Trail difficulty - single trail scale (STS)
S0 describes a single trail that has no particular difficulties. These are mostly liquid forest and meadow paths on non-slip natural soil or solidified gravel. Steps, rocks or root passages are not to be expected. The gradient of the path is easy to moderate, the curves are extensive.
On a path described with S1 you have to expect smaller obstacles such as shallow roots and small stones. Isolated gullies and erosion damage are very often the reason for the increased level of difficulty. The subsurface can also be partially unsolidified. The gradient is a maximum of 40%. Switchbacks are not to be expected.
In S-Grade S2 you have to reckon with larger roots and stones. The soil is often not solidified. Steps and flat stairs are to be expected. Often there are tight curves, the steepness is up to 70% in parts.
The obstacles must be overcome by shifting your weight. Constant readiness to brake and shifting the body's center of gravity are necessary techniques, as well as precise metering of the brakes and constant body tension.
Blocked single trails with many larger boulders and / or root passages belong to S-Grade S3. high steps, hairpin bends and tricky inclined journeys often occur, relaxed rolling sections are rare. Often slippery ground and loose scree are to be expected, steepnesses over 70% are not uncommon.
Passages that have the 3rd degree of difficulty do not yet require trial techniques, but very good bike control and constant concentration are a prerequisite for mastering S3. Exact braking and very good balance are necessary.
S4 describes very steep and heavily blocked single trails with large boulders and / or challenging root passages, often with loose scree in between. Extreme steep ramps, tight hairpin bends and steps where the chainring inevitably hits the ground often occur in the 4th degree.
In order to ride in the 4th level of difficulty, trial techniques such as moving the front and rear wheels (e.g. in the hairpin bends) are absolutely necessary, as are perfect braking techniques and balance. Only extreme riders and exceptional bikers can cope with the S4, even carrying down these passages is often dangerous.
The S-grade S5 is characterized by block-like terrain with counter-climbs, scree fields and landslides, loop-like switchbacks, several high, successively successive ledges and obstacles such as fallen trees - all of which are often extremely steep. If at all, there is little run-out or braking distance. Obstacles must z. T. be mastered in combination.
Only a handful of freaks try to cope with passages in the 5th level of difficulty. Some obstacles have to be skipped. It is hardly possible to move in switchbacks. Even carrying the bike becomes almost impossible here, as you have to hold on or even climb while walking.