Upside-down suspension forks are nothing new, nor is there a technical achievement that makes them particularly attractive right now. However, the fact that a high-volume manufacturer like Fox is jumping on the upside-down bandwagon with the Podium leaves room for speculation. Our first comparison test of the new USD enduro fork from Fox set the first exclamation marks. We spoke to Cornelius Kapfinger, the founder of Intend, about the current USD hype.
BIKE: With the Flash 38, you have just introduced a completely new upside-down fork. Unlike Fox (Podium 36 mm), this one comes with 38 millimetre stanchions. Why so thick?
Cornelius Kapfinger: To be honest, we assumed in advance that Fox would also go for 38 millimetres for its new fork and sized our Flash accordingly.
Was stiffness perhaps also an issue when deciding on the dimensions of the new Flash 38?
Personally, I have no problem with a lack of stiffness in upside-down forks. However, to be on the safe side and appeal to a wider audience, a higher stiffness doesn't hurt. The 38-millimetre drop tubes therefore offer more reserves and bring the fork to a level where nobody needs to worry. This increases acceptance on the market. We already had many positive enquiries about the Flash 38 at Eurobike.
And what about the higher weight?
At the moment, many bikers don't seem to care about weight. People want thick, heavy parts without having to keep an eye on the scales. With the spread of e-MTBs, many people have lost sight of weight. It no longer matters whether the bike weighs 25.4 or 25.7 kilos.
Upside-down design will always have a lower torsional rigidity
According to Fox, a lot of experimentation with different stiffnesses was carried out on the new USD Podium fork. Too much torsional stiffness was already perceived as negative by the test riders.
That an upside-down fork should suddenly offer too much torsional stiffness is total nonsense. That sounds more like a marketing claim to me. Due to the upside-down design with a missing fork bridge, the torsional stiffness will always be significantly lower than with a conventional fork. So the question of too much stiffness doesn't really arise.
So why are there two thru-axle options for the Flash 38 with 15 or 20 millimetres? That also influences the stiffness.
Although the Flash 38 is compatible with both thru-axle sizes, the dropouts remain the same. The influence on stiffness therefore hardly makes a difference in practice and is not really noticeable. We don't have a measured value or direct comparison between the two axles. I prefer to rely on rider feedback. With the two options, we are therefore primarily increasing compatibility.
Why do you think USD forks are so popular right now, even with big manufacturers like Fox?
Fox has been working on this topic for some time and allegedly bought all the current upside-down forks on the market years ago and tested them extensively. One of the forks must have been so convincing on the test bench that Fox has now started its own series production. The hype surrounding Fox is certainly an advantage for the acceptance of USD forks. However, this hype can also fade quickly.
We have already tested the new Fox Podium extensively against the established competition and were extremely impressed. Traction and response behaviour under load are impressive. Do you think this performance can also be achieved with a conventional fork design?
I believe that a USD fork is superior to a conventional fork in terms of design. The increased bushing distance and optimum lubrication of the seals simply cannot be realised with a rightside-up fork. I think the time for conventional forks is over.
