quick everybody burn your helmets...

I wonder how he rode along the road. Was he hugging the side or taking
the lane? Seem the more you hug the side of the road the closer people
will try to pass you.

In Washington State the law is a motor vehicle must give a cyclist 3
feet (approx. 1 Meter 😉 ). Law is only effective if the motorist is
aware.

Several years ago we drove the Icefields Parkway from Jasper to Banff,
BC. A lot of the cycle tour riders had a flag on a pole mounted
horizontally on the left side to encourage people to give more room (it
also had a spring so it would give way if struck).

Another observation regarding how helmet useage varies: My sister and
brother in law just got back from Holland. They said the only people
who wear helmets there are tourists or serious cyclists. Everyone else
goes without.

--
UniBrier

Steve

Hop Drop & Roll

“If something is to hard to do, then it's not worth doing. You just
stick that guitar in the closet next to your
shortwave radio, your karate outfit and your unicycle and we'll go
inside and watch TV.” – Homer
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domesticated ape said:

U-Turn, I'm pretty sure that the risk compensation stuff has been found
to apply to normal everyday cycling as well as MTB, BMX etc. Can't be
bothered to look it up though!

Some degree of risk compensation happens in cyclists: The fact that
downhill bicycle racers choose to wear protective gear is evidence of
this. The question is how the choice to wear a helmet effects the
likelyhood and severity of injury in particular cycling scenarios.
Unfortunately, the answer to this is not settled. We don't really
know whether an individual's choice to wear a helmet results in an
overall increase in risk or a decrease. The conclusion that helmets
are more dangerous is accepted as fact partly because comes from
studies of the effects of helmet laws on large groups of cyclists, not
individual decisions.

By the way, the scientific literature offers solid arguments
countering claims that helmets increase risk because of their shape,
extra mass, increased rotational forces, etc. My opinion is that
there are reasonable arguments against mandatory helmet laws and in
favor of wearing helmets in circumstances where head impacts are a
distinct possibility.

By the way, I found the news of the study very interesting. It really
does suggest a possible explanation for the statistics put forth by
the anti-helmet(law) crowd. U-Turn's criticisms are also interesting,
and a good reminder that this is not yet an accepted scientific
theory. For my part, I wonder what sort of methodology resulted in
the researcher being bumped off his bike twice while conducting his
experiment. For many years, I commuted on my bicycle in a wide
variety of conditions and have never been hit by a car. Something is
fishy about this aspect of the report.

Quoted message said:

Also, your comments on choosing times to ride and avoiding rush-hour
roads are fair enough regarding leisure cycling, but what about when
the cyclist is also a commuter? I agree that cycling on roads at less
busy times and on roads with less cars is probably safer, but for
commuters and other utility cyclists this is not always an option.

I am sure someone will disagree, but unicycles don't belong on crowded
roads with fast traffic, particularly during rush-hour. The speed
differential is too big, the drivers too angry, and the perceived
likelyhood of a UPD too great (regardless of the rider's actual
skill). Sidewalks and bike paths are generally better choices.

That's easy for me to say because I live in a city with extremely wide
streets; many bike routes, lanes, and paths; relatively modest
traffic; and where it is legal to ride on the sidewalk.

Despite my love of unicycling, I have to recommend riding a bicycle
for more challenging commutes. There is less of a speed differential
and (somewhat) greater understanding by motorists of how a bicycle
will behave.

Ken

UniBrier said:

Another observation regarding how helmet useage varies: My sister and
brother in law just got back from Holland. They said the only people
who wear helmets there are tourists or serious cyclists. Everyone else
goes without.

I think that the more motorists are exposed to cyclists on the roads,
then the more likely they are to act apropriately towards us. The
Netherlands is renowned for being very cycle friendly, so lots of
cyclists use the roads and it becomes safer - a self perpetuating
"cycle" of improving safety / motorist consideration.

The recent trend in the UK of incorporating dedicated cycleways on the
pavements rather than as part of the road has the effect of removing
the few cyclists there are from the motorists sphere of consideration,
therefore perpetuating a downward cycle of safety / motorist
consideration.

Boycott all cycle lanes that don't use the road, mix with motorists as
much as possible and help to reclaim the roads for all legitimate road
users, rather than abandoning them to the motorists alone.

I feel a rant coming on 😠 , so I'm going to finish here...

Chris

p.s. I don't really notice any difference in motorists behaviour with
respect to passing distances whether I wear a helmet, hi-vis vest,
flashing-led rear light, wig, kilt, nothing ...

--
munidobs
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Here's a correction of my article...

Remove the words by the Xs:

Quoted message said:

The conclusion that helmets are more dangerous XisXacceptedXasXfactX
XpartlyXbecauseX comes from studies of the effects of helmet laws on
large groups of cyclists, not individual decisions.

Quoted message said:

The conclusion that helmets are more dangerous comes from studies of
the effects of helmet laws on large groups of cyclists, not
individual decisions.

UniBrier said:

I wonder how he rode along the road. Was he hugging the side or taking
the lane? Seem the more you hug the side of the road the closer people
will try to pass you.

He examined that as a variable, and actually concluded the opposite.
In the summary already referenced there's even a graph showing just
this variable.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

rob.northcott said:

I used to be very anti-helmets (at least for road riding) but since I
got into the habit of wearing one I've had at least two accidents that
would have been worse (but probably not fatal) had I not been
helmetted.

Cue Ian Smith...

thats whats he's saying, maybe those cars would have given you the
space you needed if you hadn't been wearing your helmet.

anyways though, my prblem is with doors, ever get a door opened on you
as your riding down a sidewalk? helmet or not, the hurts

--
joshuni

hi.
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Ok, I'll give one more shot at this, then that will probably be it.

Ian Smith said:

U-Turn said:

And yes, using skills I developed doing masters and phd-level
research and reading and critiquing thousands of technical journal
articles,

Did you? Or did you just base your opinion on what the funnies page
in the local newspaper had to say about them - which seems to be what
you're doing here.

Quoted message said:

I did read the article.

I asked if you had read the paper, not whether you had read the report
by a popular journalist about the research. I assume from your
failure to answer the question, that the answer is no.

Quoted message said:

Since the article quotes Dr. Walker as saying:

"Either way, this study suggests wearing a helmet might make a
collision more likely in the first place"

I figured it was reasonable to think that the -researcher -was

making

Quoted message said:

the connection. What do you think, Ian?

But that's not a conclusion of the research, and is not presented as
such.

I'll ignore your simply rude approach and address the issue of the
origin of the statement. In fact, there is no paper published yet, so
no one here could have read it without inside connections. There are
three manifestations of this article that I could find.

1) The news article originally linked in the first post in this thread.
This is basically a trimmed version of the official press release from
Bath University. It has basically no contribution of a reporter in it,
which is usual for this kind of press release. They scan and trim and
print.
2) The official press release from Bath University, the institution
that performed the study. This is likely to have been written by or
significantly contributed to by the researcher, and is a serious paper
that not only summarizes the research, but allows the researcher and
the university to put the research into context and comment on it less
formally.
3) A "Professional Briefing Document" (PBD), which is a summarizing
extract from the paper-yet-to-be-published. This would have been
written by the researcher, although an author is not stated on the PDB.
This is a serious, career-level abstract. It is drier, more
technical, and slightly more reserved than the official press release.

The quote above was located in the news article and the official press
release, but not in the PBD. I don't know whether the quote is in the
yet-unpublished paper or not. When the researcher included the quote
in the press release, he opened the door for criticism of that logical
step.

When you said, "I asked if you had read the paper," to which of those
three were you referring?

Ian Smith said:

I asked if you had read the paper, not whether you had read the report
by a popular journalist about the research.

Since there is no byline on the BBC News article, how did you come to
the conclusion that there was a "popular journalist" involved? Sounds
like you are just itching to flame someone. There is no substance
behind your criticism of me, and this casts all kinds of doubt on any
subsequent comments by you.

Ian Smith said:

Besides, I'd say that statement, as quoted is 100% correct. If you
disagree, it can only be if you are CERTAIN that passing wider
increases the chance of a collision. Do you actually believe that?
How can that possibly be? You know that missing something with a
bigger gap increases the chances of hitting it?

This too, is a pretty easy concept to grasp. For a trivial example,
let's say a 1" ball is sitting on a plane. Roll another 1" ball at it
with such skill that you might hit it somewhere, or you have a chance
of missing it by as much as 1 inch. This is our base case.

Now, aim one foot to the left of the stationary ball and roll with the
same skill. You'll miss it by a distance that varies from 9.5" to
13.5", but you will always miss it.

For the last case, aim three feet to the left of the stationary ball
and roll with the same skill. You'll miss it by a distance that varies
from 33.5" to 37.5", but you will always miss it.

So from case two to case three, the separation has increased, but the
chance of hitting the stationary ball has not decreased.

It should be easy to grasp that giving a rider more room on the road
does not necessarily increase his safety level, though in many cases it
would. The real issue is: given a specified rider skill level, what
separation is reasonable? Passing with a separation greater than that
would not significantly increase the rider's safety.

<< skipping ill-mannered stuff >>

Ian Smith said:

On a bike or unicycle you have unimpeded 360 degree vision, and
immediate proximity to all extremities, all of which can be easily
observed. In a car you have neither of these conditions. The
visibility on a bike or unicycle is vastly superior to that in a car,
and consequently there is no need of mirrors.

Are you really claiming that a unicyclist without the use of a mirror,
riding in traffic on a narrow road with questionable surface at rush
hour (a typical commuting situation), has the ability to instantly see
behind him and then make a quick judgment call and navigational change?
😕

Ian Smith said:

Quoted message said:

On (7) taillights: This opinion is NOT an assumption, this is an
observation by me. I have seen drivers give me more room during

dry,

Quoted message said:

bright daylight hours, because I was using a flashing taillight on

my

Quoted message said:

unicycle. And I'm not talking centimeters, I'm talking meters - at
least half a lane more room.

That _IS_ an unproven assumption. You're ASSUMING that the specific
driver in the specific conditions would have left less space if you
had not been lit with a flashing light. You're ASSUMING the reasons
for the gap which was left.

Nope, it's observation of a pattern. Drivers consistently slowed down
earlier and gave me more room when I used the light. It's useful
information to me, since I really, really don't want to get hit by a
car.

Ian Smith said:

Quoted message said:

Well, yes an obviously serious rider in full Lycra and helmet would

be

Quoted message said:

more skilled, more in control, and less likely to take unexpected
action in most or all situations.

No, you're getting carried away again. Putting on lycra does not
miraculously impart greater skills to the person in question. You
cannot tell from the clothing how skilled a specific cyclist is.

Yes, but the point here is that it's reasonable for a driver to think
that. It's not reasonable for a driver to think that an apparently
serious rider is likely to do something foolish. That kind of mental
load is unsupportable for year-in, year-out driving.

Ian Smith said:

Quoted message said:

It's reasonable for a driver to give
him/her less room than a bare-headed kid on a bmx bike who is

talking

Quoted message said:

to his buddies and swerving around or doing wheelies.

That's not what the article (or the research) says though.

You are right; that's my opinion. My post was a mixture of opinion and
critique, and I think it's pretty clear what is which.

<< skipping more ill-mannered stuff >>

--
U-Turn

Weep in the dojo... laugh on the battlefield.
'LiveWire Unicycles' (http://www.livewireunicycles.com)
'Strongest Coker Wheel in the World'
(http://www.unicyclist.com/gallery/albup39)
'29er Tire Study' (http://u-turn.unicyclist.com/29erTireStudy/)
'New York Unicycle Club' (http://www.newyorkunicycle.com)
-- Dave Stockton
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turns out this guys research is true...

there was a couple cyclists i had to pass this morning on my commute to
work.

a tour de france type cyclists completely lycra clad with only one of
those lycra peaked caps to protect his head... i gave him about 900mm
of clearance...

i also passed a small girl on a pink barbie bike, with safty
stablisors, high visablity streamers from the ends of her handle bars,
she had matching pink helmet, knee pads, elbow pads and padded
gloves.....
i had to mount the curb to drive into her, and then had to reverse to
actually knock the little girl of her over stable bicycle.

andy parry said:

turns out helmets are dangerous!!!

more studenty types, making stupid claims based on dumb research...
GET A REAL JOB... Loser...

sorry... i didn't sleep well last night and this article anoyed me

http://news.bbc.co.uk/1/hi/england/somerset/5334208.stm

U-Turn said:

It should be easy to grasp that giving a rider more room on the road
does not necessarily increase his safety level, though in many cases it
would. The real issue is: given a specified rider skill level, what
separation is reasonable? Passing with a separation greater than that
would not significantly increase the rider's safety.

Yes, but the point here is that it's reasonable for a driver to think
that. It's not reasonable for a driver to think that an apparently
serious rider is likely to do something foolish. That kind of mental
load is unsupportable for year-in, year-out driving.

In terms of how much room you should give, at least in the UK, there's
a pretty clear rule about it. It basically says that you should
basically pretend the cyclist is as wide as a car and give a car's
width. Most drivers ignore this rule though. In France I believe
there's a similar rule and in my experience almost all French drivers
follow the rule in the countryside and some ignore it in the city,
although they're not as bad around bikes as UK drivers even in the
city.

As for the second bit I quoted, according to the advanced driving test
stuff here (it's an extra driving test you can do in order to learn to
be a better driver and pay less on your insurance), you should
basically always assume other road users may do the stupid thing and be
ready for it. I've always taken this approach to riding bikes and
unicycles and it makes things much less stressful.

Going back to something someone said earlier, about UPDs. I don't think
you should *ever* UPD on a major road. If there's much traffic, you
shouldn't be riding at a pace beyond your control level, such that a
UPD is possible. I've ridden on major roads in the rush hour almost
every day for 5 years now and have never UPDd on a main road. As for
cycle paths, many cycle paths are so dangerous compared to main roads
that I wouldn't use them.

Incidentally, I've noticed a massive difference in passing distances
riding a unicycle vs. riding a bike. People give you way more space on
the coker, I guess you could hardly say "I didn't see the 7 foot tall
unicycle covered in reflective tape" if you did happen to hit me.

Joe

--
joemarshall

my pics http://gallery.unicyclist.com/albuq44
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joemarshall said:

Incidentally, I've noticed a massive difference in passing distances
riding a unicycle vs. riding a bike. People give you way more space on
the coker, I guess you could hardly say "I didn't see the 7 foot tall
unicycle covered in reflective tape" if you did happen to hit me.

I think that's just motorists being more cautious when they don't
immediately recognise what they're dealing with - I get more space
when I'm on my unicycle, or on my recumbent tricycle, or on a bicycle
pulling a trailer than I get on a 'normal' bike.

It's quite depressing - it proves that they are capable of passing a
cyclist with a decent gap, they just don't most of the time.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

joshuni said:

thats whats he's saying, maybe those cars would have given you the space
you needed if you hadn't been wearing your helmet.

The accidents I was refering to didn't involve any other vehicle. One
was ice, one was a crumbled edge of the road. I've only actually been
hit by cars twice in the whole time I've been cycling (lots of years
and lots of miles), and those were both before I started wearing a
helmet on the road - I didn't hit my head either time (skinned most of
the rest of my body one time though), which is partly what reinforced
my belief that there was no need to wear a helmet on the road. I
started wearing one for mountain biking, then started wearing it on the
road in winter, then it just became a habit and I almost always wear it
now. It certainly provides useful protection in some types of crash -
that crash on ice last winter would have been very nasty had I not been
helmetted: my head hit the road very hard and actually cracked the
helmet slightly. But most of the time when I've fallen off (or been
knocked off) bikes or unicycles my head hasn't touched the ground. In
those rare cases though it's nice that it's there.

As for the original theory about people giving less space to pass
helmetted riders, I can't say I've noticed any difference, but I
haven't actually measured. Most people pass sensibly but there are
always the idiots who either force their way past too close or swerve
right over to the other side of the road (not dangerous but it annoys
me almost as much).

When I've been riding a unicycle on the road I think most people do
give me more room than when I'm on a bike, but I've still had a few
close shaves from the BMW brigade.

It's an interesting concept that how you look can affect how you're
treated by other road users. I wonder if I started wearing a wolf mask
would the sheep be less likely to step out in front of me? That would
really be a safety improvement round here 🙂

Regarding Joe's comment about France, I can certainly say that in my
experience of cycling in France, the French are in general much more
aware and respectful of cyclists than the British.

Rob

--
rob.northcott

'Dartmoor Muni Weekend'
(http://www.unicyclist.com/forums/showthread.php?t=46116) - Last
weekend in May 2006
Same again next year anyone? It'll be dry, I promise.
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when i'm on my bike people honk at me for riding on the road. (weird, i
only get the honks when i'm doing the speed limit down a hill).

when i'm on my uni it's like everybodys trying to get as far away from
me as possible, there are cars and people running out of the way and
staring at me. i'm not a crappy rider they just are amazed at what i'm
riding.

--
iridemymuni

munipsycho said:

Just a bit of advice: never vomit while wearing a full-face helmet.

guess what !

'Bike Coalition!!' (www.bikecoalition.com)
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U-Turn said:

Ian Smith wrote [stuff interleaved, marked '> > ']

[but this is U-Turn]

Quoted message said:

When you said, "I asked if you had read the paper," to which of those
three were you referring?

None of them. If I meant newspaper article or press release or
something else I would have said so. I said 'paper' because I meant
'paper', strangely enough.

The fact that it is as yet unpublished does not alter the validity of
my question. Nor does it make it OK to criticise the research from a
position of ignorance.

Quoted message said:

Quoted message said:

I asked if you had read the paper, not whether you had read the report
by a popular journalist about the research.

Since there is no byline on the BBC News article, how did you come to
the conclusion that there was a "popular journalist" involved?

Partly because if it was by a specialist technical journalist it would
have said "by our traffic psychology correspondent" or some such.
Mainly because I have never noticed any attribution from the BBC to
any relevant specialist journalist - I do not believe they have a
journalist who is specialist in this field.

Quoted message said:

Quoted message said:

Besides, I'd say that statement, as quoted is 100% correct. If you
disagree, it can only be if you are CERTAIN that passing wider
increases the chance of a collision. Do you actually believe that?
How can that possibly be? You know that missing something with a
bigger gap increases the chances of hitting it?

This too, is a pretty easy concept to grasp. For a trivial example,
let's say a 1" ball is sitting on a plane. Roll another 1" ball at it
with such skill that you might hit it somewhere, or you have a chance
of missing it by as much as 1 inch. This is our base case.

Your example here is completely invalid, for several reasons:

1: You are assuming a finite bounded error. This is extremely
unlikely to be true. Assume a normal distribution (or indeed any
other distribution with a tail) and your whole argument collapses.

2: Even with the bounded error, you are assuming that the statement
made applies to movements outside the bounds of the error, or that it
can be extrapolated to such. Neither of these are true. The increase
in space observed is an increase that remains within the reasonable
scatter of the unintended variation in vehicle paths. No-one has
suggested it can be extrapolated to very wide passing distances.

3: Even ignoring both those fatal flaws in your argument, you are
ignoring the fact that no-one has claimed that this proves that
helmets do increase the chance of collision - only that they MAY
increase the chance, and you disagreed with that statement.

Quoted message said:

Are you really claiming that a unicyclist without the use of a mirror,
riding in traffic on a narrow road with questionable surface at rush
hour (a typical commuting situation), has the ability to instantly see
behind him and then make a quick judgment call and navigational change?

No, I'm claiming a unicyclist without a mirror can do that as quickly
and as reliably as one with a mirror. In fact, I would expect that
one without can do it more safely than one with.

Quoted message said:

Ian Smith wrote

Quoted message said:

Quoted message said:

On (7) taillights: This opinion is NOT an assumption, this is an
observation by me.

Actually, I did not. U-Turn wrote that, but has attributed it to me.

He also wrote this:

Quoted message said:

Quoted message said:

Quoted message said:

I have seen drivers give me more room during dry,
bright daylight hours, because I was using a flashing taillight on
my unicycle.

That _IS_ an unproven assumption. You're ASSUMING that the specific
driver in the specific conditions would have left less space if you
had not been lit with a flashing light. You're ASSUMING the reasons
for the gap which was left.

Nope, it's observation of a pattern.

X happened BECAUSE Y is not an observation. It's a statement of
cause. You are assuming a cause - you simply can't claim that "driver
left more space because I had a light" is nothing but an observation.
You are making an observation and then assuming a cause. In previous
posts you've gone so far as to assume a train of reasoning for the
observation.

It's simply rubbish to claim your statements on this topic do not
contain assumption.

Quoted message said:

Drivers consistently slowed down
earlier and gave me more room when I used the light.

That's an observation. You are at liberty to assume a reason for this
observation, but it remains a statement of fact that your conclusion
is an ASSUMPTION of the cause.

Quoted message said:

Quoted message said:

No, you're getting carried away again. Putting on lycra does not
miraculously impart greater skills to the person in question. You
cannot tell from the clothing how skilled a specific cyclist is.

Yes, but the point here is that it's reasonable for a driver to think
that.

No, it is not.
It is dangerous and unreasonable for a driver to assume that.

Quoted message said:

It's not reasonable for a driver to think that an apparently
serious rider is likely to do something foolish.

Again, your criticising conclusions (or opinions) that no-one holds.
No-one has claimed what you are implying. You are embarking (yet
again) on an argument with a straw man.

Quoted message said:

You are right; that's my opinion. My post was a mixture of opinion and
critique, and I think it's pretty clear what is which.

No, it is not. You have filled a couple of posts with all sorts of
statements, most of which are presented as equal criticisms of the
research (research you are yet to actually read). You have not
distinguished between your made-up stuff and the stuff that is
applicable to the research, and whenever you're challenged on any
point you simply say something like "oh yes - of course that's some of
my made-up stuff".

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

So there we have it, the mere mention of helmets and in comes Ian Smith
with his blinkered views to argue tiny trivial points. And this time
about a helmet related “paper” (I know what you really meant 😉 ) with
a flawed methodology.

[image: http://www.4wd.com/4wdforums/images/smilies/brick.gif]

I have a theory (or maybe a postulation) about Ian. Whilst out riding,
and NOT wearing a helmet, in an accident he received a nasty blow to
the head so as he forgot all about said accident. This also caused him
a compulsion to argue, at the drop of a hat, anything regarding
helmets. There is still hope he’ll recover though as he now gets his
T’s and H’s the right way around which is a good sign.

BTW has anybody seen Ian ride a unicycle? Or a photo maybe? [image:
http://www.connected-moms.com/community/images/smiles/icon_huh.gif]

Do you know it’s such a long time since I posted anything I’ve
forgotten my password and had to create a new account. I shall retire
to lurking again. [image:
http://www.dexpot.de/forum/images/smiles/wave.gif]

--
Irideononetoo
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Irideononetoo said:

So there we have it, the mere mention of helmets and in comes Ian Smith
with his blinkered views to argue tiny trivial points. And this time
about a helmet related paper (I know what you really meant 😉 ) with
a flawed methodology.

How do you know teh methodology was flawed? Have you read the paper?

Do tiny trivial things like accuracy and truth not matter to you?

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

Ian Smith said:

The fact that [the paper] is as yet unpublished does not alter the
validity of my question. Nor does it make it OK to criticise the
research from a position of ignorance.

Agreed: The fact that the paper has not yet been published is not
cause for criticism. On the other hand, the University of Bath has
opened itself up for criticism by publishing a news release with a
strongly provocative title that is not the subject of the research:
"Wearing a helmet puts cyclists at risk, suggests research."

This is a publicity stunt and frowned upon in scientific circles.
Science should stick with the facts, leaving the speculation to be
quietly and carefully studied by scientists or loudly debated by
armchair know-it-alls.

I have read the extended abstract ("Professional Briefing Document"😉
and I really wonder about the validity of the results as they apply to
cyclists who know what they are doing. The problem is that the study
measures vehicles passing distances as the cyclist rides absurdly far
from the side of the road. If a cyclist has to ride in traffic 1.25m
from the edge of the lane for any significant distance to avoid
"debris, car doors, and drivers’ attention patterns at junctions",
then that rider should simply take up the whole lane. Notable, the
study shows that, when riding at what I beleive to be a reasonable
distance from th edge of the road (0.25m), the ratio of "particularly
near" to "particularly far away" overtaking events is not correlated
with helmet-wearing.

In other words, this data suggests to me that passing behavior is not
influenced by helmet-wearing when a cyclist rides "as close as
practicable to the ... curb or edge of the roadway" as directed by the
Uniform Vehicle Code [http://www.swcp.com/~nmts/laws/UVCBicycles.htm].
My take is that drivers assume helmeted cyclists are more likely to
take corrective action when there clearly is room for them to move
over to allow the cars safe passage.

Also, one has to question a methodology that resulted in two
collisions during the course of one short study. In all probability,
the rider was acting in an unusual manner, which the vehicles failed
to accurately predict. My best guess is failure to share lanes
properly.

So, is it fair for me to criticise this research without having read
the paper? I think it is at the very least fair to criticise the
presentation offered sinch the university that supported this research
sent out a provocative and likely controversial press-release. The
abstract raises significant questions.

Quoted message said:

Your example here is completely invalid, for several reasons:

1: You are assuming a finite bounded error. This is extremely
unlikely to be true. Assume a normal distribution (or indeed any
other distribution with a tail) and your whole argument collapses.

Nonsense. U-Turn's argument easily extends to infinite distributions.
We then simply consider the distance required to achieve n standard
deviations of confidence that a collision will be avoided, for
whatever n you prefer. Thus we can determine the distance needed to
reduce collisions to whatever small probability you are willing to
accept.

Quoted message said:

3: Even ignoring both those fatal flaws in your argument, you are
ignoring the fact that no-one has claimed that this proves that
helmets do increase the chance of collision - only that they MAY
increase the chance, and you disagreed with that statement.

When Bath university picked the title "Wearing a helmet puts cyclists
at risk, suggests research", they knew (or by all rights should have
known) that this is exactly what they were suggesting to the majority
of readers. Most people will interpret the clarifying phrase
"suggests research" as though it means "shows research". There is, in
fact, research demonstrating this tendency for people to make overly
"optimistic" inferences from science news items in lay media.

Cheers,

Ken

cline said:

Ian Smith said:

The fact that [the paper] is as yet unpublished does not alter the
validity of my question. Nor does it make it OK to criticise the
research from a position of ignorance.

I have read the extended abstract ("Professional Briefing Document"😉
and I really wonder about the validity of the results as they apply to
cyclists who know what they are doing. The problem is that the study
measures vehicles passing distances as the cyclist rides absurdly far
from the side of the road. If a cyclist has to ride in traffic 1.25m
from the edge of the lane for any significant distance to avoid
"debris, car doors, and drivers’ attention patterns at junctions",
then that rider should simply take up the whole lane.

But as you are aware, the 1.25m is merely one limit - the data is for
distances from 0.25 to 1.25m. Those look like reasonable limits for
the band of 'normal' cycling - I'd rarely be that close or that far
from the kerb, but I don't see anything fundamentally wrong with them
as limits for study. Looking at the data in the briefing, the
conclusions hold even if you eliminate the extreme points.

Quoted message said:

Notable, the study shows that, when riding at what I beleive to be
a reasonable distance from th edge of the road (0.25m),

That's an extremely dangerous and unreasonable location - road
markings are further out than that, and it's extremely dangerous to
try and ride along the thermoplastic used for them. Standard drain
gratings extend to 450mm from the edge, and it is similarly dangerous
to ride over them, since they are normally inclined and always
slippery (especially when wet).

Quoted message said:

In other words, this data suggests to me that passing behavior is not
influenced by helmet-wearing when a cyclist rides "as close as
practicable to the ... curb or edge of the roadway" as directed by the
Uniform Vehicle Code [http://www.swcp.com/~nmts/laws/UVCBicycles.htm].

The data does not purport to say anything whatsoever about behaviour
in a jurisdiction covered by the Uniform Vehicle Code.

The guidance for the jurisdiction the data _does_ represent says
something very different. For example, 'Cyclecraft', which is the TSO
book with detailed recommendations on cycling describes two positions
- 'primary' and 'secondary'. Primary is dominating the lane - occupy
the centre of the path taken by motor traffic (you've already
referred to this technique). More relevant to this discussion is
secondary, which is the position to take up to allow other vehicles
to pass more easily, where it is safe to do so. This is "not closer
than 0.5m to the edge of the road". The figure of 0.5m as an
absolute minimum is restated elsewhere, and is perfectly sensible -
you should not ride across drain gratings - that's simply asking for
trouble.

Quoted message said:

Quoted message said:

Your example here is completely invalid, for several reasons:

1: You are assuming a finite bounded error. This is extremely
unlikely to be true. Assume a normal distribution (or indeed any
other distribution with a tail) and your whole argument collapses.

Nonsense. U-Turn's argument easily extends to infinite distributions.

No it doesn't - in essence he said if your margin is greater than your
scatter then increasing margin does not affect chance of collision.
That's true, but only if you have finite scatter. If you have
infinite scatter (as for a normal distribution), your margin would
need to be infinite for his argument to work.

Even with a finite scatter, the research seems to be well within the
range of likely scatter - and the briefing note makes no claim that
the conclusion can be extrapolated to any clearance.

I agree that there is no reduction in risk passing at infinity + 10cm
compared to passing with infinite clearance. I'm not aware of any
vehicle ever having passed any cycle with infinite clearance.

Quoted message said:

We then simply consider the distance required to achieve n standard
deviations of confidence that a collision will be avoided, for
whatever n you prefer. Thus we can determine the distance needed to
reduce collisions to whatever small probability you are willing to
accept.

In this context I am prepared to accept any probability, provided the
probability at greater clearance is identical.

For the statement U-Turn says is false to be false, the probability at
distance s must be identical to (or less than) the probability at
distance s+interval. For an infinite distribution this occurs only
when s is infinite. S is never infinite.

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

iridemymuni said:

when i'm on my bike people honk at me for riding on the road. (weird, i
only get the honks when i'm doing the speed limit down a hill).

when i'm on my uni it's like everybodys trying to get as far away from
me as possible, there are cars and people running out of the way and
staring at me. i'm not a crappy rider they just are amazed at what i'm
riding.

Exactly, distance the cars leave is also affected because of age and
what you are riding, unicycle or bike, suppose you're riding an adult
tricycle, they'll probably leave more space than usual, and if you're
riding a bike, just about everyone can ride a bike, so they don't think
twice. Suppose we have a family of unicyclists, A is the Father, B is
the mother, C is a male teenager, D is a female teenager, E is a male
7-year-old, and F is a female 7-year-old. A is more likely to get less
space than B, C will get as much space as B, D will get a little more
than C, E and F will get...a space about as wide as them lying on the
floor! Now, if they're all riding their bicycles, A and B won't get a
lot of space, B and C will get some more than their parents, D getting
more, and E and F are taking up almost as much room as them with their
unis! Possibly...None of it is actual research.

--
Andy912912

Need for (low) speed!Level Bored!Plain Crazy!I reject your reality and
substitute my own!(Adam, Mythbuster)I now ride for Christ(though I
always did, now I'm in that group) but I still need my daily dose of
(low) speed!
------------------------------------------------------------------------
Andy912912's Profile: http://www.unicyclist.com/profile/12601
View this thread: http://www.unicyclist.com/thread/53205

Ian Smith said:

Quoted message said:

Notably, the study shows that, when riding at what I beleive to be
a reasonable distance from the edge of the road (0.25m),

That's an extremely dangerous and unreasonable location - road
markings are further out than that, and it's extremely dangerous to
try and ride along the thermoplastic used for them.

DANGER WILL ROBINSON!!! [arms flail] DANGER WILL ROBINSON!!!

Not only have I made a practice of riding at about that distance
during years of commuting and other road cycling, I just passed three
bicyclists on the road and all of them were well outside of the line
painted on the road. That line was approximately 1/5 meter from the
edge of the pavement.

There you have it. Proof that us Yanks all live for extreme danger.

Quoted message said:

Standard drain gratings extend to 450mm from the edge, and it is
similarly dangerous to ride over them, since they are normally
inclined and always slippery (especially when wet).

Sucks to be you: Where I live now there are no grates to ride over.

Still, I used to ride every day in all weather on narrow streets with
heavy traffic in a city that was decidedly not bicycle friendly. The
proper approach to road debris and gratings in those circumstances was
to hop over them, not veer into traffic or hog the lane.

By the way, wet conditions were cake. Icy slush piled up above curb
height in a blizzard made the commute more interesting.

Correction:

Not only have I made a practice of riding at about that distance
during years of commuting and other road cycling, I just passed three
bicyclists on the road and all of them were well outside of the line
painted on the road. That line was approximately 1/2 meter from the
edge of the pavement (i.e. they were about 1/3 meter from the edge).