Cycling UK Forum

I suspect the logical thing is to use lights but to kid yourself that you aren't.
A difficult belief to maintain

Me too, but I'm affected by the number of things around cycle safety that are contrary to popular wisdom:

* it does seem that cycle facilities are, on average, less safe than the road (discuss in this thread, not here)

* smooth tyres are safer than deep treads

* there's a debate on helmets (lots of relevant threads, not here)

* it's safer to ride further out in the road than many people expect

* signalling can be dangerous

and so on and so forth. I'm not about to stop using lights on the basis of a couple of lots of stats, but I'm open-minded enough, and serious enough about my own safety, to want to understand what's going on.

drossall wrote:* it does seem that cycle facilities are, on average, less safe than the road (discuss in this thread, not here)

That one wouldn't surprise me.

* smooth tyres are safer than deep treads

Not remotely surprising as it is (even in Britain) dry more often than it is wet, and cycle tyres are narrow enough that aquaplaning (the only reason to have tread) is exceedingly unlikely.

* there's a debate on helmets (lots of relevant threads, not here)

I'm utterly unconvinced by that study.

* it's safer to ride further out in the road than many people expect

No surprise at all.

* signalling can be dangerous

I don't know the context for that, but I can think of situations where that would definitely be true.

Ben

Literal interpretation of statistics can be risky.

Cycle facilities: Probably more risky of incident but would need to know fatalities re. miles travelled compared to minor accidents all balanced against rider take-up and perception. Throw in central and regional government support, quality of provision, etc, etc and the picture is anything but clear.

Bike tyres: Don't aquaplane but smooth tyres are less tolerant of the slippery surfaces associated with surface water, inc diesel spills, ice, hidden road features, irregularities. Manufacturers include stipes for a reason.

Helmets: Almost certainly useful in specific types of accident but these are far from the most common type and have to be balanced against risk perception by riders and surrounding motorists.

Research is a useful tool but is rarely comprehensive enough to accomodate associated factors and social contexts. Instinct is, as ever, a very useful tool.

drossall wrote:* it does seem that cycle facilities are, on average, less safe than the road (discuss in this thread, not here)

Just remind me how many cyclist have been killed when using a 'cycle facility' and by this I assume we are talking about the 'off road' facility commonly known as cycle paths/tracks. Even allowing for low use and limited miles, I think the stats will show them to be somewhat safer than the road. Agree that improvements can be made to some/many, but I find them quite useful and very much safer than the road.

glueman wrote:Bike tyres: Don't aquaplane but smooth tyres are less tolerant of the slippery surfaces associated with surface water, inc diesel spills, ice, hidden road features, irregularities.

The only function of tyre tread is to prevent aquaplaning.

For maximum grip, you want as much of the tyre as possible in contact with the road. In dry conditions, that is achieved with a slick tyre - tread means there is less rubber in contact with the road.

On a wet surface, slick tyres can build up a wedge of water in front of them. If there is enough water there, then the tyre can ride up on top of that wedge of water, ie. aquaplane.

What tread does is provide an escape path for the water, through the groves, while the rest of the tyre remains in contact with the road.

Tread does not help with diesel, ice or irregularities. In all other conditions except standing water, it reduces grip.

Ben

"The only function of tyre tread is to prevent aquaplaning."

Hmm, I know that's the party line Ben but I suggest things are a bit more complicated. A narrow slick - the kind of thing I and many here use most of the time - is very good at cutting through surface water to the road below. If you increase tyre width and ride on a slick 1.75 in heavy rain, say, you'll find handling and grip much more uncertain with less feedback. Manufacturers introduce stipes and patterns to move water into the grooves by increasing surface area in large section tyres. If there was no need for them, the makers wouldn't put them in - and almost all do.

Other factors come into play like tyre pressure, which is a compromise between staying on the rim, putting the right tyre area down on the surface and tread shuffle. You can over-do surface area, true MTB tyres have only small blocks in contact with the road, great for grip in soft going but lousy for wet roads and inclined to move under braking. Narrow tyres are surprisingly good off road riding so long as the ground isn't too broken, much better than wider slicks for example. There are other factors like air pocket size and pinch points but I've never bought the direct equivalence with aquaplaning on slick motor racing tyres because of these variables. Irregularities are an important factor, imo.

Yes, as I said originally:

Not remotely surprising as it is (even in Britain) dry more often than it is wet, and cycle tyres are narrow enough that aquaplaning (the only reason to have tread) is exceedingly unlikely.

So I too am sceptical about tread on narrow cycle tyres, and suspect it has more to do with covering their ass legally than genuine effectiveness.

I was merely disagreeing with your assertion that tyre tread was useful in any other circumstances. Tyre tread exists for one reason only (a reason that probably doesn't apply on bikes with narrow tyres).

Ben

I am surprised that so much faith has been placed in the police 'study.' I have not seen it so this is conjecture, but I imagine it was prepared in response to one of the perennial demands to 'do something' about cyclists without lights. By concidence, in the early 1980's I did a similar 'study' in West Yorkshire and the main thing that I found was that the available statistical information was rubbish. I should not want any policy decisions made on the basis of my research.

It seems obvious to me that in a given situation, an illuminated object is less likely to be hit than an unlit one.

Therefore, any difference between lit and unlit cyclists is likely to be the result of different behaviour. Ie. Legal cyclist behaving as part of the general traffic, habitually unlit cyclist acting as an honorary pedestrian.

On the other hand, being extremely well-lit confers no immunity from risk. This can be seen from the high rate of collisions involving single vehicles and conspicuous street furniture. I think it is easy for cyclists, especially those without driving experience, to assume that their lights will always be obvious to drivers.

IMO this is particularly relevant at junctions, where many accidents occur. The headlights of an emerging vehicle will not be directed at an approaching cyclist so any reflectives are useless. The driver will be concentrating on looking for powerful car headlights, and may even be dazzled by them. If there is an approaching line of traffic, a cyclist may only appear as a short gap in the line- an invitation to an impatient driver to emerge.

I commuted around West Yorkshire for a number of years, always with well-maintained lights. The Ever Readies, which were all that was really available up to the mid 1990's, were utterly rubbish in the circumstances I have described and through experience I made extra allowance. I got some CatEye Daylights a year or so before I retired. Single lamp version, converted to plain glass. The heavy gell cell was a pain and the charging regime can be a faff on rotating shifts but I immediately noticed a huge change in the behaviour of drivers waiting to emerge. (I also have a theory that drivers subconciously equate bright light with extra speed because I often found drivers would wait unnecessarily as I plodded towards them.)

Finally, I think that the developing indifference to minor shunts in traffic increases the vulnerabilty of cyclists. The apparently minor 'knock for knock' collision which only involves a new light fitting for a motorist can result in serious injury or even death for a cyclist.

I didn't really want to broaden the discussion, but simply to provide examples for the point that it is not enough to accept that such-and-such an approach (to paths, tread or whatever) is "obviously" safer; evidence needs to be taken seriously. Therefore I'm reluctant to reply too fully for fear of taking us off-topic here; we're meant to be on lighting.

Very briefly then, and there are relevant threads on most of these where discussion would be better:

* I don't think those who replied on cycle facilities read the thread I cited, as it includes a link to an extensive summary by the respected cycle-safety expert John Franklin that addresses the questions raised

* Ben Lovejoy is right on treads, but the point is still that you have to think about it, and the idea that treads are obviously a good idea is, well, not in the least obvious!

* Ben refers to one study on helmets, which is odd as there are lots (on both sides); again, refer to a relevant thread

*thirdcrank - no-one's placing lots of faith in one police study, but it is consistent with national figures as I understand them, so that's two; even then we're only asking questions, and no-one here is remotely near putting enough faith in anything to change what they actually do

Drossall

It was my impression that the entire thread had taken the study hook, line and sinker. Most national data on accidents also originate from the stat sections in police accident books and from my own experience a lot of that is at best 'open to interpretation' (E.g. the way accident causation factors are assessed enables people to suugest that speed has little effect in collisions.)

All I am saying is that I don't know the true picture and when I tried to find out for myself, with unfettered access to the available data (in fact limited only by the problems of trawling through paper systems) I was not much the wiser. It is my imppression that whenever police accident stats are compared with potentially corroborating info., such as hospital records, discrepancies are revealed

I would imagine that if it were possible to collect data by magic and if you were able to compare the accident results of say, Cyclists with fully inflated tyres, vs. cyclists with soft tyres or cyclists using clipless pedals vs. those without the results might be just the same. And my personal guesswork/ intuition would be that cyclists who behave as part of the traffic rather than as hon. peds. in modern conditions are more vulnerable. (I speak as someone who really does try to comply with the law and has always taken the line that a cyclist is part of the traffic.)

It is a sorry state of affairs

Incidentally, if I can rather crudely suumarise what you seem to be saying, you accept that cyclists without lights outnumber those with them; however the latter group has more accidents; you do not know why this should be but seem to reject the possible causes suggested by others; you reject in particular any suggestion that a cyclist on the road is more vulnerable than one off it.

As Auchmill observed, it does seem that a number of posters are sceptical of scientific methods here and I've noticed it on several occassions when people are discussing a study. There's nothing magical about it and the results are open for debate and interpretation, but not usually completely meaningless or just fabrications.

Thirdcrank, you make an interesting point about police data recording being open to interpretation by the person recording it. The lighting factor seems much less open to interpretation than the speed-related ones. In particular, lack of lights would be quickly to be flagged up as a cause of the accident if it were the case as it is regarded as nearly universally dangerous, and it is also a yes or no question rather than on a scale as speed is. I think it's less likely to be under-recorded.

thirdcrank wrote:my personal guesswork/ intuition would be that cyclists who behave as part of the traffic rather than as hon. peds. in modern conditions are more vulnerable. (I speak as someone who really does try to comply with the law and has always taken the line that a cyclist is part of the traffic.)

Yes, I agree. My gripe with cyclists who ride on the pavement, RLJ, go unlit and the rest of aberrant behaviour is that they never force motorists to accomodate cycling as a meaningful way of using the roads. Individuals may justify their actions as safer and it may save them time but any dilution of status is seen as symptomatic of the mode of transport. If cyclists really behaved like cars they'd force the government into taking them seriously in a week.

glueman wrote:My gripe with cyclists who ride on the pavement, RLJ, go unlit and the rest of aberrant behaviour is that they never force motorists to accomodate cycling as a meaningful way of using the roads. Individuals may justify their actions as safer and it may save them time but any dilution of status is seen as symptomatic of the mode of transport. If cyclists really behaved like cars they'd force the government into taking them seriously in a week.

Nicely put!
Bicycles are vehicles by definition. Vehicles travel on roads and obey The Highway Code.

Sares

The completion of the police stats form was problematic during the whole of my career (I retired in 1997 so it may have changed.)

Overall the problem is that as well as dealing with the accident and collecting evidence, there is then the stats form to complete. Not all police officers are keen to deal with accidents (and over the last 40 years or so, the type of accident the police will submit reports on has been reduced. Since I retired the benchmark of 'all injury accidents' has been replaced, Ibelieve by KSI - killed or seriously injured) and the time-consuming stats form is widely regarded as more unnecessary paperwork.

The interplay of criminal and civil proceedings as well as the compilation of stats can make officers cautious about what they allege.

These and other similar issues make me doubt the value of much of the data obtained.

Something I didn't mention before was the difference in reporting habits of lawbreakers against compliers. Obviously, in serious accidents the cyclist is scraped up off the floor but at a less serious level, I suspect that somebody who knows they were breaking the law, e.g. riding without lights, is much less likely to make a report to the police than somebody who feels they are on firm ground. (Of course, they may still be fobbed off but that is another issue.)