the conventional rider poops out and walks uphill.This extra low gear will allow me to simply downshift a couple sprockets and walk up the hill sitting down.Ready for this?Okay listen up.

I have cut off a mountain bikes rear end to build this trike.(Dont whimper mountain bike person)It has suspension from the factory that built the left the pedals intact just under and to the rear of the tadpoles seat.Cutting off the pedal arm on the right side as you would sit on the bike(before you cut the frame).You need a second pedal/sprocket setup from another multi-speed bike.this new setup should be of a type to fit your current pedal shaft.Note that  the pedal shaft is sometimes square and other times round with a hardened pin through the pedal arm  near the sprockets to lock it onto the shaft.This has to match-up on both sides of the pedal-shaft.A loose or non-fitting  sprocket is going to be nothing but problems.This completes the rear left side jack-shaft  part of the super low gears.OK,Hang with me on this its going to get more interesting.

Next you need to find another rear gear changer/ really does not have to be for a wide gear/sprocket range.A 5speed gear changer from an old bike will do just fine for what we want.For the moment you can just put this deraileur aside.We wont need it till we accomplish a few more real easy steps.Don’t get discouraged at this point.This is a grand design for powering up the usually butt busting hills ahead.This will be well worth the effort when you pass those who Poo-Poo our “bents”as freaks of engineering.You know,Those guys that boohoo’d in the 1930’s when recumbant riders whooped them athletic types on conventional bikes.Those days are a changing.Some cheery things to say as you pass the walking sweating conventional rider  might be,”nice day for a ride when you can”or “Yeah,I used to ride one of those things too”:) But I digress here a bit.Getting back  2 my project.The front sprocket on your tadpole trike is on the side its usually found conventionally.This is where we get creative.I’m sure every possible innovation has been tried on wheeled pedal vehicles.This next trick is found on tandems(bikes built for two).Take the  front tadpole pedal assembly and reverse the drive sprockets.That is, take the pedal arm with your drive sprocket and switch it to the opposite side it normally is on.Trade sides with your pedal arm that would normally be on the left side.It will now be on the right side.Sprockets  on the left of the pedal shaft as you sit on the trike.No need to mess with bearings on anything that allows pedals and spockets to be removed without messing with the bearings and shaft.This Jack-shaft sprockets  is your super low gears.You now join the front reversed sprockets/pedals with a shortened chain to the makeshift Jack-shaft just behind your seat.How does this make more gears,you ask…I am getting to that and I hope you have followed to this point.

The 5speed gear changer I obtained has to go ahead of the secondary(Left hand sprockets).I reversed the    gear changer.Turning it upside down and  backwards to what you find on the rear wheel of a bike.I also found it best to place the 5speed deraileur on the bottom  of the chain.This position allows a smooth gear change and also acts as a chain idler.This would be the part of the chain returning from the front sprockets.You may have to experiment a little to find the sweet spot that smoothly shifts the sprockets best.I placed an idler flat belt pulley from the hardware($8.00),on the top part of the chain to help maintain it from slopping around.I bolted this to the frame with 3/8″bolts.The deraileur also is bolted to the frame.There’s lots more sophisticated ways of doing what I have done.If you have suggestions please feel free to comment.You have to ask why I would build what i could buy?Its the shear thrill of seeing what your own abilities and imagination can create.This setup can give you hours of tinkering to create the gearing for the rides of your dreams.I have yet to invent,(I guess),a way to shift the front gears on this trike.So-far i have 21gears on the rear sprockets.Three sprockets on the right side jack-shaft.Three sprockets on the opposite side of the jack-shaft and 2sprockets on the front main drive at the front of the trike.T 3 three sprockets in the main/front drive pedals so far have been a rather uncooperative project.The chain idlers have been reluctant to take up enough slack to stay on the sprockets in extreme low gears.This would be very useful if you were pulling a loaded trailer uphill.I will post the solution when I find it ,or you find it and impart the in genius idea to me in the comments.

The gear changers need to be tuned very tight on the jack-shaft (right/rear sprockets).That is, the limiting screws for hi and lo will be nearly as far screwed in as possible.This being because you wont be changing 5,7or 9gears,Only 2 or 3 sprockets.A real short distance.They were not designed for the large sprockets and its going to take patience to find the perfect setting.Believe me when I tell you how much power it puts into the hills.Lastly,You need to add gear changing levers and run new cables to them.They should be tightly adjusted to work properly.A bit more tinkering by you(the pro by now).Almost done with this.

I mounted a pair of conventional gearshifts on the down-post to my trike.My deraileurs were mostly Suntour and Shimano.They are what I had from bikes I was given to experiment on.You might use other parts that work better.Please feel free to share.Your 15 minutes? of fame…

This super-gear setup will either have you pedaling like crazy to climb a hill at a snails pace or going 30miles per hour as I have been clocked doing by a rather shocked  automobile driver following  behind me.(I blew a tire at 30mph and nearly ditched it)!Next time,26″fat tires instead of700s

I really hope to include photos soon of my rather unique project.I really have not had time to make a proper journal for anyone to use yet.This will follow in the future making a clearer instruction manual for those adventurous enough to dare to go where few riders have gone before.The world of human powered vehicles.Humans can put about the equavilant of 14 horse-power to those pedals and to the rear wheel as it hits the blacktop.This is what I have often read anyway.A super-gear simply provides a way to convert all that “Horse Power” into power pulling torque.Yeah,it is very slow in double granny.I don’t have a schedule when I ride and the super high gear is a rollie-coaster ride for the strong hearted.I really must look into disc brakes in the future.Those friction wheel pinchers really stink when your doing 25mph and a deer jumps out to see what this thing looks like up close and personal.Yup…..disk brakes n deer whistles 🙂

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Posted by on April 18, 2014 in Uncategorized


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