Observation Mapping between switch and fixture controlled > 7 years interaction, still trial and error

Anthropometric Data

HUMF 5001 – Team 4Danielle PlutStephen WhitlowAlan Wyman

Definitions Anthropos Man Metron Measure

Anthropometry Anthropo

Introduction to Ergonomics, 3rd Edition, Chapter 3User-Centered Workspace Design Using Anthropometric Data

Based on a statistical normal distribution

0 2 4 6 8 10 12 14 16 18 200

0.05

0.1

0.15

0.2

0.25

Breaking out by gender and using real data

Comfort on bicycles and the validity of a commercial bicycle fitting system

Comfort on bicycles Assess “seated” comfort of utility bikes

– scientific contribution since most previous work focused on racing road bikes

Validate conventional bike-fitting practices

Propose alternative bike-fitting system

Issues > 1 M Dutch suffer from several

varieties of “saddle” soreness More women than men Women's’ issues are more serious Occurs even in short bike rides 3-10km

(2-6 miles)

Factors that impact riding comfort Environmental – temperature, wind,

rolling resistance on road Clothing – biking shorts can prevent

chaffing Mechanical – gearing Biomechanical – bike geometry Physiological – fitness level

Saddle(seat) Height Previous findings indicate 107% of crotch

height, current study used 108% Too high rider tends to hyper-extend knees Too low puts pressure on patellofemoral joint Patellofemoral pain syndrome “(PFPS) is a

syndrome characterized by pain or discomfort seemingly originating from the contact of the posterior surface of the patella (back of the kneecap) with the femur (thigh bone). It is the most frequently encountered diagnosis in sports medicine clinics” [wikipedia]

Distance between Saddle Pads No appropriate rules Pressure distribution on saddle requires pads

that support pelvic bones Distance between bones different for men and

women, bone shape differences as well Notched saddles can relieve prostrate

pressure Can lead to slipping off front edge

Crank length 20% of crotch height

This length produced “superior” measurements of heart rate, oxygen consumption, and perceived exertion

Has greater performance impact than discomfort impact– unless significant deviation from standard

Saddle angle No specific rules are available beyond

guidance that is should be “slightly upward” or “slightly downward”

Handle Height and Body Posture No appropriate rules High handlebars reduce lower cervical spine and

neck extension issues 15% forward lean reduces weight on thoracic cage Upright cycling position

Nearly all weight on saddle, discs become pinched and supporting ligaments stretched

Forward position puts more weight on arms, extends spinal column so

reduces disc pressure At low workload, an upright posture produces lower

HR than a racing position

Handlebar width Should be same width as rider’s

shoulders-- allow ample room for breathing and control

Less than width-- reduces steering efficiency

Distance between saddle and handlebars No scientific data Racing rule of thumb is not reliable Netherlands rule of thumb – underarm

length

Frame angle Less steep frame angle (seat tube

angle) – reduces jarring, saddle soreness and hand and wrist ache

Pilot study Pilot Study to collect objective anthropometrics

and assess comfort in prototype bike fitting  system

Bike Show 453 subjects (60% male, 40% female) Mean age for women was 45, men was 46 132 subjects (76 men and 56 women) completed

both anthropometric measurements and comfort assessment

Research Tools Anthropometric measuring station

Body length and weight Trunk length Shoulder breadth Grip reach Upper leg length Crotch height Distance between pelvic bones

Computer program Generate optimal bike configuration based on rules of

thumb Remote-controlled bicycle simulator

Dynamic comfort assessments and adjustments Impose adjustable loads via pedals

Bike Simulator

Procedure Subjects cycled for 2 minutes at chosen

pedal load level with personalized bike fit Subjects then instructed to ask for a

change to bike geometry if they experience discomfort say “stop” when adjustment is OK 3 chance for changes

Results 60% of subjects complained of discomfort

35% mentioned saddle sores Women reported more discomfort than men

Preferred seat height does not correspond on rule of thumb (108% of crotch height) 106% for men, 107% for women

No correlation between grip reach and preferred saddle to handlebar length

No other physical measurements predicted preferred riding configuration

Large variability in relation between distance between pelvic bones & preferred seat width

Riding posture is more upright in simulator, likely due to static nature of simulator (low balance requirement)

Lab Experiment Investigate variables not investigated

during pilot study – seat angle, handlebar width, etc.

Contribute to design specs for Commercial Bicycle Simulator

Critical interest was in relationship of saddle and handlebar position in relation to crank axel and other body segments

Research Methods Equipment--same as pilot study

Subjects measure with anthropometric measuring station

Subjects shown how to adjust saddle and handlebar while riding

Initial settings conformed to rules of thumb Asked to maintain a 15 km/h pace (9.3 mph) Rode for 12 minutes and were prompted to

make adjustments every 2 minutes (5x)

Results 64% of subjects reported discomfort (74% of women, 55% of

men) Most frequent areas

lower arms and hands-- 32% saddle sores -- 29% neck & shoulders -- 18% Knee -- 10% Most subjects reported multiple areas

Crotch height is good predictor of preferred saddle-to-pedal distance

Higher correlation between grip reach and preferred saddle-to- handlebar distance than in pilot though still only accounted for 29% of variance in men and 26% in

women No correlation between age and preferred frame angle

Preferred saddle geometry has low correlation with pelvic bone distance, weight and age

Conclusions Comfort on bikes driven by individual needs

only 1 physical measurement was reliable predictor of preferred geometry (crotch height)

Non-trivial number of subjects preferred seat tube angle that are not within standard geometries

Researchers surprised by lack of finding for relationship between measurements and preferred saddle geometry

Validates the need for a highly configurable bike fitting simulator since rules of thumb were generally poor predictors of comfort

Manufacturers would need to support more configurability of bike  setup – could be marketed as “personalization”

Simulator could be another tool for knowledgeable salesperson

Nice Ride Bicycleshow do they compare?

Only one adjustment available– seat height– also the only reliably predictive

variable in study for bike comfort

Relevant Chapter 3 Material

Body size and proportion vary across populations should use population data where system is to be

deployed E.g., Equipment designed for 90% of US males would

only fit 10% of Vietnamese Anthropometric surveys are expensive and time-

consuming – nice to use existing datasets – provided data still valid According to US CDC mean stature (height) of US

males and females has not changed since  the 1960s Should not design for “average” user since half of

population is above and half below for normally distributed variable

Anthropometric AnalysisCrotch Height (mm) US Male US Female

Average 819 742

Standard Deviation (SD) 49 46

Z value(# of SD for 95% male, 5% female)

1.64 -1.64

Crotch Height (95% male, 5% female)

899.36 666.56

Nice Ride Max/Min Seat Height 955 720

Preferred Seat Height as a percentage of Crotch Height (Rule 108%)

106% 107%

Optimum Seat Height 953.3216 713.2192

Conclusion Within Nice Ride Range

Outside Nice Ride Range

Estimated percentage of the population accommodated

95.025% 94.840%

Crank length 160 mm

95% Male 20% = 183 mm

5% Female 20% = 130 mm

160 mm

680 mm

Middle of seat to tip of handlebar

Seat height Top of seat to top

of pedal a bottom position

Lowest position 720 mm

Highest position 955 mm

Saddle• Style• Size, width, and length

Team 4 would like to thank Nice Ride Minnesota for complimentary use of one of their bikeshttps://www.niceridemn.org/