Alan Salas, Kevin Dahms, Jess Zarker, Jose Ordonez, Robbie Moss

ENGS 171Industrial EcologyRedesigning the Bicycle

Recap from last time

Materials Manufacture Transport Use Disposal/End of Life0.00

5000.00

10000.00

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20000.00

25000.00

Water Use Audit

Phase

Wat

er U

se (k

g)

Frame Wheels Air Tube

Fork Handle Bar

Crank Rear Wheel Frame

Front Wheel Frame

02468

101214161820

Materials: Components with Highest Embodied CO2

% o

f Tot

al C

O2

Part 2: Redesign

Design Requirements

Seat Mast Tube

FUNCTION:To support the weight of the person. Acts as a column in compression

OBJECTIVES:Ideally, minimize environmental impact and mass

CONSTRAINTS:RecyclableHigh strength and stiffness

FREE VARIABLES:Material choice, shape, color

IndicesFor minimizing environmental impact (embodied energy and CO2)

Minimizing Embodied EnergyMinimize Hmρ/ E1/2 for stiffnessMinimize Hmρ/ σy for strength

Minimizing CO2

Minimize CO2ρ/ E1/2 for stiffnessMinimize CO2ρ/ σy for strength

Indices for other componentsPart Configuration Function(s) Constraint(s) Objective(s)

Fork1 Beam (loaded in

bending)2 Columns (in compression)

Provide support; link between handlebar

and front wheel

High stiffness, high strength

Minimize: mass, embodied energy, carbon emissions

Frame6 Beams (loaded in

bending)1 Column (in compression)

Provide structural support for bike

Handlebar1 Beam (loaded in

bending)1 Column (in compression)

Give direction, provide stability, support part of rider's weight,

platform for break handles

Seat Mast Tube

1 Column (in compression)

Support rider's weight

Indices for other components

Material Selection

Analysis for seat mast tube (modeled as a column)

Material Selection

Bamboo!

Low-alloy steelLower embodied energy!

Material Selection

Bamboo!

Low-alloy steel

Lower CO2

Material Selection

Bamboo!Lower density

Low-alloy steel

Trade-off Strategies

Mass vs. Cost

Bamboo, Softwood and Hardwood

Low-alloy steel

Cheaper

Mass vs. Embodied Energy

Bamboo, Softwood and Hardwood

Low-alloy steel

Less embodied energy

Cost vs. CO2

Bamboo, Softwood and Hardwood

Low-alloy steel

Less CO2

Cost vs. Embodied Energy

Bamboo, Softwood and Hardwood

Low-alloy steel

Less embodied energy

Shape

29 mm

38 mm

4.5 mm

Shape

- These specifications are for Iron bamboo, which is the strongest type

- If it is a more flexible bamboo, use wider and thicker tubing

- If internal diameter is less than 29 mm, there will be a hoop stress, which we didn’t look into carefully in this analysis.

http://www.useful-arts.com/sua/instructions/bamboobikekit/harvest/

Use Phase Analysis• Negligible environmental impact• NEXT Bike• Maintenance: paint, wheels, lost accessories, oil• Once child grows, bike becomes obsolete

Use Phase Analysis (cont.)• BamBIKE:• Introduce a service program• Convert the product into a service• Incentive: offer free repairs (only cost is

purchasing the parts), offer discounts, etc.• Return old bike, obtain new larger bike at a

discount

“If your child grows faster than bamboo, we have a solution for you!”

Discussion of Redesign

Frame

Joints + bamboo

Fork

Handle bar

Seat tube

Eco-Audit of redesigned bike

_x0008_M

ateria

l

_x000b_M

anufac

ture

Transp

ort

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_x0008_D

isposal

_x0015_E

nd of Life

potential

-300

-200

-100

0

100

200

300

400

500

Original

New Design

2nd Life (Remanufactured)

Ener

gy (M

J)

34% reduction

_x0008_M

ateria

l

_x000b_M

anufac

ture

Transp

ort

_x0004_U

se

_x0008_D

isposal

_x0015_E

nd of Life

potential

-15

-10

-5

0

5

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Original

New Design

2nd Life (Remanufactured)

CO2

(kg)

CO2 of Entire process

40% reduction

Specifically looking at components

_x0005_FrameHandlebars

_x0004_Fork Seat Tube0

10

20

30

40

50

60

70

Original

New Design

Ener

gy (

MJ )

75% reduction

87%

CO2 of materials

_x0005_FrameHandlebars

_x0004_Fork Seat Tube0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Original

New Design

CO2

( kg

)

74% reduction

87%

Water-audit of redesigned bike

Materials Manufacture Transport Use End of Life0

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Water Audit: Existing vs. Redesign

OriginalRedesign

kg o

f Wat

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Why isn’t there a significant change???

Economic Analysis• Materials:• Low alloy steel

• 0.89-0.93 USD/kg• At 3.68 kg, price is $3.35

• Bamboo• 1.37-2.05 USD/kg

• At 0.4 kg, price is $0.82

• BUT, labor is a problem:• More labor intensive to assemble BamBIKE, so higher costs are

associated• This is why it is currently only offered to very specialized, high end

consumers

Economic Analysis• CNN article published today about a bamboo bike company

located in Zambia:

http://edition.cnn.com/2012/05/31/business/bamboo-bicycles-zambia-zambikes/index.html?hpt=hp_c4

“Each frame takes between 40 and 60 man hours to make […] Every piece of bamboo is having different colors, different bend, so every frame is unique."

• That explains the high costs, and why these “high-end, lightweight bicycles” have “a price tag of around $900” and are “primarily aimed at the international market”.

Considering Aesthetics: Paint and Plastics

Aesthetics are a major feature refractive quality of paint, extra features (painted plastic), logo designs

Aesthetics are also subjective; malleable• Don’t outweigh the environmental impacts:

• Greenhouse gas emissions: VOCs, CO2, NOx, SOx , and PM

• Health Concerns for workers• “Eco-Design”

Water-based paintWater-based non-toxic wood varnish

logo

Conclusions and Recommendations

Findings• Bamboo is an appropriate substitute for steel

Considerations• Industrial infrastructure is currently nonexistent• This is the foundation for a sustainable lifestyle

• Saving 91 MJ per bike means saving energy of

245 bananas per unit!!!

There are other important benefits of bamboo that could be further exploited:

“One of nature's fastest growing resources”

“Has great shock absorbing abilities that contribute to a smooth and eco-friendly ride”

http://edition.cnn.com/2012/05/31/business/bamboo-bicycles-zambia-zambikes/index.html?hpt=hp_c4

Conclusions and Recommendations

Moving forward… Hemp

Wood

Wood

and ideally…

DIAMOND!

Questions?