MTB Trail Grades Explained: Green to Double Black
You pull into a new trailhead, scan the sign at the start, and see a grid of coloured shapes — green circles, blue squares, black diamonds, the occasional double black. Each one points to a different section of the network. The question isn't which trail looks most impressive; it's which trail matches what you can actually ride. Understanding what those symbols mean, and how Australia grades its trails, is the difference between a great day and one that ends with a long walk out.
Here's exactly what each grade means, how the Australian system works, and what to watch for when you're making the call.
Quick picks
- Green (Easy): Wide, smooth, gentle gradient — no real obstacles, rideable on any bike without specific technique
- Blue (Intermediate): Singletrack with rocks, roots and berms; requires intentional braking and body position
- Black (Difficult): Technical features you can't easily roll around — rock gardens, significant drops, steep chutes
- Double black (Expert): Mandatory exposure, large drops and sustained steepness; not graduated into without serious trail time
- When in doubt: On any unfamiliar network, start one grade below where you think you sit. The trail tells you more honestly than the map.
How the Australian MTB grading system works
Australian mountain bike trails are graded using the Trail Difficulty Rating System (TDRS), administered by AusCycling. The system is based on IMBA's international framework but was adapted for Australian conditions and park-building culture, with revisions in 2018 and again in October 2020.
The system splits its criteria in two: guiding criteria (trail width, surface, gradient, quality of signs) and risk-assessable criteria — technical trail features (TTFs) and exposure. The October 2020 revision brought rail trails into the very easy grade, raised gradient thresholds, increased exposure levels, and added new obstacle types with higher height specifications. A trail isn't a black diamond just because it's steep. It earns that rating when it contains features where a rider who can't execute the technique faces real consequences. That's an important distinction, and one that guides how serious builders talk about it.
The core grading criteria are:
- Trail width
- Tread surface (hardpack, loose, rooty, exposed rock)
- Average gradient and maximum gradient
- Natural obstacles (rocks, roots, logs, ledges)
- Technical trail features (drops, rock gardens, bridges, mandatory jumps, berms)
- Exposure (consequences of a fall)
One important quirk: the TDRS grades trail difficulty, not trail fitness demand. A steep, sustained climb on a smooth wide fire road might destroy your legs but still grade green. A short 100-metre rock garden may be technically black while requiring minimal aerobic effort. Those two things are graded separately if a trail manager is doing it properly — though not all of them are.
The four grades at a glance
| Grade | Symbol | Suits | Gradient (ave / max) | Surface | What defines it |
|---|---|---|---|---|---|
| Easy | Green circle | First-timers, families | 7% or less / 15% | Smooth hardpack or gravel | Wide trail, clear lines, unavoidable obstacles to 100 mm, low-consequence mistakes |
| Intermediate | Blue square | Riders building technique | 10% or less / 20% | Compacted dirt; some roots, loose patches | Berms, roots, small rocks, unavoidable obstacles to 350 mm; requires basic bike-handling input |
| Difficult | Black diamond | Experienced riders | 20% or less / 30% | Variable; can be loose, exposed, rocky | Rock gardens, unavoidable obstacles to 500 mm, tight switchbacks, TTFs where technique is mandatory |
| Extreme | Double black diamond | Advanced riders only | 20% / 40% | Widely variable; exposed rock, steep loose | Unavoidable obstacles over 1000 mm, unavoidable gap jumps and doubles, exposure, no beginner-friendly lines around features |
Australia's system has also added two intermediate sub-grades — "Easy with Intermediate Sections" between green and blue, and "Intermediate with Difficult Sections" between blue and black — which appear in official park documentation, though most trailhead signs and apps still present the four-colour shorthand.
Green: what it actually is
The green circle means a trail has been designed so that riding it wrong — braking too late, not tracking the berms, sitting on the back wheel — doesn't get you into serious trouble. The gradient stays low, the corners are gentle or swept, and the most technical thing you'll hit is a small root or a smooth roller. Anyone who can balance and steer can ride green.
In Australian parks, green trails are typically the signed loop that connects back to the car park at multiple points. That's the design intent: a beginner should always be able to bail without retracing the whole trail, and green loops make that possible. The 12-station Playground Loop at Stromlo, the Beginners/Kids Loop at Kalamunda, and Lysterfield's Trailmix are good examples. All three give first-timers somewhere to run laps, build comfort, and develop basic feel for how a trail responds to input.
Green is also where pump tracks and skills areas sit — structurally, they're designed with the same logic: low consequence, high repetition, feedback-friendly. You can make a mistake on a green trail and fix it. On black, a mistake may not give you a chance to fix anything.
Blue: where the riding actually starts
Blue is where most Australian trail networks put the majority of their kilometres. It's the workhorse grade: singletrack, moderate gradient, features that reward technique but don't require it at the expert level.
What changes from green to blue:
- Trail width narrows. You're on singletrack, often just wide enough for one rider. Handlebar clearance between trees becomes something you're aware of.
- Features are present and require input. A berm can be railed or ridden flat. A rock section can be absorbed through the pedals or rattled through sitting. A small drop can be pumped off or rolled cautiously. The trail rewards correct technique but doesn't punish error with a guaranteed crash.
- Consequences are real but survivable. Most riders who take a blue trail at a pace that doesn't match their skill level leave with scrapes, not serious injuries. The same can't be said for black.
A blue trail at a well-designed network will have a range within the grade. A long, smooth blue with sweeping berms and predictable surface sits at the easy end. A tight, rooty blue with short punchy climbs, roots across an off-camber line, and a couple of small mandatory drops sits at the harder end — sometimes close to black territory on parks that grade conservatively.
Falls Creek's purpose-built flow trails, part of a 50 km gravity network, are the best blue-grade riding in Victoria: designed from scratch for speed, big sweeping berms, consistent line, minimum tech. The bulk of Mt Buller's 120+ km XC network runs blue. Most of the Blue Derby network is blue, with the easier lines through north-east Tassie's temperate rainforest being among the most scenic in the country.
Black: technique is mandatory
A black diamond means the trail contains features where the correct technique is required, not optional. You can't always look at a line and pick an easier path. The rock garden goes straight through. The drop is the exit. The steep chute has no slow-rolling option.
What distinguishes black from blue:
- Technical trail features (TTFs) with consequence. An unavoidable drop up to 50 cm where landing badly means an impact, not just a skid. A rock garden where the wrong line or misjudged speed sends you over the bars. A narrow feature (bridge, exposed slab) where falling means hitting something hard.
- Steeper sustained gradient. Not just a brief pinch, but sections where maintaining speed control requires active braking technique — weighted back, modulated, not grabbed.
- Tighter, less predictable lines. Loose over rock, off-camber roots, switchbacks that need precise entry speed and exit weight.
The right bike matters more on black. A short-travel hardtail is manageable on blue. On black with any regularity, 120–140 mm of travel (front and rear) makes the difference between riding the trail and surviving it. A trail helmet covers blue; a full-face or enduro helmet is worth considering before a day of black trails with shuttle access.
Smithfield MTB Park in Cairns has hosted UCI Mountain Bike World Cup rounds and World Championships on its harder trails, and Blue Derby has hosted the Enduro World Series and the UCI Enduro World Cup, which contextualises how demanding the upper end of the grade gets.
Double black diamond: there's no easy way in
Double black diamond trails are not "really hard black." They're a category above, where mandatory drops, large exposure, extreme steepness, or freeride-scale features mean there is no conservative way to complete the trail. You either have the skills or you walk around the feature — and on many double-black sections, there is no walk-around.
The defining difference:
- Unavoidable obstacles over 1 metre, sometimes well above, with no runnable alternative line
- Sustained exposure: sections where the consequence of an error is not a scrape but a serious fall
- Freeride-scale technical trail features: wall rides, step-downs, unavoidable gap jumps and doubles — features that require confident commitment, not just technique
- Extreme gradient: pitches steep enough that most riders would need to manual or pump through rather than pedal
Maydena Bike Park's upper mountain gravity lines, Detonate at Blue Derby (voted EWS Trail of the Year in 2017), and Thredbo's DH race line are the correct reference points for double black in Australia. These trails weren't built to challenge upper-intermediate riders; they were built for gravity specialists.
If you've never ridden black consistently and you're eyeing the double-black map, the gap is larger than it looks. Spend a season — or several — on black before committing to double black at an unfamiliar park.
Why grades vary between parks
Here's the real thing: a black at one park is not the same as a black at another. This is not a bug in the system; it's a reflection of how grading works in practice.
Each trail is assessed by the people who built it or manage it. A conservative grading crew tends to rate trails one notch harder than the international average. A crew who mostly rides expert terrain tends to rate easier trails more leniently. Parks built 20 years ago to older trail standards were graded against different thresholds than the ones in force today. New parks built to World Trail or IMBA standards tend to be more consistent.
Trailforks partially solves this: rider comments and "condition" reports let you calibrate before you commit. Read what riders actually say about a trail rather than the star score beside it — that decimal is a satisfaction rating out of 5, not a difficulty score, so a well-liked easy trail and a punishing one can both sit at 4.1.
The practical rule: ride one grade below your confidence level on a new network. Every experienced rider has a version of the story where they over-estimated a grade at a new park and found out the hard way that it was graded conservatively.
The seven TDRS levels (and why you'll see in-between grades in park documents)
The TDRS provides seven levels of difficulty, and they are named rather than numbered. The colour shorthand maps onto them like this:
| TDRS level | Colour equivalent |
|---|---|
| Very Easy | Green (fire road, rail trail or wide singletrack, no obstacles) |
| Easy | Green |
| Easy with Intermediate Sections | Green–Blue (also shown as a green/blue split badge on some apps) |
| Intermediate | Blue |
| Intermediate with Difficult Sections | Blue–Black (technical but short of full black consequence) |
| Difficult | Black |
| Extreme | Double black |
The two in-between levels are the Australian additions to the IMBA system — one between green and blue, one between blue and black. Note that double black is not an unofficial extra bolted on above the standard: Extreme is a full TDRS level with its own symbol and its own row in the classification matrix.
Trailforks doesn't use a numeric difficulty scale at all. It uses the same named levels — green, blue, black, double black, plus "proline" — with separate fields for climb difficulty and physical rating. So when a trail shows black on Trailforks and a black diamond at the trailhead, they're saying the same thing. Don't get hung up on the format; look at the colour symbol and the rider comments.
FAQ
What does a green MTB trail mean in Australia?
Green means easy — wide, smooth, low gradient, no mandatory technical features. A rider who can balance and steer can complete a green trail without specific mountain bike technique. It's the correct starting point for a first-ever ride on singletrack, and for adults with road-cycling fitness but no off-road background.
What's the actual difference between black and double black diamond?
Black trails have significant technical features where correct technique is required. Double black trails have mandatory exposure where there is no conservative line — large drops, extreme steepness, freeride-scale features. A confident, experienced rider can complete a black trail on a moderate bike. Double black requires specialist skill and appropriate equipment, and there's typically no way around the hardest features.
Are Australian trail grades consistent with overseas systems?
Broadly, yes for the colours — green/blue/black/double black maps to the IMBA international system used in North America, Europe and New Zealand. The specific interpretations vary: Australian black trails trend slightly harder than North American blacks at some parks (particularly eastern Australian parks built before the 2020 revision), slightly easier than New Zealand blacks at others. Treat the grade as a starting point and calibrate via Trailforks rider comments.
Why does a black at one Australian park feel totally different to a black at another?
Because each trail is graded independently by its managers. Trail character also plays a role: an eastern Australian black in volcanic clay after rain, in steep rainforest gullies, on roots and exposed rock, is a different experience from a dry granite black in the south-west WA jarrah forest. Same grade, different soil, different plant cover, different consequence profile. The grade tells you the difficulty floor; the terrain tells you the character.
Do I need a full-face helmet for black MTB trails?
For shuttle-served gravity black trails — Maydena, Thredbo's DH zone, Ourimbah's gravity lines, Mt Buller's DH track — most riders wear full-face, and it's the right call. For pedalled black trails with no shuttle (most of Blue Derby's black network, Kalamunda's black lines, Mt Coot-tha's Gap Creek blacks), a trail helmet with MIPS and good coverage covers the risk profile. Look at what riders are wearing at the trailhead when you arrive — it's the most reliable local calibration.
What are the in-between grades you see in park documents?
These are the two sub-grades Australia added to the IMBA system. "Easy with Intermediate Sections" sits between green and blue (basic technique starting to matter, some roots and minor features, unavoidable obstacles to 200 mm). "Intermediate with Difficult Sections" sits between blue and black — unavoidable obstacles to 400 mm, avoidable ones to 1000 mm, and tabletop jumps up to 2000 mm, so it is technical but short of full black consequence. On apps, you may see these shown with a split-colour badge or listed as "upper blue" / "lower black." They're not widely used on trailhead signage but are common in official park plans and databases.
Use the grades as a starting point, not a verdict
The grade on the sign tells you what the builder intended and what the managing body has assessed. It's not a guarantee that the trail matches your expectations. Trails change — tree falls create new lines, erosion steepens corners, new features get added — and grades don't always update with them. Rider comments on Trailforks track changes in real time; check them.
And once you're on the trail: the terrain gives you better feedback than any sign. Start cautious at a new network. Walk any feature you're not confident about. The grade will still be there on your second lap.
Browse trails by state — New South Wales, Victoria, Tasmania, Western Australia, Queensland, South Australia — or use the Australia-wide trail map to find your next ride. If you're getting started and want parks with the best green and blue infrastructure, the best beginner MTB parks in Australia lists the networks where building from the bottom up is genuinely supported.