Even though we are seeing air shocks more and more on our standard trail and enduro bikes, the coil shocks are starting to increase in popularity, especially amongst the professional enduro riders.
What exactly are the pros and the cons of using a coil-sprung rear shock on enduro bikes, and even trail bikes, and should you maybe upgrade to one? Those are the questions that this article will work on answering for you so that in the end you’ll be able to make an informed decision for yourself.
What is a coil shock?
A coil shock is essentially a steel or titanium spring that has been wrapped around the shock body and normally has a linear spring rate. Since the shock is a spring, the force that is required to compress it increases at the exact same rate in relation to how compressed the spring is at that current moment.
The most traditional place that you’ll be able to find these types of shocks is on downhill bikes. The main two reasons that this was so popular in this discipline was because weight was less of a consideration and the longer race runs favoured damper consistency and resistance to heat build-up.
If you are cycling for a while then the dampers in air shocks actually tend to heat up, which will then cause the oil’s viscosity to become thinner and as a result will then affect the shocks consistency.
However, even with these benefits, air shocks aren’t necessarily uncommon on downhill bikes because of their high tunability. Since the downhill shocks have a longer stroke and eye-to-eye shock lengths it means that the heat build-up is a lot less of an actual problem since the leverage rates are lower. All of this means that the shock won’t have to do as much work as a bike that would have a shorter-stroke shock.
During this modern era of riding we see a lot of air shock designers trying to make their shocks a lot better at dissipating heat than they have been previously.
What is an air shock?
Then moving, we have the air shocks, which are air-sprung shocks that we mostly see on trail and enduro bikes nowadays and these shocks use pressurised chambers instead of the springs that coil shocks use.
Most air shocks that we see out there have two chambers, one being a positive spring chamber that is supposed to support the riders weight and then the second chamber being the negative spring chamber whose job it is to counter this and can also help improve the overall sensitivity by either ‘sucking’ or ‘pulling’ the shocks shaft into its travel. With these types of shocks we’ll see the use of rubber seals in order to stop the pressurised air from escaping.
Unlike the coil spring above, the air shocks spring rate is progressive, which essentially means that as it is getting compressed the rate at which it becomes harder isn’t related in a linear fashion to how much it is compressed.
Can my bike run a coil or air shock setup?
Some people may get the wrong idea that you can just pick between a coil or air shocks setup for your bike, but it is very important for you to check your bikes frame design and suspension kinematics in order to know whether a coil or air shocks setup is even compatible with your bike.
Most bikes nowadays, come with air shocks as standard because of their high tunability, so the bikes suspension kinematics would be designed around them instead as it is such a large and important feature of your bike. However, this may be the norm for a lot of new bikes but there is a growth in popularity of the bikes that are able to work with both air and coil shock setups, such as the Whyte G-180 and Santa Cruz Nomad.
If you are in any way uncertain or unsure with regards to your bike and its compatibility then you can always speak to your bike/shock brand or suspension tuner to find out more.
Coil Shocks
Advantages
So, with a coil shock setup you will receive a few advantages such as an increase in small-bump sensitivity, a pretty decent mid stroke support and then a better damper performance, which are definitely the biggest and most noticeable advantages to running a coil shock setup.
The coil shock setup is able to give you this because of its reduced static friction. The coil shock is able to move because of its reduced number of seals compared to what an air shock would have, this means that when the coil shocks activates the travel over smaller bumps it’ll actually require less breakaway force. This is a huge benefit for riding over those small aggressive bumps on the trails as it’ll essentially help keep your rear tyre on the ground as things start to get loose, which will not only give you this more planted feel but also give you more rear-wheel traction.
Another huge advantage to running a coil shock setup on your bike is that they will require less maintenance because of its reduced number of seals. Not only do they require less maintenance and service but they are also more resistant to heat build-up, which means that they are able to remain consistent on your long downhill trails or sections.
Disadvantages
The first disadvantage that you’ll get with the coil shock setup is that it’ll be harder for you to find the right spring rate for your personal weight and riding style. This is a lot harder than on an air shock because you will have to physically swap coil springs, which will require you to remove the shock completely from your bike and only then will you be able to remove the coil from your shock to switch it out.
The spring rates that you get from a coil spring also come in set increments, this means that if you personally need a spring weight that isn’t yet available to you then you’ll struggle to set up your shock correctly.
Coil shocks are also known for offering you less bottom-out resistance than what you could maybe get from an air shock setup, however depending on which coil shocks you get you could have some bands that have progressive springs and incremental rate adjustment. If this is a big problem for you and your style of riding then you could also get large bottom-out bumpers to improve this.
More often than not you’ll also find that a coil shock setup is heavier and bulkier than an air shock setup, which is because of the added weight that the coil brings. It is also worth it to remember that these coil shocks aren’t compatible with all bike frames when it comes to fitment as well as the frame’s suspension kinematics.
Air Shocks
Advantages
Since an air shock setup doesn’t have a metal coil that will add mass to your suspension setup, it means that the air shocks are normally a lot lighter than a coil shock setup. So, if you are someone that is looking to save as much weight as they can on their overall bike setup then this is, more often than not, the way to go.
One of the biggest advantages that you’ll get from having an air shock suspension setup is that you’ll be able to tune the air spring pressure almost infinitely for different rider weights and preferences, just by using a simple shock pump.
Another great thing that you will be able to do with an air shock setup is increase or decrease the progressivity of the spring by using volume spaces, which you will do to alter the bottom out resistance.
Then when it comes to the actual riding experience with these shocks you will notice that they will give a better bottom-out resistance. You can even go a step further with these shocks and can tune them to work with compression damping in order to improve mid-stroke support as well.
Disadvantages
Since the air shocks need more seals, in order to keep the air under high pressure in your suspension, which then adds friction and as a result just won’t feel as supple as a coil shock would. Then, because of these extra seals, you’ll need to do more maintenance on them than on the coil shocks.
When you compare the air shocks to coil shocks you’ll notice that there is less sensitivity in the shocks and this is mainly because of the initial stiction that the air shocks have. However this is only quite a big difference in the beginning because as the shock gets moving you’ll almost instantly feel that the stiction basically disappears.
Another large contributing factor as to how supple your air shocks will be is the size as well as pressure of the air shocks’s negative spring chamber. So, if you have an air shock setup with larger negative springs that are inflated to higher pressures are going to be more supple than the ones with smaller springs. However, even after this it’ll still be hard to beat the smoothness that you’ll get from a coil shock setup.
One large disadvantage that you have with air shocks is that they are a lot more affected by heat build-up, since the air inside of these shocks get hot when compressed. When the air inside gets hotter it can then lead to an increase in the stiffness of the springs and could lessen the performance as a result, especially during your longer descents.
Conclusions: Which one is best?
Just like a lot of different gear and bike choices within the riding world, there isn’t a right choice that will suit everyone, the best option will come down to what type of terrain you’re going to be riding on and then your personal riding style as well.
A piece of advice to remember when picking your shock setup type is that if you are riding on some very steep terrain then a coil shock will probably perform better for you as it will allow your bike to sit more back on its travel, which will then allow you to keep a slacker head angle and give you more confidence in your riding.
