Sorry to obsess on the filtering question, but I wonder what the legal situation is about it - is it actually against the law? Do cyclists have to
stay on the pavement side of cars?
I ask because my girlfriend was knocked off her bike by a careless person
opening their door in her face a couple of years ago (they were in a rush to catch a train, so it was their fault and they admitted it). She did quite well out of the insurance, £2000 I seem to remember. However, I wonder if it'd have been different if she had been on the other side of the car.
Right - we clearly need to get this straight!
No - it is definitely NOT against the law to overtake on the right, except in certain circumstances, one of which has already been mentioned. In fact, you are on dodgy ground when undertaking (filtering on the left). The Highway Code is actually a bit inadequate here (as so often when it comes to cycling). However, the cycling section (Rule 67) refers cyclists to Rules 162-169, which in my view relate more usefully to drivers. However, Rule 163 says:
You should only overtake on the left if the vehicle in front is signalling to turn right, and there is room to do so.
Rule 165 gives the conditions under which it is illegal (MUST NOT, as opposed to the SHOULD NOT advice in 163) to overtake on the right; these include double white lines, as mentioned in an earlier post, but also various others.
Cyclecraft, which is the essentially the Bikeability manual (I'm a qualified instructor, working mainly with school children) gives more helpful, specific and complete advice:
It is unreasonable to expect cyclists to wait in long queues of traffic whe there is room for them to pass, but filtering through traffic requires great care....Normally, overtaking should only take place on the right, and this should be your preference. But on congested roads where there is insufficient clearance from oncoming vehicles, or where there is more than one lane in your direction, this may be impractical, and it is acceptable to pass to the left - a process sometimes referred to as "undertaking", and not without reason!
The obvious risks are that you will be squeezed if drivers move left, that a door will open in your path, or that you will hit pedestrians crossing when they expect no one to be moving. You are also vulnerable to vehicles that a driver in the queue ahead allows to turn right across your path.
(Page 162, Cyclecraft by John Franklin - http://www.amazon.co.uk/Cyclecraft-comp ... 301&sr=8-1
There's a lot more advice in Cyclecraft on this, and if you are unsure about the legality and sense in what's being said then in my view you'd be well advised to read it. If you don't mind my pointing it out, your girlfrield has rather proved the point that John Franklin and I are making!