Matthew's Journal

gerald_duck: Your interpretation is clearly contradicted by the picture. Have you looked at it ?

As for the rationale:

Cyclists need to be able to wobble. Wobbling is an inherent feature of the way that bike stability works. They also need to be able to swerve to avoid uneven road surfaces, objects in the road, and so on. They can be caught by gusts of wind and blown sideways. Emperor has mentioned slipstream too. And of course there needs to be room for error on both sides - it's one thing to take a risk of some scratched paintwork, and quite another to risk a serious injury.

Why are cycle lanes so narrow ? Because they're there to get cyclists out of the way of Important People In Motor Cars, not to serve the needs of cyclists. The recommended width of a cycle lane in official government guidance is 2.0m. There are no lanes in Cambridge of this width. The Traffic Regulation Orders for cycle lanes in Cambridge all specify a maximum width (generally of 1.5m) but no minimum, and there are numerous lanes that are less than 1.0m wide.

I almost never ride in a cycle lane in Cambridge - and despite my very assertive nature, there are routes I no longer take because riding safely (as even the Institute of Advanced Motorists approves of) often results in an assault. In most places outside Cambridge (and apparently Coventry) the situation is very different.

As to why cyclists sometimes give themselves less space: Personally I always try to give myself as much space as I would want to be given in return. But bear in mind that the cyclist is aware of all of the above factors which influence the safe passing distance in a way that the driver isn't, and the cyclist can also plan their manouevre so that their lean is correct for the situation in a way that they can't if they aren't in control. (Remember that to move away from a close passing vehicle, a cyclist needs first to steer towards the hazard.) And of course many cyclists, particularly in Cambridge, are untrained and ignorant - they are making the same mistake as you, in thinking because 1.0-1.5m cycle lanes are common, that must be the safe space.

References:

Warrington Cycle Campaign:
http://homepage.ntlworld.com/pete.meg/wcc/facility-of-the-month/index.htm
http://homepage.ntlworld.com/pete.meg/wcc/report/cycle-lanes.pdf

Roadpeace:
http://www.roadpeace.org/

Parliament Transport Select Committee:

http://www.publications.parliament.uk/pa/cm200708/cmselect/cmtran/460/460.pdf
"Ending the Scandal of Complacency: Road Safety beyond 2010"

IAM:
http://www.iam.org.uk/Resources/Institute%20Of%20Advanced%20Motorists/Documents/News/Factsheets/fac17001.pdf
http://www.iam.org.uk/pressroom/drivingtips/Sharing+the+road+with+cyclists.htm
http://www.iam.org.uk/pressroom/drivingtips/Motorists+and+cyclists+share+the+road.htm

Ian Jackson