author: DAVID QUER
Co-founder of Trialworld. Instructor at Trialworld School. More than 20 years as a trial expert in specialized motor media.
It is clear to all of us that good suspension is key to the performance of the trial bike and, consequently, to the efficiency of the riding. In fact, it is usually one of the differentiating points between the different ranges offered by the brands and one of the aspects that the enthusiast considers relevant in order to decide on one or the other motorcycle.
Focusing on the field of front forks, this reflexivity is inversely proportional to the information that the vast majority of us have about their regulation or maintenance. And there is only one brand that practically monopolizes the entire market, such as Tech (only the Cota 4RT Repsol -Showa- and the Beta EVO -Paioli- do not carry it). What’s more, the trend is so clear that in the entire market only Beta opts for 38mm bars (39mm all the others).
IS THERE LIFE BEYOND TECH?
The answer is yes.
And for this we have taken on the challenge of testing for six months the M4 Parts fork manufactured by Nani Racing, one of the great references in the field of offroad suspensions since 2005.
It all started while we were doing the dynamic test of the 2020 Electric Motion EPure, the first trial bike to be fitted with the M4 Parts fork from series production. The dynamic sensations caught our attention, but of course, at that time everything was new: electric propulsion, electronic throttle, other inertias, other piloting… And then there are these forks.
Well, nothing. We started pulling strings and got a set of M4 Parts forks to ride on our regular bikes. Only in this way would we be able to clear up any doubts. And so begins this article on the first air fork born exclusively for trial bikes.
WHAT IS THE M4 PARTS FORK LIKE?
TECHNICAL DETAILS M4 FORK PARTS
- Constructed from high-density aircraft aluminum and forged with M4's unique system
- 39mm aluminum bars
- It is equipped with an integrated dust detent system in a single cartridge
- Air pressure regulation (left bar) and hydraulic pressure regulation (right bar)
- M4 Parts fork weight: 3,784 grams
Yes, indeed, it is an air fork. Let’s explain its particularities. It is a suspension inspired by the technology applied in high descent and enduro of the most technologically advanced bicycles on the current scene.
The main idea of M4 Parts has been to scale this technology to the trial motorcycle market with the idea of offering a great product that brings together three major ingredients: technology, reliability and a significant weight reduction compared to everything that the trial market currently offers.
This fork is constructed from high-density aircraft aluminium and forged with M4 Parts’ exclusive system, which gives it great resistance to the lateral traction and leverage moments to which trial forks are subjected in the most extreme conditions.
Another peculiarity is that this fork is equipped with a dust detent system integrated into a single cartridge, with a much higher protection capacity than what we are used to in conventional forks. This type of seal reduces maintenance and provides much smoother friction.
M4 Fork Dynamic Test
How, then, is the aforementioned lightness achieved?
Well, you have to keep in mind that this fork does not have a spring and the amount of oil in the compression bar is very small.
The two bars incorporate a system that lubricates the bushings constantly with each compression, making the glide of the assembly even smoother. Now let’s see what each of its bars contains:
LEFT BAR FORK M4
The left bar is responsible for the function equivalent to the spring. It’s the one that bears the weight. Inside, it houses a compressed air pressure of between 5-9 bar.
It is the regulation of this pressure that will allow us to regulate the preload to be able to adapt it to riders between 35 and 120 kg without the need to make other internal changes that we usually see in hydraulic forks, such as changing the springs or putting spacer bushings.
Additionally, this bar carries a small amount of oil to lubricate the bushings, which are mono block and have a technology that greatly reduces friction compared to traditional fork bushings.
RIGHT BAR FORK M4
The right bar incorporates the full hydraulic system and performs the same hydraulic retention and compression functions as in a conventional fork, but with two important differences:
The first, which offers a hydraulic adjustment margin not seen until now in this type of fork, allowing the fork to be easily adapted to competition trial conditions or to an excursion trial style to ride at higher speed with a more enduro-like character.
The second advantage is the design of the hydraulic cartridge, which greatly improves the compression behavior of the assembly and, therefore, stability and progressivity.
WEIGHT OF TRIAL FORKS
Now that we understand the differentiating points and the nature of how this fork works, let’s compare it in terms of weight against its 39mm rivals.
As the dynamic test during these months has been mainly focused on a Montesa Cota 4RT, the first forks to pass through the scales have been the Showa.
Weight of Showa 39mm trial forks: 5,227 grams. As we said before, this fork is currently only seen in the Montesa Cota 4RT Race Replica (Repsol).
Weight of Tech 39mm forks with steel bars: 5,162 grams. This fork is fitted to the TRRS One Raga Racing (standard starter), the TRRS One Gold and the standard Montesa Cota 4RT 260.
Weight of Tech 39mm forks with aluminium bars: 4,571 grams. It is the lightest hydraulic trial fork and the most popular among brands. We find it in the rest of the TRRS (One R and the electric start versions), GasGas, Vertigo, Montesa Cota 301RR, Sherco, Scorpa and Electric Motion.
Weight of M4 Parts forks: 3,784 grams. This represents a saving of between 1 and 1.5 kg compared to their hydraulic counterparts on the market.
M4 Fork Dynamic Test
Let’s be honest. We didn’t really weigh all the forks until the last day of the dynamic test . Why? Basically so as not to be suggested, since we knew that there was a weight difference in its favor, but we wanted to test it well in depth without giving all the prominence to this data.
Although the truth is, when you take them out of the box, you are already amazed by their lightness. The finishes are spectacular and it is clear that Nani Racing knows how to do their job very well. As they say in colloquial language, “they haven’t fabricated this to draw.” They’ve pulled out all the stops.
The assembly itself takes no more than 15 minutes and is very simple. Wheel out, brake caliper out, fork bridge out, release seatposts and proceed to change them. They fit perfectly with all models that have seatposts that receive 39mm forks.
On the left bottle you have a cap that releases with a screw and protects the inflation valve to adjust the preload and adapt it to the taste or weight of the pilot. You can take that little bike fork inflator with you and dynamically test it in a very simple way.
Once we have done a small set up, we go to the mountains. Their habitat. In our case, we swapped the Showa for the M4 Parts, quickly noticed the difference in weight, making the Cota 4RT much more agile and playful , but without losing an ounce of poise where you need it.
Perhaps what has caught our attention the most is theirability to copy small obstacles. It eats everything, transmitting very sweet and noble sensations to the pilot, especially in the first third of its course. In any case, you can mark it with the settings if you prefer this sensitivity or greater harshness. It’s a matter of taste. Whatever you decide, you will see how the glide is very smooth and precise, which is a real joy both in sections and sections of interzone.
THE OPINION OF ORIOL NOGUERA (PROFESSIONAL PILOT)"I didn't test the fork much, as it coincided with a dynamic multi-bike test, but I don't dislike its behaviour at all. The little I've tried I notice a lot in the weight and in the movements at a standstill (changes of direction). I would have to try the different regulation and response options for a high-level rider, but a priori I am very satisfied with the performance."
THE OPINION OF CHEMA QUER (TRIALWORLD TESTER)"The main fear I had with this fork was that it would offer me very different sensations to what I had been riding with hydraulic forks and that would leave me unsettled. But nothing, quite the opposite, there are differences, but also many meeting points and you don't feel "strange". It gives it a great plus of lightness and the consequent help to move the front end, especially in the case of this Cota 4RT. Also, in this specific case, it gives us extra speed compared to the standard Showa."
Conclusions
In short, this is a very attractive component that we could well have on our bike and move on to successive models, since as we pointed out, it adapts to any 39mm bar seatpost.
And above all, I would like to applaud the great work of the entire Nani Racing team, which has sought to go beyond what we have right now, taking on the role of the Challenge of providing lightness and technology, building new formulas that seduce both in terms of performance and low maintenance and ease of set-up.
The best
- Lightness
- Ease of regulation
- Balance between sensitivity and poise
- Quality of finishes
To be improved
- It requires a small margin of adaptation to the sensations of the pneumatic system
- Price
- Access to regulations with fork mounted
