Sag targets and spring rate by rider weight (web-validated)

Every number below traces to a named manufacturer manual or suspension authority (KTM, Ohlins, Race Tech, MXA/Bones Bacon, Enduro21, Bud Racing). Where sources disagree, both the range and the sources are given. Where a figure could not be pinned to a citation it is stated as a directional principle, not a number.

Why weight comes first

Springs carry your weight; clickers only control how fast the oil moves. Stock springs are fitted for an average rider - the Bud Racing KTM factory-spring chart centres its "Standard" band on roughly 75-85 kg (Bud Racing KTM spring rate chart). Ride far outside that band and no clicker will fix it. So the order is always: spring rate first (set via sag), then damping.

Sag targets by discipline (cited)

Race (rider) sag = extended height minus height with rider aboard in full gear. Static (free) sag = extended minus the bike's own weight, no rider.

Discipline	Race / rider sag	Static / free sag	Source
Motocross (450)	90 mm (KTM SX-F EU), 100 mm (SX-F USA / XC-F)	30 mm	KTM 450 SX-F EU Owner's Manual 10.7-10.9
Enduro / off-road	105-115 mm (~1/3 of travel); PDS ~115 mm	35-40 mm; PDS ~35 mm	Enduro21 (Kiwi's Bike Shop + OEM manuals)
Road (street)	front 45-50 mm, rear 40 mm	front ~30 mm, rear ~10 mm	Ohlins road setup (via ANZE Ohlins tech-info)
Track (superbike)	front 35 mm, rear 30 mm	front 25 mm, rear 5 mm	Ohlins track setup (via ANZE Ohlins tech-info)
MX free sag (Ohlins)	ride height rear = 30% of total stroke	rear 25+/-5 mm, front 25+/-5 mm	Ohlins 38 MXF fork manual

Conflict noted: MX static sag is quoted as 30 mm by the KTM 450 SX-F manual, 30-40 mm as a rule of thumb by MXA/Bones Bacon, and 25+/-5 mm (i.e. 20-30 mm free sag) by Ohlins. Treat 30-40 mm as the working window and your own bike's manual as the exact target. Percentage rules of thumb (Race Tech: static ~25-30% of travel, rider ~30-35%) agree with the enduro "~1/3 of travel" figure.

How to read your sag to know if the spring is wrong

Set race sag first with preload, then measure static sag - MXA's Bones Bacon is explicit: "you must set your race sag before measuring the static sag." Then read the two numbers together (MXA / Bones Bacon rule, big bikes)

• Static sag over ~40 mm (too much) means the spring is too STIFF for you. The spring is not compressed enough to let the suspension extend on its own; the rear will not hook up and passes bump energy to the rider.
• Static sag under ~30 mm (too little) means the spring is too SOFT for you. You had to wind in so much preload to hit race sag that the rear is near topped-out; it feels loose and wallowy and tops out under light braking.
• Race sag on target AND static sag inside its window means the spring matches your weight. (Same logic front and rear.)

Directional principle (Race Tech method + MXA, not a single verbatim quote): if you cannot land BOTH race sag and static sag inside their windows within the preload range, the spring rate is wrong - change the spring, not more preload. Preload positions the bike; the spring carries the load.

Spring rate by rider weight (cited change per band)

Real manufacturer charts step the spring rate in weight bands, not per single kg. From the Bud Racing KTM MX chart (rider weight without gear, 10 kg bands, "Standard" = OEM band)

• Fork: about +0.02 kg/mm (~+0.2 N/mm) per 10 kg band.
• Shock/rear: about +0.2 kg/mm (~+2 N/mm) per 10 kg band.

Worked example - KTM 450 (Bud Racing chart, rear shock)

• 65-75 kg rider -> shock ~5.4 kg/mm (~53 N/mm), fork ~0.48 kg/mm
• 75-85 kg rider -> Standard (OEM) spring
• 85-95 kg rider -> shock ~5.8 kg/mm (~57 N/mm), fork ~0.52 kg/mm

So a jump from a ~75 kg rider to a ~95 kg rider is roughly two rear bands stiffer (about +0.4 kg/mm ~ +4 N/mm) and two fork bands stiffer. Note: Bud Racing lists rates in the European kg/mm convention; multiply by ~9.81 for N/mm. The Race Tech Spring Rate Calculator reaches the same conclusion from first principles - it takes rider-plus-gear weight, bike weight, motion ratio and target sag and returns a stiffer rate for a heavier rider (Race Tech method).

Coil-spring steps are discrete. A superbike/track shock or fork spring follows the same idea: heavier rider -> next spring up, chosen so both sags land in range at moderate preload; Ohlins supplies its forks with optional rate pairs (e.g. the 38 MXF fork ships with 3.1 and 3.5 N/mm and offers 3.3/3.7/3.9 N/mm) precisely so the rate can be matched to rider and track (Ohlins 38 MXF fork manual).

Air forks are a special case

On an air fork the air pressure IS the spring rate, so you dial it to your weight directly off the gauge rather than swapping a coil - which is why air forks tolerate riders far from the stock weight. Do not copy coil N/mm numbers onto an air-pressure (bar) parameter; they are different quantities (fork_spring_pressure vs fork_spring_rate).

What LAISA does with this

LAISA computes a recommended spring rate from your weight as a STARTING POINT, consistent with the live weight rule, and shows the sag targets for your bike and discipline so you can verify on the bike. The recommendation is a starting point, never a safety guarantee.

-- Starting point, not a safety guarantee: these figures are a starting point and never a safety guarantee - always verify on the bike and against your model's own manual.