Introduction: Steering Assisted Adaptive Trike
This is another trike designed and built for the Shepherd of the Valley Lutheran Bicycle Ministry. Details regarding the Bicycle Ministry can be found here https://hotrodjalopy.com/hot-rod-jalopy-builder/adaptive-bicycle-program/ . We have found this particular bike design to be the most flexible in meeting the needs of a wide variety of special needs students. This has become our “go to” design for nearly every student. By altering the wheel size and extending the frame a couple inches we can fit a wide range of age groups with a wide range of special needs.
Building adaptive bicycles requires a welder and basic welding skills (or access to someone willing to do the welding). It also requires collecting at least two old discarded bicycles and tools to cut and drill metal. Our hope is our bicycle Instructables will encourage other individuals, churches and civic organizations to join in an effort to provide the joy of bicycle riding to all students, including those with special needs.
Step 1: Step 1: Main Frame
The main frame is made up of three pieces of 1 ½ x 1 ½ square tubing with .090 wall thickness. The main rail is 28 ½" long with the front cut at a 30* angle. The upright is 12 3/4" long with a 30* angle at the bottom and a 45* angle at the top. The rear axle support beam is 22 ½" long. (Photo 1) These three pieces are welded together. (Photo 2) These frame dimensions are for the smallest version of the trike using 16" wheels front and rear.
Step 2: Step 2: Steering Head
The steering head is cut from a discarded bike. Remove the bearing cups (Photo 1) Extraneous connections to the head are cut away and ground smooth. (Photot 2) Cut a piece of 1 ½ x 1 ½ tubing approximately 1" longer than the steering head. Cut away one face of the tubing to form a U-channel. (Photo 3) The steering head should fit snug in the U-channel. (Photo 4) The pieces are welded together and scrap metal used to weld the ends closed. (Photo 5)) The steering head assembly is welded to the frame upright. (Photo 6)
Step 3: Step 3: Rear Axle Bracket
The rear axle bracket is made by first cutting two 6" lengths of 1 x 1 ½ .090 wall rectangular tubing. (Photo 1) A hole is cut in the exact center of each piece of tubing using a 1 1/8 " hole saw. (Photo 2) The tubing pieces are then marked and cut exactly in half. (Photo 3) Axle support tubes are cut from 1" EMT conduit. (Photo 4)
Step 4: Step 4: Power Bracket
A power bracket is cut from a discarded bike. (Photo 1) Extraneous connections to the power bracket are cut away and ground smooth. (Photo 2) Cut a piece of 1x2" rectangular tubing approximately 1/8" shorter than the width of the power bracket. Cut away one face of the tubing to form a U-channel. (Photo 3) The power bracket should fit snug in the U-channel and should be pressed fully into the channel. (Photo 4) Weld the bracket to the U-channel along the top edge of the channel (see red arrow). (Photo 5) Cut two 3/16" plates 2" long. Drill matching holes in one end of each plate for 1/4" bolts. Weld the plates to the bottom side of the U-channel using a piece of 1 ½ x 1 ½ tubing as a guide for the spacing. (Photo 6) The bracket should slip over the main frame rail of the bike and be just loose enough to slide forward and back on the rail so the pedals can be adjusted to fit the student’s leg length. (Photo 7)
Step 5: Step 5: Freewheel and Brake Assembly
This particular trike design uses a freewheel assembly to drive a solid mounted rear axle sprocket. The freewheel assembly is a coaster brake/freewheel hub removed from a single speed bike. (Photo 1) The input sprocket will be the stock sprocket which came with the coaster hub. An “output” sprocket must added to the opposite side of the hub to drive the rear axle. A coaster sprocket from a discarded bike is used for the output sprocket. (Photo 2) To attach this sprocket to the hub, the spoke holes on that end of the hub are drilled out to 1/8". (Photo 3) The output sprocket is centered on the hub. (Photo 4) The sprocket is spot welded to the hug through each of the enlarged holes. (Photo 5) This allows the sprocket to be welded to the hub without the welds interfering with the teeth of the sprocket. (Photo 6) The freewheel and coaster brake are re-assembled. (Photo 7) If the student is unable to operate the coaster brake or is prone to pedaling backwards which might engage the brake by mistake, the internal parts can be taken out of the coaster hub.
Step 6: Step 6: Freewheel Mounting Bracket
The freewheel assembly needs to be adjustable so that the drive chains can be tightened properly. A mounting bracket is made using the “drop outs” from the rear axle of a discarded bike. (Photo 1) The drop outs are cut away from the rest of the frame. (Photo 2) The drop outs are welded to 1/8" flat stock. (Photo 3) The freewheel assembly is bolted to each drop out. (Photo 4)
The freewheel mounting bracket is positioned on the main frame so that the input sprocket will line up with pedal sprocket at the front of the bike. The bracket is clamped in place and a tubular support (red arrow) is also clamped in place to insure the bracket is level with the main rail of the bike frame. (Photo 5)
The bracket is tack welded to the frame. (Photo 6) To improve strength of the bracket, triangular sections of 1/8" flat plate (arrows) are welded in place. (Photo 7)
Step 7: Step 7: Mounting the Rear Axle
The rear axle bracket (fabricated in Step 3) is positioned and welded to the frame. (Photos 1 and 2) Flanged bearings made for wheelchair castors will fit the 1" EMT conduit. These are ½" bore and 1 1/16" O.D. flanged bearings. The fit is quite snug and may need to be driven into the ends of the EMT tubing using a 7/8" socket and hammer. (Photo 3)
Step 8: Step 8: Rear Wheels and Axles
Each rear wheel is mounted on a separate axle and each axle is cut from ½" keyed shaft. (Photo 1) Keyed shaft is VERY expensive and it is possible to make your own keyed shaft using typical 1/2" shaft and then cutting the key with a metal cutting wheel on an angle grinder. The photos here show the use of a manufactured keyed shaft.
All bicycle hubs are sized to fit metric axle shafts, anywhere from 10 to 14mm. This means the hubs have to be altered to fit generic ½" axle shafts. The left wheel and axle (viewed from the rear) is driven by the pedals/chains and the right wheel and axle rotate freely. Each hub and axle is altered a little differently to fit a ½" axle. Note also that hubs can vary quite dramatically from one bike manufacturer to another. What worked with these particular wheels/hubs may not work with all hubs. So be prepared to do some digging around to find parts and pieces that will fit.
The free rotating right side hub is from a 16" FRONT wheel and hub. To fit the ½" axle the bearing cup must first be bored out to ½". It is best to do this on a drill press using a stepper bit (Photo 2) but with a steady hand a drill could be used. A ½" bore, 7/8" O.D. collar slips just inside the hub opening. Four collars are used. (Photo 3) The inner collar on each side is slipped on the axle without a set screw since there is no access to tighten the screw. (Photo 4)
The outer collar is slipped on the axle making sure the set screw is directly above the grove in the keyed shaft and the set screw is tightened. The same is done with two collars on the inside of the hub. (Photo 5) With the collars firmly tightened, they are welded to the hub. (Photo 6)
The “driven” left side hub is from a 16" REAR wheel and hub. This is a coaster brake type hub and has a much larger I.D. However, the opening on each side of the hub is a different diameter.
On the outside of the wheel a “V” style, ½" bore weld-on sprocket hub is used. (Photo 7) The V style hub is the exact same diameter as the outside of the bicycle hub. (Photo 8) The hub is clamped in place for tack welding. (Photo 9) With the clamps removed the hub is fully welded in place making sure you avoid welding near the access hole for the set screws. (Photo 10) The other side of the hub requires a slightly different configuration. A ½" bore, 1" O.D. collar is used along with two custom made washers to space out the collar and help center the axle. The custom washers are made using 1 1/4" fender washers. (Photo 11) The washers are bored out to ½" using a stepper bit in a drill press. (Photo 12) The bored out washers fit in the hub opening. (Photo 13) The axle is placed in the hub, two washers are slipped over the axle and then the 1" collar. With everything centered, the collar and washer are tack welded to the hub (Photo 14) and then fully welded in place making sure to avoid the access area for the set screw. (Photo 15)
The rear axle, wheels and freewheel can now be test fit to insure all the sprockets will line up. (Photo 16)
Step 9: Step 9: Rear Axle Drive Sprocket
A sprocket needs to be mounted on the left side axle to drive the left side wheel. This sprocket must align with the output sprocket of the freewheel assembly (see Step 5) and it should be removable and adjustable to facilitate alignment and assembly of the trike. We also want a 1:1 overall drive ratio so that one revolution of the pedals creates one revolution of the rear wheel. The pedal sprocket has 28 teeth and the freewheel assemble has the same size sprocket on the input side as the output side. So we need a 28 tooth sprocket on the rear axle to achieve an overall 1:1 ratio.
The rear axle drive sprocket is made by adapting an old 6 sprocket cassette from a 12 or 18 speed bike. We will use the cassette mounting body, the 28 tooth sprocket from the cassette and a type “V” weld-on sprocket hub. (Photo 1) All the other sprockets from the original cassette are removed and discarded.
The weld-on sprocket hub slips inside the cassette mounting body. Note that a notch is cut in mounting body to provide access to the set screw(s). (Photo 2) The 28 tooth sprocket is fitted on the mounting body so that the tabs on the sprocket slip into the notches on the mounting body. (Photo 3) The sprocket is then welded to the cassette mounting body. The “V” style sprocket hub is welded to the cassette mounting body from the inside taking care not to get any slag in the bore hole. A “key” is cut to length and the sprocket can then be mounted on the keyed axle shaft.
Step 10: Step 10: Adjustable Seat Post
To accommodate students of different ages and sizes we want 6" to 8" of adjustment in the seat height. To do this the seat post will be held in place by upper and lower clamps. An extra long seat post is made by slipping an original seat post (arrow) inside a longer section of tubing then welding it in place. (Photo 1) A hole is cut through the main frame rail so that the extended seat post can be mounted at a 30 degree angle and whatever portion of the post extending below the frame will not come in contact with the pedal power bracket. (Photo 2) The seat and post can be temporarily mocked up to insure the post will easily slide up and down through the hole in main frame and not contact the power bracket. (Photo 3)
The seat post clamps are made using 1x2" rectangular tubing. A hole the same size as the seat post is drilled through the tubing. Holes for 1/4" tightening bolts are also drilled in the tubing as shown. (Photo 4) Once the holes are drilled the clamps at cut at 2" lengths and then each clamp is sliced cut in half. Note that each clamp piece is marked to that they can always be assembled the same way and all the bolt holes will line up. (Photo 5) The clamps are temporarily bolted onto the seat post. (Photo 6)
A 12" length of 1x1 square tubing (arrow) is cut with a 30 degree angle at each end. The seat post and clamps are positioned on the 1x1 square tubing and checked to insure the post is square with the frame. The 1x1 square tubing is then tack welded to the main frame rail and the back side of each adjusting clamp is tack welded to the 1x1 tubing. (Photo 7) Later, all the welds are completed. (Photo 8) A 1x1 post brace is cut and welded in place. (Photo 9) The seat and post are temporarily installed to insure everything fits and that the seat can be easily adjusted upward or downward. (Photo 10)
Step 11: Step 11: Push Bar
Not all students will need to have assistance steering or pedaling the trike. This trike is designed with removable components to allow the trike to be pushed from behind by a parent or adult and to also be steered from behind when necessary. If the student masters steering and pedaling on their own, these components can then easily be removed from the trike.
The push bar (arrow) is a 30" length of 1x1 square tubing. The length can be varied to fit one's comfort level. (Photo 1) The bar mount is made using two lengths of 3/16" flat stock with holes drilled to mount the bar. The flat stock is welded to the frame of the bike at a 30 degree angle as shown. (Photo 2) The push bar is held in place with two quarter inch bolts. (Photo 3)
A handle for the push bar is cut from an old discarded set of handlebars. (Photos 4 and 5). The handle slips into the end of the 1x1 push bar and two 1/4" holes are drilled through the push bar and handle. Two 1/4" bolts secure the handle in place. (Photo 6) A handlebar grip is fitted on the push bar handle. (Photo 7)
Step 12: Step 12: Assisted (rear) Steering
The steering assistance mechanism is made by first fabricating a clamp (red arrow) exactly like the clamps for the seat post made in Step 10. The only difference is this clamp is bolted to the handlebar stem. (Photo 1) A tab is cut from 2" wide 1/8" flat stock. Holes are drilled for two U-bolts and the tab is welded to the stem clamp. (Photo 2)
A steering arm is cut from 1" black pipe. The length depends upon the width of your handlebars. You want the end of the black pipe to extend about 1" or so beyond the outer tip of your handlebars. Cut a tab from 1" wide flat stock and drill a 3/8" hole in one end. Cut a slit in one end of the black pipe just wide enough for the tab to slip in place. (Photo 3) Weld the tab to the black pipe. (Photo 4) Insert the steering arm into the U-bolts on the stem clam and tighten in place. (Photo 5)
The control rod which runs to the back of the trike is made from ½" EMT conduit. The length will vary depending on the trike. The rod should extend from the tip of the steering arm to a comfortable walking/pushing position behind the bike. Bend one end of the rod with a conduit bender. (Photo 6) On the other end of the rod weld a 3/8" heim joint connector. (Photo 7) When welding any galvanized metal such as conduit, always remember to sand or grind off the galvanized coating until you see bare metal. Welding galvanized material can be hazardous to your health.
The heim joint end of the control rod is bolted to the hole in the front steering arm tab and the curved end of the control rod extends to the rear of the bike. To support the rod two pieces of 1/8" flat stock are cut and drilled for two bolts. (Photo 8) The two pieces are bolted to the push bar and can be slid up and down the push bar to adjust the height of the steering control rod before tightening them in place. (Photo 9) A length of ½" threaded rod is cut and one end bent at a right angle. A small tab is cut from 1" flat stock and an eye bolt, large enough for the conduit to fit through the eye are use to make the steering rod support bracket. (Photo 10) The straight end of the threaded rod is bolted to the push bar. (Photo 11) The tab and eye bolt are attached to the curved end of the threaded rod. (Photo 12)
The section of conduit which slides through the eye bolt can tend to create some metal on metal noise when the bike is steered from the rear. To eliminate any noise the conduit is covered with 3/4" diameter, dual wall adhesive marine heat shrink tubing available at Amazon. (Photo 13) The heat shrink comes in a roll and is cut to the length desired, slipped over the conduit (Photo 14) and shrinks to fit tight when heat is applied with a small torch or a heat gun. Photos (15 and 16) show additional views of the assembled steering rod and support bracket.
Step 13: Step 13: Back Support
Many special needs students require back or torso support to sit on a bicycle. The back support for this trike is attached to the rear push bar and is made so it can be adjusted both up and down as well as forward and back.
Flat stock is used to create a sliding clamp. The clamp is made in two halves. (Photos 1 and2) When the two halves are joined on the push bar and tightened down, the clamp remain stable and parallel with the seat and main frame of the trike. (Photo 3) Two pieces of ½" I.D. tubing are cut to the same length as the clamp. (Photo 4) A tube is welded to the top of each section of the clamp. (Photo 5) The clamp can now be bolted to the push bar. (Photo 6)
A 4" length of 2"x 3/16" flat stock is cut and drilled with two 17/32" holes. The holes are spaced to line up with the two tubes which were welded to the mounting clamp. The two holes are then threaded with a coarse (13) tap. Four corner holes are drilled with a 1/4" bit. (Photo 7) Two 8" lengths of ½" threaded rod are cut and screwed into the mounting plate. The threaded rods are then slipped into the two tubes welded to the mounting clamp and ½" nuts are used to tighten the rods in the tubes. (Photo 8) The threaded rod is welded to the mounting plate as indicated at the arrows. (Photo 9)
A wood backing plate is cut from 1x6 fir or pine. (Photo 10) The wood is marked to match the holes in the four corners of the metal mounting plate. T nuts are secured to the wood backing plate. (Photo 11) The wood backing plate is also marked and countersunk to accommodate the welds at the end of the threaded rods. (Photo 12) The wood backing plate is bolted to the metal mounting plate and the threaded rods are mounted in the tubes on the mounting clamp. (Photo 13)
One inch foam is cut to match the wooden mounting plate and glued in place. The back support is upholstered with a UV resistant, marine grade vinyl. (Photo 14) More detailed upholstering instructions are provided in my other bicycle Instructables. In some cases a student might need a safety strap to help support their torso. This particular bike did not require it but the final two photos of a similar trike shows how we incorporate the strap into the back support. We use 1 ½ nylon strap and plastic buckles, both available from Amazon. (Photos 15 and 16)
Step 14: Step 14: Chain Guard
A chain guard is made using 1" flat stock. The flat stock is bent around a paint can with a slightly larger diameter than the pedal sprocket. (Photo 1) A vertical support bar is welded in place to keep the guard in the appropriate shape. (Photo 2) Tabs are welded to the frame and the chain guard is installed with 1/4" bolts making sure that none of the bolts interferes with the chain or the sprocket. (Photo 3)
Step 15: Step 15: Foot Supports
Many special needs students have difficulty keeping their feet properly positioned on the pedals. We have tried a number of methods to hold feet in place and have found the method used on this trike works about the best and is the easiest to make. Using the students normal shoe size we go to Wal Mart or other discount store and find sandals with velcro adjusting straps. The sandals must be large enough to accommodate the student’s shoe size so that their normal shoes will fit inside the sandals. (Photo 1) Usually this requires an adult sized sandal.
The sandal toes are cut off just ahead of the front straps. (Photo 2) The sandal outlines are traced on 1x6 pine and cut out. (Photo 3) The wood platforms are bolted to the pedals using fender washers on the bottom to span the openings in the pedals. Notice that the two washers are tack welded together to give them more stability. (Photo 4) T Nuts are used on the top side to secure the bolts. (Photo 5) The sandals are screwed to the wood platforms. (Photo 6)
To keep the pedals level and parallel to the ground a cord is attached to the rear of each platform using a small eye bolt. The cord is run through a small pulley which is suspended from the frame behind the seat. (Photos 7 and 8). We do the same at the toe of each pedal platform and the cord is run through a pulley suspended behind the steering head. (Photo 9) As the crank is rotated the pedals remain horizontal to the ground.
Step 16: Step 16: Cargo Bin
A plastic storage container is fitted between the rear wheels to carry whatever might be needed.