A very often-heard question from most people that plan to start cycling relates to the forks they should use for their bicycle, more exactly if it should be a rigid or a suspension one. The suspension forks’ travel has increased dramatically in the last years, and what seemed to be enough for a discipline at one point, isn’t anymore, only leading to much more questions regarding the choice.
However, most standards have been set by now according to the discipline practiced or the purpose that the bicycle was designed for. Even so, we wouldn’t view the standards as firm rules, because our extensive testing throught the years proved that a quality 100mm fork can work wonders on downhill and we’re full of other such examples.
Why should I use a rigid fork?
You shouldn’t be surprised if you’ll see cross country mountain bikes equipped with rigid forks, most commonly built out of carbon. There are some that take this as a viable option, although it will come at a price, namely hard shaking on descents. When climbing, though, the advantages soon start to appear in the form of the higher speed you’ll have. Even if the lock-out function of suspension forks evens the stiffness issue, the weight difference, which is substantial, zapps a lot of your powers. So, you’d better be an ace in handling your bike when descending if you want to enjoy the full benefits of a rigid fork on a mountain bike, because the lack of a suspension system will make your life harder downhill.
Rigid forks also make a good combination with city bicycles, where comfort can be enhanced by installing wider tires or some other component that ensure a more relaxed ride. Nontheless, manufacturers have produced purpose-built suspension forks for these bikes too.
Road bikes also belong to the world of rigid forks, although there were and still are attempts to fit shocks either on the frame or on the forks, but these models never saw mass production. And, neither do cyclocross bikes have any type of suspension systems, eventhough they deal with off-road.
Fat bikes also have rigid forks, but the extra width of the tires makes up for the comfort, even more so as they can safely run even on low pressure.
Why should I use a suspension fork?
To keep things short, for better control and improved comfort. According to the destination, forks can be categorized by their travel:
City and Trekking: 60 – 70 mm
Cross Country and Marathon: 80 – 100 mm
DirtJump and Slopestyle: 100 mm
All-Mountain, regular: 120-130 mm
All Mountain Plus: 140-150 mm
Enduro: 160-170 mm
Freeride: 180 mm
Downhill: 200 mm
Air cartridge or coil suspension fork?
The entire length of the travel will be used only when hitting serious bumps, the last 10mm of travel being more of a back-up, and being covered much harder than the rest, trying to avoid as much as possible a bottom out.
The comfort level of the fork goes hand-in-hand with its functionality. Judging by this idea, I’d opt for a coil fork rather than an air cartridge one, thanks to its finer smoothness on uneven terrain. But we are not talking about entry-level models here, but about top notch ones so it’s rather hard to sum up an average of all of these forks’ performances. Some are simply better than other.
Thankfully, air cartridge forks have come a long way and today offer not only comfort and performance, but also easy tuning by introducing or letting out air, several adjustement options and a lower weight. The less-than-good side is that all these mechanism tend to break down at one point or another, so servicing will claim you some extra time and money.
Air cartridge forks are more suited for legs like cross country, all mountain or enduro, while coil ones do a better job for urban bikers, or downhill and freeride warriors. Then again, this isn’t a rule of any sort, but more of a common sense conclusion since fitting a city bike with an expensive air fork doesn’t make too much sense.
Also, noteworthy is the fact that a long-travel fork should have a travel-reducing option, which comes in hand when climbing because it lowers the handlebar’s height, thus reducing the risk of rising into the air on steep sections.
Almost extinct are the elastomer forks, like the Suntour XCM, due to the low efficiency of the concept and of the actual performances, even if maintenance is much simpler for them.
Off-topic question: why would you need oil in the fork?
Oil sets the rebound in normal limits by passing through different chambers. Otherwise, without it, rebound would be as quick as the compression (so, very slow in fact).
Important adjustement options on a suspension fork
Suspension forks have several adjustements options. Rebound sits on top of the list, as well as lock-out. Long-travel suspension forks should also have the travel-reducing option, too. Other functions include preload (coil/elastomer forks), low/high speed compression, and, more recently, set-ups according to the terrain your are riding on (e.g.: locked, semi-rigid or open).
If I own a rigid fork, how can I improve the comfort level?
If you really want to stick to your rigid fork, you can get more comfort out things like a stem that includes a shock, a seat post that includes a shock, a spring saddle or wider tires, inflated to lower pressure.
OK, so what fork should I finally pick?
City cycling will not require a suspension fork, unlike riding in the mountains would. Tarmac, paved roads or even mild off-road trails are also something a rigid fork can handle. And if you aren’t a high-speed descent junkie, it will even do on serious mountain trails.
However, if you’ve set your sight on demanding trails, a fork with a travel of 120mm to 160mm will certainly help you. The more extreme your riding, the longer the travel. But be sure to check which is the maximum travel your frame can support because ignoring this may lead to the damaging of the frame, most probably when you’re in full action, so you can imagine further damage inflicted.