dirtbike:scale=? can be used to indicate that a specific route is known to be suitable for dirt bikes, although the exact difficulty scale is not known.
Basically dirtbike:scale=? means 0 <= dirtbike:scale <= 5
This convention seems to differ from that used with other tags. In particular, the wiki page for sac_scale does not mention the use of ‘?’ as a value, and neither does the wiki page for mtb:scale
What do you think? How should ranges of possible values be expressed when tagging?
I think for such quality tags, there cannot be a “ranges of possible values”: a way has either been surveyed and a specific value has been assigned (about which there can be disagreement), or it hasn’t been surveyed and no tag should be added. If there is a high interest in tagging a particular way, you can add a note or a fixme tag requesting a survey.
@rhhs Thanks! That seems to be inline with how other tags are applied and how I have always mapped.
Does anyone have an objection to modifying the wiki page for dirtbike:scale so that in regards to this matter it is more inline with mtb:scale and sac_scale?
I do I’m happy to use a different tag for that purpose, but removing the information or making it less accessible to renderers (like OsmAnd) isn’t a solution.
I can tell you that the alternative convention for sac_scale and mtb:scale is to use tags like foot=yes/no and mtb=yes/no. By that logic, it would make sense to use dirtbike=yes/no—but this approach is controversial, as some argue that access tags should only reflect legal or signed access, not physical practicability.
foot=yes/no and mtb=yes/no and motorcycle=yes/no are legal access tags. My impression is that there is consensus on this, and those arguing otherwise are wrong
What useful information does ‘dirtbike=?’ tells us? If it’s legal, motorcycle=yes. If it’s rideable, take a guess at a difficulty level.
I think it’s better to hint that a trail is rideable rather than risk giving an inaccurate estimate. At least this way, it encourages some end-users to try it out and provide a more accurate value. A fixme tag, on the other hand, is unlikely to be noticed by the average user.
There’s a consensus among forum regulars, myself included, but if you ask all users of the ‘mtb’ tag, you’ll likely get a different perspective. The issue is that both mtb:scale and dirtbike:scale include values that span from passable to impassable (e.g., level 6). Yet, there still seems to be a need for a general indicator of rideability—which is why many people continue to use mtb=yes/no for that purpose.
Following up on this, what do you think about alternative tags to dirtbike:scale=? to prevent mappers from misusing legal access tags to describe trail practicability when the exact scale is unknown?
dirtbike:scale=unknown: similar to how access=unknown is used.
dirtbike:scale=fixme: indicates that mappers should provide a more precise value.
dirtbike=yes/no: use dirtbike access tags to denote practicability, similar to how mtb is used controversially, while keeping motorcycle=yes/no strictly for legal access.
dirtbike:practical=yes/no: a new tag to specifically indicate trail practicability.
The purpose of these tags is to serve as a temporary measure until more accurate data can be collected. Removing this information is not a viable solution, as it provides valuable motivation for mappers to survey well-known trails and enhance difficulty ratings.
I question how much “information” is contained in dirtbike:scale=?. Something like: “the difficulty of this trail for dirt bikes is somewhere between the most easy and the most difficult, but I am not sure because I haven’t seen the trail, because if I had, I would have a more precise value. I just really want it to show up in the app I am using”? From what I have seen this tag is being applied over wide geographic areas in single changesets (indicating most likely no on the ground survey) to any trail that is legally open to motorcycles. If the trail had been surveyed, the mapper should have a better idea of the dirtbike:scale. Thus, the “information” that is being “lost” is de facto embedded in the motorcycle tag as the mapper is most likely guessing that any trail where motorcycles are legally allowed must also be suitable for dirtbikes.
How is it that a mapper can know that a trail is suitable for dirtbikes, but not have some idea as to the level of difficulty?
If you find a trail that is legally open to motorcycles, but is not suitable for dirtbikes, tag that trail dirtbike:scale=6 (which the wiki says means “entirely impassable for dirt bikers”). Then data users/consumers can just assume that in the absence of dirtbike:scale that the trail is somewhere between 0-5, since it appears that those mappers applying the tag dirtbike:scale=? are making that assumption.
In my area, most riders aren’t interested in contributing to OSM directly, but many do share GPX traces with me. I add those to OSM, but they rarely come with info about trail conditions. Estimating difficulty from average speed isn’t reliable — it depends too much on the rider’s skill and pace.
We have a massive trail network here, most of it unmapped or unridden in years. So even just knowing a trail was recently ridden or walked is valuable. It helps prioritize surveys by the few active mappers. And visualizing that data helps users identify possible escape or rescue routes. If there’s no trace, the trail may be abandoned or never existed — just old imagery or noise.
Aside from a few signed trails in national parks, nearly all trails in Thailand are legally open to motorcycles. So formal access tags aren’t reelvant here.
That’s a bad assumption. Missing data shouldn’t imply suitability. The trail could be abandoned, fictional, or just traced from poor sources like old imagery or heatmaps.
That doesn’t work well either. Trails marked impassable or unsuitable often get tagged by hikers, not actual riders. A rider would use the appropriate dirtbike:scale or mtb:scale, not default to 6.
Most casual riders also don’t want complex scales — a simple yes/no tag is more practical. If you’ve followed discussions like this one, there’s clearly a need for a better tagging approach. Without that, people will keep misusing access tags to describe suitability.
Just sharing another idea for an alternative approach:
Instead of using dirtbike:scale=?, I could check for the presence of an access tag like motorcycle=yes, motorcycle=unknown, or motorcycle=permissive to get a sense of whether a way is likely or potentially rideable. Based on that, I could render these ways differently to reflect their assumed accessibility.
For example, if I add a new path based on a dirtbike GPS trace, I would tag it with motorcycle=unknown rather than dirtbike:scale=?. That way, it’s clear that both the access and difficulty are currently unknown and still need to be verified—while also distinguishing it from a bare highway=path that could be misleading.
I’m really trying to find a reasonable compromise. Hope we can move forward!
I’m happy to use a different tag for that purpose, but removing the information or making it less accessible to renderers (like OsmAnd) isn’t a solution.