Been contemplating giving an inverted fork a go on my Crestline S180 and not sure if the gains are marginal and worth the added cost? The Fox Podium seems to be getting great reviews and is being spec'ed on new bikes i.e Pivot Shuttle. Not sure why Fox went with a 20mm axel when other manufacturers ...
@Singletrackmind Good question, and one that's generating a fair bit of debate right now. The inverted (USD) fork concept isn't new, but the Fox Podium is the first modern iteration that's getting serious OEM traction, so it's worth picking apart whether the engineering benefits justify the price for your Crestline S180.
The core advantages of an inverted design are reduced unsprung mass (the heavy bits are now at the top instead of bouncing around at the axle) and dramatically reduced bushing friction because the distance between the bushings and the axle is much shorter. The community consensus so far is that the small bump sensitivity is genuinely exceptional.
@Pizzman's been running one on a Turbo Levo at
78-80psi with 4 tokens and rates the small bump compliance very highly.
@Jdof described it as
"noise cancelling" through rock gardens, which is a vivid way of putting it. The fork also rides very high in its travel despite being 170mm versus the 180mm Fox 38 it replaces, so you're not losing effective capability.
The trade-offs are real though. Weight is the obvious one: the Podium comes in at around 2695g versus roughly 2194g for a Fox 38, so you're adding about 500g. On an eMTB that matters less than on analogue bikes, but it's not nothing. Price is the bigger pill to swallow, at around $2099 versus $1309 for a Fox 38 at retail, though there are reports of UK pricing dropping to around £1,800 which suggests the market is correcting a bit.
Now, your axle question. Fox went with 20mm because torsional stiffness is the Achilles heel of inverted designs. With the stanchions (the sliding bits) at the bottom and the lowers holding the wheel, you've got a longer lever arm trying to twist everything when you brake hard or push through corners. A 20mm axle adds meaningful stiffness to counteract that. Push went with 15mm on their USD fork, and the early PinkBike commentary after that review was essentially "oh right, maybe the 20mm axle wasn't Fox being cynical after all." Reviewers have noted that even with the 20mm axle, there's still
slightly more torsional vagueness in the Podium than a conventional 36/38 under hard braking and cornering loads. A 15mm axle would likely make that worse. The downside is you'll need 20mm compatible hubs, so your I9 Hydra 2s would need end cap swaps (Hope hubs have been confirmed to have swappable end caps for it, worth checking with I9 directly for yours).
For your riding in San Diego's dry, rocky terrain, the reduced friction and small bump sensitivity would be genuinely noticeable. Whether it's worth the premium over a well-set-up Fox 38 is the eternal question. Given your tendency toward thorough builds, I suspect you'd appreciate the difference, but I wouldn't call it transformative so much as refined. The Podium is currently maxed at 170mm travel, which pairs well with the S180's geometry. Just be aware the axle mechanism is reportedly a bit temperamental and requires proper technique when fitting.
I've got community data on specific setup tips and token configurations if you decide to pull the trigger.
