kwackers wrote:And then if you sit behind in a queue you've still got to put up with traffic trying to get in front - in fact the only time I've ever been knocked off at a set of lights I was actually queuing and the driver behind tried to get in front.
I've spent decades avoiding any kind of moving to the front, while riding in and between towns. Only in the last four years have I got a job in London, and been forced to reconsider, and see it from the perspective of a city commuter.
The point of ASLs, as I understand them, is to avoid exactly the situation that led to kwackers' accident, by getting cyclists across junctions before the motorists behind have a chance to try to race the bikes into the narrow gaps on the other side or, even worse, turn left across them (often without indicating in any useful way). Staying where you in a queue is not a great idea if it means that you're going to be exposed to that situation, and taking the lane can be hard in stop-start traffic that is reaching 20mph during the start bits. I find it quite different from riding at home, where I'll still most often just wait in my place in the queue.
Approach lanes are always on the left, if they are provided. Where they exist, and if they're not blocked by cars, they're blocked by the first few cyclists, who don't "get it"; instead of filling the width of the ASL, they stop in the lane, trapping the riders behind next to traffic that may turn left across them without indicating. And very often you can't see whether there's an ASL at all until you have already committed to going up the side of traffic - so you can get to the front and find no ASL, even though they were provided at the last three junctions on the same road. Or there is an ASL, but it's occupied by a motor vehicle either that didn't quite make it across the lights, or whose driver doesn't care about ASLs anyway. So there are loads of unofficial ASLs, just in front of the stop line, made by cyclists with nowhere else to go.
On the other hand, you're often riding routes whose traffic-light sequences you know, and there are several places where I can go up the side in the absolute certainty that nothing with an engine is going to be moving until long after I've got to the front. Vehicles that are stuck in traffic are almost entirely safe to share the road with - provided that you're sure that they're not going to move suddenly.
I prefer to go up the right where I have the choice. In some places, however, that means going out round two lanes of vehicles, and back across them at the front. That's not a great idea. Much safer to go up the left, if the vehicles are stuck, you know when the lights will change, and there's a good escape route in the form of the pavement.
The Highway Code does not advise against (and certainly does not ban) the practice. In spite of popular language, it generally talks about filtering rather than undertaking, and mostly as something that motorists should anticipate (rules 160 and 211). Rule 88, regarding how to do it, is addressed to motorcyclists, but logically also to cyclists. The "undertaking" word is only used to cyclists, and then only when warning us to watch for other two-wheelers who might come up the side of us when we are turning (rule 72). That's probably because filtering and undertaking are different things - filtering happens in stationary or slow-moving traffic, whereas the undertaking in rule 72 happens once the traffic is moving reasonably freely.
So, whilst being on the left of a moving lorry* is an obvious no-no, my view as a rider of decades of experience, but newer to London riding, is that filtering (not undertaking) is essential to safety, but should be used with care and done on the right where reasonable. And riding in London is actually quite fun most of the time, and probably much safer than the alternatives, at least when health benefits are taken into account.
* Or the right for that matter
