Introduction: Chair Force One - Wheelchair Retrofit Kit

Chair Force One is a wheelchair retrofit kit to make a standard medical wheelchair electric. This would be great for nursing homes or retirement communities where there are a lot of older people with limited mobility. For those that already use electric wheelchairs, they are often heavy, expensive, and not very easy to transport. The Chair Force One aims to make a lightweight, inexpensive motorized wheelchair that is easy to maneuver and transport that can attach to any standard medical wheelchair.

The Bill of Material I located below. *Note that there is a standard medical wheelchair on the BOM. For the retrofit kit only, please disregard the purchase wheelchair*



In addition to the Bill of Materials, you will need:

1) Welder

2) Angle Grinder

3) Table Grinder

4) Metal Chop Saw

5) Metal File

6) Bike Handle Bar

7) Eye Protection

8) Work Gloves

9) Welding Mask

10) 2 2-inch casters

11) 4 3/4-inch bolts

12) 1 3/4-inch x 3-ft steel pipe

13) 2 24-in zip ties

14) 4 1/2-in pipe U bolts 2 metal brackets

Step 1: Handlebar

Parts Needed:

1 Bike Handlebar

1 T-Fitting

The set of twist throttles

1 Hand brake from the original bike handlebar

1 Universal brake cable


1) Insert the bike handlebar into the full T fitting and weld in place (the handlebar centered on the T fitting) to provide secure the connection onto the main steering column.

2) The brake system was created using a universal brake cable purchased online. Measure the desired length of the cable by measuring the distance from the brake lever to the wheel's braking system, with around 3 inches of excess brake line to allow for proper steering and maneuverability.

3) Once all components are ready for mounting, securely fasten the throttle and brake assembly using the provided screws.

Step 2: Steering Column

Parts Needed:

Southland Pipe 1-in x 36-in 150-PSI Threaded Galvanized Pipe


1) Use the measuring tape to measure lengths of 6 inches and 17 inches from either end and mark with the permanent marker. These will be the two cuts you make to shorten the shaft. Note, it is not required to use these exact measurements from one end, just as long as there is an 11-inch gap between the two marks.

2) Use the metal chop saw to cut the pipe on the two marks you made.

3) At this point, you should have two lengths of pipe with threads on one end, and one length of pipe with no threads. Discard the length with no threads.

4) Use the welder and PPE to weld the two lengths of pipe with threads together, so that you have a 25in length pipe with threads on both ends.

5) Use the table grinder to smooth the weld, flattening any excess metal from the outer circumference. As a test, roll the shaft across a flat surface such as the floor to show signs of imperfections along the outside. The shaft is now complete.

Step 3: U-Bracket

Parts Needed

Sheet of hot rolled steel

1 T-fitting


1) Cut a two-inch-wide strip of steel into three parts, two parts should be 5.5-inches long, and one part should be five inches long.

2) In each of the two 5.5-inch sections, cut a U out of the middle of one side approximately a half-inch across and about an inch deep (See photo). Round edges if desired. The method that we used was to drill a hole in each section one inch into the metal and used a metal file to file out the rest of the "U".

3) Weld the two 5.5-inch sections to the five-inch section at right angles.

4) Weld the cut in half T fitting to the top of the five-inch section.

5) Lastly, grind/sand all edges so that they are smooth

Step 4: Mounting System

Parts Needed:

1.5-inch steel pipe

6-ft length of pipe


1) Cut a 10.5-inch section out of the 6 ft pipe

2) Take the 1.5 in steel pipe and use the angle grinder to create a “U” centered in the middle of the pipe as seen in the picture

3) Weld the cut pipe from step 1 into the “U” made in the 1.5 in steel pipe from step 2 so that there are 4.5 inches of pipe (from step 2) from the center of the weld to the top of the pipe

*The end product should look something like a cross*

Step 5: Battery Hook-up

Parts Needed:

2 24-in zip ties

4 1/2-in pipe U bolts

2 metal brackets


1) Take the two metal brackets and attach to the bottom of the wheelchair frame with 5 inches of space between them.

2) Using the ½-inch pipe U bolts secure the brackets to the frame of the wheelchair. This will allow you to place the batteries side by side under the wheelchair.

3) The battery can be secured to the mounting bracket using 2 24-inch zip ties.

Step 6: Wheelie Bar

Parts Needed:

2 2-inch casters

4 3/4-inch bolts

1 3/4-inch x 3-ft steel pipe


1) Attach the 2 3/4 inch X 11.75-inch pipes to the horizontal pipes coming from the back of the wheelchair with 3/4” bolts.

2) Then attach a caster wheel to each pipe using ¾ inch U bolts. This will prevent the wheelchair from tipping backward.

Step 7: Assembly

1) Screw the handlebar onto the steering column

2) Insert the steering column into the mounting system

2a) Make sure that the shortest side of the mounting system is facing up

3) Screw the U-bracket onto the bottom of the steering column

4) Attach the hub motor onto the U-bracket

5) Attach the mounting system onto the wheelchair using the scaffolding clamps

5a) The scaffolding clamps should be attached to the wheelchair just below the attachments for the leg stabilizers

6) Attach the battery under the chair

7) Connect the hub motor to the battery using the alligator clips

8) Connect the hub motor, motor controller and the twist throttle together using the attached video

9) Attach the wheelie bars

Step 8: Operation

It is recommended that the user is no more than 250 lbs

*You will need one person to help you get into the chair.*

1) Prior to getting in the chair, loosen the scaffolding clamps and allow the steering column to drop down to the ground.

2) Sit down in the chair, then have your helper pull the handle up to you so that the front wheels of the chair raise off of the ground (about 1/2 inch)

3) Tighten the scaffolding clamps so that the steering column can only swivel but not fall forward or be pushed back toward the operator.

4) Drive around