Take the example where a bicycle lane is on the road, rather than the pavement. There is a queue of cars waiting at the lights, and the bike lane is clear right up to the lights. If you were to cycle right up to the lights, you would be passing all the queuing cars on the way, on the passenger side ("Undertaking"). Is this an example of "dangerous driving", or otherwise frowned upon (UK)? What if the cars were moving? What if there wasn't a bike lane, but you were staying to the side of the road so that other cars could overtake you if they wanted?

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    Under- and overtaking is legal for cyclists AFAIK. chroniclelive.co.uk/news/north-east-news/… If the bike lane is clear, why wouldn’t you cycle up to the lights? Isn’t that partly what the lane is for?
    – Traveller
    Jul 15, 2020 at 8:46
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    I'm in the US, and a bit of translation from English-English to North-American-English would be helpful. I believe UK "pavement" = US "sidewalk", and UK "overtake" = US "pass". But what exactly does "undertake" mean? In the US, an undertaker means the same thing as a mortician, and to undertake means to attempt. "Two peoples divided by a common language," for sure! (US "for sure" = UK "indeed", ha ha.) Would someone please enlighten me?
    – rclocher3
    Jul 16, 2020 at 0:15
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    @rclocher3 just to confirm, your interpretations of pavement and overtake are both correct. “undertaking” (in this context) is the same thing as overtaking, but from the wrong side. Jul 16, 2020 at 5:09
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    @rclocher3 so to pass on the left. In the US I suspect that passing on either side is a little more accepted, especially on freeways/multilanes, but in UK it is definitely frowned upon for vehicle drivers to pass on the nearside (left) in free flowing traffic. In certain circumstances a driver could be prosecuted for it, see askthe.police.uk/content/Q891.htm, so that puts the question into a bit of context. (if you had a dime for each such prosecution you would still be poor, but it shows how it is viewed culturally)
    – Swifty
    Jul 16, 2020 at 11:57
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    @Daniele re: "It's absolutely incorrect"; I'll let the UK know that they're using language wrong. It is a regional question, and anyone who doesn't know what undertaking is, probably isn't qualified to answer the question. Undertaking in a car is a thing, it's basically illegal and it's rude and dangerous. This question is therefore asking whether those things apply on a bicycle.
    – Swifty
    Jul 17, 2020 at 8:47

4 Answers 4


As the previous answer states, you're perfectly within your rights to continue along the cycle lane in this situation, regardless of any cars to your right.

Some junctions even have advanced stop lines (see rule 178), which are explicitly designed for exactly this purpose: allowing and encouraging bicycles to pass beyond the stopped cars and position themselves in front of other traffic (this is generally preferable, as it makes the cyclists much more visible to drivers).

You should of course still maintain awareness of the traffic (especially if there are large vehicles such as HGVs or buses, which often have significant blind spots), and be prepared to make a quick stop if it appears that a vehicle is about to cross the cycle lane.

But not only is this allowed for bikes, in the specific situation you're asking about - passing traffic which is stopped at a red light - it's also perfectly fine (and indeed expected) for cars to undertake.

See Rule 163 of the highway code:

Rule 163
Overtake only when it is safe and legal to do so. You should:
stay in your lane if traffic is moving slowly in queues. If the queue on your right is moving more slowly than you are, you may pass on the left

(my emphasis)

Note also (admittedly now getting some way from the original question) that the points in rule 163 are governed by "You should", not "You must". As explained in the Wording of the Highway Code, that indicates advice rather than legal requirements per se (failing to follow the advice can lead to liability in an accident, but isn't prohibited in itself).

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    could you add the case of Advanced Stop Lines (bike boxes) which are common, where entering the box at the front of the queue is even encouraged?
    – Swifty
    Jul 15, 2020 at 10:19
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    Adding to the third paragraph, I don't go up the inside of a stopped (big) vehicle unless I'm sure of getting out in front where I can be seen by the driver before the lights change. If it's signalling to cross the bike lane I may not go even then, unless I can see the the vehicle's way is physically blocked. (I know it's confusing, but I'm a different Chris H to the one who wrote the answer!)
    – Chris H
    Jul 15, 2020 at 11:14
  • Yes it’s legal but dangerous. You should really be careful about other vehicles crossing into your lane while you are overtaking from an unexpected side. Be wary of parked cars or people suddenly opening doors at a red light. Be wary of pedestrians using the opportunity to cross the road.
    – Michael
    Jul 15, 2020 at 12:18
  • These cautions are also really important, worth including. When there is a turning left, vehicles pose a big danger and large vehicles are especially dangerous (in part because driver's visibility is compromised). So yes, pass on the left in a bike lane up to lights, but avoid passing vehicles this way which might be about to turn left and always vigilant
    – Swifty
    Jul 15, 2020 at 12:43

Take the example where a bicycle lane in on the road, rather than the pavement. There is a queue of cars waiting at the lights, and the bike lane is clear right up to the lights. If you were to cycle right up to the lights, you would be undertaking all the queuing cars on the way. Is this an example of "dangerous driving", or otherwise frowned upon (UK?

Absolutely not, you have a cycle lane allocated to you. There’s no point to slow down because some cars next to you slow down. You have a free path ahead of you so you can move forward. I’ve seen people do this all the time. It’s one of the main reasons cycling is better and quicker.

What if the cars were moving?

Same rules apply, you have a cycle lane, use it.

What if there wasn't a bike lane, but you were staying to the side of the road so that other cars could overtake you if they wanted?

That’s also fine, in fact you should stay at the side of the road (especially a busy one). Ducking in the middle of the road could be “dangerous driving”.

  • But if cars do the same thing (stay in their lane and pass another car on the wrong side), it's dangerous because a driver isn't expecting a vehicle passing them on that side. So why is it different for bikes? Jul 15, 2020 at 8:46
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    @simonalexander2005 Bikes are different than cars, if a bike has a lane they will only stay in that line. Not like cars which have several lanes
    – user49462
    Jul 15, 2020 at 8:49
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    @simonalexander2005 in the example you've outlined (traffic stopped at a red light) it's not different for bikes. Nobody expects you to wait at a random point in the road because there's a line of stationary cars to your right. Jul 15, 2020 at 9:14
  • @Daniiln with respect to your comment, that's not true for several reasons. There may be more than one bike lane, going in different directions, or the bike lane may be blocked, unsafe, or otherwise unsuitable.
    – Chris H
    Jul 15, 2020 at 11:18
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    An example of the latter. The bike lane is to the left of a left-turn lane & the bike lane itself isn't marked left only, but when a bike can go straight, cars can turn across it. If going straight, the best thing to do is reject the unsafe bike lane, and stay out in the general lane until the bus(+bike) lane starts. Forget trying to move right out of the bike lane in rush hour, unless you can match the speed of traffic, and pull out into a tiny gap.
    – Chris H
    Jul 15, 2020 at 11:21

This isn't the example situation described in the question, but it is what immediately what came to mind when I read the title, which is:

Undertaking another cyclist whilst on a bicycle is in my experience extremely frowned upon, and to me (when I am the one being undertaken) feels very dangerous. My rationale for why it feels like this to me is that as cyclists we have a constant sense of threat from motor traffic, and our "emergency escape route" is to move away from the traffic towards the side of the road. Furthermore unless we have moved in to a separate lane away from the side of the road (for example if we are going straight on at a roundabout with a left-turn lane) we only expect (and therefore only check for) traffic coming from behind to appear on our right side. Then the appearance or presence of an obstacle inside this emergency channel and in a position we would not normally check for before executing a leftward manouevre feels extremely sketchy.

  • Good point - passing other cyclists should be done on the centerline side, not the curb-side of the rider being passed. Its very rare to find a slower rider in such a position that theres no space between them and the car traffic.
    – Criggie
    Jul 16, 2020 at 20:49
  • Absolutely, good points Judy, a rider isn't expecting to be undertaken, making collisions more likely. welcome to the site!
    – Swifty
    Jul 17, 2020 at 15:14

As we talk about the UK, yes ride on to the stop stripe (or the lights) unless that gets you in an unsafe situation.

As many of the bike lanes in the UK are too narrow for cycling when cars are stopped close, you may have to get off if you want to move forward, even when the car is in the proper position on the road.
And many of the bigger vehicles warn you not to pass while it is stationary, like stopped for a light. I have seen those stickers on buses as well as on heavy goods vehicles.
If you need to pass one of those vehicles with such a sticker, consider staying behind it, (as the drivers may not check well for cyclists on the inside even though law tells them to do so.) Too many lives have been lost in accidents where the driver did not see a bike next to the lorry.

Where the bike lane is safe to continue, wide enough and with enough separation cars do not cross it while turning, you should continue on.

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