In reply to Co1in H: Tricky one this! I am a car driver, cyclist, truck-driver and student of ethics, and I have been a road-motorcyclist before I went racing, so I have a few perspectives on this issue.
Firstly, here’s the Highway Code’s view:
• ‘give motorcyclists, cyclists and horse riders at least as much room as you would when overtaking a car (see Rules 211 to 213 and 214 to 215).’
And here’s the Code’s advice to cyclists:
• ‘66
You should
o never ride more than two abreast, and ride in single file on narrow or busy roads and when riding round bends...
o be considerate of other road users,’
So, if the road is wide and straight enough, there’s no reason not to wide two-abreast. But that is a pretty big if, particularly bearing in mind the geography of many popular riding areas.
Driving trucks gives another perspective: cycling on country A-roads is dangerous! We must be pragmatic about the speeds of vehicles and the visibility on these roads; being able to stop within the distance you can see to be clear is not a phrase given much credence by many road users. Combine a narrow, winding A-road, a truck and cyclist on the same bend both going the same direction and oncoming traffic—the potential for tragedy is very clear. So the cyclist should be considerate of others and not put him/herself at risk by cycling on unsuitable roads. I choose my routes so as to minimise the potential for conflict with other road users; I wish we all did this!
Shouldn’t drivers just make sure that they can stop within the distance they can see to be clear?
Two things to say about this: first, we must deal with the world we live in and not the world we wish we lived in. Secondly, relatively few drivers have sufficient awareness of their vehicles’ abilities or themselves have the skills to exploit those abilities. So, many drivers would not in fact be able to adhere to the stop within the distance you can see to be clear maxim, even if they wanted to. A driver who lacks these skills might be driving at an appropriate speed and still not stop in time; or he might—luckily—stop in time. Do we want to put our safety in his hands? Of course not—so don’t be the cyclist who puts his safety in the hands of others; pick an appropriate route!
https://www.gov.uk/rules-for-cyclists-59-to-82