Fox go reverse arch...

And I always wondered on bigger forks why no-one copied Magura and Pace to have twin arches.

Tooling costs? Way cheaper to make one arch deeper and stronger/stiffer than add a second arch. Even though the weight/stiffness is better with two than one (beyond a certain point)

I guess this is to do with the in-arch air chamber patent?

Even though the weight/stiffness is better with two than one (beyond a certain point)

When does stiff become too stiff? End of the day forces have to go somewhere.

Still got my Manitou Sherman in the shed. A reminder that reverse arch can work for burly forks as well.

When does stiff become too stiff? End of the day forces have to go somewhere.

We've barely even achieved the "stiff enough" telescopic fork yet, think too stiff is a fair way off yet.

Is an arch of equal size/design not as stiff front or back? And you'd think that a company like Fox who have used front arches for 20ish years would have that idea of good/bad and experimented with reverse arches in the past... so why now?

so why now?

BNG, 5% bettah, big new thing for 2024 etc from the marketeers.

How many of us actually threaten the integrity of any fork arch, front or back; will 1-2% stiffer be noticeable by almost any of us..?

The rear arch on the chunky Mastodon attached to my fatty works just fine.  So does the front arch on the Helm on my bouncer.  Marketing BS, probably.

Why now?

- current buyers have forgotten (or never even saw) past use of reverse arch, so it doesn't look like copying other brands, or admitting you were wrong... or super cynically, what Matt says... it looks like the "latest thing" all over again

- we had a period of trying to squeeze the maximum travel out of a limited axle to crown length, while also increasing tyre clearance for fatter rims and tyres, and reverse arch made that harder rather than easier because of frame clearance... that time is over... forks are now longer for their travel than they once were (at both the short and long travel ends of the market anyway)

- tech allows for better comparison of different arches now... and can even grow more optimal arches for you if you fancy (although they tend to look awful in my opinion, but can be tidied up by humans while keeping a lot of their advantages, which I suspect is what Fox are up to here)

Marketing BS, probably

I think this ^ too.

Front or back an arch of the same size, mass and shape will have the same stiffness. This just 'looks' different and hence garners attention for the launch etc....

It isn't necessarily the same shape though (which also affects size and mass). The tyre is lower behind the fork leg than in front, so arch shape (and the trade off between clearance, stiffness, weight and strength) can we be quite different.

BANG: real reason as to "why now"... RA patent has expired in the USA

https://patents.google.com/patent/US6607185B2/en

I didn't even realise there was a patent. Thanks for the thread OP. Some proper breakfast bike chat.

Definitely nothing new. Round our way Halfords have been supplying bikes with reverse arches for years 😉

At the very least there will be less mud stuck in the fork arch!

And I always wondered on bigger forks why no-one copied Magura and Pace to have twin arches.

Old PACE forks were brilliant - way ahead of their time.

However the twin arch used to clog completely with mud and stop the wheel spinning (at least they did in Yorkshire clay) At least a single arch is less likely to clog.

Should've included the side view pic, that's one funky looking arch, the crown is different too, worth having a look on bikerumor, maxxis high roller 3 article too.

I like the look of it, but always reckon a twin arch would be better for side to side stiffness (and hopefully make the forks legs move closer to the same time) - I suspect this is more marketing stuff, but I like the look of it.

why no-one copied Magura and Pace to have twin arches.

I had a pair of Magura Thor 140mm forks. They looked really cool, but I can honestly say that the twin arch made zero difference to the riding experience. Plus at the time they were a utter PITA to get serviced/find service parts for, so they went tits up way before they should've for lack of distributor in the UK. Lesson learned.

RA patent has expired in the USA

Who is RA?

Ah, reversed arch, I get it!

Sorry, “Reverse Arch”… link shows the Answer patent for it… presumably that was passed on to Hayes when they bought Manitou.

I suspect this is more marketing stuff, but I like the look of it.

Well most stuff is these days.

The advantage to me of a reverse arch that it helps stop getting mud on the stanchions and getting passed the seals.

maxxis high roller 3 article too.

Now you're talking.

Looks similar to Schwalbe's new Tacky Chan eh? Are they both copying the successful Continental tread pattern?

Next someone is going to go crazy and use a "new" larger axle size to increase stiffness with no real weight penalty - maybe something like 19.99m +0.01

As per Daffy could be better for mud shedding, but conversely, also hard to find a mudguard for.

Can't easily see why it would be stiffer compared to a front arch?

also hard to find a mudguard for

That'll be solved with 5 minutes of launch. It was just hard to get them for Manitous as they are a smaller player in the market. RRP, Muckynutz, etc will be all over it in no time

This is why Manitou say it's better: https://hayesbicycle.zendesk.com/hc/en-us/article_attachments/360055903834
Basically is just the the arch can be smaller (as mentioned above) and lighter for the same stiffness, or stiffer whilst still being a bit lighter. And it also works better with mud. Not really earth shattering stuff

mashr
Full Member

Next someone is going to go crazy and use a “new” larger axle size to increase stiffness with no real weight penalty – maybe something like 19.99m +0.01
Posted 2 minutes ago

Zero chance of that happening mate.

(It will be 20.5)

Pace used it originally because they reckoned it dealt with brake forces better, pushing away rather than pushing against if you know what I mean? That was in the canti brake days though so not really relevant now.

Suprise suprise that other brands jump on this now the patent has expired 😄.

It's an ugly implementation though.

I'd be interested to see a front to back cross arch - so, rear left leg to front right & rear right leg to front left.

Would probably look a bit 'challenging' and be a bit of a mud-trap, but I think you could get some pretty stiff lowers doing that.

Would hit the crown without some major engineering. Could work with a double crown where the lower crown is low profile.

That’ll be solved with 5 minutes of launch. It was just hard to get them for Manitous as they are a smaller player in the market. RRP, Muckynutz, etc will be all over it in no time

RRP Rear guard works well on reverse arch forks.

kelvin

Would hit the crown without some major engineering.

🙂
Ah yes. I suppose that would be a bit problematic.

Is an arch of equal size/design not as stiff front or back? And you’d think that a company like Fox who have used front arches for 20ish years would have that idea of good/bad and experimented with reverse arches in the past… so why now?

key thing is the rear arch implementation as per Manitou is not the the same size, as the arch can be lower (therefore overall smaller) as needs less clearance to the tyre at the rear vs front due to the differing wheel position relative to the fork.

nixieFull Member
Surprise surprise that other brands jump on this now the patent has expired 😄.

It’s an ugly implementation though.

It's just ugly period.  no amount of "it's a bit better" will make me buy a RA fork. Manitou went from making one of the best looking forks ever (X-Vert)  to making something they struggled to give away.  A real shame as by all accounts the damping is pretty good.

I had some Magura Menja's (130mm travel QR)  with the dual arch.  They were noticeably stiffer than similar  contemporary forks. Maybe bolt through minimizes some of that difference but they were definitely stiffer.

And personally, I've always liked the look of Manitou forks, although that FOX reverse arch is almost as ugly as the current skiny semi-circular conventional arches.

When does stiff become too stiff? End of the day forces have to go somewhere.

We're nowhere near that point yet though, and there's different parts that need to be stiffened.

-Making the lowers move together in tandem and keeping the stanchions parallel prevents bushings binding.

-Any 'good' flex would occur sideways at the crown/steerer. And I don't think anyone's got anywhere near making that joins stiff enough yet, otherwise we wouldn't sill use dual drown forks.  It would probably be easier to build that flex into the Head/top/downtube area and work on making the forks stiffer which his how motorbikes have worked on that problem.

I guess this is to do with the in-arch air chamber patent?

That's in the crown, not the lowers. I don't think anyone's attempted hollow arches?

Is an arch of equal size/design not as stiff front or back?

Front or back an arch of the same size, mass and shape will have the same stiffness.

The arch itself has the same stiffness, it's effectiveness in the system changes though. It's all about the distance to the axis of the applied bending loads.

That’ll be solved with 5 minutes of launch. It was just hard to get them for Manitous as they are a smaller player in the market. RRP, Muckynutz, etc will be all over it in no time

Trimmed down double ended muckynutz works fine on reverse arch forks, so they should be able to sort a new one out pretty quickly.

Bike frame geo is basically perfect nowadays so the industry has to keep playing with insignificant stuff to keep us all buying.

Makes fitting mudguards a pain.

Manitou supply theirs with a mudguard that fits fine.

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Maybe they've gone as technologically as far as they can with materials, etc and this is as above something to keep us buying.

I bet Manitou are feeling rather smug right now.

Ah yes. I suppose that would be a bit problematic.

Just remembered this...

Specialized dual crown fork, where the arch is smack bang in the middle.

I bet Manitou are feeling rather smug right now

They'll be rolling around in their plies of cash and laughing their bums off, just like the folks who invented betamax or hd-dvd.