Air versus coil is the suspension question that gets the most opinions and the least clear answers. Air-shock advocates argue weight savings and adjustability. Coil-shock advocates argue feel and consistency. Both are right inside their own use case and wrong outside it. The real answer depends on your bike, your weight, your terrain, and what you actually want out of a suspension upgrade.
This guide covers the practical differences between air and coil rear shocks, where each one shines, the trade-offs nobody mentions in the marketing copy, and how to decide which is right for your setup.
How each spring works
The fundamental difference between air and coil is how they store energy.
An air shock uses a sealed volume of compressed air as the spring. Compress the shock, and the air gets squeezed into a smaller volume, which raises pressure and pushes back. The spring force gets larger faster as you go deeper into stroke, because air is naturally progressive.
A coil shock uses a steel spring. Compress the shock, and the spring deflects linearly. Twice the compression equals roughly twice the force. The spring rate stays constant through travel.
That single physics difference drives most of the practical trade-offs.
What air shocks do better
Weight. An air shock is roughly 200–500 g lighter than a coil shock of equivalent travel. For trail and all-mountain riders who pedal up everything they descend, weight matters. On a long climb, an extra pound shows up in your legs.
Adjustability. Air spring rate is changed with a shock pump. Five minutes and a few pumps and the shock is sized for a different rider. Coil shocks require swapping the actual steel spring, which means owning multiple springs at $50–80 each.
Travel range. Air shocks support more bikes and more bike sizes with one shock. The same shock can be tuned for a 130 lb rider and a 220 lb rider.
Progressivity adjustment. Volume tokens let you adjust the air-spring curve to match your bike and riding style. Coils have no equivalent — the spring is what it is. The volume spacers and tokens guide covers this in detail.
Climbing efficiency. Air shocks generally pedal better thanks to the natural progressivity of air and the higher-resolution low-speed compression that most air-shock dampers offer.
What coil shocks do better
Small-bump compliance. Coils have less internal stiction at the start of stroke. The spring is just steel — no seals to overcome before the wheel starts moving. Riders consistently report coil shocks feel plusher on chatter and high-frequency hits.
Consistency. A coil spring does not change behavior with temperature, ride duration, or recent pumping. An air shock's pressure can shift slightly as it warms up over a long descent. A coil does not care.
Heat resistance. On long sustained descents, dampers heat up. Air shocks are more affected by oil heating than coils are, partly because the air spring's behavior also depends on oil temperature inside the damper. Coils are more thermally stable on park-style runs.
Bottom-out feel. A linear coil spring with a hydraulic bottom-out bumper feels different from an air spring's progressive ramp. Some riders prefer the coil's smoother approach to full travel for hard-and-fast riding.
Durability. Coil shocks have fewer dynamic seals. The seals that exist see lower pressure differentials. A coil shock's spring assembly is essentially indestructible. The damper still needs service like any other shock.
What does not actually differ
A few things that get cited as differences are not really differences anymore:
- Modern air shocks are not noticeably less plush than coils for most riders. The gap closed considerably over the last five years. On a smooth trail, a fresh-out-of-service air shock and a coil shock feel very similar. The gap shows up specifically on repeated chatter, fast rocks, and heat.
- Air shocks are not less reliable than coil shocks. They have more parts and more seals, but the parts are designed for the loads. A serviced air shock is not less reliable than a serviced coil shock.
- Coil shocks do not pedal terribly. A coil shock with an open damper and a low-speed climb switch can be perfectly efficient on most climbs. The myth comes from older designs.
Which is right for your bike
Bikes have leverage curves. A bike's leverage curve dictates how much the shock needs to ramp up to produce a desired wheel-rate ramp.
- Progressive bikes — leverage curve falls a lot from start to end of travel — pair well with linear coils. The bike's frame is doing the progression. A linear coil makes for a balanced overall curve.
- Linear bikes — leverage curve stays flat — pair well with progressive air shocks. The bike is not progressing on its own, so the shock needs to.
Most modern enduro bikes are designed to be progressive enough to run a coil if the rider wants. Most modern trail bikes are designed for air. Check the bike manufacturer's recommendation. Most have a guideline.
Which is right for you
A rough decision tree:
- You ride mostly XC or trail with significant climbing? Air. Probably no question.
- You ride aggressive enduro on long, rough, repeated descents? Coil starts making a real case, especially if your bike has a progressive frame.
- You ride bike park, shuttle laps, or downhill? Coil, almost certainly.
- You ride a mix and pedal moderately? Air still wins, especially with modern dampers.
Two gotchas:
- Light riders often have a hard time finding the right coil spring. Stock springs come in 50 lb increments. If you are right between two rates, neither is ideal.
- Heavy riders can find air shocks need maximum tokens to keep the rear from blowing through travel. Past a certain weight, a coil is sometimes the only practical option.
The rider weight guide covers how weight changes the picture.
What changes if you switch
Going from air to coil on the same bike means:
- The bike sits slightly different on the rear. Sag math is the same percentage but using shock stroke, not coil-spring travel.
- The fork might need re-tuning. A coil shock often runs a bit deeper in stroke, which steepens the head angle slightly and can require less rebound damping in the fork to balance.
- Volume tokens are no longer a tuning tool for the rear. You decide everything by spring rate.
- Progressivity is now whatever the frame provides. If the frame is not progressive, you will bottom more.
Spring rate selection is the trickiest part. Manufacturer charts based on rider weight are starting points. Many riders find they need one rate softer than the chart suggests for trail use, or one rate firmer for park.
Setup order is the same
Whether you run air or coil, the setup order is the same: sag, rebound, then compression. The dial behaviors are largely identical between air and coil dampers. The spring system is what changes, not the damper logic.
The diagnostic for "is the shock right" is the same: bike feels balanced front to rear, uses most of its travel on hard hits without bottoming hard, supports you in turns without wallowing, and tracks the trail through chatter without packing down.
If your bike does all of those things on its current shock — air or coil — you do not need to change shock types. The grass is rarely greener.
When the answer is "try it"
Some riders go back and forth several times before they figure out what they prefer. There is nothing wrong with that. A coil conversion on an enduro bike is reversible at the cost of one shock service interval. An air shock is the standard option that came with most bikes and is always available again.
If your current shock is properly serviced and tuned, and the bike still feels off, the issue is more likely setup or service than shock type. Run through reading suspension symptoms before swapping hardware.
Where to go from here
If your air shock feels off and you are wondering if a coil is the answer, work through the setup chain first: sag, rebound, compression, tokens. Most "I need a coil" thoughts are really "I need a service" thoughts. The fork service intervals guide covers shock service alongside fork service.