THE GREAT DEBATE

AIR SHOCK VS COIL SHOCK

WHAT’S THE “BEST” SHOCK FOR MOUNTAIN BIKING

Words By Drew Rohde
Photos Dusten Ryen and Brian Niles

Here at the Wolf Den, we get quite a few purchasing and technical assistance requests through our inbox, and one that we see regularly is buying advice on air shocks vs. coil shocks. Usually, the responses we give aren’t as easy as this or that, best or worst. Mountain biking is a highly personal sport. Everything from fashion to ideal performance traits is up to each rider, and that’s one of our favorite things about this amazing sport. When it comes to friends or fans reaching out before buying a new bike that can be spec’d with either an air or coil rear shock or if they’re toying with switching a bike, they already own, there are plenty of pros and cons to consider when putting air shocks and coil shocks to task.

For this video and test we chose to work with Pivot Cycles and used their Mach 6 as our official test mule since it’s got a nice rising-rate suspension design that compliments a coil shock and will also work well with an air shock. It’s also a bike we’re big fans of and beyond that, it’s one that we’ve gotten several questions about from friends and readers who want to buy one and can’t decide which shock to get. If you’d like to learn more about the Pivot Mach 6, we Dissected it earlier this year and you can check it out here.

CONSIDERATIONS

When debating if a coil shock or air shock is going to be “better” for your mountain bike experience, there are a few things to take into consideration before we even get into the pros and cons of each shock. First is, will your bike work well with an air or coil shock? Not all bikes have the versatility to swap between and still offer the brand’s desired ride characteristics. If a bike was designed around a linear coil spring and has progression built into the kinematic for example, you may find it difficult to reach full travel with a naturally more progressive air shock. Conversely, if a frame relies on an air shock’s built-in compression to give the desired ramp up (progression) towards the end of travel, coil shock convers may regularly bottom out harshly.

Now, obviously there are ways to compensate for these traits, by removing volume reducers in air shocks, or finding progressive coil springs, but these steps can cost a bit more money and require some more advanced skills in both tuning and mechanics.

Next, you’ll want to consider exactly what it is you’re hoping to achieve from your bike. Shock technology, tuning and performance improved exponentially over the last couple of decades, but there are still some differences that riders can feel on the trail and will offer some advantages, or disadvantages, depending on who you are and what you are looking for. Let’s get into those next.

PROS AND CONS OF AIR SHOCKS VS. COIL SHOCKS

Assuming you’ve got a bike that is designed to accommodate either an air shock or coil shock, like our Pivot Mach 6, then you can start to hone in on the differences between the two products. Ride characteristics, weight, serviceability, length of time between services, climbing performance vs downhill performance and plenty of other subtleties can put researchers into the dreaded state of analysis paralysis.

We’ll try to simplify it and keep is as generic as possible, and yes, we do know there are exceptions and workarounds, but these are going to be the basic and widely accepted pros and cons of air shocks and coil shocks.

AIR SHOCKS

PROS

Lighter than a coil shock, up to about 475grams in some cases.
More progressive, which means more ramp up towards end of travel. This equals more bottom-out resistance. I really like the progression of air shocks because it keeps me from bottoming out frequently.
Usually a better climbing shock, especially when compression/climbing switches are activated. More mid-stroke support.
Better platform for “pushing off of” whether that’s in berms or off a jump.
Can offer a livelier, more active and poppy feel. This means the bike can be more active and ride lighter. As a rider who loves bouncing and hopping from side to side, air shocks feel noticeably better when trying to unweight the bike, pre-hop obstacles, or press and explode out of turns or lips.
Infinitely adjustable spring rate (air pressure). No need to swap coils or experiment in 25lb or 50lb increments, air pressure can be adjusted easily and furthermore you can add or take out volume reducers to also tune end of travel progression. This potentially means less cost (buying multiple springs) and an easier, quicker setup process.

CONS

Lack the suppleness of a coil.
Suffer more degradation in performance due to heat. Long downhills will result in heat build-up and therefore affect the damping and oil viscosity, meaning compression and especially rebound will feel different at the top compared to the bottom of the track. The difference is not massive, though riders who are in-tune with their bike will feel a difference.
Require more regular servicing. Air shocks have more seals to maintain a high-pressure chamber. More seals mean more parts that require a clean, lubricated surface and care, which results in these shocks needing to be serviced more frequently to maintain that new shock feel.
More seals, more surface area and larger shaft size also means more stiction. Static friction, or stiction reduces the off-the-top sensitivity or how easily the shock can slide as it encounters impacts. This is one of my biggest issues with air shocks. Over the course of a ride, thousands of micro-impacts and chatter get transmitted to the rider and a coil shock will help with the reduction of fatigue and feedback.
Reduction in traction on loose or wet obstacles. The aforementioned stiction and increased break-away force to move an air shock means that when you’re fighting for traction, the smallest difference could separate you from rolling forward or sliding sideway. This is another area that I put a lot of weight on as a rider who regularly enjoys loose, marbly desert trails.

COIL SHOCKS

PROS

Supple and sensitive off the top. Less stiction and break away force means the shock can trace obstacles and keep that tire on the ground better than an air shock.
Improved traction. Thanks to that open, smooth and ready shock, riders who struggle with traction will love how the rear tire hugs the trail.
Better resistant to heat fade and changes in performance on descents.
Not as susceptible to dirt, mud, debris ingress. This means you can get away with longer maintenance intervals without drastic performance changes.
More reliable!
A linear feel throughout the stroke. This means that as you go through the travel, the travel will remain the same and give you a smooth feel, until bottom out. This could also be a con for some riders, myself included. If you never hit bottom out on your air shock or have a bike that’s got a naturally progressive curve, a coil may be a good option to get more travel and a smoother ride.
Less fatigue for the rider due to a smoother ride.

CONS

Heavier than air shocks.
Can be a more expensive and time-consuming endeavor to tune. Coil shocks typically come in 50lb increments, and while there are calculators and ways to get yourself pretty close, some weights and rider/terrain preferences could put you in a grey zone between two spring rates.
More linear feel can mean more frequent and harsher bottom outs. Depending on the bike’s kinematics and the rider’s preferred trails or riding style, this could be an issue.

SO, WHAT’S BETTER? AIR SHOCK OR COIL?

Well, if the pros and cons list of air shocks vs coil shocks above didn’t give you a clear direction as to which way to go, let’s pretend you walked into Loam Wolf Cyclery and we’re your local salesman. First off, we’d ask you which bike you’re riding, how much travel it has and what trails you ride most frequently. After learning a bit about your kit and trails, we’d next ask you what aspect of mountain biking you love most, and what part of that ride experience do you feel your current bike is lacking.

Some people just feel the need to try something because they saw people talking about it on Pinkbike, or they saw a YouTube video saying this new shock is the best thing ever. Others may have a genuine issue and they just can’t jive with their bike on their favorite DH, or it is too sluggish for their weekly trail ride.

If there is an area that they want to improve we can better dive into what the “con” or negative part of their ride is and evaluate how important other potential cons would be compared to the potential benefits they’d gain by switching.

For example, if you’re riding a 140mm bike and on one gnarly downhill trail that you hit once a month, the bike tires you out and you feel that it’s bucking you in high-speed chatter, the idea of getting a coil shock could seem quite tempting. If however, you swap to coil and find that now, the trails you ride every week, where pedaling efficiency, speed and a more poppy platform reward you with fun and speed, that once a month downhill performance increase may not be worth the trade.

Conversely, if you’re riding a 160/170mm bike that you always feel is a bit too stiff, you can’t seem to find traction on your loose trails and you just never seem to use full travel, then a coil option could be a great option. Do you shuttle or ride bike park often? Is climbing just a means to get you to the top of your favorite downhill trails? Are you ready to lose some uphill performance, weight gain and pop for the sake of a more composed, ground hugging bike that will smooth out the terrain and give you access to all 160mm + of travel? If so, then you’d be a great candidate for coil.

These two examples are opposite ends of the spectrum and there are plenty of riders who could love a coil on a 140mm bike and even more riders who love an air can on their 160mm bikes. The reality is that there is no right or wrong answer for everyone. As we said up top, mountain biking is a beautifully individual sport, and no two riders are the same. Even if they’re on the same bike, riding the same trail, riders could have very different feelings from their bikes and be justified in going either way.

I know for a fact I could ride and have a great time on this Pivot Mach 6 with a coil and love it while my friend on his Mach 6 would rave that air is the only way to go. Ultimately each rider will have to evaluate what it is they care most about on the trail, where the biggest negatives lie in their trail experience and if the improvement in that area would be worth potential drawbacks in another.

No matter how far into the weeds you get on spec, components or tuning, always remember, mountain biking is for fun! As long as you’re smiling, enjoying the views, saying high to fellow trail users and feeling stoked at the bottom of the trail, you’re winning and that’s what matters most.

INTERVIEW WITH PIVOT CYCLES’ HEAD OF ENGINEERING – KEVIN TISUE

TLW: When it comes to working with your team athletes and doing timed runs, what do you typically find they like and why?

KT: Different athletes certainly have different priorities, so it is always important to listen to what they are looking to get from their suspension. Some athletes on the more descending side of things may lean towards coil shocks because the reduced friction in the shock provides for a more supple feel. On the other hand, if a rider is very particular about setup, air shocks offer much more adjustability with infinite pressure adjustment, but also with the ability to change the progressivity of the shock with volume spacers. This can make air shocks more ideal for some athletes and can give them better tools to get the feel they are looking for. For some athletes, the extra weight is simply the deciding factor.

TLW: Is one shock usually faster than another? Is there a downside to being faster? We know not everyone cares about the clock, so faster may not be best for casual rider if it comes at the price of comfort.

KT: I wouldn’t say that overall, one type of shock is clearly faster than another. It really comes down to whichever shock is going to mesh the best with the rider and what will allow them to be their best at whatever it is that they want to do.

TLW: If a person wants to change the shock from air to coil, or coil to air after market, what are things they should consider?

KT: First a coil is not adjustable like an air spring, so if you are switching to coil, it is possible that you may have to try several spring rates before you get the bike setup properly. Also, going from air to coil will generally make the suspension behave less progressive. Traction will likely improve, but you will likely need a little more compression damping and you will likely feel bottom outs a little more. From coil to air it will be much the opposite, you may lose a little plushness off the top and have slightly less traction, you’ll probably run slightly less compression and you will feel a little less in bottom outs. You will also gain some adjustability in your spring rate and in progressivity with volume spacers.

TLW: Will certain types of riders (weight/skill/speed vs play-focused) have a shock that is “better” for them?

KT: Coil springs really do have a great feel, but it isn’t for everyone. I wouldn’t say rider weight, skill, or speed really can guide a rider to one type of shock compared to another. Coil shocks may fit riders that want to plow through things rather than play through them, but that is not to say you can’t get plenty of plow and play out of either setup. In longer, high speed situations, coil shocks will dissipate heat better, so there can be performance/consistency advantages in that situation.

TLW: What is a scenario or terrain/rider where you’d suggest they ride a coil?

KT: Long descents or anywhere you are looking to maximize traction or any situation where you may need to just point and shoot through rough terrain and/or are looking for a really plush feel.

TLW: Same question, but air shock –

KT: Anytime you are worried about weight or if you need extra adjustability. Often air shocks are the faster choice because they have the ability to stay up in the travel and keep the bike tracking on top of the bumps.

TLW: Do you ever find yourself switching for your own desires, or do you just pick one and leave it? And what is that preferred choice for you?

KT: I certainly ride air shocks most of the time, but I very much enjoy a coil on a longer travel bike, especially on park days.