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Proposal status: Proposed (under way)
Proposed by: JPinAR
Tagging: mtb:scale:amtb=*
Applies to: node, way, relation
Definition: Rating system for Adaptive Mountain Bike cyclists

Draft started: 2021-11-22
RFC start: 2022-06-24
Example of adaptive cycle and rider


Adaptive MTB Rule #1: Never ride "new single-track" alone. A good ride is a ride everyone comes back from.

This proposal looks to add three related tags to OpenStreetMaps: (Yes, I will make separate pages on OSM wiki for each tag but for approval purposes, I wanted these tags to be considered collectively as a set for answering the broader questions about what can an adaptive rider expect so they can select a ride that will work for them.)

  • mtb:scale:amtb=1-3/no - to answer the question 'Is support needed or not?' (More on ‘no’ flag explained below)
  • mtb:scale:amtb:inclusive=yes/no - to answer if trail is 'Friendly for ALL aMTBs by meeting Minimal Trail Standards'
    • There are a wide variety of 'Minimum Trail Standards' for which a trail can be 'Friendly for ALL aMTBs'
    • This is intended to compliment the aMTB rating on signage with the addition of a plus (+) symbol after to aMTB rating so aMTB1+ or aMTB3+ is possible.
  • mtb:scale:amtb:technical=yes/no - to answer if trail has 'Advance Technical Features or Terrain' that require 'Extra Skill or Practice'
    • This is intended to compliment the aMTB rating on signage with the addition of an 'X' character after to aMTB rating so aMTB1X or aMTB3X is possible.

Note: You should never have a plus (+) and 'X' combination as the addition of 'Advance Technical Features or Terrain' that requires 'Extra Skill or Practice' also means it will not be 'Friendly for ALL aMTBs'.

There are presently multiple adaptive MTB rating systems, why suggest this one for OpenStreetMap tagging? To be frank the proposed trail rating system aligns with OSM's Best Practices in complying with One feature, one OSM element. Each tag serves to answer one and only one key question relevant to adaptive cyclists and doesn't try and duplicate or reinvent present trail rating systems like mtb:scale:imba=* or even mtb:scale=* instead it aims to complement those existing ratings.

In contrast, another popular trail rating system that also identifies as aMTB comes from Kootenay Adaptive Sports Association (or KASA) and has gained adoption specifically in British Columbia particularly and probably most famously at Whistler MTB park. The KASA standard has 7 tiers, each combining aspects of Trail Width, Tread Surface, Obstacles (Technical Trail Features), Unavoidable Bridges, Camber (Turns & Straights), Corner Radius, Exposure, & Recommended Equipment. While these are all good things to know the KASA trail rating system does not fit a strict 'One feature, one OSM element' alignment and I'd say subjectively serves better as a trail-building classification standard. This serves a purpose but isn't a good fit for OSM. An interesting consideration though is that a trail that meets the KASA trail building classification/rating system will most likely get a mtb:scale:amtb:inclusive=yes which shows how these two are complimentary but not wholly compatible.

The proposed rating system has been picked up by Trailforks which at the time of this post has:

  • 1349 - aMTB1 rated trails
  • 417 - aMTB2 rated trails
  • 66 - aMTB3 rated trails

This makes this adaptive trail rating system more widely adopted than any other as well so it appears to work.

Why wouldn't existing rating systems work? Why is a new separate take needed? Ironically many IMBA green trails (mtb:scale:imba=1) make for terrible adaptive MTB trails. The 'why' has to do with have we tend to design trails to easier as we tend to spread them out and round out the corners more with more switchbacks and fewer direct drops. The issue is that many of those things we tend to make the trails more off-camber (or tilted) which for adaptive riders are common variations of trikes that can cause the rider to tilt over and fall off their adaptive bike. So what makes things easier for non-adaptive cyclists can inversely make the trail less ridable for adaptive riders. Where a drop in straight down a rock face that we might rate an IMBA blue and above (mtb:scale:imba=2-4) will be less likely to have off-camber (tilt) issues.

I use this as an example of how counterintuitive for instance the IMBA rating system works vs. the proposed adaptive MTB rating system. They still can be complementary but they are by no means interchangeable. Also, don't assume that just because a cyclist rides an adaptive cycle that they need or even want milder and less adventurous trails just like typical riders some will and some won't.


There really isn't that much to tell adaptive mountain bikers about their specific needs. A trail could be an easy (green) IMBA rating but not be wide enough, pass through trees that are too narrow, or had berms than don't work for adaptive use because of how gravity works differently for three wheels vs. two. I selected this based on similar rating of established MTB ratings like mtb:scale:imba=*, mtb:scale=*, and mtb:scale:uphill=*. Yet it is distinctive to this use case and the abbreviation has already gained wider adoption at places like TrailForks with requests for support at other MTB community websites.

Although aMTB looks a lot like MTB, that is kind of the point, and when seen in the context of mtb:scale:amtb=* some might need a moment to evaluate that MTB was not just listed twice and that something is distinct. I do expect the second MTB to be capitalized when possible to this point but even when it's not I believe it's clear enough.


aMTB Trail Difficulty Rating System
Tag / Category Challenge Support need (for most cyclist)
mtb:scale:amtb=no Mountaineering not Mountain Biking Support required for greater than 20% of the trail
mtb:scale:amtb=1 No challenges exist Support not needed
mtb:scale:amtb=2 Some challenges exist Support recommended
mtb:scale:amtb=3 Major challenged exist Support needed
No rating Never ride "new single-track" alone! A good ride is a ride everyone comes back from, do not go without support!

Note: A trail requiring more than one support rider, support for more than 20% of the trail, separation from a rider’s equipment, or extra equipment, is deemed expedition level and therefore not suitable for aMTB by the standards of this system. We understand that anything is passable with a crew, gear, proper planning and determination, but the goal of this project is to direct adaptive riders onto trails and routes that provide the best experience for mountain biking, not mountaineering.

aMTB all Inclusive vs Normative Tagging
Tag / Category Description
mtb:scale:amtb:inclusive=yes When paired with mtb:scale:amtb=* this change the 'most cyclist' to 'all cyclists'
mtb:scale:amtb:inclusive=no or absent When paired with mtb:scale:amtb=* rating remains for 'most cyclist'

EX: aMTB1 (mtb:scale:amtb=1) - Most riders will not need support vs aMTB1+ (mtb:scale:amtb=1 + mtb:scale:amtb:inclusive=yes) All riders will not need support.

aMTB Technical Tagging
Tag / Category Description
mtb:scale:amtb:technical=yes When paired with mtb:scale:amtb=* this indicates the trail has unavoidable technical challenges specific to an adaptive rider that skill and practice might be needed
mtb:scale:amtb:technical=no or absent When paired with mtb:scale:amtb=* basically the traditional and adaptive rider challenges are the same.

Some examples of what can get a mtb:scale:amtb:technical=yes rating:

  • small radius wall ride
  • narrow bridge
  • sharp turn with limited room to get speed for
  • drop that might present an opportunity for a front-wheel drive adaptive bike
  • enough off-camber tilt that getting the speed right is hard to dial in

Note: Almost all of these are things that can present challenges specific to adaptive riders. Where a narrow tree gate with no ride around might instead get a mtb:scale:amtb=no rating instead of a mtb:scale:amtb:technical=yes.

More specific tags


Deadhorse Point (near Moab, UT) (See trail blog here for reference and as cited source)

For this I'm going to start by linking to an Overpass Turbo query for this area where I've added multiple mtb:scale:amtb=* and mtb:scale:amtb:inclusive=yes tags.

  • Intrepid (aMTB1+ - mtb:scale:amtb=1 + mtb:scale:amtb:inclusive=yes) - A quick 3/4 mile jaunt to the lookout and connection with Big Chief.
  • Great Pyramid (aMTB3 - mtb:scale:amtb=3) - The trail itself is pretty much aMTB1, but there are two steep ledgy sections where most riders will need help and one semi off-camber slick rock section where some riders will need a spot. You could forego these spots by taking Raven Roll instead of the Great Pyramid and linking to Big Chief via the northern section of the Great Pyramid, but I did not ride this section and am not sure how it is AND you would miss the amazing views.
  • Big Chief (aMTB2 - mtb:scale:amtb=2) - This is where most of the fun is. There is an extremely fun ledgy DH section (see video below). Suspension is highly recommended. At the bottom of that section and along the traverse north, there are two slightly off-camber sections where some riders will need a spot.
  • Raven Role (aMTB1+ - mtb:scale:amtb=1 + mtb:scale:amtb:inclusive=yes) - Adaptive riders should have no problem at all on this trail. It's wide open and mostly downhill back to the trailhead.

Lunch Loops (near Grand Junction, CO) (See trail blog here for reference and as cited source) For this I'm going to start by linking to an Overpass Turbo query for this area where I've added multiple mtb:scale:amtb=* and and mtb:scale:amtb:technical=yes tags.

  • Third Flats Road (aMTB1 - mtb:scale:amtb=1) - Wide open fire road that runs through the middle of the area
  • Twist-n-Shout (aMTB1x - mtb:scale:amtb=1 + mtb:scale:amtb:technical=yes) - This trail is long and littered with flow and tech. More DH if ridden clockwise. It even has a cool slick rock section after the Nut-n-2-It intersection. Most riders will good, but there is some technical terrain so it gets a little x.
  • Rocky Stumble (aMTB2x - mtb:scale:amtb=2 + mtb:scale:amtb:technical=yes) - There is a semi off-camber section in the beginning (if linking from Twist-n-Shout). Once past this, the trail gets visually interesting with cool-looking unique terrain. There a couple technical climbs so power assist, full suspension and rear wheel drive recommended.
  • Quad Rocker (aMTB2x - mtb:scale:amtb=2 + mtb:scale:amtb:technical=yes) - THIS is the best trail we rode! If ridden clockwise, the DH section is insanely fun. There is a staircase which takes some line choice strategery and the lead into it is a little tricky. I got a spot on the lead in to be safe, but with practice I think its do-able solo. After that, let it rip! We did not ride the southeast section — climbed up Roll Over instead — but I'm told its all good. The quick climb back to the road is steep. Power assist and rear wheel drive recommended.
  • Roll Over Ridge Road/Cedar Point Trail (aMTB1 - mtb:scale:amtb=1) - Wide open fire. road, but its steep and loose. Riders with front wheel drive will probably need a push, but most will be good to go.


I know there have been signs but up using the icon-based sign found here here. I'm in touch to make sure there is permission to use this and that it's not under any trademark or copyright restrictions. Ideally, I'll have 9 versions of this logo to cover the 3 levels and the two optional add-on tags:

Caption text
Rating Symbol (SVG)
aMTB1 - mtb:scale:amtb=1
Adaptive Mountain Bike Rating 1
aMTB1+ - mtb:scale:amtb=1 + mtb:scale:amtb:inclusive=yes
Adaptive Mountain Bike Rating 1 - All AMBTs
aMTB1x - mtb:scale:amtb=1 + mtb:scale:amtb:technical=yes
Adaptive Mountain Bike Rating 1 - Technical
aMTB2 - mtb:scale:amtb=2
Adaptive Mountain Bike Rating 2
aMTB2+ - mtb:scale:amtb=2 + mtb:scale:amtb:inclusive=yes
Adaptive Mountain Bike Rating 2 - All AMBTs
aMTB2x - mtb:scale:amtb=2 + mtb:scale:amtb:technical=yes
Adaptive Mountain Bike Rating 2 - Technical
aMTB3 - mtb:scale:amtb=3
Adaptive Mountain Bike Rating 3
aMTB3+ - mtb:scale:amtb=3 + mtb:scale:amtb:inclusive=yes
Adaptive Mountain Bike Rating 3 - All AMBTs
aMTB3x - mtb:scale:amtb=3 + mtb:scale:amtb:technical=yes
Adaptive Mountain Bike Rating 3 - Technical

The above Adaptive MTB symbology and can be used to rendering of trails based on their respective rating.


Features/Pages affected

Definitively Mountain_biking, also will like have also use tagging references for mtb:scale:imba=*, mtb:scale=*, and mtb:scale:uphill=*

External discussions


Please comment on the discussion page.