Invisible Cyclists in Solstice Dark

wrote:
peter wrote:

Mean and average are synonyms so it's not clear how these could differ
by a factor of 20.
Perhaps some other statistical measure was actually reported?

Sorry that should read median not mean.

Right. And the paper specifically points out that there was one
respondent with a medical expense of $250,000 (i.e. an outlier).
"Clearly such an amount will exert a strong upward bias on the
average." IOW, the median value is much more realistic. The median
"serious" crash cost only $150. That does _not_ sound like the cost of
fixing a broken leg! That's more like what an ER will charge for
putting a band-aid on your finger.


This is a compilation from many surveys that
are now outdated, but his contention of a steep
learning curve and vast differences of accident
rate depending on experience level continues to be
corroborated by newer surveys like Moritz, and
the personal experience of high-mileage cyclists
with good memories.

None of that looks like a quote from Forester nor a reference to any of
his writing. I would also be interested in seeing exactly what
Forester supposedly said about the rate of accidents among bike
messengers.

It's in Bicycle Transportation: A Handbook for
Cycling Transportation Engineers, 1994. What
he claimed was that 10 years of riding experience
reduced a rider's injury rate by 80%.

Wait, Robert! Not only does that say nothing at all about bike
messengers; that says nothing at all about how the number was
determined!

One of your main arguments is that the "cycling is safe" figures are
worthless unless we know _exactly_ how they were determined! After
disparaging the "safe" data, it's VERY hypocritical to put up such a
vague paragraph - let alone to keep quoting the data as frequently as
you do!

ISTM your standard is really this: If it makes cycling sound
dangerous, no proof is needed; if it makes cycling sound safe, no proof
is sufficient.

- Frank Krygowski

SMS wrote:

It's amusing when you see the posts by cyclists in countries with MHLs,
claiming that they've been riding for 20, 30, 40, 50, years, etc., but
gave it up when the MHL was enacted. Then they claim that the number of
cyclists has gone down, solely because of the MHL, yet the
injury/fatality rate has declined only linearly with the alleged decline
in the number of riders. There's at least three problems with their
claims. First, if indeed cycling has declined, it was not due solely to
the MHL. Second, if it's the long time riders that have given up cycling
rather than wear a helmet, then the average experience level of the
remaining cyclists has gone way down, and third, the injury fatality
rate reduction must be attributed to helmets, since it's now less
experienced cyclists, which have more accidents, that are comprising a
larger proportion of the cycling population.

Of course, none of their original claims have been proven, so until a
real study is done, there is no way of knowing any of this.

Those are some interesting observations. Particularly about what the
experience distribution of cyclists abandoning cycling in response to
MHL's might be. I have no idea what that distribution might be but
certainly if it varies from the overall experience distribution of pre
MHL cyclists then before vs. after injury rate copmparisons are
problmeatic even if non reported accidents are somehow addressed.

Interestingly if you look at many groups of very experienced cyclists,
by a variety of measures, you are very l ikely to find that many (of
us) now use helmets but certainly if you are over the age of , say, 50
it is very likely that lots, even most, of that cycling experience was
gained helmetless.

Just like the idea of risk compnesation, which is a valid concept but
very hard to measure for this question, so is the idea of what
behaviorial differences might exist between adaptors and non adaptors
of helmets. And since these variables are not well addressed in the
extant studies we simply don't know. And given boththe relatively low
accident rates and the very low rate of "who cares" it is likely that
we will never have a really good handle on this unless some motivated
individual or organization actually goes out and sponsors the conduct
of a proper study.

wrote:
wrote:

You believe? Wait a minute - aren't you the guy who's forever asking
for not only data, but all the details on how the data was collected?

No, I'm the guy who points out that your data is
worthless until there is some way we can check
the work.

Then you should not be quoting vague estimates by John Forester without
detailed methodology. (That's reference to my other response, just
completed.)

I'm also the guy who says that anybody
who sets out to prove or disprove the danger of
cycling with accident statistics is in for a rough
road and will have to step around a lot of horse
hockey.

The main reason for the "rough road" is that there are too few serious
bike injuries to get ahold of statistically.

As I mentioned the other day, the paper by Ji, Ming et. al., "Trends in
helmet use and head injuries in San Diego County", Accident Analysis &
Prevention, Vol. 38, pp. 128 - 134, gives data to indicate that less
than 0.01% of that county's population had a serious bike injury in a
typical year. And that's a county with excellent year-round cycling
weather. I'd suspect the average across the US (or most other
countries) is even lower.

IOW, cycling is so safe, it's hard to come up with statistics on its
danger. This is not a bad problem to have!

Naturally, I'll expect you to meet your own standards now, and tell us
he injury rate per mile and per hour for "veteran bike messengers,"
with full documentation. ;-)

I'm afraid no surveys have been conducted.

Then, by your own standards, you should not be pretending the result is
known!


No surveys, but I personally have been well
acquainted enough with the accident and medical
history of perhaps 100 messengers to tell you
a thing or two about how it all shakes out.
For instance, it is obvious that the accident rate
of rookie messengers is astronomical compared
to the veterans. It is also obvious that most of
the veterans ride much longer between serious
wrecks than the 30,000 or so miles of LAB members
in the Moritz survey.

I'm sorry, but no thinking audience will accept the "It's obvious to
_me_..." statements from someone who's demonstrated such bias.




Compare,
for instance, to Moritz' survey of LAB members
with an average of 17 years riding experience,
which found them injuring themselves about
every 30,000 miles (iirc).

Something like that. Skinned knees mostly, remember?

That is incorrect. According to Moritz '96 survey of
LAB members (averaging almost 15 years cycling
experience), almost 10% reported suffering some
*serious* crash in the previous year.

Read it again. The definition of "serious crash" was "resulting in at
least $50 of property damage or medical expense." IOW, if a person
didn't unclip at a traffic light, fell to the right and smashed his
derailleur, that could be termed "serious."

It's a shame that Moritz didn't use a more realistic threshold.

Again, median medical expense was only $150. That means most of these
guys probably did go to some sort of clinic or ER, where it costs that
much to get in the door. But it also means little was needed to patch
them up, because even a precautionary X-ray will generate much more
expense.

Briefly, the median medical cost is consistent with getting gravel
scrubbed out of road rash. And that corroborates well with Stutts, et.
al, "Bicycle Accidents: An Examination of Hospital Emergency Room
Reports and Comparison with Police Accident Data," Transportation
Research Record #1168, which had the vast majority of bike ER patients
being treated for minor injuries.

And it's consistent with the ER doctor I'm close to, who frequently
talks about the minor injuries that take up his time in the ER.


These crashes
had an average and mean medical expense of 3000
and 150 dollars respectively.

Another post has already corrected your sentence above, which should
read "average and median..."

Again, the "$3000" average includes the extremely distorting effect of
one undescribed $250,000 accident. The mathematical "median" is
specifically designed to give realistic answers when one fantastic
outlying data point throws the average way off. IOW, the median value
of $150 should be used for further discussion. Ask your friendly
neighborhood statistician.

almost
one third of survey respondents reported
any sort of accident in the previous year.
That's the 'skinned knees' you're talking about,
a much more frequent occurrence.

IIRC, there were no guidelines given for the definition of non-serious
accident, except "less than $50 damage." IOW, the responses could
include toppling over while attempting a track stand, or falling off
the mountain bike when riding through sand.

As in other parts of this discussion, "minor" accidents are
inconsequential. The only ones who focus on them are fearmongers.



Interestingly, this corresponds quite closely
with Ken Kifer's much smaller 2001 survey,
most of the respondents to which were touring
cyclists who heard about the survey on Ken's
website. These riders reported a similar level
of experience and average age to those on
Moritz' survey, and reported wrecking (serious
vs. minor) at a very similar rate. Kifer notes
something very important: the average accident
rate among all respondents for what he called
'real injuries' was a seemingly chill once per
23000 miles. But, among those who actually did
the wrecking, their serious wrecks came about
once per 2000 miles.

His "real injuries" included mere scrapes, Robert. Here's a quote:

"Q. 19: When asked about the nature of their most serious
cycling-related injury during the last 12 months,
161 said there was no accident or no injury that was a problem the next
day.
53 said they experienced road rash or other significant abrasions.
4 said they experienced minor concussion resulting in nothing worse
than a headache.
9 said they had a puncture wound, simple fracture, or broken bone.
2 said they had a major concussion resulting in loss of consciousness
or other short-term brain injury.
2 said they had a compound or skull fracture, and/or multiple broken
bones and non-permanent injuries.
None said they had a permanent injury or disability of any kind."

If we remove the really minor punctures (chainring tooth in calf?) and
the really minor broken bones (hairline fracture of little finger?)
you've got very little to worry about in that list.

And Ken was careful to note the probability of distortion from the
small sample size and self-selection of the respondents. IOW, of all
the people who visited Ken's site while the survey was in process, the
ones who had crashed would likely be more interested in something
saying "safety." Those who had never crashed probably went elsewhere
in the site, looking for information about how to camp for free, make
one's own panniers, etc.

Citation?

Read it again. 'Old messengers I know.' I know them
well enough to know their rates of serious injury.

IOW, no citation. Just the personal opinion of someone who likes to
make cycling sound dangerous.


Beginning riders wreck/injure themselves at
at least 10 times the rate of old messengers (Forester).

You've alluded to this before, but I don't recall the details. What
exactly did Forester say, and how exactly did he determine it?

This is a compilation from many surveys that
are now outdated, but his contention of a steep
learning curve and vast differences of accident
rate depending on experience level continues to be
corroborated by newer surveys like Moritz, and
the personal experience of high-mileage cyclists
with good memories.

Please! Adhere to your own standards! Give us citations and
specifics!



Last time I pressed you for a
definition, you said "If there are any motor vehicles anywhere on the
road, it's traffic" ... or words to that effect.

IOW, riding on a wide road that's deserted except for you and one other
car passing the opposite way at 20 mph is riding in "traffic." So
beginners should be warned that even that is ... dangerous!!! wring
hands here

If passing of the vehicle coincides with an
intersection of any sort, it's plenty dangerous.
Otherwise, not so much.

wring hands here

And there you have it, folks. Any time you are passed (in any
direction, at any speed) by a vehicle at any sort of intersection
(driveway?), Robert thinks it's "plenty dangerous."

According to Robert, you must ride in fear!

- Frank Krygowski

SMS wrote:
wrote:

It's in Bicycle Transportation: A Handbook for
Cycling Transportation Engineers, 1994. What
he claimed was that 10 years of riding experience
reduced a rider's injury rate by 80%.

It's amusing when you see the posts by cyclists in countries with MHLs,
claiming that they've been riding for 20, 30, 40, 50, years, etc., but
gave it up when the MHL was enacted. Then they claim that the number of
cyclists has gone down, solely because of the MHL, yet the
injury/fatality rate has declined only linearly with the alleged decline
in the number of riders. There's at least three problems with their
claims. First, if indeed cycling has declined, it was not due solely to
the MHL. Second, if it's the long time riders that have given up cycling
rather than wear a helmet, then the average experience level of the
remaining cyclists has gone way down, and third, the injury fatality
rate reduction must be attributed to helmets, since it's now less
experienced cyclists, which have more accidents, that are comprising a
larger proportion of the cycling population.

Of course, none of their original claims have been proven, so until a
real study is done, there is no way of knowing any of this.

Of course, all the above has come from Scharf's imagination.

Prove me wrong if you can, Steven. First, point us to the posts where
riders riders said they quit due to a MHL after 20, 30, 40 and 50
years riding.

Second, tell us why your claims disagree with Robinson, D.L., Head
Injuries & Bicycle Helmet Laws, 1996, Accident Analysis Prevention, vol
28, pp463 - 475, which clearly shows a step drop in cycling exactly
coinciding with the MHL's date, and with the reason confirmed by
telephone surveys.

Third, give us your proof that the drop in riding disproportionately
affected older, more experienced cyclists.

The only true statement in that entire post of yours was the last one:
"There's no way of knowing any of this." IOW, you made up the entire
thing.

- Frank Krygowski

wrote:

Sorry that should read median not mean.

Right. And the paper specifically points out that there was one
respondent with a medical expense of $250,000 (i.e. an outlier).
"Clearly such an amount will exert a strong upward bias on the
average." IOW, the median value is much more realistic.

Yes! Any nasty injuries or particularly bad
experiences of individuals must be expunged
from our accident survey, to make 'more
realistic' results! Clearly these 'outliers' will
'exert a strong upward bias on the average'
so we shall ignore them lest they jack up
our surveys! Careful readers of the Kifer
survey, for instance, may notice that he has
chosen not to report the injuries of one
respondent who claimed 4 injuries in the
previous year. Of course, the experiences of
any who ride 50 years with no injury will
be gleefully included without an eye-blink.
Stats are fun aren't they?

The median
"serious" crash cost only $150. That does _not_ sound like the cost of
fixing a broken leg! That's more like what an ER will charge for
putting a band-aid on your finger.

If the respondents are anything like the riders
I know, several of these serious wrecks resulted
in rather substantial injury for which the rider
(stupidly perhaps) sought absolutely no medical
treatment. If he had, it might have cost thousands--
x-rays, physical therapy, etc.

It's in Bicycle Transportation: A Handbook for
Cycling Transportation Engineers, 1994. What
he claimed was that 10 years of riding experience
reduced a rider's injury rate by 80%.

Wait, Robert! Not only does that say nothing at all about bike
messengers; that says nothing at all about how the number was
determined!

It says a great deal about bike messengers.
He's saying experience reduces accident rates.
Veteran messengers have more experience in
traffic than any other type of cyclist. A commuter
would have to ride about two and a half hours
each way, every day, year round, year after year
to keep up with a full-time messenger
in terms of hours in the saddle. And I'm saying
that yes, Forester's claim does seem to be
corroborated in real life, and it does seem
generally applicable to the whole spectrum of
cyclists, from the kids right up to the old bike
messengers, even if Forester did not explicitly
address bike messengers at the time. The
exact nature of the curve is in question, but the
fact that it's quite a hill is obvious at this point.
I doubt Forester himself would acknowledge
that messengers may actually be the safest
riders on the road because it would call into
question his entire philosophy and the Effective
Cycling industry that has grown up around it.

Forester's claim is a product of compilation of
statistics from several surveys, Schupack, et al,
Kaplan '76, Watkins' survey of CTC riders.
Tricky business to be sure! But the statistical
importance of experience continues to be
supported in newer surveys like Kifer and Moritz.

One of your main arguments is that the "cycling is safe" figures are
worthless unless we know _exactly_ how they were determined! After
disparaging the "safe" data, it's VERY hypocritical to put up such a
vague paragraph - let alone to keep quoting the data as frequently as
you do!

ISTM your standard is really this: If it makes cycling sound
dangerous, no proof is needed; if it makes cycling sound safe, no proof
is sufficient.

I don't get it. What about these surveys above says
'cycling is safe' or 'cycling is dangerous?' [1] It's clearly a
more complex picture than you make it out to be.

Why do you think Forester's claim that 10
years of cycling reduces the accident rate by
80% makes cycling sound dangerous? That's not
exactly what I would take away from that number.
To me that says we have the power to control
our own fate while on the bike, that it's not some
random crapshoot of falling and getting hit by
cars. If it were, accident rates would be normalized
across experience levels, and clearly they are not.
This is good news! Or bad news, depending on
your level of experience.

Robert

[1] Other than Kifer's finding that 'injury is 33 times
more likely to occur from riding a bike as opposed
to driving a car for the same distance.' I admit
that does make cycling sound dangerous.

SMS wrote:

It's amusing when you see the posts by cyclists in countries with MHLs,
claiming that they've been riding for 20, 30, 40, 50, years, etc., but
gave it up when the MHL was enacted. Then they claim that the number of
cyclists has gone down, solely because of the MHL, yet the
injury/fatality rate has declined only linearly with the alleged decline
in the number of riders. There's at least three problems with their
claims. First, if indeed cycling has declined, it was not due solely to
the MHL. Second, if it's the long time riders that have given up cycling
rather than wear a helmet, then the average experience level of the
remaining cyclists has gone way down, and third, the injury fatality
rate reduction must be attributed to helmets, since it's now less
experienced cyclists, which have more accidents, that are comprising a
larger proportion of the cycling population.

Of course, none of their original claims have been proven, so until a
real study is done, there is no way of knowing any of this.

Oh, I think we can make a pretty good guess. What do you think are the
chances that the MHL induced experience profile change you claim was
such that it exactly cancelled out in each state and in each country the
reduction in head injuries that you claim the MHL would have prevented?

--
Tony

"The best way I know of to win an argument is to start by being in the
right."
- Lord Hailsham

wrote:

Yes! Any nasty injuries or particularly bad
experiences of individuals must be expunged
from our accident survey, to make 'more
realistic' results! Clearly these 'outliers' will
'exert a strong upward bias on the average'
so we shall ignore them lest they jack up
our surveys! Careful readers of the Kifer
survey, for instance, may notice that he has
chosen not to report the injuries of one
respondent who claimed 4 injuries in the
previous year. Of course, the experiences of
any who ride 50 years with no injury will
be gleefully included without an eye-blink.
Stats are fun aren't they?

When you're looking at insurance, the number of outliers is what needs
to be carefully considered. I.e., in health insurance and life
insurance, most people are not outliers, which keeps the rates from
being outrageous, but the statistical probability of outliers is an
important consideration. Of course some insurance companies desperately
try to keep the people that are likely to be outliers from obtaining
policies in the first place.

My favorite papers are the ones that add up the medical expenses and
compare them against the cost of the helmets. Invariably, the conclusion
is that helmets are a bad deal, because the cost of treating a
relatively few number of more severe injuries is less than the total
expenditure on helmets. As if people that are debating whether or not to
wear a helmet are calculating their deductibles, co-pays, and maximum
out of pocket expenses, versus the probability that they will ever have
a crash where a helmet would make any difference.

gds wrote:
SMS wrote:
It's amusing when you see the posts by cyclists in countries with MHLs,
claiming that they've been riding for 20, 30, 40, 50, years, etc., but
gave it up when the MHL was enacted. Then they claim that the number of
cyclists has gone down, solely because of the MHL, yet the
injury/fatality rate has declined only linearly with the alleged decline
in the number of riders. There's at least three problems with their
claims. First, if indeed cycling has declined, it was not due solely to
the MHL. Second, if it's the long time riders that have given up cycling
rather than wear a helmet, then the average experience level of the
remaining cyclists has gone way down, and third, the injury fatality
rate reduction must be attributed to helmets, since it's now less
experienced cyclists, which have more accidents, that are comprising a
larger proportion of the cycling population.

Of course, none of their original claims have been proven, so until a
real study is done, there is no way of knowing any of this.

Those are some interesting observations. Particularly about what the
experience distribution of cyclists abandoning cycling in response to
MHL's might be.

Well clearly it's not kids that abandoned cycling when an adult MHL was
implemented, when an MHL for kids already existed. The people
complaining the most about the MHLs are the long time cyclists, with
good reason, but I don't think that they are representative, as most
long time cyclists that didn't already wear a helmet wouldn't give up
riding just because they had to now wear one. The once-a-year cyclist,
with the bikes hanging in the garage, except for that sub-10 mile ride
once a year, may be the most likely. The real question is whether or not
there was a step change in cycling levels that was caused solely by a
helmet law, and that as prolonged (not measured immediately after the
helmet law took effect). What the AHZ people often do, is to equate
correlation with causation.

Interestingly if you look at many groups of very experienced cyclists,
by a variety of measures, you are very l ikely to find that many (of
us) now use helmets but certainly if you are over the age of , say, 50
it is very likely that lots, even most, of that cycling experience was
gained helmetless.

Yes, this is true. That said, much of that experience was gained under
different circumstances than we have now, in terms of the experience and
skill level of the vehicle drivers. I live in an area where more and
more of the population learned to drive in their 30's and 40's, rather
than in their teens. These people are particularly poor drivers, and it
affects the number of cyclists and pedestrians, especially kids.

Just like the idea of risk compnesation, which is a valid concept but
very hard to measure for this question, so is the idea of what
behaviorial differences might exist between adaptors and non adaptors
of helmets. And since these variables are not well addressed in the
extant studies we simply don't know. And given boththe relatively low
accident rates and the very low rate of "who cares" it is likely that
we will never have a really good handle on this unless some motivated
individual or organization actually goes out and sponsors the conduct
of a proper study.

I doubt if anyone cares enough to fund such a study. You might get the
helmet manufacturer's to fund it, but then the AHZ's wouldn't believe it
anyway, so what's the point?

Cheap sniping, but as you've so disparaging of views based on studies which
don't conclusively prove things:

1.

I live in an area where more
and more of the population learned to drive in their 30's and 40's,
rather than in their teens.

2.

These people are particularly poor drivers,

3.

and it affects the number of cyclists and pedestrians, especially kids.

Of course, none of your original claims have been proven, so until a
real study is done, there is no way of knowing any of this.

SMS wrote:

Well clearly it's not kids that abandoned cycling when an adult MHL was
implemented, when an MHL for kids already existed.

And your reference for this is?

The people
complaining the most about the MHLs are the long time cyclists, with
good reason, but I don't think that they are representative, as most
long time cyclists that didn't already wear a helmet wouldn't give up
riding just because they had to now wear one.

And your reference for this is?

The once-a-year cyclist,
with the bikes hanging in the garage, except for that sub-10 mile ride
once a year, may be the most likely.

And your reference for this is?


--
Tony

"The best way I know of to win an argument is to start by being in the
right."
- Lord Hailsham