Even more curious.

There doesn't seem to be a sign on the south bound approach on the A5 from Bangor, and the sign on the north bound approach doesn't specify which direction on the A55.

If there are such signs on all the approaches, this is evidence that they are not of themselves prohibition signs. Otherwise it would be illegal to ride through the roundabout S-N on the A5. You have not marked a ban from any of the signs, nor are there any signs at the places you have mapped a ban.

For a ban to be legal there must be a traffic regulation order. So I can only conclude there isn't actually a ban.

Curious.

That sign appears to be intended as advance waring of a cycle ban, rather a prohibition itself. But there are no signs actually banning cyclists at the junction itself, or at the roundabout exit.

The same appears to be the case at the other end, with advanced signs on the approaches to the roundabout at LLanfairfechan, but no indication of an actual ban at the roundabout exit.

Do you know if there is a traffic regulation order in place actually prohibiting pedal cycles from using that stretch of road, or are the signs over enthusiastic promotion of the national cycle network by Sustrans?

Are you sure cycling is prohibited? It seems very unlikely that cycling would be banned from a road where walking is allowed.

Using maxspeed:type=GB:nsl_restricted is incorrect in Wales. It means 30mph!

I guess there could be a CY:nsl_restricted tag.

I am using the Welsh government map of exceptions:
https://datamap.gov.wales/maps/roads-affected-by-changes-to-the-speed-limit-on-re/view#/
It looks like I missed that one.

Waiting for someone to get round to locating every individual sign post will mean that the map will continue to be incorrect for 99% of Welsh roads for decades (there are still plenty of roads that have not caught up with the speed limit changes to 40 or 50 mph from 20 years ago. Even then mistakes will still be made.

no it was an accident

Indeed.

It is the END of the cycleway from the south (crossing the road) - which means it is the start of the cycleway heading in the opposite direction. ie SOUTH across the road.

Highway Code Rule 62
Cycle tracks may run alongside footpaths or pavements and be separated by a feature such as a change of material, a verge, a kerb or a white line. You MUST keep to the side intended for cyclists as the pedestrian side remains a pavement or footpath.

Exactly the same as motorists reaching the end of a cul-de-sac - or perhaps trying to traverse the low traffic zone on Grange Avenue.

If the council had intended for there to be a continuous route they would have not have placed clear signs indicating the end of the cycle route and they would have provided a parallel crossing that was legal for cyclists to use.

The map has to reflect the world as it is, not how you would like it to be. By all means launch a campaign to legalise pavement cycling, but until that is the case cycling on footways is illegal and the appropriate tag is "no".

Exactly the same as drivers of motor vehicles who might want to drive to along routes where motor vehicles are prohibited.

The idea is to be more specific from the perspective of cyclists.. The default access for footpaths is undefined which isn't very helpful. I am trying to distinguish those paths were cycling is prohibited (eg pavements or where there are no cycling signs by explicitly tagging "Bicycles=no" and those where there is a wide surfaced route as paths (where the default is "Bicycles=yes")

I think it is likely that the line is an early draft of this boundary:
way/581801454#map=15/53.5607/-2.8513

Looks like some kind of boundary that I dagged with a speed limit by mistake when I was attempting to tag Dicks Lane at the SW end. I certainly didn't draw it, but I might have cut it from a longer line.

The context here is that there is a S-N cycle route (The Sankey Valley Trail) that crosses Liverpool Road at this point. There is refuge some distance to the east:
https://www.google.com/maps/@53.3840854,-2.625147,3a,75y,105.48h,92.61t/data=!3m6!1e1!3m4!1s0lmA7JTsCVLR3oB2gtDv2g!2e0!7i16384!8i8192
so the council recommends that cyclists and pedestrians divert along Liverpool Road, cross at the refuge and walk back. See this sign on the approach from the south:
https://www.google.com/maps/@53.3839888,-2.6254958,3a,27.4y,7.87h,88.13t/data=!3m6!1e1!3m4!1sWBaQ5u80zozL1uCMkcQc8w!2e0!7i13312!8i6656

Of course everybody simply ignores the sign and crosses directly (the council simply doesn't understand pedestrian desire lines) - and certainly cyclists were not going to get off and walk - which used to be the case:
http://wcc.crankfoot.xyz/facility-of-the-month/February2010.htm
so they put up signs to allow cyclists to ride on the pavement from the Sankey Valley Trail to the refuge and back. (though neither the refuge nor the pavement not the refuge are suitable for cycling). The signage refers to this stretch.

Now you can't put the sign in the middle of the road - it either has to be before the cycleway starts (as in this case) or after it starts. In either case it is absurd to map the cycleway from the location of the sign rather than the junction (in one case you end up with a short stub in the other you end up with a disconnected route).

Exactly the same is true for a one-way street meeting a main road. The No Entry signs are not placed on the centre line of the main road, but a shot distance along the one-way side road - but you map the whole side road as one-way - all the way to the junction; not a short stub of two way street as just as far as the sign.

Dismount tradionally is the sign they put at the end of a cycleway to tell you that IT IS NOI LONGER A CYCLEWAY.

It did when I surveyed it just TWO HOURS ago.

I presume you have not coincidently visited Daresbury in intervening period.

The ONLY section of shared pavement is to enable cyclists heading N-S on the Sankey Valley Trail to make a short diversion to the east to cross at the island. (Though neither the pavement or island is is actually suitable).

You can't put the sign in the middle of the road - it has to be one side or the other. It is utterly ridiculous to put a short stub to the west just because the sign is on the west - just as it would be absurd to create a break in the route if the sign happened to be on the other side.

Exactly the same is true for restrictions such as speed limits and no entry signs on side roads. Again the signs of necessity will be offset from the centre line of the main road - but you don't include a short stub of two way road on the grounds that it would be perfectly legal to drive the wrong way up the street just as far as the sign.

I really cannot understand why it is considered in any way controversial or worthy of debate to tag ways where cycling is not allowed as bicycle=no. Certainly having tagged them as such there can be no justification for someone to subsequently go round deleting or changing that tag to anything else.

OSM is a map of the world. A cycle route application designer, possibly based on a different continent, cannot be expected to know the precise rules of who is and who isn't allowed to use any of the menagerie of colloquial names for different crossing types on a small island off the coast of Europe. As with footways "whatever the law is locally" really isn't a very helpful description.

Well google street view is up to date at the southern end and these are the two signs that are visible looking north across Boston Boulevard from the semi-circular cycleway to the south:
https://www.google.com/maps/@53.4002326,-2.6430699,3a,15y,18.36h,90.88t/data=!3m6!1e1!3m4!1s4DK55ObgEpe22bdVrWBMTw!2e0!7i16384!8i8192

https://www.google.com/maps/@53.4004129,-2.6424403,3a,15y,328.49h,93.59t/data=!3m6!1e1!3m4!1sJr87OIKUW6Su3QZCynNuhQ!2e0!7i16384!8i8192

Whereas the semi circular cycleway is clearly signed as such:
https://www.google.com/maps/@53.4004129,-2.6424403,3a,26.3y,176.1h,82.51t/data=!3m6!1e1!3m4!1sJr87OIKUW6Su3QZCynNuhQ!2e0!7i16384!8i8192

At the northern end it is very out of date, but providing photographs of the non-existence of signage is rather tricky.

Not unless the council was out this afternoon putting up signs it isn't