Modified Bicycle for Child With Cerebral Palsy

Ford is a delightful and inquisitive five-year old boy with cerebral palsy who needed a way to ride a traditional bicycle that would conserve energy as he traveled down the street to a friend's house. While he has enthusiasm and willingness for mobility and social interaction, he tired quickly from the exertion it takes to walk there because his cerebral palsy limits his movement. Several adaptations to a traditional bicycle would allow him to steer the bike in a straight path, keep his feet on the pedals, and continue moving forward, even when he is not pedaling.

Adaptive bikes on the market are quite expensive, making them out of reach to some children who could really benefit from them. Our team modified a standard bike with materials and tools that could be found at a local hardware store.

Thanks to the generosity of a private donor, the $200 cost of this project was fully covered and the bicycle was provided at no cost to the family.

The adaptations we made can be customized as well as mixed and matched to an individual child's needs. For example, a child may need something to keep his feet on the pedals, but he can reach the handlebars and steer just fine. Choose the steps and adaptations that create the best bike for your child's needs.

Supplies

Materials:

Bicycle to fit the child; we used a Trek bike the family had purchased
WALD 742 Training Wheels
Butterfly Handlebars
Pool Noodle
Hardware:
- 1/2-in x 4-in x 2-ft Clear Pine Appearance Board Square Unfinished Radiata Pine Board (x2)
- 1/4-in Zinc-Plated Standard (SAE) Regular Wing Nuts (x4)
- 1/4-in Zinc-Plated Standard (SAE) Flat Washer (x4)
- 1/4-in x 3-in Zinc-Plated Coarse Thread Carriage Bolt (x4)
- Screws
- 1-in Steel Galvanized Corner Brace
- 1-1/2-in Corner brace (x1)
- Machine Screws (x3)
- Nut for machine screw (x1)
- Spring Ext 5/8x3-1/4 (x1)
- 1/4-in x 1-in Zinc-Plated Coarse Thread Hex Bolt (x2)
- 1/4-in x 20 Zinc-Plated Steel Hex Nut (x4)
- 1/4-in Zinc-Plated Standard (SAE) Flat Washer (x4)

Tools:

Drill press
Hand drill
Band saw
Sander
Miter saw
Bench vise
Ratcheting Bar Clamp
Rubber Mallet
Drill bits for wood
Drill bits for metal
Wrenches

Step 1: Meeting Our Client and PT Team

The first step of this project was to meet our sponsor and get to know the team as well. Meeting with the team and the sponsors is a vital part in the project because it is important to know who you are working with and who you are working for. In our first zoom meeting we met with the mother and she gave us background about Ford.

In addition to Ford's mother being a physical therapist, we also had a doctoral physical therapy student on our team. Both helped us learn about the mechanics of the human body and Ford's specific needs.

The second half of our meeting consisted of a special team member from Canada, sharing with us her expertise in adapting bikes. She shared a PowerPoint with us over Zoom that showed many different kinds of adaptions made to bikes and what the adaptions are meant for.

Our team took all this into consideration and started brainstorming ideas that would make riding a bike easier and more comfortable for Ford.

Step 2: Measurements of Client

The measurements we needed to take for more prototyping and getting the bike adequately adapted for Ford included:

leg length,
arm length to wrist,
arm length to fingertip,
shoe size,
circumference of shoe,
width of shoe,
shoulder to hip,
shoulder width,
hip to knee, and
knee to foot.

To make the correct sized foot holds for his feet we took the measurements listed above about about the feet.

The other measurements were taken to make sure the bike was at the right height where he could eventually get on it on his own and to where the foot hold connected to the wheels would not touch the ground when pedaling. Also that he was able to bend his knee at the right angle to continue to have momentum to pedal.

Step 3: Wheel Build

For the wheel build we changed the gear system to a direct drive train. Because no team members were that familiar with bikes we had to take the bike to a bike shop in order to do this step. The direct drive train essentially means that the wheels will move when the pedals move. This adaption is also implemented to help teach the child how to pedal and to keep pedaling.

This process will vary based upon what bicycle is used as a base to build off of. We started with a TREK, seven speed, 26 inch bike (measure from the outer limits of the tire, not the wheel as you would do with a car). The goal of the process is to replace the gearing and axle hub that it is attached to, with a differently designed wheel hub. This means that after the rebuild is complete, the bike will not have different gears to change between, and so ultimately the bike will be a single gear bicycle. NOTE: (In most cases training wheels will not mount properly to a geared bicycle, therefore this needs to be done before training wheels are mounted)

This process can be difficult for someone without prior knowledge and experience. Seeing as how we were building this bike for a child, safety as our number one priority so we chose to leave the wheel rebuild up to a professional bicycle mechanic.

The end goal is to have a bicycle drive system where the pedals always move if the wheels are moving, thus they pedal forward if the bike is pushed forward and similarly they pedal backwards if pushed backwards. This allows the child to learn the motion of the petals even if being pushed or moving down hill. This can be through with a bicycle mechanic in order to describe the build that needs accomplished for the specific bike. In this case, we were told that this type of bike drivetrain is referred to as a "Fixie".

Step 4: Training Wheels

Training wheels are necessary for the client to maintain balance when riding on the bike.

The training wheels we purchased was the WALD 742 training wheels kit. We purchased ours through a local bike shop. Installation can be done personally or through a bike mechanic.

Installation takes very little know how, the only tricky part may be balancing both training wheels to be at roughly the same height. This is important as when the bike is held upright, the training wheels should rest slightly off the ground to give the bike room to tilt travel, this will make the bike much more easy and comfortable to ride.

Step 5: Pedals

It was necessary to adapt the pedals on the bike so that Ford’s foot would not slip off the pedals. To do this we used wood pieces to make a longer pedal, PVC pipe to create a heel cup so his foot wouldn’t slip off the back, and Velcro to help secure his foot to the pedals. The adapted pedal is connected to the bike’s original pedal by sandwiching the bike pedal between two pieces of wood and using bolts and nuts to tighten the pieces together. Our pedal adaptation was based on a DIY that one of our physical therapists recommended to us. It can be found here: https://coltenrobert.com/do-it-yourself-tutorials-for-special-needs-equipment/do-it-yourself-adaptive-pedals/

Materials Needed

1/2-in x 4-in x 2-ft Clear Pine Appearance Board Square Unfinished Radiata Pine Board (x2)
1/4-in Zinc-Plated Standard (SAE) Regular Wing Nuts (x4)
1/4-in Zinc-Plated Standard (SAE) Flat Washer (x4)
1/4-in x 3-in Zinc-Plated Coarse Thread Carriage Bolt (x4)
Screws

Tools Needed

Drill press and bits for wood
Hand drill and bits for wood
Band saw
Sander
Miter saw
Bench vise
Ratcheting Bar Clamp

First, we measured out the wood pieces. To give Ford a little extra room to grow in the pedals, we made them slightly longer than his shoe measurement. The top pieces of wood were 3 inches wide and were cut to a length of 10 inches with the miter saw. Then a band saw was used to cut the arc on each end. We drew out the arc using a radius of 1.5 inches. After the arcs were cut, a sander was used to smooth all the edges. We made the bottom pieces of wood were cut to be 5 inches long with the miter saw. The corners were sanded down so they were not sharp.
Next, we decided where the holes for the bolts should be located. In order to thread them through the bike’s pedal, they needed to be about 2 inches apart. We thought about how the ball of the foot should be over the pedal and ended up placing the holes 3 and 5 inches from the top of the 10-inch wood pieces. The holes on the bottom, 5-inch pieces were 1 and 3 inches from the top. The pieces of wood were clamped to a bench and the holes were drilled with a hand drill. The holes were made so that the bolts would slide easily through. After hand-drilling the holes, a drill press was used to make a ¼ inch counter-bored hole on the top pedals. This was so that the top of the carriage bolts would sit flush with the top pedal.

Then we cut PVC pipe for the heel cup. We found some scrap PVC and cut it down to about 2.5 inches high. The pipe was then cut approximately in half. The corners were sanded down to a soft curve and the edges were sanded smooth as well. Then the PVC was screwed onto the back of the pedals using a hand drill and screws.

To customize the bike to Ford’s interests, one team member painted the pedals with Plants vs Zombies characters. Then the paint was sealed to increase the life of the paint job and of the pedals.

The last step for the pedals was to staple the Velcro straps to the top pedal. Two straps were stapled to each pedal, one towards the front and one towards the back. The straps can be Velcro-ed straight across, or diagonally, depending on preference and what is more secure for the user.

The installation of the pedal adaptation to the bike is simple. We just put the bolts through the top pedal, place the top piece on the bike’s original pedal, then sandwich the bike pedal with the second wood piece. Washers were used between the wood and wingnuts and the wingnuts were finger-tightened to secure the pedal adaptation.

Step 6: Steering

Since Ford struggles with gross motor movement and his CP also causes his muscles to be very tight, we adapted the steering so it would be easier to steer straight. Originally the front wheel of the bike would naturally turn to one side or the other when the handlebars are not held. We installed a spring to add tension that would keep the front wheel steering forward more easily.

Materials Needed

1-in Steel Galvanized Corner Brace (X1)
1-1/2-in Corner brace (x1)
Machine Screws (x3)
Nut for machine screw (x1)
Spring Ext 5/8x3-1/4 (x1)
1/4-in x 1-in Zinc-Plated Coarse Thread Hex Bolt (x2)
1/4-in x 20 Zinc-Plated Steel Hex Nut (x4)
1/4-in Zinc-Plated Standard (SAE) Flat Washer (x4)

Tools Needed

Hand drill and bits for metal
Bench vise
Rubber Mallet

In order to create this steering adaptation, we first hammered the 1-1/2 in corner brace to have a short step in it. We clamped it in the vise and used the rubber mallet, hitting it on the tip to create the extra angle. It bent fairly easily into the shape we desired. An unbent 1-1/2-in brace and a modified one are shown in the pictures above.
Next, we drilled holes into the frame of the bike. The 1-in corner brace was installed below the handlebars, so the first hole was drilled into the preload adjuster that sits right above the front wheel. We found the center and drilled into the bike with a drill bit meant for metal. We ended up using a drill bit a little bit too large for our machine screw, so when we screwed on the brace we had to put a nut on the screw it to hold it in. This can be seen in the pictures above.

For the spring set up, we put each end of the spring through a 1-in bolt, between two washers. The ends were fastened tightly with a nut, which also acted as a spacer between the spring and braces. Then each end was connected to one of the braces with another nut. It was added to the 1-in brace after the brace was secured to the bike frame. Once it was on the 1-in brace, the bolts were tightened very well to ensure it would not come undone.

For the holes in the down bar, we added the spring set up to the 1-in brace and the 1-1/2-in brace, then pulled it to the tension we desired. To find a tension that would work, we held the back brace to different points along the frame, lifted the front wheel off the ground and saw how steady the wheel stayed. If it was too loose, we pulled the spring back a little further. Once an appropriate tension was found, we marked where the holes in the brace were on the bike. We flipped the bike upside down to drill the holes. Since we needed to have the screws hold in the metal without a nut, we used a smaller bit. It was hard to get the screws in, so we reamed out the holes a little more, with the same smaller bit. We also used a little WD40 to help make it a little easier. Then, with some difficulty and force, we were able to hand screw the machine screws into the frame, securing the modified 1-1/2-in brace and spring set up. We tightened the nuts on the spring set up with all the parts in place to again ensure it wouldn’t come loose.

Step 7: New Handlebars

Ford was unable to reach the handlebars very easily, so we decided to find some alternative handlebars that would extend further towards the seat of the bike so he could reach better and be able to steer and brake on his own. Based on the advice of our physical therapy associates, we selected a butterfly style handlebar. It was simple to install. The original handlebar was removed by loosening the clamp that attaches it to the frame of the bike. The clamps for the brakes were also loosened and removed from the original handlebar. Then the new handlebar was positioned and clamped into place. The brakes were tightened on the ends of the butterfly handlebar so Ford could easily reach them.

The butterfly handlebars we ordered did not come with any grips or padding, but handlebar tape or padding would be good to make the handlebars more comfortable.

Step 8: Padding

The top tube and down tube needed to be padded because Ford's knees tend to adduct due to very tight muscles. This means his knees would hit the metal bar while he pedals. For padding on the two middle bars we used a pool noodle. This was probably the best solution as it is already hollowed out in the center and pretty sturdy.

After adding the holes and hardware for the steering, we were then able to cut and place the padding onto the bars and adjust the size as needed. Making sure the bottom pad is not rubbing against the pedal and chains. For our padding, the top bar pad is 19 inches long and the bottom is 13 inches long.

We got zip ties to tie it around the poles, and are adding some fabric around the pads to ensure extra safety and care of the noodles so they do not chip or get holes from being scratched off from something. The fabric also ensures they do not move around and if they do that they will not fall off because the part that was cut open to put them on is now covered. Further, the fabric should decrease friction between Ford's knees and the padding.

Step 9: Happy Customer!

The team made sure to decorate Ford's bike with his favorite cartoon characters and colors, Plants VS Zombies. We even put his nickname on the padding piece.

Ford was so surprised and excited to see his new bike. He took time to look at all the details and tell us about his favorite characters. When he was ready, his mom helped him onto the bike, secured his feet in the pedals, and Ford took off on the first try! He was really looking forward to riding his bike in his neighborhood with his family now.