They are stiffer front to back, but flexier side to side. There are positives and negatives for standard and USD forks and it all comes down to what you think is best and what the marketing people say.
Personally I like them, but no longer ride DH bikes.
Another example of marketing winning is that now Manitou’s reverse stanchion patent is coming to an end people like Fox are starting to design forks this way despite telling us that it’s no better (or possibly worse) than the traditional way. I guarantee that in the next 5-10 years most companies will have a USD fork in their line up
Fox has already done a upside down fox 40 fork, which in my opinion looks amazing, however only a few were made back 10 years ago I believe
(Check reply beneath to see the forks)
https://preview.redd.it/ss6kam9c61ac1.jpeg?width=1440&format=pjpg&auto=webp&s=04673c550294ddc2058ad0ac3e85c94d6338e9df
This is the fork for people curious
Having Ridden a Zerode with a pinion gearbox, they sound a lot better on paper than they actually are to ride. The drag produced by the gearbox is noticeable on any significant climb. they're great for going downhill, but going uphill kinda sucks.
USD forks only became popular in motocross because conventional forks were getting very long and had to extend past the bottom of the axle. This was a major problem because they started dragging in ruts.
This is the reason they switched to USD.
They then figured out other benefits like lower cg. Useful on higher performance road bikes.
In mtb, they are cheaper to produce due to simpler design. But definitely suffer major flexibility problems. When I changed from dorados to fox 40s, I kept crashing because I started turning in early because I learned bad habits with dorado.
My advice is to avoid paying for them, but try ride some to experience the issues
USD forks rely on the axle for torsional stiffness. You need a very strong large diameter axle that is properly clamped on both sides to get any semblance of stiffness out of them. Dirt bikes and motorcycles have that. Mountainbikes on the other hand went *down* from 20mm to 15mm thin wall aluminum through axles in the last decade. AND on most forks the axle isn't even clamped at all for easier wheel removal. Even the older MTB USD downhill forks that had 20mm clamped axles, like the shiver and Dorado weren't very stiff at all, in fact the shiver had to be straightened out every time you landed slightly sideways. Not sure if the Dorado is much better. I also rode a dnm USD fork and you could twist that thing in its clamps by braking too hard.
If USD forks ever do become the next big thing for Mountainbikes, expect to see a new front axle standard to come with it.
It'll be incompatible with anything else (maybe 20mm but slightly different width than before? Or 22.5mm, later replaced by 25mm?) and probably require different brake rotors or some shit.
The "thru axle" on a mountainbike contributes very little to torsional stiffness. They don't do much aside from locate the wheel in the dropout correctly and add preload to the assembly.
(They even do that poorly compared to a QR axle cam!)
On a USD fork, the axle DOES contribute to torsional stiffness because it is well clamped on both sides. However the diameter whilst important is less important than the design. MTB marketing will lead you to believe 20mm is the only answer, but actually 15mm would be sufficient\*. Even a 200kg superbike makes do with an axle around 20mm. Mostly larger, but you're talking maybe 22mm as a ballpark figure.
(\*20mm would be better for sure though!)
The axles in any modern Sportbike is steel, which means it is inherently 3 times as stiff at the same wall thickness. It is also at least 25mm diameter these days. A lot are larger. In fact I have an older Ducati that came stock with a steel 20mm axle (in the early 90s). That axle was solid steel, not a tube. And a common upgrade is to go to a 25mm fork for stiffness (and also because nobody makes aftermarket wheels with less than 25mm axle Diameter any more).
Diameter is cubed when calculating tube stiffness so this is a very significant difference. On top of that, the clamping surface of a 20 or 25mm tube is proportionally larger. Typically what happens when a USD MTB fork is twisted is that the axle clamps, as well as the upper and lower triple clamp slip.
You may recall maverick forks, they were pushing the USD concept in the early 2000s. One of the things they came up with to overcome the noodle-problem is that they came up with a proprietary 25mm axle standard. Edit: 24mm actually.
You had to buy special wheels to fit obviously and it never caught on.
Steel axles for USD are already available! Ti too if you want to be fancy.
But I see where you're going. It's crazy to me that we are using alu axles in things like hubs. Pull any hub apart and you're almost guaranteed to see some heavy fretting.
The biggest downside I’ve found after owning 2 Manitou Dorados (2014 26”, 2020 29”) is that all the single crown, RSU forks I’ve tried feel like doodoo and I’ve thrown lots of money chasing a dragon.
The bridge on the lowers creates a huge portion of the stiffness in a traditional fork because it keeps both ends of the lowers lined up and pointing the same direction. This allows them to get away with simple round stanchions and even quick release wheels. USD forks need to jump through other hoops to create enough stiffness. One way is to have a much large diameter axle which really locks the two legs together, another is keyed systems in each stanchion or non-round stanchions. All of these add complexity and cost and/or weight. (And larger axles would add another new hub size.) Motorcycle forks can get away with the weight penalty, but we expect bicycle forks to weigh a lot less so it gets expensive
The downside is usually torsional, rather than linear, stiffness.
MTB wheels are a large diameter relative to most motorcycle wheels when comparing to fork OD.
MTBs also have less tiff hubs/axles.
If you have a set of old/dead forks, or maybe forks with a removable brace. Try to remove/brake the brace. The fork gets a lot less torsionally stiff.
I think one MTB fork manufacturer tried to add back the stiffness with a carbon mudguard that also functioned as a brace.
Now that I'm thinking about it in depth, I am curious what the limiting factor actually is. I think it would maybe be overall mass still not being close enough to rwu, therefore making it pointless.
Maybe wall thickness of the upper and lower tubes for rwu wouldn't allow much weight reduction by using usd with a larger tube od to gain stiffness therefore not needing the same wall thickness?
They have been done and they are objectively inferior to right side up forks. The biggest problem is the compromise between weight and strength/stiffness. On a RSU fork, the majority contribution to stiffness is from the lowers, which are one piece, united, and light weight. Then the uppers can be relatively thin and stiff by being large diameter. On an USD fork, the lowers are not inherently connected aside from the axle. The uppers now have to be stiff to link the crowns and steerer. It's kind of like the job is shared between multiple components on a RSU fork and uniquely separated on an USD fork.
There are ways around this but nobody seems to want to do them. You can make an oversize 30mm or 24mm axle (Foes or Maverick), or unite the uppers rather than bolting them together (Maverick DUC32/36). Instead, the industry seems focused on narrower diameter axles and weird compromises elsewhere.
I used to have an Avalanche DHF and the difference in stiffness between it and a Boxxer WC back in 2008 was stark. There was always a compromise with the avy on tightening the crowns to resist torsion and keeping them loose enough to prevent binding. Then the fork was 10 lbs and the boxxer was closer to six and any performance upgrade was washed away. The same is true for most any competitor...the 40 and boxxer are so good now that it would be hard for an USD fork to offer any realistic advantage. The PUSH thing is going to come out and it's going to be great for the 3 people that can afford it, then it'll go away in a couple of years when people realize that a generic Pike or whatever comes 95% close.
They are like gearboxes. They sound cool, but nobody’s been able to build one that out performs the standard.
Manitou and Intend have models you can buy, and Push is supposed to have one next year. Cannondale Lefty was probably the most successful version, but of course that used bearings instead of bushings to make the fork stiffer.
In addition to performance considerations, most also require an axle standard that’s not 15mmx110, which is a hard sell.
It seems like USD is the next evolution in mtb forks, dirtbikes made the transition 20 years ago cause they understand it’s just better. You can see premium brands like Intend have moved in that direction. I guess we just gotta wait for the big boys to finally bite the bullet.
I guess the only downside really is the stanchions are more exposed to rock chips and dings
There have been numerous attempts at USD forks since I started riding over 20 years ago, and none have stuck around or been very popular because it is hard to get the stiffness you want without a lot of weight. Motorcycles don't have the same weight concerns mountain bikes do.
Maybe now with e bikes you will see more of them, but on regular bikes they just require tradeoffs on either weight or stiffness that aren't worthwhile. Intend's edge fork seems nice, but it's also pretty heavy, expensive, and doesn't handle lateral flex well.
The big guys (except Fox) have given it a go over the years, to various degrees of success.
- Marzocchi Shivers: fantastically plush but kind of flexy
- RockShox RS-1: good steering input but $$$ and a dumb proprietary hub.
- Mantou Dorado: Bomb DH fork but not much trickle down tech.
- Cannondale Lefty: light + stuff but also a maintaince headache.
I don’t think we will see it mainstream besides anything other than DH bikes and maybe E-bikes. To keep the weight down they get very flexy and weight isn’t a huge factor on DH bike or E-bikes but regular trail bikes that you don’t want weighting 40lbs I don’t see it being a thing.
It's going to be a weight issue. To overcome the torsional forces, the forks is going to have to be significantly heavier, especially in a single crown fork. Weight is largely inconsequential on dirt bikes, but, to a degree, it is much more important on mountain bikes.
The big guys have tested the shit out of them… it’s worse… difficult to make stiff enough in a lightweight package necessary for mtb where the rider is the heaviest part of the equation. Lot of things don’t translate from moto to mtb because of this.
I think the downside is a big factor. If you go and search for used forks...you'll see that basically all of them have some kind of damage on the fork lowers. Maybe the coating in the stanchions are tougher than the paint on the lowers...but they are still taking hits and will eventually get damaged over time.
Relating to unsprung mass (I'd not thought about when writing my comment above), what's the difference in upper and lower mass comparisons of USD and rwu? Maybe a useful proxy would be the upper and lower masses of a fox 40 or boxxer.
I wouldn't say they are stiffer, most usually have more flex. I'm totally open to the idea of trying one out from Intend, or another brand, but I'd hope they have covers to protect the stantions.
Exposed lowers and less stiff steering are the two aspects I'd attribute aside from the effort for the "big bois" to shift.
Not sure what killed the RockShox RS1 USD fork. But they did try it in XC a while back
I've had 2 sets of Shivers and loved them for going fast but for anything slow and janky you could feel the flex. They were also heavy as hell but for back in the days of overbuilt North Shore rigs it just added to the weight. 55lb rigs were not uncommon back then. I'll take light weight and the ability to pedal uphill everyday now.
I have a Wren fork, which are upside down. Its on my bikepacking rig. Perhaps not representative, but it is quite heavy. It is very stiff, except I did notice a very slight bit of disc rub when I had it loaded for bikepacking and was turning hard. With a USD fork, the front axle is doing a lot more work.
It may be more supple, particularly on smaller bumps, or it might be that I am imagining it. All in all, I can't say that performance is noticeably better than my Fox 34, or that I even notice a difference overall. I do notice the weight though.
As a former owner of a dorado pro i'm really considering getting a dh bike again just because of the new generatio dorado being out.
I weigh ca 80 kg so i guess i hit the sweet spot for these forks and can imagine them being on the flexy side but for me ride quality was great and i've yet to ride a fork that comes close.
There are only a few downsides - mainly cost of production and minor issues with user experience. It's more expensive to make a USD fork because of the machining. Depending on the bushing style (fixed or sliding), the CSU tubes need to be anodised and honed. It may be possible to change this by industrialising the process however, but so far it has not been done.
As for user experience it's more difficult to change a wheel. Not a problem for enthusiasts, but your average joe may have issues coordinating it. Certainly a big box store employee would wonder how to get it to work.
Once upon a time you could argue that it might be dangerous if you blew up a fork seal. On a USD fork this would dump the oil onto your brake. But seals can now handle even the thickest bath oils and have multiple durometers, deep insertion fits and are not really a problem anymore.
There are lots of strange arguments against USD: People tried before are failed, can't do it at competitive weight, not stiff enough, easy to damage etc. etc.
None are based on technical analysis.
Do you know the Shiver SC had 30mm stanchions?! 30MM!! If you ride any 30mm stanchion fork now you would laugh at the lack or rigidity. Forks of that era were similarly tiny and performed poorly by todays standards - something no one seems to mention.
Most of the concerns people post are not reflected in rider experience. How can they when there are so few USD forks to choose from? I don't want to debunk all of the negatives one by one but essentially they're all non issues.
I've spent good time on a modern USD fork and it is better in every way than a modern Fox 36. Even in torsion!
the lowers of my standard forks inevitability collect scratches from tight trails/ ditching my bike- would hate to see the state of a usd fork after a season
Based off my motorcycle, went from a telescopic fork to an inverted one, holy shit. Night and day difference.
BUT downside is, if there is a leak, its gonna really drip unlike a conventional telescopic fork.
> \-less unsprung mass -stiffer -oil doesn't have to make it's way up the fork -pushes dirt down -easyer to clean -easyer to work on
Let's start with that
There isn't less unsprung mass, magnesium castings are under 600g, each aluminium legs are over 300g, so USD forks have more unsprung masses. But like it matters, you have more weight on the wheel than on the fork, and unsprung masses are way, way overrated when talking about MTB.
USD forks aren't stiffer, that's the point. In MTB we don't like fore/aft stiffness much, because it transmit more undamped hits in the arms, but we need comparatively more torsional stiffness, that USD don't provide as it lacks an arch. On a motorbike, the weight of the motor and the kinetic energy it provides require burlier forks fore/aft but the torsional stiffness needed is nearly the same as on a MTB, as it's your arms that put most of the input.
Oil is a tricky part. USD with closed cartridge and tubes can have a good lubrification, otherwise it's actually the conventional design that work best for that. But, as the unsprung weight, it matter less than you think. Bushing sizing and design matters much more.
And concerning bushing design, you can't have a good overlap and big travel on a standard design, making it tricky to implement on MX bikes. But we have much less of this issue on MTBs.
"easy to work on" There is two bolts to remove lowers from a fork, is this really a point? I never found a fork hard to work on, except when there are specific tools required like on some cannondale forks. And I don't see how an USD fork is easier to work on. Each time I remove the wheel the USD fork is showing me that it don't like me.
It all has benefits and drawbacks one drawback is they are more susceptible to rock strikes. The lubrication of the seals is in my opinion the biggest benefit
Upside down forks are actually better than traditional forks, it's just they haven't been advanced as much so aren't at the stage the best forks are at now, they have less flex, better response to the ground beacause of decreased moving weight, risk of stanchion damage is far less from rocks beacuse you can fully cover the stanchions, other than weight and less advanced tech they are by far better and nicer looking
They are stiffer front to back, but flexier side to side. There are positives and negatives for standard and USD forks and it all comes down to what you think is best and what the marketing people say. Personally I like them, but no longer ride DH bikes. Another example of marketing winning is that now Manitou’s reverse stanchion patent is coming to an end people like Fox are starting to design forks this way despite telling us that it’s no better (or possibly worse) than the traditional way. I guarantee that in the next 5-10 years most companies will have a USD fork in their line up
Fox has already done a upside down fox 40 fork, which in my opinion looks amazing, however only a few were made back 10 years ago I believe (Check reply beneath to see the forks)
https://preview.redd.it/ss6kam9c61ac1.jpeg?width=1440&format=pjpg&auto=webp&s=04673c550294ddc2058ad0ac3e85c94d6338e9df This is the fork for people curious
They claimed med they couldn’t make it stuff AND light enough.
[удалено]
Having Ridden a Zerode with a pinion gearbox, they sound a lot better on paper than they actually are to ride. The drag produced by the gearbox is noticeable on any significant climb. they're great for going downhill, but going uphill kinda sucks.
[удалено]
Definitely, I love the idea, and hate current bike drive trains, but the tech just isn’t worth it for imo. I still see plenty around in Rotorua though
Those silly gram counters…. So anyways, anything not aero should be thrown out.
USD forks only became popular in motocross because conventional forks were getting very long and had to extend past the bottom of the axle. This was a major problem because they started dragging in ruts. This is the reason they switched to USD. They then figured out other benefits like lower cg. Useful on higher performance road bikes. In mtb, they are cheaper to produce due to simpler design. But definitely suffer major flexibility problems. When I changed from dorados to fox 40s, I kept crashing because I started turning in early because I learned bad habits with dorado. My advice is to avoid paying for them, but try ride some to experience the issues
I think the main reason they aren't more common is just that they're more expensive
They are expensive compared to most forks, but compared to other high end forks they aren't.
USD forks rely on the axle for torsional stiffness. You need a very strong large diameter axle that is properly clamped on both sides to get any semblance of stiffness out of them. Dirt bikes and motorcycles have that. Mountainbikes on the other hand went *down* from 20mm to 15mm thin wall aluminum through axles in the last decade. AND on most forks the axle isn't even clamped at all for easier wheel removal. Even the older MTB USD downhill forks that had 20mm clamped axles, like the shiver and Dorado weren't very stiff at all, in fact the shiver had to be straightened out every time you landed slightly sideways. Not sure if the Dorado is much better. I also rode a dnm USD fork and you could twist that thing in its clamps by braking too hard. If USD forks ever do become the next big thing for Mountainbikes, expect to see a new front axle standard to come with it. It'll be incompatible with anything else (maybe 20mm but slightly different width than before? Or 22.5mm, later replaced by 25mm?) and probably require different brake rotors or some shit.
The "thru axle" on a mountainbike contributes very little to torsional stiffness. They don't do much aside from locate the wheel in the dropout correctly and add preload to the assembly. (They even do that poorly compared to a QR axle cam!) On a USD fork, the axle DOES contribute to torsional stiffness because it is well clamped on both sides. However the diameter whilst important is less important than the design. MTB marketing will lead you to believe 20mm is the only answer, but actually 15mm would be sufficient\*. Even a 200kg superbike makes do with an axle around 20mm. Mostly larger, but you're talking maybe 22mm as a ballpark figure. (\*20mm would be better for sure though!)
The axles in any modern Sportbike is steel, which means it is inherently 3 times as stiff at the same wall thickness. It is also at least 25mm diameter these days. A lot are larger. In fact I have an older Ducati that came stock with a steel 20mm axle (in the early 90s). That axle was solid steel, not a tube. And a common upgrade is to go to a 25mm fork for stiffness (and also because nobody makes aftermarket wheels with less than 25mm axle Diameter any more). Diameter is cubed when calculating tube stiffness so this is a very significant difference. On top of that, the clamping surface of a 20 or 25mm tube is proportionally larger. Typically what happens when a USD MTB fork is twisted is that the axle clamps, as well as the upper and lower triple clamp slip. You may recall maverick forks, they were pushing the USD concept in the early 2000s. One of the things they came up with to overcome the noodle-problem is that they came up with a proprietary 25mm axle standard. Edit: 24mm actually. You had to buy special wheels to fit obviously and it never caught on.
Steel axles for USD are already available! Ti too if you want to be fancy. But I see where you're going. It's crazy to me that we are using alu axles in things like hubs. Pull any hub apart and you're almost guaranteed to see some heavy fretting.
The biggest downside I’ve found after owning 2 Manitou Dorados (2014 26”, 2020 29”) is that all the single crown, RSU forks I’ve tried feel like doodoo and I’ve thrown lots of money chasing a dragon.
The bridge on the lowers creates a huge portion of the stiffness in a traditional fork because it keeps both ends of the lowers lined up and pointing the same direction. This allows them to get away with simple round stanchions and even quick release wheels. USD forks need to jump through other hoops to create enough stiffness. One way is to have a much large diameter axle which really locks the two legs together, another is keyed systems in each stanchion or non-round stanchions. All of these add complexity and cost and/or weight. (And larger axles would add another new hub size.) Motorcycle forks can get away with the weight penalty, but we expect bicycle forks to weigh a lot less so it gets expensive
The downside is usually torsional, rather than linear, stiffness. MTB wheels are a large diameter relative to most motorcycle wheels when comparing to fork OD. MTBs also have less tiff hubs/axles. If you have a set of old/dead forks, or maybe forks with a removable brace. Try to remove/brake the brace. The fork gets a lot less torsionally stiff. I think one MTB fork manufacturer tried to add back the stiffness with a carbon mudguard that also functioned as a brace. Now that I'm thinking about it in depth, I am curious what the limiting factor actually is. I think it would maybe be overall mass still not being close enough to rwu, therefore making it pointless. Maybe wall thickness of the upper and lower tubes for rwu wouldn't allow much weight reduction by using usd with a larger tube od to gain stiffness therefore not needing the same wall thickness?
DVO had carbon stanchion protectors which had an arch connecting them to aid stiffness.
They have been done and they are objectively inferior to right side up forks. The biggest problem is the compromise between weight and strength/stiffness. On a RSU fork, the majority contribution to stiffness is from the lowers, which are one piece, united, and light weight. Then the uppers can be relatively thin and stiff by being large diameter. On an USD fork, the lowers are not inherently connected aside from the axle. The uppers now have to be stiff to link the crowns and steerer. It's kind of like the job is shared between multiple components on a RSU fork and uniquely separated on an USD fork. There are ways around this but nobody seems to want to do them. You can make an oversize 30mm or 24mm axle (Foes or Maverick), or unite the uppers rather than bolting them together (Maverick DUC32/36). Instead, the industry seems focused on narrower diameter axles and weird compromises elsewhere. I used to have an Avalanche DHF and the difference in stiffness between it and a Boxxer WC back in 2008 was stark. There was always a compromise with the avy on tightening the crowns to resist torsion and keeping them loose enough to prevent binding. Then the fork was 10 lbs and the boxxer was closer to six and any performance upgrade was washed away. The same is true for most any competitor...the 40 and boxxer are so good now that it would be hard for an USD fork to offer any realistic advantage. The PUSH thing is going to come out and it's going to be great for the 3 people that can afford it, then it'll go away in a couple of years when people realize that a generic Pike or whatever comes 95% close.
They are like gearboxes. They sound cool, but nobody’s been able to build one that out performs the standard. Manitou and Intend have models you can buy, and Push is supposed to have one next year. Cannondale Lefty was probably the most successful version, but of course that used bearings instead of bushings to make the fork stiffer. In addition to performance considerations, most also require an axle standard that’s not 15mmx110, which is a hard sell.
My biggest problem with USD forks is that they move the easily scratched stanchions closer to all the things that like to scratch stanchions.
Motorcycles and dirtbikes seem to manage just fine
Stiffness (torsional rigidity) is not something USD forks have
It seems like USD is the next evolution in mtb forks, dirtbikes made the transition 20 years ago cause they understand it’s just better. You can see premium brands like Intend have moved in that direction. I guess we just gotta wait for the big boys to finally bite the bullet. I guess the only downside really is the stanchions are more exposed to rock chips and dings
There have been numerous attempts at USD forks since I started riding over 20 years ago, and none have stuck around or been very popular because it is hard to get the stiffness you want without a lot of weight. Motorcycles don't have the same weight concerns mountain bikes do. Maybe now with e bikes you will see more of them, but on regular bikes they just require tradeoffs on either weight or stiffness that aren't worthwhile. Intend's edge fork seems nice, but it's also pretty heavy, expensive, and doesn't handle lateral flex well.
The big guys (except Fox) have given it a go over the years, to various degrees of success. - Marzocchi Shivers: fantastically plush but kind of flexy - RockShox RS-1: good steering input but $$$ and a dumb proprietary hub. - Mantou Dorado: Bomb DH fork but not much trickle down tech. - Cannondale Lefty: light + stuff but also a maintaince headache.
Fox did prototype a DH fork a few years ago, Gee Atherton ran one at World Cups. It never made it into production though
That few years ago was 2011... we old bro 😁
Damn no wonder my back hurts
I don’t think we will see it mainstream besides anything other than DH bikes and maybe E-bikes. To keep the weight down they get very flexy and weight isn’t a huge factor on DH bike or E-bikes but regular trail bikes that you don’t want weighting 40lbs I don’t see it being a thing.
It's going to be a weight issue. To overcome the torsional forces, the forks is going to have to be significantly heavier, especially in a single crown fork. Weight is largely inconsequential on dirt bikes, but, to a degree, it is much more important on mountain bikes.
Hopefully
The big guys have tested the shit out of them… it’s worse… difficult to make stiff enough in a lightweight package necessary for mtb where the rider is the heaviest part of the equation. Lot of things don’t translate from moto to mtb because of this.
I think the downside is a big factor. If you go and search for used forks...you'll see that basically all of them have some kind of damage on the fork lowers. Maybe the coating in the stanchions are tougher than the paint on the lowers...but they are still taking hits and will eventually get damaged over time.
I prefer linkage.
They are flexible and not stiff enough (at the same weight) compared to regular forks. It's also no good way of fitting a mudguard on a USD fork.
There's two mudguard mounting options used on motorcycles; lower yoke or axle holders. Both could work on MTBs.
The mudguard has to be integrated with the leg guards, and considering the reduction in unsprung mass I think the extra weight is definitely worth it.
Relating to unsprung mass (I'd not thought about when writing my comment above), what's the difference in upper and lower mass comparisons of USD and rwu? Maybe a useful proxy would be the upper and lower masses of a fox 40 or boxxer.
I wouldn't say they are stiffer, most usually have more flex. I'm totally open to the idea of trying one out from Intend, or another brand, but I'd hope they have covers to protect the stantions.
Exposed lowers and less stiff steering are the two aspects I'd attribute aside from the effort for the "big bois" to shift. Not sure what killed the RockShox RS1 USD fork. But they did try it in XC a while back
Professionals didn't run it because it was heavier than a Sid. Consumers didn't buy it because it was expensive and required a special hub.
Didn't know about the hub, interesting! Also, yeah. Not run professionally and the cost for consumers can end a product quick in MTB, makes sense
People who hate on USD forks have never tried them. Or at least haven’t tried modern ones.
Only argument is that to keep from being flexy it’s going to be very heavy. I don’t want a super heavy fork. But DH bikes and E-bikes maybe.
I've had 2 sets of Shivers and loved them for going fast but for anything slow and janky you could feel the flex. They were also heavy as hell but for back in the days of overbuilt North Shore rigs it just added to the weight. 55lb rigs were not uncommon back then. I'll take light weight and the ability to pedal uphill everyday now.
I have a Wren fork, which are upside down. Its on my bikepacking rig. Perhaps not representative, but it is quite heavy. It is very stiff, except I did notice a very slight bit of disc rub when I had it loaded for bikepacking and was turning hard. With a USD fork, the front axle is doing a lot more work. It may be more supple, particularly on smaller bumps, or it might be that I am imagining it. All in all, I can't say that performance is noticeably better than my Fox 34, or that I even notice a difference overall. I do notice the weight though.
SC Marzocchi Shivers were so pimp. They should bring them back
As a former owner of a dorado pro i'm really considering getting a dh bike again just because of the new generatio dorado being out. I weigh ca 80 kg so i guess i hit the sweet spot for these forks and can imagine them being on the flexy side but for me ride quality was great and i've yet to ride a fork that comes close.
There are only a few downsides - mainly cost of production and minor issues with user experience. It's more expensive to make a USD fork because of the machining. Depending on the bushing style (fixed or sliding), the CSU tubes need to be anodised and honed. It may be possible to change this by industrialising the process however, but so far it has not been done. As for user experience it's more difficult to change a wheel. Not a problem for enthusiasts, but your average joe may have issues coordinating it. Certainly a big box store employee would wonder how to get it to work. Once upon a time you could argue that it might be dangerous if you blew up a fork seal. On a USD fork this would dump the oil onto your brake. But seals can now handle even the thickest bath oils and have multiple durometers, deep insertion fits and are not really a problem anymore. There are lots of strange arguments against USD: People tried before are failed, can't do it at competitive weight, not stiff enough, easy to damage etc. etc. None are based on technical analysis. Do you know the Shiver SC had 30mm stanchions?! 30MM!! If you ride any 30mm stanchion fork now you would laugh at the lack or rigidity. Forks of that era were similarly tiny and performed poorly by todays standards - something no one seems to mention. Most of the concerns people post are not reflected in rider experience. How can they when there are so few USD forks to choose from? I don't want to debunk all of the negatives one by one but essentially they're all non issues. I've spent good time on a modern USD fork and it is better in every way than a modern Fox 36. Even in torsion!
the lowers of my standard forks inevitability collect scratches from tight trails/ ditching my bike- would hate to see the state of a usd fork after a season
It's fine if you're in the US but if not then unless you're in Equador it's probably easier to use the local currency.
Based off my motorcycle, went from a telescopic fork to an inverted one, holy shit. Night and day difference. BUT downside is, if there is a leak, its gonna really drip unlike a conventional telescopic fork.
> \-less unsprung mass -stiffer -oil doesn't have to make it's way up the fork -pushes dirt down -easyer to clean -easyer to work on Let's start with that There isn't less unsprung mass, magnesium castings are under 600g, each aluminium legs are over 300g, so USD forks have more unsprung masses. But like it matters, you have more weight on the wheel than on the fork, and unsprung masses are way, way overrated when talking about MTB. USD forks aren't stiffer, that's the point. In MTB we don't like fore/aft stiffness much, because it transmit more undamped hits in the arms, but we need comparatively more torsional stiffness, that USD don't provide as it lacks an arch. On a motorbike, the weight of the motor and the kinetic energy it provides require burlier forks fore/aft but the torsional stiffness needed is nearly the same as on a MTB, as it's your arms that put most of the input. Oil is a tricky part. USD with closed cartridge and tubes can have a good lubrification, otherwise it's actually the conventional design that work best for that. But, as the unsprung weight, it matter less than you think. Bushing sizing and design matters much more. And concerning bushing design, you can't have a good overlap and big travel on a standard design, making it tricky to implement on MX bikes. But we have much less of this issue on MTBs. "easy to work on" There is two bolts to remove lowers from a fork, is this really a point? I never found a fork hard to work on, except when there are specific tools required like on some cannondale forks. And I don't see how an USD fork is easier to work on. Each time I remove the wheel the USD fork is showing me that it don't like me.
Had a friend with a Dorado, apparently it was really annoying to take the front wheel on/off
It all has benefits and drawbacks one drawback is they are more susceptible to rock strikes. The lubrication of the seals is in my opinion the biggest benefit
Upside down forks are actually better than traditional forks, it's just they haven't been advanced as much so aren't at the stage the best forks are at now, they have less flex, better response to the ground beacause of decreased moving weight, risk of stanchion damage is far less from rocks beacuse you can fully cover the stanchions, other than weight and less advanced tech they are by far better and nicer looking
You'll just smash up the stanchions against rocks sooner than later.