Suspension on a gravel bike: Exploring a thorny issue

Suspension on bikes has been around for decades now, but it has usually only been reserved for mountain bikes. In the new world of gravel, however, we are seeing bike design evolve to accommodate suspension forks, and even seeing frames with rear suspension built-in.

Suspension offers both increased traction and comfort on loose and rough surfaces. The ability of the wheel to move up and down to conform to the contours of the surface keeps the tyre in contact with the ground more of the time.

The benefits of this – on paper at least – make sense: suspension gives you more grip as well as keeping your tyres in contact with the ground more of the time. This is only a good thing when it comes to power delivery and rider efficiency.

• Read more: How to choose a new gravel bike

However, there are some drawbacks to using suspension. Firstly, the hard-to-avoid fact is that adding suspension to any bike is going to increase its weight. Secondly, although on rough surfaces suspension can increase efficiency, on more groomed and smoother surfaces it can sap your energy. As you pedal, some of the effort you put into the frame will be absorbed in what is known as pedal bob, although most systems do now come with the ability to lock out the suspension.

And yet, when we're talking about gravel suspension, we're not just talking about the traditional active suspension that you'll see on a mountain bike. In recent years, a number of innovative attempts at shock absorption have hit the market, offering new ways to introduce compliance.

There are other considerations to weigh up, too, with suspension sure to introduce a fresh set of design constraints and increase your maintenance to-do list. As you can tell, this question is not as straightforward as it first might seem on the surface.

Rear suspension systems

© GCN

A full mountain bike style rear suspension on a gravel bike

There are several ways to introduce compliance at the rear of the bike, the most visually obvious method is a traditional active suspension shock absorber. This is what we are most used to seeing on mountain bikes and gives the most adjustability and control over how the suspension behaves. The downside to this is that it adds a lot of complexity, cost and maintenance.

This isn't the only type of rear suspension on offer with soft tail bikes such as the BMC URS using an elastomer between the seat stays and the seat post. The elastomer allows for the rear triangle to flex and dampen out high-frequency vibrations. Although this is suspension, it is mostly used to increase rider comfort.

© Specialized

The Expert model in Specialized's Diverge range comes with this striking rear suspension system

Seat post-isolation is something that isn't new to cycling, first appearing on the Trek Domane in 2012. The concept has evolved with both Specialized and Canyon creating their own versions. Essentially it looks to allow the seat post/seat tube to flex. Both Trek, Specialized, and Cannondale use a system that allows the whole seat tube to flex whereas Canyon uses a split seat post to achieve the same effect.

Seat post isolation keeps the rider damped out of high-frequency vibrations, although it might not be an active rear wheel suspension that can increase grip it will increase comfort.

Front suspension systems

© Canyon

Canyon's Grizl Trail comes with a suspension fork

Much like rear suspension solutions, the front end of the bike has more than just the obvious suspension fork on offer.

We are seeing brands head in-house to design suspension units that sit inside the steerer of the fork. BMC, Specialized, and Cinelli use this to offer 20-30mm of travel at the rider's hands. This solution is neater and lighter than a dedicated suspension fork. It also has the added bonus of being tucked up out of the way. A nice addition to this solution is the ability to tune the dampening on the fly with an adjuster that sits on top of the stem.

Although a bit more niche, passive suspension forks like those from Lauf are also a popular choice. The leaf spring fork offers 30mm of undamped suspension in a robust package that requires zero servicing. This option will not feel as plush as an active suspension fork but it will remove chatter and high-frequency vibrations.

You can even get dedicated suspension stems, such as the one from FreeQENCE that Alex Paton tried out in the video below.

Why would I want suspension on a gravel bike?

At this point, you are probably wondering why you would want to equip a light and efficient gravel bike with some energy-sapping and weight-adding suspension. It is a valid question but it all comes down to rider preference and the terrain it is going to be used on.

If you typically find yourself riding a mix of paved roads and light gravel paths, then a traditional gravel bike is going to be the right tool for the job.

Read more: Suspension, motors and hub gears: Gravel trends from Rouleur Live

© GCN

Cinelli's new Nemo Gravel features an elastomer dampener above the fork

However, as you turn up the intensity of the environment to include rough, chattery gravel on far-from-manicured surfaces, suspension starts to become a more attractive proposition.

The difference between a full-suspension gravel bike and the more traditional rigid variety is comparable to the differences between an endurance road bike and a thoroughbred aero race machine. They do the same thing but at different ends of the spectrum.

But is the spectrum really broad enough for there to be two different bikes to achieve the same goal?

Other suspension considerations

Suspension gravel bikes have a greater complexity than a traditional rigid alternative. Basically, it introduces more parts and more materials into your set-up, which in turn means more maintenance and more chance of things breaking down.

This is especially true of active suspension units, which will need regular servicing to keep everything running smoothly. This is common for mountain bikers to encounter, but for gravel riders and roadies, this is definitely something extra to consider.

The added complexity also means that it is less ideal for big trips that head into the wild for prolonged periods. Having a simple, easy-to-fix and dependable bike will probably rank as a higher priority for most riders when picking an adventure bike.

Isn’t a full-suspension gravel bike just a mountain bike?

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Niner's full-sus gravel bike

On the surface, it can be easy to see how this could be the case. A lot of the defining features that make a mountain bike a mountain bike can indeed be found on a full-suspension gravel bike.

Things like 1x gearing, knobbly tyres, and of course suspension point towards the fact that they are the same type of bike.

However, a dive into the characteristics of both types of bikes quickly highlights the significant differences that set them apart. Most notably: the geometry.

Mountain bikes are designed to tackle technical terrain, including jumps and drops. This means the geometry is designed around control more than efficiency. It also means that they are designed to be ridden out of the saddle on technical descents.

Some of the main geometry attributes that separate a mountain bike from a gravel bike include a more relaxed head angle, a longer wheelbase, a longer front triangle, and much shorter stems.

• Read more: Gravel bike vs mountain bike: which is best?

On the flip side, a full-suspension gravel bike is designed for long rides and prioritising efficiency. The suspension systems offer a far smaller amount of travel than typical on a mountain bike. This is because the surfaces each bike is intended for differ massively. A mountain bike has to soak up roots, rocks, and drops whereas a gravel bike needs to dampen out the chatter and vibrations of loose surfaces. Gravel bikes are also designed around a predominantly seated and static riding position.

Although it could be argued that there is plenty of overlap between the two bikes, they are best suited to very different scenarios.

Timing a full-sus gravel bike against a traditional gravel bike

© GCN

The Niner full-sus MCR (top) is compared to the rigid RLT

A few years ago, GCN put suspension to the test, pitting a full-sus gravel bike from Niner, the MCR, against the US brand's rigid gravel bike offering, the RLT.

The time trial took place over a short course in Fort Collins, USA, boasting a mix of tarmac and gravel as well as climbing and descending on the rough stuff. Finishing off the loop was a section of singletrack to test the ‘go anywhere’ adventure credentials of both bikes.

• Read more: One bike to rule them all: Can a gravel bike double up as a road bike?

The results were close, with the traditional gravel bike clocking in at 11 minutes and nine seconds to take the contest by a mere three seconds.

As you might expect, the rigid bike was faster on smoother surfaces, whereas the full-sus bike had the upper hand when it came to the more technically demanding sections.

The fact that both bikes are so close on a mixed course shows that the right choice really will depend on what type of riding you envisage yourself doing more of.

It is fair to say that if the course had featured more twisty singletrack or chunky gravel descents the advantage would have swung in favour of full-sus. Likewise, more groomed gravel and the gap would have no doubt extended.

Where does this leave suspension on gravel bikes?

© Canyon

This Canyon Grizl Trail pairs active front suspension forks with a dampening split seatpost

It is easy to look at all this information and think we are back where we started, with question marks over the identity and necessity of gravel bikes in general.

While full-suspension gravel bikes haven't widely caught on, at least in full-build form, the range of aftermarket options and compliance innovations have combined to plug the holes in that spectrum between road bikes and mountain bikes.

Whether a suspension gravel bike or rigid gravel bike is going to be faster, or simply better, depends on the terrain you'll be taking it over. If you're sticking largely to well-groomed gravel, suspension will be less of a concern, but if you're incorporating rougher terrain, it could significantly improve your ride.

With all the aforementioned innovative compliance options available to you, active suspension might not seem like the best investment for a gravel bike, but if you do ride a lot of rough and technical gravel or spend time riding over washboard gravel at high speeds, some form of isolating technology could well be worth it, to keep you in control and keep fatigue at bay.

The key is to figure out where your priorities lie. Despite all the choices now available to us, there are still compromises to be made. Many of us will use gravel bikes to hit up a wide range of terrains in the same ride, so it's a case of figuring out which are most important to you, and which aspects of riding – be it speed, comfort, or handling – you're willing to take a slight hit on.

Ultimately, the more choice we have, the better. Suspension on gravel bikes will continue to divide opinion, but being able to customise our bikes to the terrain we ride and our needs as riders can only be a good thing.

Do you ride with suspension on your gravel bike? We would love to hear your thoughts and opinions in the comments below.