SHIFT Learning by Design trike power

This document describes the background and primary goal of an engineering design project. The project is a stationary tricycle that will power a bubble machine, built by team Z.E.B.A Engineering of ENGR 205: Introduction to Design at Cal Poly Humboldt. Cal Poly Humboldt is a university located in Arcata, California. BubbleBike was commissioned by the Child Development Lab at Cal Poly Humboldt to provide children in the pre-K to Kindergarten level with a fun and educational device.

Z.E.B.A is a team of four engineering students from several different sub-disciplines. Our names are Evie Thunder, Angela Mae Hernandez, Zayden Bronson, and Brenden White. Through our ENGR 205 class, we’ve been given the opportunity to select a project that will aid in the learning development of adults and/or children. The project we’ve chosen consists of designing and constructing a stationary, power-generating tricycle that can be utilized by children aged 2.5 to 5 years. The project idea is inspired by the blender bike at Cal Poly Humboldt’s Campus Center for Appropriate Technology (CCAT), which is a student managed live-in demonstration home for appropriate technology. The purpose of this project is to promote energy education, encourage a healthier lifestyle, and to provide an entertaining device. The final product will be given to Cal Poly Humboldt’s Child Development Lab at the end of the Fall 2026 semester.

The objective of this project is to design and build a stationary trike that powers something fun and interesting for young children. The tricycle will be designed to engage young children and support their development. It should be lightweight and durable — and easily assembled, adjusted, and maintained.

This analysis is an overview of the specifications, considerations, and criteria that will be used in choosing the ideal project design for making the BubbleBike.

The specifications for this project include:

• Users are children aged 2.5 to 5 years
• Will be used in the Child Development Lab’s playground area
• Budget of $400 from SHIFT grant
• Must be under 50 lbs if stationary
• Will build upon existing trike provided by the CDL

The considerations for this project include:

• The CDL is located in Arcata, California, where the humidity averages 85% and days of rain a year averages 115-124
• Should be enjoyable and encourage teamwork for children in the CDL.
• Will be stored under a tarp outside for short periods or indoors for long periods of time
• Children will always be supervised during trike use

Table 1 lists the criteria, constraints, and weights for this project. Criteria will inform decisions; constraints are the limits each criterion must meet.

Table 1: Criteria with associated constraint and weight for the BubbleBike

Criterion	Constraint	Weight (0–10, 10 highest)
Cost	Less than $400 to build	5
Transportability	Must be under 50 lbs, wieldy, and can be carried by one adult	6
Durability	Must support the weight of a 5 year old child (60 lbs), last 3 years with a regular usage of 3 consecutive hours twice a week	8
Fun	Minimum 4/5 kids reported enjoying	10
Inclusivity	Can be enjoyed by plenty of kids at one time	9
Safety	No children are harmed with regular use of the trike under constant supervision by a responsible adult. Safeness after our product is added must be roughly equal to safeness before.	8
Adaptability	Easily replicated and assembled on other trikes / easily fixed	4
Accessibility	Can be enjoyed by all kids who otherwise enjoy riding tricycles at the CDL.	4

A single BubbleBike will be produced and used by a class of 10 children ages 2.5 to 5 twice a week.

This literature review is an annotated bibliography covering the client, bike-power, child interaction, bubble formation, and construction. These sources inform how users will interact with the tricycle, how it might work, and how it might be made.

The client is the Child Development Lab (CDL) at Cal Poly Humboldt. The final product will be used by children ages 2.5 to 5 years in the CDL.

Summary: We talked to Larisa Cole and the Head Teacher at the CDL. They shared a focus on collaborative play rather than competitive play, and emphasized the active lifestyles of the children.

Relevance: Larisa and the Head Teacher suggested a mobile, bubble-producing tricycle that could be enjoyed by everyone.

Interview

Summary: The CDL is a licensed preschool that offers programs for children from 2 years and 9 months to 5 years old. It is operated by and is integral to the Child Development Department at Cal Poly Humboldt. They care deeply about inclusivity and their philosophy is to allow children to build their autonomy and develop a foundation for learning.

Relevance: The age range of children at the CDL will inform the goals of the project. This information is relevant to making an age-appropriate and ability-conscious tricycle.

Web

Seeing as this project will use human energy from a tricycle, it is important to know how bikes and bike-energy mechanisms work.

Summary: This book is a guide on how to modify and customize bikes. It overviews affordable hacking, structural attachments, and harvesting energy using basic shop tools.

Relevance: The book describes how to harvest kinetic energy from the bike by extending the secondary chain. It also addresses cargo attachments and making bikes stationary.

Book

Summary: This page presents an Engineering 205 project from 2014, which was to create a bicycle powered fan for middle school students. It is a comprehensive review of the materials, costs, and assembly of the project. Their device uses a six-gear system that drives a flywheel, chain, and an intermediate shaft to power a fan.

Relevance: This project serves as an example of a bike-powered device used for fun and education. It gives an idea of what kind of system is needed to harness bike power for a spinning device.

Web

Summary: The authors studied human energy in children’s playground rides and their potential as a green energy source. The article describes how the motion of playground rides can generate energy. It details how mechanical energy can be converted into electrical energy with a DC generator, chains, and gears.

Relevance: This source supports the idea that mechanical energy generated by spinning bike wheels could be turned into electrical energy.

Peer-reviewed journal

Since the tricycle is made specifically for children between 2.5 and 5 years old, it is important to consider how the children will interact with the tricycle and what role the tricycle will play in their development.

Summary: Play helps children develop skills in critical thinking, communication, and emotional regulation, and social development. Specifically, play in which children utilize their muscles allows them to develop gross motor skills and become stronger. Unstructured play fosters curiosity, imagination, and exploration of their interests.

Relevance: Since children benefit and learn a lot through play, the product should aim to encourage play. Ways to encourage play and support child development during play are listed under “How You Can Support Play.”

Web

Summary: Research that analyzed tricycles have reached conclusions about the factors that play into stability. There are also studies in the ergonomic benefits of adjustable seating and a variety of additional modifications that increase accessibility. Research on the frame of the tricycle revealed durable and lightweight materials are most suitable.

Relevance: Considering toddlers and preschoolers are still developing their gross motor skills, and spillage of the bubble solution should be reduced, the trike should be constructed with stability in mind. An adjustable seat would also allow accommodation for the children that fit in the age range of the product.

Peer-reviewed journal

Summary: Toddlers and preschoolers go through different developmental stages as they age through this period of their lives. They will develop varying levels of motor skills and modes of interaction with each other. The age range for the product generally spans a period of significant physical growth as well.

Relevance: Different ages will have different comfort levels with the trike, and therefore the trike should be able to function under all the different directions and speeds of motions. The product should also aim to create an environment that fosters cooperation to enjoy a shared outcome (a favorable motivation for children).

Book

The client has requested a moving trike that generates bubbles as it operates.

Summary: Though this book is quite old, it is an in-depth scientific source focusing completely on soap bubbles. This book includes sections such as: Soap films; their tension and curvature, Soap-Films on Frames, The Soap-Bubble, and The Colour and Thickness of Bubbles. It also includes many depictions of experiments where this information is discussed.

Relevance: This book could be very useful if we need more in-depth scientific information on anything bubble related.

Book

Summary: This is a peer review journal that aims to understand the science behind a bubble forming. It includes a description of the difference in bubble generating mechanisms between kids wands and bubble machines. Then, it uses an interesting method to test bubble formation, oil bubbles underwater, which is used to better calculate how fluid interacts with film when a bubble is formed.

Relevance: The description of different bubble generation methods will likely be useful to us. Creating an oil bubble underwater could be useful as well, if issues with wand shape are encountered, this approach could be used to see what is going wrong close up and in slow motion.

Peer-reviewed journal

Summary: This webpage from AutoDesk gives step by step instructions on how to build a 12V bubble machine. It includes parts used, assembly steps, and even 3D printing blueprints. This article is also published as a makerspace project, so have access to all the tools needed for its creation.

Relevance: This article will definitely be useful for understanding how to make a bike powered bubble generator. If all else fails we could also create a very similar design and forgo bike power, having it just run on a switch.

Web

Because an existing product is being provided, it will have to be modified with crafted parts and tools; the new product will need to be tested to see if it is still stable.

Summary: This online article gives a beginner guide to calculating the center of gravity for both two dimensional and three dimensional objects. The guide includes example situations of how you would calculate the center of gravity using two different methods.

Relevance: This information can be applied to the construction of a tricycle powering something. Since a currently established product that had been put through safety testing is being modified, it would be important to make sure the modifications don’t affect the center of gravity of the tricycle in a way that would make it unbalanced and unsafe for the user.

Web

Summary: The peer reviewed article The feasibility of wood and its derivatives as a bicycle frame building material is an in depth study pertaining to the construction and design of bicycles using both traditional and historical materials as well as adopting the historical materials to modern designs.

Relevance: This information can be applied to the construction of a tricycle powering something because the provided material can be adapted to fit the needs of a three-wheeled vehicle rather than just two wheels because it describes both adult and child transportation. This will allow for tested practices to be applied to a different, yet similar, architecture.

Peer-Reviewed Article

Summary: Modern Woodworking covers information about how to construct things using wood as the medium and the proper tools necessary to accomplish it. While the information is dated to be relevant in mostly 1967, woodworking itself has not changed much over the years and it covers topics such as: adhesives, joinery, how to pick materials, hand tools, power tools, larger machinery, workshop safety, and detailing.

Relevance: This helps the construction during the project in the event that we need something more sturdy than printed plastic, but won’t be hard to work with like metal. There is a chance that we may need to build a sturdy support for a storage container.

Book

• The product should also aim to create an environment that fosters cooperation to enjoy a shared outcome.^[9]
• Mechanical energy generated by spinning bike wheels could be turned into electrical energy with a DC generator, chains, and gears.^[6]
• Spillage of the bubble solution should be reduced and the trike should be constructed with stability in mind ^[8]
• Bubbles may be formable with just wind force, a correctly shaped wand ring and specific bubble film.^[10]
• If it became the most practical solution, an electric bubble machine can be made in the makerspace and mounted to the bike so that it would work independently. ^[12]

To evaluate our team’s best ideas, we generated 5 solutions inspired by a group brainstorming session. These solutions center around methods of bubble generation on the trike and different types of power sources.

Introduce this section in one to two sentences specific to your project.

Define each criterion from Table 1 as it is used to judge the alternatives. These are definitions, not constraints. For example, the constraint on cost is the budget, but cost might be defined as the cost of materials only, or as materials plus operation and maintenance. If your criteria changed, update Table 1 so the two match.

Cost

Definition...

Taste

Definition...

Explain the decision process your team used (e.g., decision matrix, Pugh chart). First person is appropriate here. Refer to the table, e.g., Table 2 summarizes the decision matrix.

Table 2: Decision matrix. Scores are 0-10; weighted totals are the sum of weight × score.

Criterion	Weight	Alternative A	Alternative B	Alternative C
Cost	10	7	5	9
Taste	7	8	9	4
Weighted total		126	113	118

Name the chosen solution and justify it with reference to the criteria and Table 2.

Show your most impactful prototypes from earliest to final. Include at least one prototype for function (does it work? e.g., testing a mechanism, material, or dimension) and at least one prototype for desire (will people want to use it? e.g., a mockup shown to the client or users for feedback). Each caption should say what the prototype is, whether it tested function or desire, and what you learned from it. Early sketches, failed attempts, and photos of materials and hands at work all help tell the story.

• 
  Prototype for desire: cardboard mockup of ... shown to the client. We learned that ...
• 
  Prototype for function: test of ... We learned that ...

Describe the final design, starting with the big picture and then going into detail. Use labeled images and refer to them in the text. This is usually a big section.

• 
  CAD drawing of ... by Yourname1.
• 
  Drawing of ... by Yourname2.

Give a complete description of how the final design is built, with lots of images, so someone else could replicate it. Use one {{Step}} per step. This is much easier to write as descriptive (what you did) instead of prescriptive (what another person should do), but you can take either approach.

Z.E.B.A Engineering's proposed timeline for the production of the BubbleBike.

Table 3: Project timeline.

Date	Description	Status
September 16, 2026	Met team and chose project	Complete
September 20, 2026	Background and problem statement posted	Complete
September 24, 2026	Met client and learned their vision for the project	Complete
September 27, 2026	Literature review posted	Complete
October 4, 2026	Problem analysis and timeline posted	In progress
October 10, 2026	Observations and interviews conducted	Not started
October 11, 2026	Alternative solutions posted and parts ordered	Not started
October 18, 2026	Decision posted and first prototype built	Not started
October 21, 2026	First prototype tested	Not started
October 25, 2026	Second prototype built	Not started
November 15, 2026	final prototype build and presentation slides drafted	Not started
November 22, 2026	Full Appropedia page drafted, presentation slides finalized	Not started
December 2, 2026	BubbleBike presented to peers	Not started
December 6, 2026	Complete Appropedia page posted	Not started
December 17, 2026	BubbleBike pitched to press	Not started

Introduce the three kinds of cost below in one to two sentences.

Show the total human hours your team spent outside of class, grouped into categories (e.g., research, brainstorming, prototyping, construction, documentation). Three teammates working for one hour is three human hours.

Introduce the costs to build the design, including donations and reused materials. Note whether costs are actual or proposed. If replication would cost a different amount, say so.

Item	Amount	Cost per unit	Total
Thing - from the thing store — Purchased	3	USD 5.75	USD 17.25
Another thing - 3' x 2', yellow — Donated by ...	1	USD 0.00	USD 0.00
PrintGrand total			USD 17.25EUR 14.84 <br />GBP 12.59 <br />CAD 21.39 <br />MXN 359.66 <br />INR 1,291.16 <br />

Introduce the ongoing costs in time and money, usually per year.

Table 4: Yearly maintenance cost.

Task	Frequency	Time per year (hours)	Cost per year (USD)
Example task	Monthly	2	0.00
Total		2	0.00

Introduce how to use the design, then give step-by-step instructions with labeled images. Use {{Step}} if the process has more than a few steps. A short video is a great addition:

Introduce this maintenance section. Answer these questions:

• Are there any needed actions for maintenance?
• How often?
• Who should perform maintenance?

This is when to maintain what. Please keep the format the same as it can be used to auto-populate maintenance tables.

Daily

• A daily task
• A daily task

Weekly

• a weekly task
• a weekly task

Monthly

• a monthly task
• a monthly task

Yearly

• a yearly task
• a yearly task

Every __ years

• task
• task

Give step-by-step maintenance instructions, using {{Step}} if helpful.

Describe how you tested the final design and what the results were. Compare the results to your criteria, e.g., in a table like Table 5.

Table 5: Final design performance against criteria.

Criterion	Constraint	Result	Met?
Cost	Less than or equal to $3 per ounce	$2.50 per ounce	Yes

Discuss what the testing results mean.

Discuss what your team learned and what you would do differently next time.

Discuss next steps for the project as it goes on into the future.

Cover basic operating problems only. For complex issues, the suggestion might be to contact ________.

Problem	Suggestion
Example issue	Example solution or suggestion
Does not turn on	Make sure it is plugged in.
Another issue	Etc.

Include an inspirational video for sharing.

Introduce the team and semester, e.g., This project was completed in SEMESTER YEAR by Team TEAMNAME:

• Lonny Grafman
• Emilio Velis
• One bullet for each team member, in the format [[User:Username|Full Name]].