Stuart A. Schupack
and
Gerald J. Driessen
Report No. 051-7
Research Department
National Safety Council
425 North Michigan Avenue
Chicago, Illinois 60611
July 1976
This report came about through the converging and constructive energies of many
persons and organizations. Ken Licht and Jack Green, Sr. of the School and
College Department of the National Safety Council were especially helpful in
making contacts for data collection at the various colleges and universities.
Harold Heldreth of the Youth Department was highly cooperative and effective in
acting as liaison with various organizations. Tom Chlapecka did much of the
exploratory work on earlier attempts to collect data, organized the final
survey, and supervised data collection from the cooperating schools. The local
school personnel, many of them safety supervisors, were a necessary and vital
link in the data chain. The students who provided the self-reports that are the
basis of the results were, from one point of view, the most helpful of all.
Thanks are also due to Joan Planek for editing the manuscript and to Norma
Melnick for typing it and organizing the myriad of details necessary to complete
the report. Finally, we are grateful for the generous (and patient) support of
the Schwinn Bicycle Company whose grant served as partial support for this
project. The corporate allocation of funds for research to determine the causes
of accidents and find effective countermeasures is an enlightened, constructive
decision. Such action deserves the explicit acknowledgment and clear expression
of gratitude that these words are intended to convey.
Note: Footnotes have been incorporated into the text lines, between curly brackets { ... }
Note: The Horizontal Lines indicate a page break in the original. The page number is shown at the bottom center of the page. Some short pages have been combined with the previous page. Therefore, some page numbers are not used.
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| Page | |
| PREFACE | 1 |
| INTRODUCTION | 3 |
| METHOD | 6 |
| Survey Design | 6 |
| Survey Instruments | 6 |
| Data Collection | 7 |
| Data Analysis | 8 |
| RESULTS | 10 |
| Response Rates | 10 |
| Univariate Descriptions | 10 |
| Demographic characteristics of the sample | 10 |
| Description of bicycle usage | 11 |
| Description of accidents | 12 |
| Multivariate Comparisons | 14 |
| Accidents, mileage, and accident rates | 14 |
| Sex and type of bicycle comparison | 19 |
| Accident group vs. no-accident group comparisons | 27 |
| Comparison of Adult vs. Children's Experience | 30 |
| SUMMARY AND CONCLUSIONS | 33 |
| REFERENCES | 36 |
| APPENDICES | 37 |
| Table # | Description | Page |
| 1 | Accident and Mileage Rates by Sex and Type of Bicycle | 16 |
| 2 | Recoded Variables Showing Original and Recoded Categories | 20 |
| 3 | Type of Bicycle by Motor-vehicle Traffic Density at Most Recent Bicycle Use | 21 |
| 4 | Type of Bicycle by Primary Purpose of Most Recent Bicycle Use for Males | 22 |
| 5 | Type of Bicycle by Primary Purpose of Most Recent Bicycle Use for Females | 22 |
| 6 | Purpose of Drive at Time of Accident by Type of Bicycle for Males | 23 |
| 7 | Type of Accident by Sex | 24 |
| 8 | Result of Accident by Sex for 1-speed Bicycles | 25 |
| 9 | Part of Body Injured by Sex | 25 |
| 10 | Speed at Time of Accident by Type of Bicycle for Males | 26 |
| 11 | Speed at Time of Accident by Type of Bicycle for Females | 26 |
| 12 | Accident Group by Type of Bicycle | 27 |
| 13 | Accident Group by Years Driving More than 100 Bicycle Miles from 1970 through 1972 | 28 |
| 14 | Accident Group by Primary Purpose of Most Recent Drive | 29 |
| 15 | Accident Group by Motor-vehicle Traffic at Most Recent Drive | 30 |
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| Number | Figures | Page |
| 1 | Accidents per 1,000 miles for males and females by type of bicycle | 17 |
| 2 | Accident and mileage rates by type of bicycle | 18 |
| Appendix | Page | |
| A | Survey Form | 37 |
| B | Procedure Letter | 43 |
| C | Cooperating Schools and Number of Forms Returned | 44 |
| D | Responses to Questionnaire | 45 |
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This document represents the fourth major research report on bicycle safety
issued by the Research Department of the National Safety Council in the last 9
years. {Earlier studies were by Vilardo, Nicol, and Heldreth (1968), Vilardo and
Andersen (1969), and Chlapecka, Schupack, Planek, Klecka, and Driessen (1975).}
The original initiative for this work began with the energy, enthusiasm, and
concern of the Youth Conference of the National Safety Council for what they saw
as a major accident problem affecting young persons, especially children. Their
perception of the seriousness of bicycle accidents and the pressing need for
effective countermeasures have been recently reaffirmed by the high placement of
bicycles on the hazardous product list of the Consumer Product Safety
Commission. While there is some controversy about whether bicycles "deserve"
their current position at the top of the list (Flora, et al, 1975), it is likely
that bicycles will continue to be listed as a highly hazardous product because
of their widespread usage and the inherent risk of falls and collisions
associated with regular use.
The rapid increase in the use of bicycles in the past decade has been well
documented. As one would expect, this increased usage has led to a parallel rise
in the number of bicycle accidents. The safety community has been especially
concerned about children's bicycle accidents, and consequently much research and
program development activity has dealt with this problem. Based on some of the
aforementioned research, the National Safety Council developed the All About
Bikes program as a specific countermeasure to help reduce bicycle accidents
among elementary school aged children. This program is currently being used by
school systems throughout the country. Adult bicycle driving has undergone an
even more dramatic increase in popularity, but there has been little research
effort spent in examining the usage and accidents of the adult bicyclist. This
study is a preliminary step in remedying this oversight.
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The primary obstacle to be overcome in examining adult bicycling is the
gathering of a suitable sample from which to collect reliable data. Neither
bicycles nor bicycle drivers are licensed by official agencies. Most bicycle
accidents are not entered in any regular, official reporting system except for
the few injury-related motor-vehicle involvements. Traffic rules are poorly
enforced for bicycle drivers and violations are rarely, if ever, entered on
official records. Fuel consumption figures used to estimate automobile mileage
are, of course, meaningless for bicyclists. Thus, several of the important
sources of information concerning automobile usage and accidents are not
available when studying bicycles. The absence of these sources makes it
necessary to contact bicyclists directly in order to collect the required data.
The possible methodologies for contacting bicyclists were restricted by both
theoretical and financial limitations. First, the study was intentionally
restricted to young adults, aged 16 to 30. Second, we wished to gather a broad
base of general information rather than detailed answers to a few specific
questions, since the scarcity of previous research made it difficult to form any
specific, testable hypotheses. Third, the level of funding placed limitations on
the size of the sample and on the time that could be allowed for data
collection.
Two initial methods of collecting data were tried, but proved unsatisfactory.
One involved gathering data through cooperating bicycle clubs, and the other
consisted of direct interviewing of Chicago area bicyclists. The primary problem
with each of these methods was the inability to generate a sample of sufficient
size for reliable analysis. While a small amount of data was collected (some 200
cases), our judgment was that any analysis would be foolhardy. Consequently,
none of those data are presented in this report.
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The third data gathering method had more favorable results. By circulating questionnaires on college campuses throughout the country under the auspices of a professor or administrator involved in campus bicycling activities, information on over 1,000 subjects was collected. The quality and quantity of these data were sufficient to allow some meaningful analysis, which is presented in this study.
The preliminary nature of this study severely limits its scope. There are two
areas in which these limitations are most clearly seen. First, the group of
young adult subjects was one of convenience rather than a scientifically
selected representative sample, making it difficult, if not impossible, to
generalize the results to a larger population. Second, the data were collected
without reference to any specific hypothesis; rather, variables were included
that seemed likely to shed some light on adult bicycle usage or accidents on
either a common sense basis or on the basis of the earlier research on
children's bicycling. While this data collection method yields a large amount of
univariate descriptive data, which was previously unavailable, it also makes any
multivariate analyses, even simple cross-tabulations, a haphazard process.
Considering these two limitations, any conclusions drawn from this study must be
viewed cautiously. The conclusions should be used as aids for further research
rather than as facts with immediate program implications.
Despite these limitations, the reasons for conducting and reporting this
research are clear. The methodology involved requires this type of pilot test
before refinements can be added and before greater amounts of money are spent
for more extensive studies. The basic data concerning certain parameters of
adult bicycling usage and accidents have not been adequately documents in
current survey literature, and these results, while limited, can serve as
starting points for further research. It is hoped that this study will, indeed,
stimulate further research in the area of adult bicycling.
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Questionnaires were sent to a total of 55 colleges and universities representing
each of the nine standard U. S. Geographical areas. Schools were selected on the
basis of two criteria--geographic location and the availability of a professor
or administrator known to be involved in cam-pus bicycling activities. This
contact on each campus was requested to oversee the distribution and collection
of the survey forms and to return the completed forms to the National Safety
Council.
The questionnaire (Appendix A) consisted of over 100 items divided into five
sections: You, Your Bicycle, Most Recent Bike Use, Bicycle Accidents, and Local
Bicycling Conditions. The items were selected partly from an NSC form used to
investigate children's bicycle accidents (Chlapecka, Schupack, Planek, Klecka,
and Driessen, 1975) and included additional variables to help focus on the
experience of young adults.
Questions concerning the bicyclists included sex, age, bicycle driving
experience, and several measures of exposure. The exposure measures were, months
of regular bicycle driving, bicycle mileage driving time, and amount of driving
on various roadway types. Information on the bicycle included length of time
owned, frame size, wheel size, gearing, brake type, handle-bar configuration,
and maintenance history. Questions concerning the respondent's most recent
bicycle use were asked in order to obtain accurate details of the
characteristics of a typical bicycle outing. These details included day of the
week, time of the day, weather, driving surface, traffic density, type of
roadway, and purpose of drive.
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Accident details were requested for the most serious accident within the past 12
months, or, if there were none that recent, within the past 5 years. Some of
this information concerning the accident paralleled the topics related to most
recent bicycle use. Additional accident information was collected on activity
and speed before the accident, familiarity with accident location, type of
accident, and several items concerning injury severity and treatment. The final
section of the questionnaire was concerned with the adequacy of local bicycle
routes or lanes.
Standard data collection procedures were given to the campus contacts. The
procedures are described in a letter included as Appendix B. In general, it was
hoped that the questionnaire would be given to entire class-rooms in order to
reduce the bias of having only highly interested bicyclists providing
information. While the level of compliance with these instructions is unknown,
the general cooperation of the campus contacts and internal evidence to be
presented in the results section suggest that this source of bias was indeed
reduced. On the other hand, clearly no claim can be made of having a
representative sample from any of the campuses that returned forms. As stated
before, however, due to the preliminary nature of the study, this is not a
totally debilitating flaw.
Questionnaires were distributed in October, 1972. This meant that the experience
of the high bicycling summer months would still be fresh in the minds of the
respondents. It also meant that much of the reported accident experience would
be from home rather than from the college campus--a fact that increases the
geographic spread by some unknown amount and makes any generalizations even more
problematic.
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The data analyses had three planned phases. The first was to present and discuss
the basic information in the form of simple frequency distributions and
proportions and involved the first estimates of several previously unknown
parameters of young adult bicycling.
The second phase of the analysis involved several calculations and comparisons.
Variables concerning months of driving, driving distances, and accidents were
combined to calculate accident rates on a "per person" basis and, separately, on
a mileage basis. These rates were further examined by sex and type of bicycle.
Then the relationship of certain basic explanatory variables (sex, type of
bicycle, exposure) to important accident and usage details was explored. This
was done with a series of two-way cross-tabulations. The basic statistical tool
was chi-square with p < .05 as the level of significance. The same basic method
was used to explore differences between accident and no-accident groups.
The third phase of the analysis compared the results of these adult data with
previous results from a study of children's bicycle accidents and usage. The
similarities and differences between the two groups help de-fine needed areas of
further research and provide some general direction for young adult bicycle
programs and countermeasures.
Data editing was a preliminary step to all of these analyses. Three criteria
were used in editing: completeness of information, current age of the respondent
and, if accident details were reported, age of the respondent at the time of the
accident. Questionnaires with large amounts of missing data were not keypunched.
After keypunching, computer editing removed those cases where the respondents
were not young adults, defined as aged 16 to 30. Finally, accidents to those
respondents in the youngest
remaining age group were removed if they occurred more than 1 year ago. This
editing was done to insure that all accident details were indeed about accidents
that happened to young adults and not children 11 to 15
years of age. The exposure and usage data of these cases, being based on the
most recent bicycle use, were kept and included in all analyses, since all of
these people were young adults when providing this information. Analyses were
done primarily with the National Safety Council's IBM 1130 computer with some
details completed using a Wang 520 programmable calculator.
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Survey forms were sent to 55 colleges and universities. Returns were received
from 27 schools for a 49% institutional return. Forms were sent in sets of 100
per school. One school received 2 sets, however, so a total of 5,600 forms were
distributed. Returns totaled 1,370 or 24% of 5,600. Appendix C contains the
names of all cooperating schools and the number of forms they returned. Editing
for completeness and age led to a removal of 74 and 64 forms, respectively. The
final sample contained
1,232 bicyclists.
Responses to all questionnaire items can be found in Appendix D. In order to
facilitate use of this Appendix, items will often be referred to by both name
and number, e.g., Sex (Variable 1), Age (Variable 2), etc. The Appendix reports
the frequency distributions of the responses for the total group and for two
groups made up of those people who reported an accident (A) and those who did
not (NA), i.e., "no-accident." The total percentages reported in this Appendix
for any specific variable include nonresponders, usually less than 5%. The
percentages cited in the text
for a given variable will not include these nonrespondents. Not all of the items
in the survey form will be discussed in this report, and the reader is urged to
consult Appendix D for information on any specific variable in which he may have
a special interest.
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Returns were received from colleges in all nine U. S. Census areas. The number of returns from an area ranged from one (New England and Pacific) to five (East North Central and South Atlantic). While the sample cannot be considered strictly representative of the United States, it is important to note the wide geographic distribution of the returns.
The final sample of 1,232 was 62% male (Variable 1). The ages of the subjects
were restricted to 16 to 30 years with 52% between 16 and 20, 40% between 21 and
25, and 8% between 26 and 30 (Variable 2). Reflecting the methodology employed,
96% of the sample reported their education (Variable 5) as some college or more.
Variables 20-44 in Appendix D give a general description of the type of bicycles these young adults were driving. The "modal" bicycle was a 10-speed (38%) with a 26" frame (49%) and 26" wheels (51%), hand brakes (64%), regular handlebars (59%), no front light (62%) but a rear reflector (82%), bought new and assembled (56%) 1 to 6 months ago (20%), and not registered with either the city or insurance company (67%). The most common variations were in terms of gears, (28% 1-speed, 26% 3-speed), handlebars (41% drop-style), and length of time owned (17% 1 to 2 years, 16% 5 to 10 years).
Variables 46-64 report on the details of the most recent bicycle use by the
respondent. Since this information on most recent use was collected in the month
of October, much of it pertains to driving on the college campuses. Almost
one-third of the respondents, however, reported their most recent drive
(Variable 47) to be more than 1 month ago, probably indicating summer driving
while at home. Over half of the subjects reported that their most recent drive
was 1 week ago or sooner. Weekends accounted for 35% of the last driving days
(Variable 46). Bicycle driving was generally done alone {69%), on dry pavement
(91%), with moderate to light motor-vehicle traffic (81%), in a residential
area, (64%). Three-quarters of the
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respondents drove farther than 1 mile, usually driving on the street with the
traffic (71%). Most of their bicycle driving was on secondary streets (50%) or
main streets (20%). The most common purposes for bicycling were "just for fun"
(39%), exercise or health (13%), and commuting (27%). Of all the respondents, 6%
reported falling on their most recent driving day.
As mentioned earlier, one potential source of bias was that only highly
interested bicyclists would respond to the survey. This appears not to have been
the case. When asked if they had driven a bicycle more than 100 miles in 1971,
72, or 73, (Variable 7) only 13% of the respondents answered affirmatively to
all three years, and 47% did not report driving 100 miles in any
of those years. Only 17% of the sample owned and drove more than one bicycle
(Variable 19). When asked how many months they regularly drove a bicycle
(Variable 8) and how far they drove (Variable 9), 51% of the respondents
indicated they drove 4 or fewer months, and 54% estimated they drove less than
50 miles per month. Thus, it does not appear that this is a sample of
extra-ordinarily active bicyclists.
Subjects were asked to supply accident details for their most serious accident within the past 12 months, or, if there were none that recent, the most serious within the past 5 years. While 390 (32%) of the subjects {An additional 220 subjects in the 16 to 20 year old age group reported details of an accident that occurred more than 1 year ago. Since these accidents could have happened when the subjects were less than 16, they have been excluded from this report. Analysis of the excluded accidents supported the assumption that they may have been children's accidents by showing, for example, an increased ratio of falls to collisions, which is more characteristic of children's bicycle accidents than of adult's.}reported having at least 1 accident in this time frame, details are available for only approximately 366 accidents because of some respondents who gave few or no details for their reported accidents. The percentages reported in this section will use as a base the number of subjects who responded to each question.
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Variables 67 - 102 in Appendix D give a general description of the accidents of these young adults. As one would expect, the majority of accidents occurred in June (18%), July (23%), and August (11%). The 6 months from May to October included 78% of all reported accidents. Weekends, which account for 29% of the week, were not as over-represented as one might expect, with 32% of the accidents (Variable 69). Surprisingly, over twice as many accidents were reported on Saturday as on Sunday. Sixty-four percent of the accidents were reported as happening between noon and 6 p.m. (Variable 70). Most accidents occurred in the first 20 to 25 minutes of the drive (54%) and within 1 mile of home (74%) (Variable 81 and 82).
Examination of the bicycling environment did not disclose any startling
conditions. Driving tended to be in good weather (74%) and was most often on
secondary (46%) or main streets (23%) with light or no traffic (69%). Only 14%
of the driving was against traffic or in the middle of the street, the remainder
being either "with" traffic or not on a street (Variable 79). The accident area
was residential in 56% of the cases (Variable 83) and was a place where the
bicyclist had driven often before, 69% of the time (Variable 86). Intersections
of some kind were the place of occurrence in 43% of the accidents (Variable 90)
with almost half of these being the intersection of two streets.
Type of accident (Variable 89) may be categorized into falls and collisions.
Using this dichotomy, 33% of the accidents were classified as falls and 67% as
collisions. Crashes involving motor vehicles made up 32% of the collisions (21%
of all accidents). Considering the activity just before
the accident (Variable 84), the largest single category was driving straight
ahead (49%), with turns making up another 22%, and getting on, starting, and
getting off accounting for 12%. Of all the respondents, 77% were sitting on the
bicycle seat (Variable 87) and 48% were attempting some evasive maneuver
(Variable 88) as the accident happened.
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Some personal injury was the result of 79% of these reported accidents (Variable
95). Minor scrapes, cuts, and bruises were the most common results, accounting
for 79% of the injuries. Injury treatment (Variable 99) was provided by a doctor
or hospital in 12% of the cases, while 73% of the injuries were either
self-treated or not treated at all. Arms and legs were the parts of the body
most often injured, each accounting for 38% of the reported injuries. Injury
resulted from direct contact with the ground in 66% of the reported accidents
and from contact with bicycle parts in 15% (Variable 98). Some bicycle part
failed in 18% of the accidents (Variable 91), though it is impossible to
determine from these data whether the failures caused or resulted from the
accidents. The police or insurance companies were notified in only 7% of these
accidents.
While the preceding section gives a general overview of the data, other
questions require comparisons among two or more variables. One of the problems
of survey research is that the number of possible comparisons among variables is
often very large. In this study, only a few of the possible multivariate
comparisons were examined. These were chosen either because past research (often
on children) had shown these variables to be important, or because of general
interest in the bicycling community.
Variable 65 in Appendix D gives the number of bicycle accidents involving any damage or injury in the past 12 months. There were 248 subjects (21%) who reported having had at least 1 accident in the past year. These subjects reported 373 accidents for an average of 1.5 accidents. The whole group of 1,197 subjects who responded to the question therefore experienced a rate of .31 accidents per person, per year.
In Table 1, Section A, accident rates per person were broken down by sex and
type of bicycle. The male rate of .32 accidents was slightly higher than the
female rate of .30. Among bicycle types (which for the multivariate comparisons
were divided into three categories based on their number of gears), the higher
speed bicycles (5-,10-,15-gears) had a much higher per-person rate (.42
accidents) than the 3-speed (.26) or 1-speed (.21) bicycles. When sex and
bicycle type were examined simultaneously, however, the picture changed. Here
females had higher rates for both 3-speed and 5-,10-,15-speed bicycles (.35 and
.41 respectively) while the male rate increased only for the 5-,10-,15-speed
bicycles.
Variables 8 (number of months of regular driving) and 9 (miles driven per month)
were used to estimate annual mileage. These estimates, shown in Table 1, Section
B, were broken down by sex and type of bicycle. While the estimates are useful
in making comparisons between groups in this study, one must be very cautious in
generalizing these
mileage figures. Estimated average annual mileage for the entire group
was 607 miles per person. Male mileage was 55% higher than female mileage (705
miles and 456 miles, respectively). Mileage also increased steadily with number
of gears, 5-,10-,15-speed bicycle mileage of 882 miles being 80% higher than the
3-speed bicycle mileage of 491 miles which, in turn, was 70% higher than the
1-speed bicycle mileage of 287 miles per person, per year. The pattern was
similar to that shown for accidents when examining both sex and type of bicycle.
Female mileage was equally high for both 3-speed and 5-,10-,15-speed bicycles,
while male mileage increased steadily with bicycle gearing.
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| Accident and Mileage Rates by Sex and Type of Bicycle | |||||
| Sex | Type of Bicycle | Total | |||
| 1-gear | 3-gear | 5-,10-,15-gears | |||
| A Accidents per person per year | Male | .21 | .20 | .43 | .32 |
| Female | .20 | .35 | .41 | .30 | |
| Total | .21 | .26 | .42 | .31 | |
| B Estimated average annual mileage | Male | 275 | 481 | 980 | 705 |
| Female | 298 | 504 | 612 | 456 | |
| Total | 287 | 491 | 882 | 607 | |
| C Accidents per 1,000 miles driven | Male | .76 | .42 | .44 | .45 |
| Female | .68 | .69 | .67 | .67 | |
| Total | .72 | .54 | .48 | .51 | |
| D Approximate number of respondents *
|
Male | 153 | 171 | 406 | 730 |
| Female | 180 | 140 | 140 | 460 | |
| Total | 333 | 311 | 546 | 1,190 | |
*{These numbers are approximate because each of the variables involved (1, 8, 9,
24, and 65) have slightly varying numbers of nonrespondents. See Appendix D.}
Mileage and accident information were combined to calculate accident rates per
1,000 miles of bicycle driving for sex and type of bicycle groups in Table 1,
Section C. Again, although these rates are most useful in making comparisons
between groups in this study, their absolute values may or may not be reasonable
estimates of the "true" rate for young adults across the nation. The data
collection method used in this study did not control potential sources of bias
in a way that allowed precise generalizations to
a larger universe. For the same reasons, tests of statistical significance were
_not appropriate for this section. Rather the direction of large differences
were noted, and the possible importance of these differences discussed.
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The overall accident rate was .51 accidents per 1,000 miles. The pat-tern for
males and females on the three bicycle types was very different as can be seen
in Figure 1. Males, whose overall rate was .45 accidents per 1,000 miles, had a
much higher rate (.76 per 1,000 miles) on 1-speed bicycles. Females whose
overall accident rate of .67 per 1,000 miles was almost 50% higher than the male
rate, had approximately equal accident rates for all three bicycle types. The
combined accident rates for the three bicycle types showed a steady decrease
with increasing number of gears, the 1-speed accident rate of .72 per 1,000
miles being 50% higher than the 5-,10-,15-speed rate of .48 accidents per 1,000
miles.

Figure 1 Accidents per 1,000 miles for males and females by type of bicycle.
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The important difference between accidents per person and the accident rate per
1,000 miles is shown dramatically in Figure 2. Here one can see that if only
calculations for accidents per person were available it would be assumed that
the more gears a bicycle has, the more dangerous it is. When exposure (mileage)
is controlled for, however, by calculating a rate per 1,000 miles, the trend is
exactly the opposite. In other words, in these data, 5-,10-,15-speed bicycles
had more accidents only because they were driven so many more miles.

Fig. 2 Accident and mileage rates by type of bicycle.
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Two important explanatory variables explored in this study were sex and type of bicycle. Differences between males and females have been examined in research both on children's bicycle accidents and adult automobile driving. Safety differences between various bicycle types are of interest to both bicyclists and bicycle manufacturers. In the present data, there was a significant relationship between sex and bicycle type (Table 1, Section D, X2 = 77.6, df = 2, p < .001) with males having proportionately more bicycles with 5 or more speeds (56%) than females (30%). Because of this relationship, associations of sex and type of bicycle with selected usage and accident variables were more fully explored. Several of these variables were recoded for use in these analyses, as is shown in Table 2.
There were several important and internally consistent differences in the usage
pattern of the three bicycle types. Table 3 indicates that higher speed bicycles
were used in heavier motor-vehicle traffic (Variable 58), more frequently than
lower speed types. While 53% of the 5-,10-, 15-speed bike usage was reported as
being in heavy or moderate traffic, 49% of the 3-speed bicycle usage and only
38% of the 1-speed bicycle usage was so reported (Table 3). Other statistically
significant, though less dramatic, differences among bicycle types were found
with Variable 56 (1-speed bicycles used proportionately less than other types on
pavement), Variable 59 (5-,10-,15-speed bicycles used proportionately more in
business areas and less in residential areas), Variable 60 (5-,10-,15-speed
bicycles driven proportionately more on main streets and less on secondary
streets), and Variable 61 (1-speed bicycles driven proportionately more off the
street, whereas 5-,10-,15-speed bicycles were driven more with traffic). The
3-speed bicycles fall between the higher and lower speed types in all of these
analyses.
| Recoded Variables Showing Original and Recoded Categories | ||||
| Variable | Old Categories | New Categories | ||
| Number | Name | |||
| 46 | Day of week of most recent bicycle use | 1: Monday | 1, 2, 3, 4, 5, 8 | Weekday |
| 2: Tuesday | ||||
| 3: Wednesday | ||||
| 4: Thursday | ||||
| 5: Friday | ||||
| 6: Saturday | 6, 7, 9 | Weekend | ||
| 7: Sunday | ||||
| 8: Some weekday | ||||
| 9: Some weekend | ||||
| 50 | Primary purpose of drive on most recent bike use day | 1: Commuting to or from work | 1, 2, 3, 7 | Transportation |
| 2: Bike hike or touring | ||||
| 3: Traveling to or from recreation site | ||||
| 4: Racing or sporting event | ||||
| 5: Exercise or health | 4, 5, 6 | Recreation | ||
| 6: Just for fun | ||||
| 7: Traveling on an errand | ||||
| 72 | Purpose of drive just prior to accident | 1: Commuting to or from work | 1, 2, 3, 7 | Transportation |
| 2: Bike hike or touring | ||||
| 3: Traveling to/from recreation site | ||||
| 4: Racing or sporting event | ||||
| 5: Exercise of health | 4, 5, 6 | Recreation | ||
| 6: Just for fun | ||||
| 7: Traveling on an errand | ||||
| 89 | Type of accident | 1: Motor vehicle struck bike | 1, 2, 3, 4 | Motor-vehicle related collision |
| 2: Bike struck moving motor vehicle | ||||
| 3: Bike struck parked motor vehicle | ||||
| 4: Bike crashed avoiding motor vehicle | 5, 6, 7 | Other collision | ||
| 5: Bike collided with other bike | ||||
| 6: Bike hit or fell off curb | ||||
| 7: Bike hit hole, bump, or obstacle | 8, 9 | Fall | ||
| 8: Rider skidded and crashed | ||||
| 9: Rider lost balance and fell | ||||
| 95 | Result of accident | 1: Personal injury | 1, 4, 5, 7 | Injury accident |
| 2: Bicycle damage | ||||
| 3: Property damage | ||||
| 4: 1 and 2 | ||||
| 5: 1 and 3 | 2, 3, 6 | No injury | ||
| 6: 2 and 3 | ||||
| 7: 1, 2, and 3 | ||||
-20-
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|
Type of Bicycle by Motor-vehicle Traffic Density at Most Recent Bicycle Use |
||||||||||
| Type of Bicycle | Motor-vehicle Traffic | Total | ||||||||
| High | Moderate | Low | None | |||||||
| f | % | f | % | f | % | f | % | f | % | |
| 1-speed | 19 | 5.8 | 107 | 32.4 | 159 | 48.2 | 45 | 13.6 | 330 | 100.0 |
| 3-speed | 21 | 6.8 | 130 | 42.1 | 128 | 41.4 | 30 | 9.7 | 309 | 100.0 |
| 5-,10-, 15-speed | 58 | 10.7 | 227 | 42.0 | 211 | 39.1 | 44 | 8.1 | 540 | 100.0 |
| Total | 98 | 8.3 | 446 | 39.4 | 498 | 42.2 | 119 | 10.1 | 1179 | 100.0 |
X2 = 23.13, df = 6, p < .001
Variable 50, primary purpose of drive, may provide the best summary of these
differences. When dichotomized into driving for transportation or recreation,
the higher speed bicycles tended to be used more for transportation (54%), and
lower speeds for recreation (61%), with the two use categories split almost
evenly for 3-speed bikes (X2 = 19.47, df = 2, p < .001).
Usage of different types of bicycles varied when sex of driver was considered,
however. The aforementioned relationship between usage and bicycle type held for
males as shown in Table 4 but as Table 5 indicates, was not significant for
females.
It should be emphasized that there were no overall differences in bicycle use
between males and females in this sample when type of bike was not considered.
Looking at purpose of drive on the last driving day (Tables 4 and 5) for
example, we see that 49% of the males and 48% of the females used their bicycles
for transportation. The significant association between type of bike and usage
that was present for males and not for females
provides a possible explanation for the finding that male accident-mileage rates
differed among bicycle types, while female rates did not, i.e., the males tended
to use the different types of bikes for different purposes and females did not.
21
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|
Type of Bicycle by Primary Purpose of Most Recent Bicycle Use for Males |
||||||
| Type of Bicycle | Primary Purpose of Drive | Total | ||||
| Transportation | Recreation | |||||
| f | % | f | % | f | % | |
| 1-speed | 50 | 32.9 | 102 | 67.1 | 152 | 100.0 |
| 3-speed | 82 | 48.5 | 87 | 51.5 | 169 | 100.0 |
| 5-,10-,15-speed | 217 | 54.7 | 180 | 45.3 | 397 | 100.0 |
| Total | 349 | 48.6 | 369 | 51.4 | 718 | 100.0 |
X2 = 20.84, df = 2, p < .001
|
Type of Bicycle by Primary Purpose of Most Recent Bicycle Use for Females |
||||||
| Type of Bicycle | Primary Purpose of Drive | Total | ||||
| Transportation | Recreation | |||||
| f | % | f | % | f | % | |
| 1-speed | 78 | 43.8 | 100 | 56.2 | 178 | 100.0 |
| 3-speed | 67 | 49.3 | 69 | 50.7 | 136 | 100.0 |
| 5-,10-,15-speed | 72 | 52.6 | 65 | 47.4 | 137 | 100.0 |
| Total | 217 | 48.1 | 234 | 51.9 | 451 | 100,0 |
X2 = 2.47, df = 2, NS
22
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Examination of accident details also failed to provide a clear explanation for
females having higher accident rates than males. Of 25 accident detail variables
examined, only one (Variable 72) was related to type of bicycle, four (Variables
79, 89, 95, 97) were related to sex, and one (Variable 85) was related to both
type of bicycle and sex. Variable 72, purpose of drive at time of accident,
reflected the exposure difference shown in Tables 4 and 5. Table 6 shows
Variable 72 by type of bike for males, and the pattern was very similar to the
exposure pattern for males, i.e., with 1-speed bicycles being used mostly for
recreation and 5-,10-,15-speed bicycles being used more for transportation. For
females there was no significant relationship between purpose of drive at time
of accident and type of bike. The other related accident variable with an
exposure counterpart was Variable 79, orientation of bicycle in traffic. There
was no exposure difference between males and females, but at time of accident
males were driving proportionately more on the street with traffic and females
proportionately more in off-street locations (X2 = 10.45, df = 3, p < .02).
| Purpose of Drive at Time of Accident by Type of Bicycle for Males | ||||||
| Type of Bicycle | Primary Purpose of Drive | Total | ||||
| Transportation | Recreation | |||||
| f | % | f | % | f | % | |
| 1-speed | 12 | 26.7 | 33 | 73.3 | 45 | 100.0 |
| 3-speed | 22 | 53.7 | 19 | 46.3 | 41 | 100.0 |
| 5-,10-,15-speed | 87 | 56.5 | 67 | 43.5 | 154 | 100.0 |
| Total | 121 | 50.4 | 119 | 49.6 | 240 | 100.0 |
X2 = 12.60, df = 2, p < .01
23
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Table 7 shows the significant relationship between type of accident (Variable
89) and sex. This relationship remained unchanged even when examined separately
for the three types of bicycles. Males had proportionately more motor-vehicle
related accidents and females more "other collisions," i.e., collisions with
objects other than motor-vehicles. The proportion of falls was about equal for
both. Sex was also significantly related to result of accident (Variable 95).
When broken down by type of bicycle, however, the relationship was significant
only for 1-speed bicycles. Overall, 79% of the reported accidents resulted in
some personal injury. {While 79% may appear high, this is partly a result of the
"definition" of accident that appears in Variable 65.}
|
Type of Accident by Sex |
||||||||
| Sex | Type of Accident | Total | ||||||
| Motor-vehicle Related | Other Collisions | Falls | ||||||
| f | % | f | % | f | % | f | % | |
| Male | 65 | 27.4 | 92 | 38.8 | 80 | 33.8 | 237 | 100.0 |
| Female | 11 | 9.1 | 71 | 58.7 | 39 | 32.2 | 121 | 100.0 |
| Total | 76 | 21.2 | 163 | 45.5 | 119 | 33.2 | 358 | 100.0 |
X2 = 19.68, df = 2, p < .001
This held true for both males and females driving 3-speed or 5-,10-,15-speed
bicycles and for males driving 1-speed bicycles. Accidents reported by females
on 1-speed bicycles, however, resulted in personal injury 100% of the time
(Table 8). The significant relationship between sex and part of body injured
(Variable 97) was largely caused by males reporting
proportionately more injuries to arms while females reported proportionately
more injuries to legs (Table 9). Type of bicycle had no effect on this
relationship.
24
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| Result of Accident by Sex for 1-speed Bicycles | ||||||
| Sex | Result of Accident | Total | ||||
| Injury | No Injury | |||||
| f | % | f | % | f | % | |
| Male | 33 | 73.3 | 12 | 26.7 | 45 | 100.0 |
| Female | 37 | 100.0 | 0 | 0 | 37 | 100.0 |
| Total | 70 | 85.4 | 12 | 14.6 | 82 | 100.0 |
X2 = 9.52, df = 1, p < .01
|
Part of Body Injured by Sex |
||||||||
| Sex | Part of Body Injured | Total | ||||||
| Arms | Legs | All Other | ||||||
| f | % | f | % | f | % | f | % | |
| Male | 104 | 45.2 | 62 | 27.0 | 64 | 27.8 | 230 | 100.0 |
| Female | 31 | 25.2 | 74 | 60.2 | 18 | 14.6 | 123 | 100.0 |
| Total | 135 | 38.2 | 136 | 38.5 | 82 | 23.2 | 353 | 100.0 |
X2 = 37.33, df = 2, p < .001
Finally, the reported speed of the bicycle before the accident (Variable 85) was
related to both sex and type of bicycle with males and higher speed bicycles
tending to be traveling at higher speeds at the time of the accident. Males
reported higher speeds than females at time of accident for each of the three
bicycle types, though the association between speed and bicycle
type as seen in Tables 10 and 11 was significant only for males. This finding is
consistent with the other patterns in that only males reported differences in
use of the three bicycle types.
25
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|
Speed at Time of Accident by Type of Bicycle for Males |
||||||||
| Type of Bicycle | Speed at Accident | Total | ||||||
| 0- 5mph | 5 15 mph | More than 15mph_ | ||||||
| f | % | f | % | f | % | f | % | |
| 1-speed | 13 | 28.2 | 24 | 52.2 | 9 | 19.6 | 46 | 100.0 |
| 3-speed | 7 | 17.0 | 30 | 73.2 | 4 | 9.8 | 41 | 100.0 |
| 5-,10-,15-speed | 23 | 14.9 | 87 | 56.5 | 44 | 28.6 | 154 | 100.0 |
| Total | 43 | 17.8 | 141 | 58.5 | 57 | 23.7 | 241 | 100.0 |
X2= 10.72,df=4,p<.05
| Speed at Time of Accident by Type of Bicycle for Females | ||||||||
| Type of Bicycle | Speed at Accident | Total | ||||||
| 0 - 5mph | 5 - 15mph | More than l5mph | ||||||
| f | % | f | % | f | % | f | % | |
| 1-speed | 13 | 35.1 | 23 | 62.2 | 1 | 2.7 | 37 | 100.0 |
| 3-speed | 18 | 45.0 | 20 | 50.0 | 2 | 5.0 | 40 | 100.0 |
| 5-,10-, 15-speed | 20 | 41.7 | 21 | 43.7 | 7 | 14.6 | 48 | 100.0 |
| Total | 51 | 40.8 | 64 | 51.2 | 10 | 8.0 | 125 | 100.0 |
X2 = 6.22, df = 4, NS
26
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Knowledge of differences between accident (A) and no-accident (NA) groups of bicyclists in exposure and usage patterns could help point out driving habits that are especially likely to result in accident occurrence. For these analyses, the A Group (N = 390) was composed of those subjects who reported details of an accident they had as an adult within the past 5 years, and the NA Group (N = 832) was made up of all other subjects. Comparisons between these groups were made with sex, type of bicycle, exposure (Variables 7, 8, 9, and 11) and all 19 of the variables concerning most recent bicycle use (Variables 46 - 64). These comparisons can be seen clearly in Appendix D, since the frequency distributions were reported separately for the A and NA Groups.
There was no significant relationship between sex and accident group membership.
Thirty-three percent of the males and 29% of the females were in the A Group (X2
= 2.27, df = 1, NS). This was in agreement with the similarity between male and
female in accidents per person (Table 1). A significant relationship was evident
between type of bicycle and accident group membership (Table 12). Highest speed
bicycles made up 55% of the
A Group but only 42% of the NA Group, a difference of 13%. Both 1-speed and
3-speed bicycles were overrepresented in the NA Group.