Suspension setup guide
How Temperature Changes MTB Shock Pressure
Estimate how cold and hot weather affect your air-shock pressure, and learn when you should recheck pressure and SAG.
Air-shock pressure changes with temperature. When the air inside an MTB shock gets colder, its pressure generally decreases. When it gets warmer, the pressure generally increases. The effect is measurable, but there is no universal rule such as adding or removing exactly 5 PSI for every 20°C.
A rear shock set to 200 PSI at 20°C may measure approximately 185 PSI after reaching 0°C at the same altitude. At 35°C, it may measure around 211 PSI. Real measurements can vary, so use calculated values as an estimate and verify the result with a shock pump and a SAG check.
Use the MTB rear-shock pressure calculator first. This article focuses specifically on changes caused by temperature and riding conditions.
MTB shock-pressure temperature calculator
Enter the pressure and temperature at which your air shock was originally set. The calculator estimates what the gauge pressure may be after the shock reaches a different ambient temperature.
Estimate the pressure change
The estimate assumes the same altitude and a sealed air chamber that has fully reached the selected temperature.
This is a simplified physics-based estimate, not a manufacturer setting. Shock construction, chamber volume, negative-air chambers, altitude, measurement accuracy and heat generated while riding can affect the result. Never exceed the shock manufacturer’s pressure limit.
Why temperature changes air-shock pressure
An air shock contains compressed gas inside a largely sealed chamber. When the temperature of that gas decreases, its pressure also decreases. When the temperature rises, its pressure increases.
The absolute PSI difference depends on the starting pressure. A shock set to 200 PSI therefore changes by more PSI than a shock set to 100 PSI over the same temperature range. This is why a single fixed correction such as “5 PSI per 20°C” cannot be accurate for every rider and shock.
| Pressure at 20°C | Estimated at 0°C | Estimated at 35°C |
|---|---|---|
| 100 PSI | Approximately 92 PSI | Approximately 106 PSI |
| 150 PSI | Approximately 139 PSI | Approximately 158 PSI |
| 200 PSI | Approximately 185 PSI | Approximately 211 PSI |
| 250 PSI | Approximately 232 PSI | Approximately 264 PSI |
These examples assume that the shock has fully reached the new temperature and remains at approximately the same altitude. They are estimates rather than target settings.
MTB shock pressure in cold weather
When a bike moves from a warm house or workshop into cold outdoor conditions, the air inside the shock gradually cools. The measured pressure may fall and the suspension may sit slightly deeper in its travel.
Possible symptoms include more SAG, reduced support, easier bottom-outs or a softer feeling through compressions. Cold temperatures can also affect damper oil, seals and lubrication, so not every difference in ride feel comes from air pressure alone.
MTB shock pressure in hot weather
When ambient temperature increases, the pressure inside an air shock generally rises. This can slightly reduce SAG and make the suspension feel firmer or more supportive.
Do not immediately release pressure simply because the shock feels warmer after a descent. First determine whether the change comes from ambient temperature, heat generated while riding or a genuine setup problem.
Why your shock becomes warmer while riding
A shock does not stay at ambient temperature during a long or rough descent. Repeated compression and damping convert energy into heat. The damper body, oil and gas can warm up, temporarily changing pressure and damping behaviour.
A pressure reading taken immediately after a demanding downhill run is therefore not directly comparable with a cold workshop measurement. For repeatable setup work, use the same measurement process and let the shock return to a consistent temperature.
Should you change pressure for every weather change?
Minor day-to-day temperature differences usually do not require constant adjustments. Consider checking pressure and SAG when:
- The temperature differs significantly from the conditions in which the setup was created.
- The bike has moved from a heated indoor area into winter conditions.
- You are travelling from a cold climate to a much warmer riding destination.
- The shock suddenly uses noticeably more or less travel.
- Your measured SAG has changed despite using the same riding equipment.
- The suspension feels unusually soft, firm or unsupported.
How to check shock pressure consistently
- Let the shock reach the riding temperature. Avoid comparing a warm indoor measurement with a bike that has been outside in the cold for an hour.
- Use the same shock pump. Different gauges can produce slightly different readings.
- Record the temperature. Note the approximate conditions together with the setup.
- Cycle the shock. After changing pressure, compress the suspension several times to balance the positive and negative air chambers where required.
- Measure SAG again. Pressure is only a starting point; the resulting ride height is what matters.
- Change one variable at a time. Do not alter pressure, rebound and compression simultaneously.
- Stay within manufacturer limits. Never exceed the maximum pressure printed on the shock or specified in its manual.
For a complete measurement process, use SAGLY’s guide to setting and measuring suspension SAG.
Does altitude change MTB shock pressure?
Altitude can affect the gauge pressure because atmospheric pressure decreases as elevation increases. A shock pump measures pressure relative to the surrounding atmosphere, so the displayed value may change slightly even if the sealed shock chamber itself has not lost air.
For normal riding trips, temperature and measurement consistency are usually more useful to monitor than applying a generic altitude correction. At the destination, allow the bike to settle, measure with the same pump and verify SAG rather than relying on a universal PSI adjustment.
Does humidity affect shock pressure?
Outside humidity does not directly change the amount of air sealed inside the shock. Wet and muddy conditions can still affect seals, lubrication and maintenance requirements, but this is separate from the temperature-driven pressure change.
For setup guidance in wet conditions, see how to adjust MTB suspension for wet terrain.
Temperature and MTB shock pressure FAQ
How much pressure does an MTB shock lose in cold weather?
It depends on the initial pressure and the temperature change. For example, a shock at 200 PSI and 20°C may measure approximately 185 PSI after reaching 0°C at the same altitude. A 100 PSI shock would change by a smaller absolute amount.
Should I add pressure before a winter ride?
Not automatically. Let the bike reach the outdoor temperature, measure the pressure and check SAG. Add pressure only when the measurement and suspension behaviour show that the shock is running too soft.
Should I release pressure when the shock is hot after riding?
Usually not immediately. Heat generated during a descent can temporarily raise the temperature and pressure. Let the shock cool to a consistent reference temperature before comparing it with your normal setup.
Does temperature affect coil shocks?
A metal coil spring does not rely on compressed air, so its spring rate is not affected in the same way as an air spring. However, damper oil, seals and internal gas pressure can still respond to temperature changes and affect ride feel.
Is pressure or SAG more important?
Pressure is the input used to adjust an air shock. SAG shows the resulting ride height under the rider’s weight. Use the manufacturer’s pressure recommendation as a starting point, then confirm the setup by measuring SAG and testing the bike.
Final recommendation
Temperature can noticeably affect MTB air-shock pressure, particularly when the difference between setup conditions and riding conditions is large. Avoid fixed correction rules. Instead, keep a consistent baseline, allow the shock to reach the relevant temperature, measure it with the same pump and confirm the result through SAG and trail testing.
If you first need a reliable baseline, use the MTB rear-shock pressure calculator. Then save the setup together with the riding conditions so future comparisons are meaningful.
Save and improve your suspension setup with SAGLY
SAGLY helps you find starting values, save your fork and shock settings, diagnose handling problems and make controlled adjustments after each ride.
Try the SAGLY app
Download SAGLY, a complete mobile guide for your mountain bike riding, suspension settings and maintenance.
