Proposed improvements to mtb:scale:imba documentation

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There are two issues with mtb:scale:imba documentation within OpenStreetMap that I am looking to receive community feedback, consensus on, and determine whether formal proposals will be needed.

Issue 1: mtb:scale:imba wiki language

The current trail difficulty keys for mountain biking are mtb:scale (German - Singletrailskala (STS) system) and mtb:scale:imba (American - International Mountain Biking Association (IMBA) system). Why the two separate rating systems appear in OpenStreetMap is because the STS system was developed first, is primarily used in Europe, and is designed to deal with “natural” cross-country style trails. Whereas the IMBA system is primarily used in North America, but not exclusively, and is designed to deal with all trails but specifically also provides guidance for technical trail features (e.g. constructed wooden features, jump features, drop features) that are common for North American mountain bike trails.

The main problem arises on the mtb:scale:imba page where the lead paragraph says

The Trail Difficulty Rating System shall be used for mountain bike trails which are specifically designed and designated for mountain biking, to be found in “Bikeparks”, for example. For “natural” trails it is advised to use mtb:scale=* and mtb:scale:uphill=* instead.

The issues with this are:

  1. The IMBA system is also used for trails that are not specifically designed for mountain biking such as multi-use trails.
  2. The IMBA system is also used for trails that are not designated for mountain biking such as unsanctioned trails.
  3. The IMBA system is widely used outside of commercial bike parks.
  4. It advises that mtb:scale be preferred for “natural” trails without providing guidance to editors what a “natural” trail is.
  5. The advisement of using the German STS for “natural” trails leads to fragmentation in ratings in North America where constructed features and the IMBA grading system are commonly used.

Several users have brought these issues up in the talk page but it seems to have gotten bogged down into irrelevant debates over the merits of each grading system. It also seems that there is miscommunication between the American/British-English speakers and the German users. As a result the page has been edited back and forth between the two groups without community consensus and without fixing the issues.

Proposed fixes:

Fix 1: Update language on the Mountain Biking wiki page to make it clear the differences between the two systems

On the Mountain Biking wiki page under the “Basic Tags related to Mtbiking”, change the table descriptions from:

Difficulty grading for mtb use for level and downhill trails, also valid for ways that are no singletrails. Based on the German “Singletrailskala”.

and

Difficulty grading for mtb use for built tracks. Mainly applicable to North America.

to

German Singletrailskala (STS) difficulty grading system. Common in parts of Europe. Applies primarily to trails without constructed features and obstacles.

and

International Mountain Biking Association (IMBA) difficulty grading system. Common in North America. Applies primarily to trails with and without constructed features and obstacles.

Fix 2: Update lead paragraph on the mtb:scale:imba wiki page.

Rewrite introduction paragraph on the mtb:scale:imba page from:

The Trail Difficulty Rating System shall be used for mountain bike trails which are specifically designed and designated for mountain biking, to be found in “Bikeparks”, for example. For “natural” trails it is advised to use mtb:scale=* and mtb:scale:uphill=* instead.

to

The key mtb:scale:imba is used to classify a trail’s mountain bike difficulty according to the International Mountain Bicycling Association (IMBA) Trail Difficulty Rating System. Its rating system provides a standardized way to categorize the relative technical difficulty of trails and is commonly used for trails with constructed features and obstacles within North America.

Consider using the key mtb:scale if the STS grading system is more commonly used in your local area or if it’s the preference of your local OpenStreetMap community.

Issue 2: Lack of a rating for difficulty above IMBA double black

In more advanced trail networks and bike parks a “triple black” or “proline” rating is common. This commonly denotes a trail that is suited for professional riders only and has high consequence features such as large gap jumps.

Proposed fix:

Add mtb:scale:imba=5 to mtb:scale:imba wiki with

Description: Unofficial classification extension of the IMBA grading system that covers elite level difficulty trails with ratings above double black such as triple black and proline that are sometimes found at bike parks and free-ride style trails in North America. Trails with this rating commonly include large mandatory gap jumps, large drop-offs, highspeed descents, and no ride-arounds.

Common Examples:

  • :small_orange_diamond::small_orange_diamond: Proline (Double orange diamond)
  • ◆◆◆ Triple Black Diamond (Triple Black Diamond)
  • :red_triangle_pointed_up: Proline (Red diamond)

This proposed fix avoids creating a new parallel difficulty rating key and appears to be the simplest and most natural fix given there is no standardization for this difficulty level.

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This looks great. If anyone cares to look at the data you’ll see that the *imba version is widely used in north america on natural trails

The only think I’d suggest it to tweak this paragraph a little to make that clearer:

The key mtb:scale:imba is used to classify a trail’s mountain bike difficulty according to the International Mountain Bicycling Association (IMBA) Trail Difficulty Rating System. Its rating system provides a standardized way to categorize the relative technical difficulty of trails and is commonly used for all trails with or without constructed features and obstacles within North America.

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Thanks for raising these points for discussion!

I always saw mtb:scale=* as being it’s own independent OSM classification, based on and originally designed from the German STS. That’s why Key:mtb:scale - OpenStreetMap Wiki lists the values, but also has an STS equivalent column.

Therefore you can use mtb:scale=* on any MTB track globally regardless of if it has an official rating or not, and regardless of any local rating systems in use.

You’ll have some MTB tracks which have official STS scales or official IMBA scales that are signposted and decided by the builder/operator of the MTB track, but you also have a lot of informal/unsanctioned MTB tracks that were built by the local MTB community without approval from any authority, and without any signposts. Can we as mappers then assign both a mtb:scale and mtb:scale:imba based on our observations of the trail, even though it doesn’t have one officially assigned or signposted? I have been doing so, but it’s an unsolved issue.

So I think we should retain mtb:scale as being it’s own OSM scale, which maps to the STS grading system, but don’t define it as the STS grading system. If you want to do that it would be mtb:scale:sts.

I agree with this.

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Proper descriptions for trails is a worthy discussion

IMBA designations apply only to sanctioned trails within established networks

So applying this designation within an established sanctioned network would make sense.

IMBA does not support unsanctioned trails. Applying an IMBA designations to an unsanctioned trail would be inappropriate.

To quote.

“The International Mountain Bike Association maintains that all trail use and construction must be fully sanctioned by land managers, stating that “ unauthorized trail building threatens the entire sports future access” “

So yes this tag would apply to trails sanctioned by the land managers

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7 posts were split to a new topic: Usage of mtb:scale and mtb:scale:imba on informal (unsanctioned) trails

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That makes sense. And since this is a German system used throughout Europe it would be consistent to apply to sanctioned trails in sanctioned trail networks if used in other jurisdictions.

in other words, if people understand the German system they would assume this scale would be applied to similarly sanctioned and maintained trails

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There are a few issues with making a difficulty grading system only apply to sanctioned trails.

  1. It doesn’t match real world practice of proprietary commercial applications. The two most popular proprietary commercial applications, TrailForks and MTB Project, both use the IMBA grading system for unsanctioned trails.
  2. It doesn’t match current OpenStreetMap practice. Taginfo currently shows 20,882 features tagged with informal=yes and mtb:scale:imba=*.
  3. Restricting the IMBA tag to sanctioned trails would result in no way to tag a large percentage of unsanctioned trails difficulty as the mtb:scale=* tag is impractical for trails with constructed features.
  4. This would not match practice for mtb:scale (42,331 combinations with informal=yes) and sac_scale (13,425 combinations with informal=yes).
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Trailforks and MTBProject, using IMBA standards, respects their application to sanctioned trails.

Maybe current OpenStreetMap practice should respect IMBA and STS use of their designations to sanctioned trails.

Restricting IMBA tags to sanctioned trails would be the right and respectful thing to do. It would also create consistency between jurisdictions.

Maybe OpenSteertMap should work with the Land Managers to come up with a tag for unsanctioned trails

Its unfortunate mappers arbitrarily assigned tags to trails without understanding their legality in the network.

This brings up the next obvious question, should OpenStreetMap remove the IMBA and MTB rating of all trails where this tag is used? Then the mappers can go back and tag sanctioned trails with the appropriate IMBA and MTB tag.

Openstreetmap should work with land managers to come up with a new designation for unsanctioned trails.

Applying known systems (imba and sts) to unsanctioned trails would cause confusion to people who expect these designations to apply to sanctioned and managed trail systems.

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This is not accurate. For example, here is an unsanctioned trail that appears on both platforms, and both have assigned it an IMBA difficulty rating. The Trailforks page even explicitly states, “This trail is unsanctioned.”

https://www.trailforks.com/trails/5th-horseman/

OpenStreetMap US is working with land managers through the Trails Stewardship Initiative. Guidance developed as a result of the Trails Stewardship Initiative recommends tagging social trails (also commonly referred to as unsanctioned or pirate trails) with informal=yes. This is already being used in practice as per my previous examples with Taginfo. Major data consumers including AllTrails, Gaia GPS, and OnX have already adopted use of this recommendation to deemphasize such trails.

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That’s great!

So what your saying is the formal tagging of an unsanctioned trials is

Informal=yes
with no Mtb STS or IMBA tag unless sanctioned to do so.

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Finland’s freedom to roam applies fully to cycling, so almost any random path, abandoned track etc. in a forest is a legit place to use mtb:scale. These are not ”mtb trails”, or ”part of a network”. They’re just paths some mapper has ridden on a mountain bike. The whole idea of informal=* is irrelevant in this context.

Official/signposted trails would be described as a relation.

Edit. Italy is another country with massive amounts of tagged mtb:scale, not sure what the situation is there, but surely those are not any kind of ”official mtb trails” either.

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Again for consistency and as OpenSteetMap is being used more in Third party apps, designations should be consistent.

If using a designation that originated in Germany (STS) or the US (IMBA) that were defined by those areas to apply to sanctioned trails, these designations should only be used for such.

In areas where trails exist but are not part of a maintained system they should have a different designation so people know they aren’t actively maintained as part of a sanctioned system.

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I’m not sure there’s any requirement that STS trails be sanctioned, do you have a source for that claim?

But regardless, we’re using a system called mtb:scale here. There’s nothing in the tagging that claims it’s ”official STS” or whatever.

Returning to the topic of this thread, I guess mtb:scale:definitely_not_imba=* might be useful if this is a serious argument.

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if the STS designation started on Germany I’ll bet my life that it is based on sanctioned trails!

Ordnungsliebe!

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I am going to publicly note that the willful misunderstanding on display in this post and most of your posts in this thread, coming from an account that just joined today, is highly suspicious when considered in combination with the ongoing harassment campaign against @eerib .

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More concretely, “IMBA says the scale is defined as Xyz” is not a valid counterargument to “We wish to have OSM break away from the official definitions set by IMBA”

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More concretely, “IMBA says the scale is defined as Xyz” is not a valid counterargument to “We wish to have OSM break away from the official definitions set by IMBA”

Not sure your point here. OSM should continue respecting definitions set by IMBA for sanctioned trails if they continue with the IMBA designations.

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Interesting.

Do you have anything of substance to add besides attacking the messenger?

Read IMBAs guidelines for details.

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Fair points.

Ultimately I’d like to have a well documented approach to,

  1. record designated/signposted scales for official trails. eg. the sign says black diamond very difficult
  2. record the difficulty of an informal/unsanctioned trail without signage, where mappers make an assessment based on the features of the trail as to what kind of skills and experience a rider would need to ride it

which works globally and regardless of if the trail has constructed technical features, or is mostly natural.

The Trail Difficulty Rating System shall be used for mountain bike trails which are specifically designed and designated for mountain biking, to be found in “Bikeparks”, for example. For “natural” trails it is advised to use mtb:scale=* and mtb:scale:uphill=* instead.

I agree, the wording should be improved. Where I’m from in Australia I’ve only ever seen the IMBA scale in use, but it’s used for both trails that would be considered part of a “MTB park” (an area within which many trails are built (high density of trails), and the whole area is essentially exclusively used for mountain biking), and “natural” trails that run through national parks and cris-cross through hiking trails and maintenance tracks. The degree to which they make use of constructed technical trail features, vs the natural surface, rock and tree logs varies a lot.

To tweak your suggestion for the lead paragraph, I’d suggest

mtb:scale:imba=* is used to classify a trail’s mountain biking difficulty based on the International Mountain Bicycling Association (IMBA) Trail Difficulty Rating System. The rating system provides a standardized way to categorize the relative technical difficulty of trails. It is commonly used for both trails with constructed features and obstacles, or for natural trails without constructed features. It’s common in North America, Australia, [insert more here] and other regions.

It can be used for trails considered within a mountain bike park, or for those outside of a formal “bike park”.

We should also include a note about mtb:scale:imba on trails without a formal assigned rating, eg. informal trails, or even formal trails that aren’t signposted with a rating.

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Usage of mtb:scale and mtb:scale:imba on informal (unsanctioned) trails
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I agree with this suggestion.

I agree with the addition of mtb:scale:imba:informal=yes/no. Happy to handle adding this to the wiki documentation if this proposal goes through.

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