Back in 2012, Fox experimented with an upside-down double bridge fork, which was sporadically tested by Gee Atherton and Aaron Gwin on World Cup courses. However, insufficient torsional rigidity and the need to pack a lot more weight into the casting put an end to the endeavours to bring the fork to production maturity. For many years, the USD project seemed to have fallen asleep, until the Sea Otter Festival this year. The enduro bikes of several athletes featured a fairly close-to-production upside-down fork with a single crown.
Now Fuchs lets the cat out of the bag and presents the Podium. The USD Enduro fork offers a choice of 160 or 170 millimetres of travel and weighs an impressive 2770 grams. Thanks to the 20x110 millimetre steel thru-axle and a really fat casting, the Podium weighs a good 400 grams more than a Fox 38.
The Podium was developed over three years and, according to Fox, should offer the optimum combination of stiffness, weight and performance and is primarily aimed at racers, whether on an MTB or E-MTB. On the inside, Fox relies on proven technology from the existing forks. An X2 damper cartridge is used.
Why upside-down at all?
Why upside-down at all? Upside-down forks are the state of the art in the motorbike segment, but are rather rare in the MTB sector and often only found on small brands - or like the Rockshox RS-1 disappeared from the scene within a few years. But what are the arguments in favour of a USD fork?
Due to the inverted design, the bushings in the fork can be arranged at a significantly greater distance. On the Podium, the distance is 54 millimetres greater than on a Fox 38, which means that the fork tilts less under load and can glide better. With compression, the situation even improves with a USD fork because, in contrast to a conventional fork, the wheel axle moves closer to the lower bush and shortens the lever.
In addition, the inverted arrangement ensures permanent lubrication of the seals, which are optimally positioned in the oil. Dirt on the dip tubes is wiped downwards and can no longer collect so easily. Another small advantage is the slightly lower unsprung mass, which allows the fork to react more quickly to fine adjustments.
On the supposed downside is the stiffness. Although the stiffness in the direction of travel is extremely high due to the solid upper section, the torsional stiffness is very low due to the lack of a triple clamp. Unlike a conventional right-side-up fork, the fork tubes are not connected to an additional fork bridge and are only prevented from twisting by the thru axle, which also makes wheel installation and removal more difficult.
First driving impression
We have already been able to ride the new Fox Podium extensively at the presentation in the Bikepark Leogang/Saalbach on various trails. The Fork works smoothly as is typical for Fox and even goes one better in terms of response behaviour. In order to be able to fully utilise the suspension travel with two volume spacers as standard, we had to stay slightly below the compression recommendation.
The ability to swallow small and medium-sized obstacles is particularly noticeable. On initial contact with roots and rocks or on landings, the fork inhales the impact almost completely. Surprisingly little hits the rider's hands. Even when braking hard in bumps, the Podium works smoothly.
The significantly lower torsional stiffness compared to a Fox 38 is pleasantly noticeable with a rider weight of 70 kilos. The fork generates a lot of grip and holds the line, especially on rooty, hanging trails.
Softer than expected in the test lab
A massive fork crown and 47 millimetre thick stanchions make the Fox Podium extremely stiff in the direction of travel. However, the torsional rigidity is significantly lower. Fox speaks of the same torsional stiffness as a 36.
BIKE naturally checked the data in its own test laboratory. The result: While the brake stiffness in the direction of travel is even 26 per cent higher than a Fox 38 at 373 Nm/°, the torsional stiffness is around 30 per cent lower than a Fox 36. Nevertheless, the new Podium achieves the highest torsional stiffness we have ever measured on a USD fork.
The key data for the new Fox Podium
- Suspension travel 160 or 170 mm
- 2767 g incl. thru axle
- 110 x 20 mm thru axle made of steel
- 36 mm immersion tubes and 47 mm standpipes
- 30 % less torsional rigidity than Fox 36
- 26 % higher brake stiffness than Fox 38
- Price: 2400 Euro
We will find out for you how the new Fox Podium fares in direct comparison to the established competition. You'll find out more soon.
Interview: Fox developer Ariel Lindsley on the new Fox Podium
"WE DON'T FOLLOW TRENDS!" Ariel Lindsley, product developer at Fox
BIKE: What is the percentage of technical advantage vs. marketing hype in the Podium?
We don't follow trends, but only do something if it makes technical sense. We have therefore ridden many other USD forks. The project started with clear facts in favour of a USD fork.
You already cover the enduro sector with the 38. With the Podium, there is an expensive alternative for the same use. Does that make sense?
We know that with the 38 we already have an extremely good and widely accepted fork in our programme. In comparison, the Podium is much more specialised and appeals to a smaller group of buyers. Higher weight, less stiffness and a more complicated wheel change speak against the Podium. But those who are technically interested and want maximum performance in rough terrain will be happier with the USD fork.
How can the significantly higher price of 2400 euros be justified compared to a 38 Factory (1669 euros)?
The fork costs us considerably more to produce, which is certainly also due to the smaller number of units. We still have to ensure a certain margin to make the Podium profitable.
You seem convinced by the USD technology. Is it conceivable that USD will now also branch out into the DH sector and also into shorter travel classes?
We are starting with the Podium and are open about the rest of the product range. Future development will certainly also depend on market acceptance, which has been quite positive so far. In the XC sector, however, the weight disadvantage is too high and handling when changing wheels is too complicated.
There are also well-known competitors among suspension fork manufacturers who have discontinued USD forks after a relatively short time. Are there any major hurdles, especially in terms of production tolerances?
We are very good at producing chassis and have a lot of experience in this field. Secondly, we took a very close look at the existing market and tested many competitor products and specifically improved the things that we think are important. In terms of torsional rigidity in particular, we have found a sweet spot. Not too imprecise and soft, but also not too hard and not very forgiving. To get there, we tried six different thru-axles, three different crowns and a whole host of stanchion and drop tube combinations. The heavy parts always won. We always decided in favour of performance over weight.
One advantage of USD is the better lubrication of the seals. With your bypass casting, however, the conventional forks also have lubrication. Is this less effective?
It definitely helps with conventional forks. But due to gravity, USD forks are always perfectly lubricated.
A 38 is 2461 grams. At 2767 grams, the Podium is a good 300 grams heavier. Weight does not seem to have played a role in the development. So what was the main development goal?
The heavier options performed better. We could have made it even lighter, but we have other models in our programme for that. People who want to shoot and master technically demanding routes are certainly happy to accept the extra weight.
USD forks have a high braking stiffness but little torsional stiffness. What was the development goal in terms of stiffness and is that why you had to accept so much weight?
There is a kind of magic where the sweet spot is. For example, too stiff in terms of the axles was perceived as worse by many riders. Heavy riders and e-bikes make a difference, but everyone came back to the axle we have in there now.
