Modern Inverted Single Crown Forks

ebruner
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8/13/2025 2:54pm

it's all good, rhetorical questions asked into the ether are not off limits.  Either the hive mind answers them with knowledge, they get ignored or someone has a bright idea or question that stems off it.

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sethimus
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8/14/2025 6:38am

the answer is nobody knows but intend

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ballz
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8/14/2025 6:50am Edited Date/Time 8/14/2025 6:53am

Re-the torsional flex experience, there's IMHO a bit of brain adjustment required if you are used to the feeling of rigid forks like the 38. In my 1st week with the Essential, I was very aware of the difference between stiffer and flexier front hubs in the fork, and thanks to the USD lore, my mind was locked on the flex, looking for it / finding it / dreading it. I was pre-conditioned to dislike it. A few weeks later, I just didn't care anymore. My brain got used to it. I can still tell the difference between hubs but it doesn't impact my riding anymore. I am actually enjoying the little bit of flex in some situations, and I believe it's easier on my poor wrists, too.

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8/15/2025 10:11am

                                                                                                      PUSH 9.1 V2 Changes

PUSH Industries ended up replacing the entire 9.1 fork due to oil seeping from the crown and a persistent creaking. They also upgraded the spring unit to the V2 version which has some interesting features.

 

"Sub Chamber" 

There is a knob on top of the spring side leg which acts to slightly increase the spring rate (if closed off). It has not been apart yet, but I believe it seals off a chamber within the spring side effectively reducing the lower leg air volume. If so, this increases the lower leg or "casting" ramp effect. The adjustment is effective and can be felt by simply pushing on the fork. A potentially useful feature that could take the place of swapping to a stiffer spring if going from trail riding to the bike park. I currently run a 45# spring for trail riding, but swap to a 50# spring for the bike park. Unique in that it is effectively an air spring and the rate change will be progressive in nature.

sub chamber top.jpg?VersionId=nhWiZyeYIAli0Fn

 

Hydraulic Bottom Out

The pneumatic bottom out system has been replaced with an oil damper system. It is differs from the Vorsprung Smashpot HBO system in that it is itself a tiny little damper with an air pressure backed IFP. No shims, just a little piston in a sealed damper unit. It it tunable through changes in IFP pressure, and oil weight. Orifice dampers in general are very progressive in terms of damping force produced at increasing shaft speeds, and are reactive to changes in oil viscosity. More tunable than the previous air sprung unit, and it should have no effect on fork rebound damping.

HBO UNit.jpg?VersionId=LNU 0Npapwa2e xYoCWeyGPBtOnPBq

 

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TEAMROBOT
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8/15/2025 10:23am
                                                   ...

                                                                                                      PUSH 9.1 V2 Changes

PUSH Industries ended up replacing the entire 9.1 fork due to oil seeping from the crown and a persistent creaking. They also upgraded the spring unit to the V2 version which has some interesting features.

 

"Sub Chamber" 

There is a knob on top of the spring side leg which acts to slightly increase the spring rate (if closed off). It has not been apart yet, but I believe it seals off a chamber within the spring side effectively reducing the lower leg air volume. If so, this increases the lower leg or "casting" ramp effect. The adjustment is effective and can be felt by simply pushing on the fork. A potentially useful feature that could take the place of swapping to a stiffer spring if going from trail riding to the bike park. I currently run a 45# spring for trail riding, but swap to a 50# spring for the bike park. Unique in that it is effectively an air spring and the rate change will be progressive in nature.

sub chamber top.jpg?VersionId=nhWiZyeYIAli0Fn

 

Hydraulic Bottom Out

The pneumatic bottom out system has been replaced with an oil damper system. It is differs from the Vorsprung Smashpot HBO system in that it is itself a tiny little damper with an air pressure backed IFP. No shims, just a little piston in a sealed damper unit. It it tunable through changes in IFP pressure, and oil weight. Orifice dampers in general are very progressive in terms of damping force produced at increasing shaft speeds, and are reactive to changes in oil viscosity. More tunable than the previous air sprung unit, and it should have no effect on fork rebound damping.

HBO UNit.jpg?VersionId=LNU 0Npapwa2e xYoCWeyGPBtOnPBq

 

Those updates to the fork all seem really smart. Makes a lot of sense. Excited to hear your impressions once you're able to get out on the trail on it.

ebruner
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8/15/2025 1:21pm

You guys should take the arguing to PMs so you can effectively yell into the same echo chamber.  In here, we should discuss upside down suspension stuff.  You know, "Stranger things, season 4, forks and stuff"

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sethimus
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8/15/2025 2:32pm

die dumb then, i'll enjoy my flash in the meantime. without torque caps, although mine is still compatible. for whatever reason that is so very important to you.

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thejake
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8/15/2025 6:27pm

I think Pedal Bob and sethimus need to hug it out.

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Suns_PSD
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8/18/2025 8:44am
Here’s my $0.02:Robot raises a solid point different doesn’t always mean better. There’s been a lot of hype around why USD is supposed to be superior...

Here’s my $0.02:

Robot raises a solid point different doesn’t always mean better. There’s been a lot of hype around why USD is supposed to be superior, but honestly, I haven’t seen anything measurable (quantitative) that makes me a believer, especially in single crown setups.

Instead of starting with why USD might be better, I think it’s more useful to lay out some core problems with current suspension forks and then explore if USD might help solve them.

Compliance:
Across every sport I touch...skiing, moto, MTB there was a phase where “stiffer = better.” Everyone wanted to be the guy bending Head 103s or riding the stiffest setup possible. But eventually we all realized: this kinda sucks. I’ve had that same feeling riding a Fox 38. When I go back-to-back with a 36, my hands are happier, and I fight the bike less. Maybe I just need to go faster or suck less, but from stanchions to bars, we’re starting to learn that a bit of compliance is a good thing.
Do we need USD to fix that? I’m not convinced. Maybe Darren’s right and it’s easier to tune compliance into a USD design but I’m not sold you need USD to get there, especially in a single crown format.

Sensitivity & Bushing Performance:
We all want a fork that tracks well and doesn’t beat us up. Bushing alignment and low-friction movement are a huge part of that (especially under load). USD designs might help here independent legs, no arch to screw things up but again, you don’t need USD to nail this (I don't think?). The bigger issue is forks that bind under torsional/lateral loads. That’s where we lose performance. There’s been progress, but there’s more to gain, and USD might (???) improve things. I don't know, but I do know this is an area of possible improvement. 

Lubrication:
Yeah, it’s annoying that oil pools in the wrong spot when the bike is upright, but wall mounting at 90° or tipping it to 12 o’clock for 30 seconds before a run solves it. If this is the main reason to go USD, I’m not convinced it’s worth the trade-offs.

CSU Creaking:
Every single non-dual crown fork I’ve owned ends up creaking. It sucks. I’m not convinced USD single crown fixes this either. I don’t think you have to go dual crown to solve it, but I’m over it.

Two quick thoughts to wrap this up:

1. The current Boxxer is insane. It's easily the best RockShox fork I’ve ridden manufacturing, ride quality, everything. And it’s about the same weight and cost as a Nine.One. I get it, most people can’t/won’t run dual crown, but man... that fork is special.

2. I’m a moto nerd and every dirt bike worth riding runs USD. Moto has a process that is a bit more darwinistic than MTB (it seems) and whatever has worked in moto also tends to work in mtb. I love the way I can work on a dual crown moto fork, and how I can easily adjust things like offset and there is no such thing as creaking. That said, every USD moto fork I’ve used has had a nasty spike issue on big square-edged hits at speed. No clue if it’s a damper or binding issue, but MTB forks handle that way better. So even there moto doesn't have it totally figured out either. I'm simply noting moto seldom steers us wrong (pun intended) and they go USD...soooo...

Sorry for the long post! Cheers y'all. And Darren, if you want to send me a Push Nine.One to test I'm all about it Wink

I think the spiking issue on moto forks is a result of going air on Moto forks about 10 years ago and why the Factory forks take the weight penalty and run coil.

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TEAMROBOT
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8/18/2025 10:53am Edited Date/Time 8/18/2025 10:59am
Suns_PSD wrote:
I think the spiking issue on moto forks is a result of going air on Moto forks about 10 years ago and why the Factory forks...

I think the spiking issue on moto forks is a result of going air on Moto forks about 10 years ago and why the Factory forks take the weight penalty and run coil.

I'm on the outside of moto world, but are most moto forks really running air now? I thought that was a blip and everyone went back to coils, on factory team bikes and on Joe Blow OEM bikes, too.

Suns_PSD
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8/18/2025 11:41am
Paper products from Germany can only mean one thing, new fork day!  This is the Intend Flash 35,  it can be run from 160mm to 190mm.Very similar...
PXL 20250716 195308973.jpg?VersionId=42S9OmMUM0uPfe

Paper products from Germany can only mean one thing, new fork day!

 

This is the Intend Flash 35,  it can be run from 160mm to 190mm.

PXL 20250716 195412058

Very similar to the Edge; but with a more robust crown, longer legs, and slightly different uppers.

After initial riding and then a full tear down and inspection, there will be some parallel testing with a 35mm Boxxer. Both forks will be run at 190mm of travel on a DH bike. 

The capability of the 170mm inverted forks at Angel Fire was so impressive that a direct comparison of a longer travel version to a full dual crown DH fork should be interesting. There will be timed runs as well to verify perception vs reality in terms of performance.

 

Not sure if you bought this Flash 35 just for testing purposes or for personal use, but if you decide to sell it, I'm a serious buyer.

After looking at the various USD options I intend to get the Flash 35 for a new Regulator build.

 

Have you worked anything out for guards for the lower stanchions?

 

Thx.

 

PS. Great thread btw!

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jeff.brines
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8/18/2025 11:41am
Suns_PSD wrote:
I think the spiking issue on moto forks is a result of going air on Moto forks about 10 years ago and why the Factory forks...

I think the spiking issue on moto forks is a result of going air on Moto forks about 10 years ago and why the Factory forks take the weight penalty and run coil.

TEAMROBOT wrote:
I'm on the outside of moto world, but are most moto forks really running air now? I thought that was a blip and everyone went back...

I'm on the outside of moto world, but are most moto forks really running air now? I thought that was a blip and everyone went back to coils, on factory team bikes and on Joe Blow OEM bikes, too.

Air is becoming more and more of a rarity in moto. KTM/Husky/GG still use the "AER" (air) lineup of Xact forks in their motocross bikes but have moved their enduro bikes to coil. I don't follow the mx/sx stuff that much but I believe Tomac and Webb are on air right now (among others).

I've run both air and coil, both can be made to work well (similar to a mountain bike). @Suns_PSD - I'm going to disagree with your hypothesis however. While there is an adiabatic compression effect with air under very high shaft speeds, this is something we deal with in mtb too. Shaft speeds on the WC are the same as what a moto rider is going to see, so if this was really the catalyst, we'd never see anyone on air at the WC level (but we see a lot of it.) Anyone who has ever ridden an air spring then swapped to coil (and is going fast, hitting things hard) knows what this first hand. The air spring tends to feel a bit stiffer when running into stuff hard at high shaft speeds. 

The spiking I'm talking about is far more dramatic. It literally can feel like the forks are locked out. I've had it happen with air, coil, and multiple damper configurations. My hypothesis is its either coming from a damper that has its roots in moto, where you aren't running into square edged bumps at 25mph (super high shaft speed) and it can't flow enough oil OR it has something do with the bushing design and the force vector essentially preventing the forks from cycling. 

Final point, its moto, so I say forks. Which is so, so dumb of me. 

3
sethimus
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8/18/2025 1:46pm
Suns_PSD wrote:
Not sure if you bought this Flash 35 just for testing purposes or for personal use, but if you decide to sell it, I'm a serious...

Not sure if you bought this Flash 35 just for testing purposes or for personal use, but if you decide to sell it, I'm a serious buyer.

After looking at the various USD options I intend to get the Flash 35 for a new Regulator build.

 

Have you worked anything out for guards for the lower stanchions?

 

Thx.

 

PS. Great thread btw!

stanchion guards are not needed. the only thing that hit my bike this year a lot are those cow gates:

Zaundurchgänge für Wandernde und Mountainbikende

 

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Suns_PSD
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8/18/2025 4:22pm
Suns_PSD wrote:
Not sure if you bought this Flash 35 just for testing purposes or for personal use, but if you decide to sell it, I'm a serious...

Not sure if you bought this Flash 35 just for testing purposes or for personal use, but if you decide to sell it, I'm a serious buyer.

After looking at the various USD options I intend to get the Flash 35 for a new Regulator build.

 

Have you worked anything out for guards for the lower stanchions?

 

Thx.

 

PS. Great thread btw!

sethimus wrote:
stanchion guards are not needed. the only thing that hit my bike this year a lot are those cow gates: 

stanchion guards are not needed. the only thing that hit my bike this year a lot are those cow gates:

Zaundurchgänge für Wandernde und Mountainbikende

 

Glad it's working out for you.

My lowers on the other hand after about 18 months of use.20201004 080848

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8/18/2025 8:07pm

The only Intend guard options I am aware of are the Rulezman carbon fiber ones (very $), or a newer option that looks to be 3D printed out of the Santa Cruz area. 

https://www.pinkbike.com/buysell/3998707/

Intend also offers all forks (?) as a Blackline option which is a different lower leg/lug design that includes metal guards. The Flash pictured above was ordered as the version without the guards as it needed to be Torque cap compatible.  It is being run without guards for the time being, fingers crossed.

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8/19/2025 12:13am
Suns_PSD wrote:
Glad it's working out for you.My lowers on the other hand after about 18 months of use.

Glad it's working out for you.

My lowers on the other hand after about 18 months of use.20201004 080848

lower legs are made of cheese compared to stanchions. FWIW, the original intend stanchions are rather hard to score..(during transport, when most of shit happens anyway).

 

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jeff.brines
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8/19/2025 5:24am

If you were to really scratch a stanchion badly, what is replacement cost? Being its just one tube with a lug mated to it, I could see it being semi-reasonable. At least when compared to very expensive guards?

8/19/2025 6:12am

I believe lower leg replacement from Intend is only 70 Euro, so very reasonable. 

It's the whole back and forth from Germany that could add some time and money.

2
nsp234
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8/20/2025 2:44am

Only thing I care about these guards is how rad they look. In the unlikely case I ever get one of these forks I make sure they're on Smile

2
boozed
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8/20/2025 3:36am
Suns_PSD wrote:
Glad it's working out for you.My lowers on the other hand after about 18 months of use.

Glad it's working out for you.

My lowers on the other hand after about 18 months of use.20201004 080848

luisgutrod wrote:

lower legs are made of cheese compared to stanchions. FWIW, the original intend stanchions are rather hard to score..(during transport, when most of shit happens anyway).

 

Rocks are pretty hard though, and depending on how you crash, rocks care more about bulk material properties than surface hardness.  I do not see a USD stanchion surviving many of the dents and gouges my oldest fork has collected in its lowers (and which still functions just fine).  My newest fork has no damage because I got better (or more likely more cautious) but I still wouldn't risk it.

1
sethimus
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8/20/2025 5:07am
Suns_PSD wrote:
Glad it's working out for you.My lowers on the other hand after about 18 months of use.

Glad it's working out for you.

My lowers on the other hand after about 18 months of use.20201004 080848

luisgutrod wrote:

lower legs are made of cheese compared to stanchions. FWIW, the original intend stanchions are rather hard to score..(during transport, when most of shit happens anyway).

 

boozed wrote:
Rocks are pretty hard though, and depending on how you crash, rocks care more about bulk material properties than surface hardness.  I do not see a...

Rocks are pretty hard though, and depending on how you crash, rocks care more about bulk material properties than surface hardness.  I do not see a USD stanchion surviving many of the dents and gouges my oldest fork has collected in its lowers (and which still functions just fine).  My newest fork has no damage because I got better (or more likely more cautious) but I still wouldn't risk it.

getting guards (rulezman) would cost me about 4 leg replacements, so far i haven’t scratched them once

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8/20/2025 5:41am

Does anyone know if there are stanchion guards that incorporate a mudguard to fit Intend's forks? Kinda like the ones that Push have (see photo). Its the one off putting thing about USD forks for me, especially living in Ireland where you need something year round really. I know Intend have their own mudguard that fits into the bottom of the steerer tube, but it doesn't seem like as clean a solution. 

Alternatively, I wonder if Push's mudguard could be modded to fit with the intend forks?

 4385d.jpg?VersionId=Jtg J78lICX2EnQ8mL95mBSvsiEdRn9

boozed
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8/20/2025 5:53am
sethimus wrote:

getting guards (rulezman) would cost me about 4 leg replacements, so far i haven’t scratched them once

That is an insane price if true

8/20/2025 6:19am
sethimus wrote:

getting guards (rulezman) would cost me about 4 leg replacements, so far i haven’t scratched them once

boozed wrote:

That is an insane price if true

Unfortunately (for now), all of the guards on the market are way more expensive than just purchasing an extra stanchion ( 200-250 for guards vs. 70 for a stanchion).  Makes way more sense to just have an extra stanchion on hand.

FWIW, after owning my Edge for 3 years, I had my first major stanchion scare the other day, and I wasn't even riding.  Had my bike propped up just outside my garage, my son bumped it, and the stanchion hit the corner of the brick entry and proceeded to slide down the brick corner, grinding the whole way.....not a single scratch.  Not gonna lie, my butt did pucker watching it happen from across the driveway....

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sethimus
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8/20/2025 11:01am Edited Date/Time 8/20/2025 11:06am
Nic Cotton wrote:
Does anyone know if there are stanchion guards that incorporate a mudguard to fit Intend's forks? Kinda like the ones that Push have (see photo). Its...

Does anyone know if there are stanchion guards that incorporate a mudguard to fit Intend's forks? Kinda like the ones that Push have (see photo). Its the one off putting thing about USD forks for me, especially living in Ireland where you need something year round really. I know Intend have their own mudguard that fits into the bottom of the steerer tube, but it doesn't seem like as clean a solution. 

Alternatively, I wonder if Push's mudguard could be modded to fit with the intend forks?

 4385d.jpg?VersionId=Jtg J78lICX2EnQ8mL95mBSvsiEdRn9

nothing to mount them against. rulezman uses some stick on holders but they wont hold that much weight so answer is no

afaik https://visionvelo.eu/ wanted to look into making something more custom for intend forks this fall, but haven't heard anything recent yet, but probably something like their ext vaia fender: https://visionvelo.eu/product/ext-vaia-mx-mudguard/

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TEAMROBOT
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8/20/2025 1:36pm Edited Date/Time 8/20/2025 1:36pm
Nic Cotton wrote:
Does anyone know if there are stanchion guards that incorporate a mudguard to fit Intend's forks? Kinda like the ones that Push have (see photo). Its...

Does anyone know if there are stanchion guards that incorporate a mudguard to fit Intend's forks? Kinda like the ones that Push have (see photo). Its the one off putting thing about USD forks for me, especially living in Ireland where you need something year round really. I know Intend have their own mudguard that fits into the bottom of the steerer tube, but it doesn't seem like as clean a solution. 

Alternatively, I wonder if Push's mudguard could be modded to fit with the intend forks?

 4385d.jpg?VersionId=Jtg J78lICX2EnQ8mL95mBSvsiEdRn9

Whoever can make an aftermarket Push-style mudguard for the Podium that sits closer to the tire is going to make dozens of dollars. I know I'll buy one.

2
Suns_PSD
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8/20/2025 1:40pm Edited Date/Time 8/20/2025 1:45pm
I believe lower leg replacement from Intend is only 70 Euro, so very reasonable. It's the whole back and forth from Germany that could add some time...

I believe lower leg replacement from Intend is only 70 Euro, so very reasonable. 

It's the whole back and forth from Germany that could add some time and money.

The legs are priced reasonably (on the standard, not the Blackline which is a single piece and therefore surely more expensive) but also require a press. The issue is that the Intend forks are claimed to be carefully part matched so your particular parts don't bind.

I'd rather spend $250 more to protect the legs than mess with all that down the road.

For me, it's not a fork I'd own if I could not rig up some quality fork leg protection.

 

Anyways, I'm building up a new bike for the Fall to replace the Relay. It'll likely be a Regulator, Sidekick hubs laced to M8 Enve rims & probably the Intend fork.

I do want to work a bit more on getting happier with my Avy Hybrid Mezzer though. I've ridden units that have been amazing, but mine just isn't.

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8/20/2025 3:18pm
Nic Cotton wrote:
Does anyone know if there are stanchion guards that incorporate a mudguard to fit Intend's forks? Kinda like the ones that Push have (see photo). Its...

Does anyone know if there are stanchion guards that incorporate a mudguard to fit Intend's forks? Kinda like the ones that Push have (see photo). Its the one off putting thing about USD forks for me, especially living in Ireland where you need something year round really. I know Intend have their own mudguard that fits into the bottom of the steerer tube, but it doesn't seem like as clean a solution. 

Alternatively, I wonder if Push's mudguard could be modded to fit with the intend forks?

 4385d.jpg?VersionId=Jtg J78lICX2EnQ8mL95mBSvsiEdRn9

TEAMROBOT wrote:
Whoever can make an aftermarket Push-style mudguard for the Podium that sits closer to the tire is going to make dozens of dollars. I know I'll...

Whoever can make an aftermarket Push-style mudguard for the Podium that sits closer to the tire is going to make dozens of dollars. I know I'll buy one.

They would need to make sure that they had a licensing deal in place with us before doing that. We have a pending global patent in place for our fender system. 

 

Fender 0

 

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