Right across from the embassies of the Philippines and Peru on the 1600 block of Massachusetts Avenue, NW, in Washington, D.C., Brobeson Technologies is in the process of designing durable magnesium wheels called Boos for bike-share bicycles. Bike-share biking in Washington, D.C., is very popular, and several companies have footprints on the market, including DC Bikeshare, Inc., with hundreds of docked (as opposed to “dockless”) bike-share locations all over the city and surrounding areas.

City cycling takes its toll on the lightweight aluminum alloy wheels of most bicycles. After flat tires, aluminum alloy wheels that become out of round (from hitting curbs, potholes, etc.) is the condition requiring the most maintenance time from DC Bikeshare’s fleet maintainers and location rebalancers. Brobeson was asked to design a bicycle wheel built to stand up  to the pounding of everyday city cycling. Brobeson built and 3-D-printed 12 Boo mag wheelset prototypes with different designs (number of spokes) and weights (kilograms per pair) and tested them over several weeks. Below are the data they collected and the durability score attributed to each wheelset: 

Discussion Questions 

1. Using the durability rating as the dependent variable, run regressions with the following independent variables: weight, spokes, and weight multiplied by spokes. Which model seems to predict durability the best? 

2. Using the durability rating as the dependent variable, run regressions with a zero-based intercept with the following independent variables: weight, spokes, and weight multiplied by spokes. Which model seems to predict durability the best? 

3. Given the results from the above questions, what can you infer about the weight of the mag wheelsets and the number of spokes used in the design? In terms of bicycle riding, what is the trade-off at work here?

Transcribed Image Text:

WHEELSET WEIGHT SPOKES DURABILITY (NUMBER) (KG/PAIR) (NUMBER) (RATING 1-10) 001 3 002 3 003 3 004 4 005 4 006 4 007 5 008 5 009 5 010 6 011 012 2.80 3.10 3.20 2.90 3.45 3.85 2.90 3.60 4.05 3.25 3.85 4.35 6 6 4.0 4.5 4.5 3.5 4.5 5.0 6.0 7.5 8.5 7.0 8.0 8.5