Two Hands Powering Three Wheels

Jonathan Miller
Joshua Moser
Philip Martin
Ryan Kettle
Sean Morgan


Our project is designing and fabricating a hand-powered tricycle for a three year old girl who has Spina Bifida. This project will give her the chance to experience riding a tricycle outside as well as continuing to develop her upper body strength.


On the 1st of February, 2012 our team traveled to meet a three year old girl and her family. Because of Spina Bifida, she does not have use of her legs, and all of her movement relies solely on her upper body strength. The child, along with her parents, would love for her to have a tricycle so that she will be able to have the joy of riding around outside. Our team is going to design and build a hand-powered tricycle that will fulfill their wish and also allow the child to continue developing her upper body strength.

Design Specifications

1. Small and maneuverable so that she can power it without strain.
2. A frame that allows for a low center of gravity to prevent the tricycle from tipping.
3. Upper body restraint system to prevent her from falling out of the seat.
4. Backward pedal braking mechanism.
5. Brakes on the back wheels that the parents can engage to prevent the tricycle from rolling.
6. The tricycle must be VERY pink.
7. Fit her dimensions:

Design Concepts

  • Two wheels in the back and one wheel in the front
  • One direct drive with one chain and two gears running to the front wheel

Concept Evaluation

Consideration Design Concept 1 Design Concept 2a Design Concept 2b Design Concept 3
Ease Of Use 2 4 3 3
Cost 4 3 3 3
Comfort 4 5 5 4
Motion/Maneuverability 3 4 4 4
Ease Of Construction 5 2 3 4
Safety 3 4 4 4
Total Score 21 22 22 22
Design Choice Design Concept 1, 2a, 2b, 3

Design Overview

Design Concept 1:

  • simple to build
  • low cost


  • difficult to steer
  • bigger turn radius
  • leg safety

Design Concept 2a:

  • easy to steer
  • comfortable
  • legs protected


  • steering design is difficult to build
  • risk of tipping over

Design Concept 2b:

  • comfortable
  • legs protected
  • easier to build steering mechanism than design 2a


  • more difficult to steer than design 2a
  • risk of tipping over

Design Concept 3:

  • easier to maneuver and steer than design 1
  • extremely adjustable


  • higher center of gravity
  • child could feel too exposed due to height

Proposed Schedule

  • Group selection
  • Project selection


  • Calculating the force required to move the bike forward

Bill of Materials


Part Drawings

  • Whole Tricycle

Assembly Instructions

Include as many descriptive pictures as possible.

Implemented Design

Include pictures of the final product.

Summary and Conclusions