Thank you for the feedback. The reason I refer to mtb:scale=* as the STS grading system is because:
It appears to be a direct copy of the STS grading system.
The wiki documentation hasn’t had any significant alterations since the page was written in 2009, including not addressing constructed features which would have made it more applicable to North American trail designs.
The major cycling applications that use OpenStreetMap refer to mtb:scale=* as the STS grading scale. This includes RideWithGPS (documentation), Strava (photo example), Komoot (documentation).
However I can understand that we may change it in the future so am happy to re-phrase to:
Difficulty classification based on the German Singletrailskala (STS) difficulty grading system. Common in parts of Europe. Applies primarily to trails without constructed features and obstacles.
I would clarify that the IMBA tag should be for sanctioned trails. Ie part of a maintained network sanctioned by the land managers as per IMBAs guidelines. Whether it’s a bike park or not.
If it’s recognized officially by the land manager it’s sanctioned then the IMBA tag applies.
Unsanctioned trails should not have the IMBA tag. This would create confusion for users who expect trails associated with IMBA to be sanctioned.
For the MTB tag, if it’s based on the European standard their guidelines should apply. Again, for clarity for users who have expectations based on the European standard it too should apply to sanctioned Mtb trails
Unsanctioned trails should just be informal=yes so users don’t have an expectation that
Would come with the IMBA or MTB standard.
Has OpenStreetMap even asked IMBA or STS how they want their tags applied?
Also, since OpenStreetMap is being more widely used, tags should be used honestly as originally intended, not how it might be conveniently used in a different jurisdiction.
For clarification officially assigned meaning sanctioned. If IMBA tag applies.
We still need a way to say that unsanctioned trail is of X rating against the IMBA scale if evaluated against the same criteria.
For example mtb:scale:imba=3 + mtb:scale:imba:informal=yes to say it’s Black Diamond, but not “officially” assigned, or mtb:scale:imba:informal=no to say it’s officially assigned this rating.
I like this approach as it means every trail that people ride can have a rating so we know what level it is, but also helps provide guidance about where that raiting came from.
Or just go with what @eerib pointed out and informal=yes + mtb:scale:imba implies that the IMBA is not officially assigned. The problem is you can have official designated MTB tracks without an officially assigned IMBA rating which this tagging can’t capture but mtb:scale:imba:informal=* could.
I know nothing about IMBA and how the organisation works, but I do admit that in the general case, there may be some risk and it’s a valid point.
For example if IMBA started saying OSM is infringing their trademarks etc by using “imba” within the tag keys, especially if we’re tagging “imba” scales that they didn’t assign that could be infringing on their trademarks? Would be good to have some comments from LWG on that.
I think if we’re simply mapping signage showing Green, Blue, Black Diamond, Double Black Diamond and applying those observations as tag values 1,2,3,4 I’d hope there’s no legal risk in doing that, but we don’t want our tags and tagging system to be at the mercy of any other organisation.
I’ve seen quite a number of trails where the builder has said they’re unsanctioned, but has then also described them as an “extremely difficult, double black diamond trail, that should not be attempted by inexperienced riders”!
@eerib 's response to this was left in the other thread after the split. I’m confused where the discussion should take place. Since “informal difficulty vs official difficulty” is not strictly just about imba, I’ll put my comments here.
My understanding from the current documentation is that difficulty (whether officially designated or not) is done with some variant of mtb:scale, while route=mtb describes that it’s an official route. I guess there’s a gap where an official route doesn’t have an official difficulty scale, but someone has added their own (which seems like a reasonable thing to do)?
I don’t mind documenting a mtb:scale:*:informal=* to handle these situations, but I would suggest it’s implicitly a yes or implicitly a no depending on if the path is part of a route=mtb relation. Adding the missing route relation should be the preferred option instead of tagging mtb:scale:*:informal=no, but I can imagine there are situations where this is still needed (e.g. signposted difficulty on an unnamed “transfer path” between two official routes.)
As an aside, I’m slightly confused about how Tag:route=mtb - OpenStreetMap Wiki seems suggesting mtb:scale on the relation itself, rather than individual highway=* This seems wrong, and against how mtb:scale itself is documented.
While we cannot control how individual contributors or 3rd parties refer to it, I think there are benefits to not officially saying “this is STS”. Both for reasons of maintaining control of OSM tags in OSM, but also because frankly it’s not.
STS has a main website which describes the public version of the difficulty scale. That does not have + and - modifiers, nor grade 6, which mtb:scale has.
route=mtb wouldn’t imply anything about it being an official route, the tag goes with type=route on relations used to join ways together where they form a route, but the route itself might be informal, and the route may travel via informal tracks.
informal=yes/no would be where you record something is official or not, informal=no = official, informal=yes = not official.
Plus other tags like operator can help to determine how formal something is.
It might be on official/formal MTB track, but not part of any route.
I think either or, or both is fine. In the downhill MTB context you’ll typically have a “run” with a single scale/difficulty assigned (which I believe, but might be wrong is usually based on the hardest part of the run that you can’t bypass). So you wouldn’t usually split up the run to tag the difficultly sections, rather just apply the signposted difficulty for the whole run.
I believe type=route + route=mtb are currently being used in OSM both to group segments of a run together, and larger routes that pass through several runs. You’ll also find some people group all the runs in an area together into one relation as the “bike park” which I don’t think is correct.
This is what we have documented in the wiki for route=mtb:
MTB (Mountain bike) routes are named or numbered or otherwise signed routes, designated for mountain biking. They may go along roads, trails or dedicated cycle paths, or a combination of these.