Safe stopping distance?

[gbs]

In the context of an injury claim following a multibike pileup on a group ride caused by a rider falling after a pothole the S****** County County is claiming contributory negligence. This raises the the question for this thread. I suppose it is primarily a function of speed, cyclist allup weight, brake condition and dry/wet road condition. If anyone has a view I would be interested - it might even make an acceptable study for a student thesis.

FWIW, my guess, assuming dry road condition, favourable conditions generally and a moderate speeed of say 25kph (15.5mph), is that 7 meters (7-8 yards) is a minimum safe stopping distance .

Whatever plausible and favourable assumptions one makes the result will not be good news for group riders.

 

[frank9755]

In the context of an injury claim following a multibike pileup on a group ride caused by a rider falling after a pothole the S****** CC is claiming contributory negligence. This raises the the question for this thread. I suppose it is primarily a function of speed, cyclist allup weight, brake condition and dry/wet road condition. If anyone has a view I would be interested - it might even make an acceptable study for a student thesis.

FWIW, my guess, assuming dry road condition, favourable conditions generally and a moderate speeed of say 25kph (15.5mph), is that 7 meters (2 yards) is a minimum safe stopping distance .

Whatever plausible and favourable assumptions one makes the result will not be good news for group riders.

My first thought was that your distance was way under as I saw the 2 yards bit, but 7 metres is c.8 yards so maybe not too far off. However it then occurred to me that 2 metres is about 7 feet, so perhaps you could clarify?

Riding in a group necessarily involves riding closer than a safe stopping distance, ie 'tailgating' in car-speak. I'm no expert but I've heard it mentioned in similar cases that, by riding in a group, this was one of the things that cyclists consented to.

Presumably this is an insurance company defence. In which case it is one for the people who negotiate these policies to get clarification on as an accident while riding in a group is precisely the thing that people take out insurance coverage for. It's also one for those of us with policies via CTC, LCC, BC, etc to seek clarification from them on.

If the rider or club is not insured and are being sued, then they have made a bad mistake!

 

[the snail]

I think 7m is pretty optimistic - bear in mind you have to include reaction time. Riding nose to tail is clearly dangerous, bearing in mind bicycles don't have brake lights, and if you are directly behind someone you have no view of the road ahead. For car drivers it's recommended to allow a 2 second gap, so surely a similar consideration should apply to cyclists. If you're racing, then It's different - you accept that riding close is part of the risk?

 

[gbs]

post now edited re metric conversion - put it down to early morning dopiness. Thanks Frank for yr observation.

 

[Scoosh]

I appreciate that this is not directly related but it might have some bearing.

There was a court case in Edinburgh a couple of years ago - I won't try to explain it here but it was certainly a sad case.

I can't find the link to the final outcome but, IIRC, the decision was basically that cycling in a group like that carries an element of risk which you accept by riding in the group. The incident was highly regrettable but no liability could be attached to the leading rider who fell off and precipitated the pile-up.

The case was dismissed.


In terms of how close should you ride to the bike in front:
- what element of risk are you prepared to accept ?

- if high, then suck the wheel
- if low(er), hang back​

I can see the difference here where the claim is a group thing against the council for having the pothole unfilled but I guess the same principle would apply.


**I have absolutely no legal training/ knowledge but this is my 'common sense' view.**
How valid it is adjudged to be, will depend on your verdict on my 'common sense' !

 

[gbs]

@schoosh; I agree with yr commonsense view and cannot refute the contributory negligence argument. The proportionality issue then arises. With a pot hole induced pile up I feel that a substantial liability (75%?) should fall on whoever is responsible for the road. Does any one know of precedents?

The point of my rudimentary estimate of safe stopping distance is to

• confirm the obvious common sense view that, even at the limit of the zone with drafting benefits (2meters?), a rider is within the danger zone
• encourage others to estimate safe stopping distances particularly for adverse conditions - frankly I would rather learn from others than experiment.

For the moment 7-8 meters seems to be the marker for moderate speed in good conditions.

 

[BSRU]

25 kph is about 6.9 metres per second, using the two second rule that would mean a safe gap would be about 13.8 metres. Wouldn't be a very sociable ride at 13.8 metres apart.<br>

 

[Fiona N]

I think there's also an element of how well you know your fellow riders and how far you trust their judgment. I find that when I'm cycling with people how are new to me as cyclists, I tend to stay at or near the front of the bunch even if means doing more work. With people I know and trust I'm happier to ride in the bunch. There are always individuals that I watch out for and don't ride behind and/or beside as I consider them too erratic etc.

 

[frank9755]

Is CC county council? I had inferred it to stand for cycling club!

 

[gbs]

Is CC county council? I had inferred it to stand for cycling club!

County Council!

 

[frank9755]

Riding nose to tail is clearly dangerous

Is it?

It certainly is if you ride with people who are not competent (as Fiona references - I do the same!). But you don't often hear about multiple pile-ups on group rides which suggests that, done properly, it is a safe thing to do.

 

[monkeypony]

Is it?

It certainly is if you ride with people who are not competent (as Fiona references - I do the same!). But you don't often hear about multiple pile-ups on group rides which suggests that, done properly, it is a safe thing to do.

Except in pro cycling of course, where it happens all the time...

 

[As Easy As Riding A Bike]

Except in pro cycling of course, where it happens all the time...

And you would like to think they are halfway competent too.

 

[the snail]

Is it?

It certainly is if you ride with people who are not competent (as Fiona references - I do the same!). But you don't often hear about multiple pile-ups on group rides which suggests that, done properly, it is a safe thing to do.

I haven't done a huge amount of group riding, but if I'm close behind another rider I prefer to ride a bit to one side so I can see what's coming. When I go out with the club, the convention is to warn following riders of approaching cars, potholes, ice etc, but there are usually some inexperienced riders/kids along. I suppose the answer is it depends on the situation as to how close you want to get. I am Mr. Cautious though, and I would be mortified if I caused someone else to crash. The club does have a 'golden stabiliser' trophy for the most stylish / inventive crash though.

 

[classic33]

For the speed given, Cyclecraft give the following:

Gradient
0% (level).
Dry & alert- 11m(36 feet). Wet & tired - 27m(89 feet)

5% Down
Dry & alert- 11m(36 feet). Wet & tired - 30m(98 feet)

10% Down
Dry & alert- 12m(39 feet). Wet & tired - 37m(121 feet).

This I assume is based on riding alone