Настройка сага: задний амортизатор за 15 минут
Ask ten riders whether their suspension is any good and you will get opinions. Measure sag and you get facts. Sag — how much the suspension compresses under load — tells you whether the spring rate and preload match the machine and the rider, and it takes 15 minutes with a tape measure and a helper.
Terminology in 30 seconds
Free sag: bike alone, upright, settled. Rider sag: bike with rider aboard, in riding position. Spring rate is what sag actually diagnoses — preload only positions the bike within the spring's range. If a shop "fixes" bad sag purely with preload, it has moved the problem, not solved it.
The numbers
| Machine | Rider sag | Free sag |
|---|---|---|
| Street bike (road focus) | 30–35 mm | 5–10 mm |
| Sport bike (track use) | 25–30 mm | 3–8 mm |
| Dirt / enduro bike | 95–105 mm (of ~300 travel) | 25–40 mm |
The procedure
- Measure from a fixed point on the tail to the rear axle. Record it: L1.
- Have the rider mount in full gear, feet on the pegs, and bounce the rear a few times to settle the suspension. Measure: L2. Rider sag = L1 − L2.
- Same measurement with the bike alone, settled: L3. Free sag = L1 − L3.
- Adjust preload (or swap spring) and repeat until both numbers land in range.
Reading the two numbers together
- Rider sag correct, free sag too little (<3mm): spring is too soft with too much preload. The bike will top out harshly. Fix: stiffer spring.
- Rider sag correct, free sag too much (>15mm): spring too stiff, preload wound down. Harsh over small bumps. Fix: softer spring.
- Rider sag too much even at minimum preload: spring rate way too soft for the rider's weight. No amount of adjustment fixes rate.
Why fleets should care
For a distributor, sag data is sales intelligence: if your market's riders average 85 kg and the bikes you sell are sprung for 65 kg, every "harsh rear suspension" complaint is a spring problem — not a warranty claim against the shock. We produce spring rates matched to rider weight bands; asking us for the regional average rider weight is a legitimate way to specify your next shock order, and it eliminates a whole category of complaints before they happen.