Just a theory here but... I've heard plenty of complaints that the Fox 40 is just too stiff. What if the new 38 enduro fork is...
Just a theory here but... I've heard plenty of complaints that the Fox 40 is just too stiff. What if the new 38 enduro fork is a test bed not only for a burlier single crown as well as a slightly more compliant DH fork? The Fox 389?
i'd generally be inclined to agree, however remember a few years back Fox developed and abandoned an inverted 40 because it wasn't stiff enough?
Just a theory here but... I've heard plenty of complaints that the Fox 40 is just too stiff. What if the new 38 enduro fork is...
Just a theory here but... I've heard plenty of complaints that the Fox 40 is just too stiff. What if the new 38 enduro fork is a test bed not only for a burlier single crown as well as a slightly more compliant DH fork? The Fox 389?
i'd generally be inclined to agree, however remember a few years back Fox developed and abandoned an inverted 40 because it wasn't stiff enough?
That was because inverted forks are far less stiff to start with. I very much doubt they would be unable to design a conventional 38mm DH fork that that wasn't at least as stiff as a 38mm Ohlins or 35mm Boxxer. I also doubt we'll see it happen though.
Just a theory here but... I've heard plenty of complaints that the Fox 40 is just too stiff. What if the new 38 enduro fork is...
Just a theory here but... I've heard plenty of complaints that the Fox 40 is just too stiff. What if the new 38 enduro fork is a test bed not only for a burlier single crown as well as a slightly more compliant DH fork? The Fox 389?
That was because inverted forks are far less stiff to start with. I very much doubt they would be unable to design a conventional 38mm DH...
That was because inverted forks are far less stiff to start with. I very much doubt they would be unable to design a conventional 38mm DH fork that that wasn't at least as stiff as a 38mm Ohlins or 35mm Boxxer. I also doubt we'll see it happen though.
earlier when i posted that i pulled up Fox's statement on the inverted 40 that was published on pinkbike...... in 2012.... the fore/aft stiffness was higher but torsional stiffness was lower, both aspects in comparison to the regular 40. they could have made it stiffer torsionally but not at a weight that anyone would be willing to accept.
but to your point, i agree i don't think a dual crown 38 is in the cards. Just not enough demand to justify the production of it, especially if the single crown version is made stiff enough.
Just a theory here but... I've heard plenty of complaints that the Fox 40 is just too stiff. What if the new 38 enduro fork is...
Just a theory here but... I've heard plenty of complaints that the Fox 40 is just too stiff. What if the new 38 enduro fork is a test bed not only for a burlier single crown as well as a slightly more compliant DH fork? The Fox 389?
Just a theory here but... I've heard plenty of complaints that the Fox 40 is just too stiff. What if the new 38 enduro fork is...
Just a theory here but... I've heard plenty of complaints that the Fox 40 is just too stiff. What if the new 38 enduro fork is a test bed not only for a burlier single crown as well as a slightly more compliant DH fork? The Fox 389?
That was because inverted forks are far less stiff to start with. I very much doubt they would be unable to design a conventional 38mm DH...
That was because inverted forks are far less stiff to start with. I very much doubt they would be unable to design a conventional 38mm DH fork that that wasn't at least as stiff as a 38mm Ohlins or 35mm Boxxer. I also doubt we'll see it happen though.
Actually inverted forks should be stiffer than conventional forks. Back-and-forth that is. It's the torsional stiffness that does them in.
If you have a cantilever with a load applied to it on the end (which is what a fork is), ideally the cross section would increase from the point of the load (axle) towards the anchor point (crown). Inverted forks have more meat towards the anchor point so they gain stiffness in this regard. Plus their lubricated seals and all.
But yeah, torsion is a bitch... A "dual lefty" would probably solve those issues, but would bring aforementioned issues with it, some more weight and a lot more cost (facing off the tubes to accept the needle bearings must be a PITA to do accurately, plus to prepare the interfacing surfaces in the outer tube as well...
Just a reminder that back in day of Nico V. and Sunn Bikes they used USD forks BECAUSE of their torsional flex and even engineered it INTO systems to help the bike flow down the track better. And as well, Manitou's Hex axle system did a great job of managing it. I never had any problems with mine.
More pictures of the 40 RAD fork [img]https://p.vitalmtb.com/photos/forums/2020/02/20/9229/s1200_2020_02_20_1312.jpg[/img]
[img]https://p.vitalmtb.com/photos/forums/2020/02/20/9230/s1200_2020_02_20_1311.jpg[/img]
More pictures of the 40 RAD fork
Looks like less offset at the dropout/axle. Syndicate ran Mojo crowns last season....is this Fox’s answer to that?
jeff.brines as sspomer kind of showed, follow Cornelius Kapfinger from Intend, he has both a single crown and a dual crown USD fork on offer plus the Hover shock coming out, which basically uses the piggyback pressure as the spring (designed properly of course).
As for USD forks and moto, yeah, they can deal with more weight. That means thicker tubes with thicker walls, stronger clamps, a thicker (diameter and wall thickness) axle, more clamping area overlap, etc. Plus higher longitudinal stiffness is not a problem for them since they, firstly, hit obstacles with more energy (higher speed, double the weight of a MTB bike-rider system), secondly ride on, dare i say it, smoother tracks (the nature of MTB and MX riding is completely different, but by no means easier for MX!). The torsional stiffness does not incur such a difference between the two since it's still your arms dealing with most of the forces. So the change in torsional stiffness gives a 'linear gain' but a change in longitudinal stiffness is not so 'linear' (different system characteristics with different responses and different requirements). And when i mentioned smoother tracks, maybe the torsional stiffness, even if it's on the same level, is less of a problem for the 'smoother' riding of MX compared to MTB where you often need more precision to put the relatively thin tyre between two rocks, roots and the like?
As for standard forks in moto, they had them. But apparently the USD type works for them. Like we had and have USD forks in MTB, but have mostly the 'right-side-up' (RSU? Could it be DSU?
) forks in MTB. Because the benefits outweigh the negatives?
As for history, that point has already been made and is in full swing. We have a single speed consolidation of drivetrains, 'everything looks like a session' (just like MX bikes are indistinguishable between each other without graphics if you're not an MX nut), wheel sizes that you mentioned, etc.
As for dual crown vs. single crown, I think that wouldn't make much of a difference.
Speaking of putting money where your mouth is, i think a comparison analysis could actually be made with Ansys. It would be good enough for a comparison, just put a 'parking lot test' level of steering and fore-aft force into the system and see the response of a simplified (empty) fork that is either USD or RSU, has different slider diameters and thicknesses, different axle diameter, thicknesses and axle overlaps, etc. It might actually be a good learning project for Ansys
EDIT: anybody doing a service on a Boxxer, 40/49, etc. fork and could do some wall thickness and bushing position measurements and upper/lower/crown weighing?
EDIT2: another things to note is convenience. With an MX bike you know you'll have to put it on a stand and use tools to remove the (front) wheel to do anything to it. With MTBs, we have gotten used to toolless axles. While not the norm in DH, the Boxxer nevertheless uses the Maxle axle type. That thing only preloads the axle system int he axial direction and has some clearance in the mounting points in the lower, increasing torsional flex. But with an RSU system you can pay the penalty for that and not be worried while giving the user a lot more convenience when removing your front wheel.clamping the axle down with pinch bolts will help a lot. And that's exactly what DVO did with two pinch bolts spaced relatively far apart on their Emerald. Much more than wath the rest of the industry has done in this regard.
And i just thought of this, another benefit is the price. With a RSU fork you can clamp it on a nice, smooth surface of the slider, that is ground to a smooth finish and to a tight tolerance. The lower need to be somewhat precise in the axle clamp area, the brake mount and where you fit the bushings and seals. Otherwise it can be fairly rough, so casting works nicely. With an USD fork you need to have the uppers relatively precise in the clamping area and inside, where you mount the bushings and also need to make axle/brake mount blocks for the bottom of the sliders, adding components and work done to them. And regardless of the costs involved with MTB components these days, it's still a much more price sensitive application than MX.
[img]https://p.vitalmtb.com/photos/forums/2020/02/21/9234/s1200_B8B6FBEA_F446_48C2_99AC_833FFED62373.jpg[/img]
A closer look at the new canyon sender. Looks like the shock moved down but other than that looks wise it’s pretty similar.
A closer look at the new canyon sender. Looks like the shock moved down but other than that looks wise it’s pretty similar.
I regret selling my Shiver and definitely loved my Dorado, just wasn't a good fit for the way i wanted my Gambler set up.
I never felt like the torsional flex was a big deal and I always theorized that a little flex that way could help especially in rocks and roots. By flexing, it didn't jerk the bike in a funny way if you caught a weird edge and less feedback to the rider.
Watch how well moto USD forks handle chunky awful slickrock type terrain. The bikes float (and they aren't even mega tuned or anything, pretty off the shelf if i remember right). Russell is a freak for riding this in under an hour.
...and because I can't help but post it. Mario Roman from Romaniacs a few years ago. This is bonkers.
I regret selling my Shiver and definitely loved my Dorado, just wasn't a good fit for the way i wanted my Gambler set up.
I never...
I regret selling my Shiver and definitely loved my Dorado, just wasn't a good fit for the way i wanted my Gambler set up.
I never felt like the torsional flex was a big deal and I always theorized that a little flex that way could help especially in rocks and roots. By flexing, it didn't jerk the bike in a funny way if you caught a weird edge and less feedback to the rider.
My neighbor has a Shiver in his garage. He may be willing to part with it.
Why does everybody try so hard to turn our mtb’s into moto’s? Parts that are missing from the equation, roughly 200+ lbs. then there’s the motor(obvious)so unless your Steve Austin The Six Million Dollar Man you ain’t gonna ever be spinning those pedals ever at even 1hp, engine braking, the moto bikes are truly incredible but our bicycles are way more incredible at this point. The whole motorcycle industry is in a time of huge change sales are waaay down innovation has slowed with the exception of a couple of manufacturers have kept the lights on but times are changing. The days of internal combustion powered fun are coming to a end. Well partially at least as gasoline powered generators might be a big player going forward.
Jeff I’m not going to quote your post because it would cause a wall of text, but luckily you numbered your points, so I’m gonna reply to them.
0.) no, I do not ride MX. But a lot of my points were more general and did with the stiffness of the forks. And if you're looking at a certain structure, it doesn't matter what it's used for, it will have certain properties. Now...
1.) okay... So, they lowered their flex compared to their competition. But saying they have the same diameter of the axle as MTB forks do doesn't say much since you can have a different thickness of the walls (or a solid bar for that matter), you still have different fork lowers/upper, triple clamps, axle clamps, etc. The axle diameter is just one part of the story.
2.) I almost intentionally missed out hard enduro, but I am aware of it. They do charge, but to say they do it like we do it... With 100-ish kg under you the mechanics will be different to an MTB, you can't get around that. So regardless of the terrain, the riding style will be different. Plus, with the size of the tyres their precision levels (or the needed levels) will always be different. Plus, looking at the videos you posted (and I was aware of that before), MX/Enduro technical riding is mostly done uphill with the bike being lifted on the throttle a lot. They go down relatively slowly (even compared to going up) while we bomb down the hill. Mario even turned off his bike going down in some cases. It's only natural, it's harder to stop 150 to 200 kg of mass compared to 100 kg, plus if half of that mass is the thing between your legs compared to only 20 %, it's a big difference. The demands on the fork are different in these cases. And to be sure, I’m not saying MX or hard enduro is easier than MTB; far from it. It's just completely different. And it's also not like they're slow going down. I have been 'chased' and caught by MX riders on my local trails. They are fast. But still, it's not a direct comparison in either case.
3.) I think I covered this under point 2. A lot of lifting the front end over obstacles using the throttle, mostly going up, where the riding is 'high energy', going down the riding is more subdued.
4.) It’s about the same making a single crown upside down fork as a right side up fork. The triple trees will add stiffness, that is a benefit. But if that was the only reason, you could argue all dual crown forks would be USD. But are not. You could argue that it's platform sharing (Boxxers used to have the same lowers as the Lyrik) or familiar terrain for the designers, but I don't think it's only connected to that. Agreed about the handling though.
5.) agreed, any dual crown is better in this regard though. But that doesn't have much to do with upside down forks if you ask me. It's a single vs. dual crown fork debate.
6.) I didn't mean single and dual crown forks are the same. I meant it's the same in the USD vs. RSU debate. You can easily make a single or dual crown fork in either configuration. Yeah, the USD single crown fork will have a bit more of a penalty (one crown/bridge vs. 2 in single crown configuration, 2 crowns/bridges vs. 3 in dual crown configuration, crowns/bridges being linking elements) in regards to stiffness, but still, it's not like you can't do certain configurations. That's why single vs. dual crown conversation doesn't matter.
When you're mentioning bushing overlap, increased bushing overlap is, theoretically, only possible with dual crown upside down forks. Only there you have the possibility of having sliding tubes and outer tubes long enough to give you both overlap and travel. With any configuration of a single crown fork you're more or less set from the start and it's the same for an RSU dual crown fork, you can only go up to the clamps. With an USD dual crown fork you can go past a clamp (let's leave the debate about what happens when you overtighten the clamps, like it could happen with some old Boxxers, where the air piston could get stuck there).
7.) see point 6. The single crown upside down fork will do the same. And the RSU dual crown fork, since the bushings are the same distance apart. Only the uppers will flex a bit less. And if you have the same configurations of bushings in your USD fork, it will be the same. Except if you put the top bushing up in the clamp, like I mentioned above. You have to actually spread the bushings to get an effect from it.
There is the benefit of better bushing lubrication with an USD fork though... But yeah, I’m with you, I’d prefer my fork to move. I should introduce you to a friend of mine who is pissed at RS and FOX because they both make forks with a lot of play in the bushings, which can cause even more binding, can cause bushing edge wear on the sliders (he has this on his Lyrik since it was a couple months old and he's doing the servicing the way it is supposed to be done), hates the 'rattling' from oscillations of the fork due to bushing clearance when braking, etc.
8.) a lot of people have gone to bolt axles, yeah. That doesn't change the fact that Boxxers don't have pinch bolts. Which means your axle still is not clamped the way it could be, lowering the stiffness of the system. It's not quick release vs. bolt axle, it's axial bolting vs. pinch bolting. There's a world of difference between these two.
9.) I beg to differ. 10k bikes are essentially race bikes. Hell, 5k+ bikes are race bikes. How much does a race motorcycle cost? I do not doubt a 2k fork would sell, it already does. But how large is the market for it? In bikes, the market is OEM, not aftermarket. When it comes to OEM stuff, the conditions are different to aftermarket in regards to what the components can cost and what sells. How many OEMs are speccing said linkage forks? Would you buy a bike fitted with one?
10.) Please do. But it's not that the tolerances need to be tighter or better. It's that you need to handle more components to a tighter finish. You need to grind the sliders in a dual crown fork. If you clamp them, you have a perfect surface. You're not spending much more to have the clamping surface finely prepared. With an USD fork, you do need to spend extra to prepare that surface, because the outer surface of the upper is otherwise 'non-functional' or cosmetic. With an RSU lower that part is a raw casting with some paint over it. Cheaper and faster to make. That is my point. It's not about the tolerances and their level themselves, it's about how many components of a BOM you need to make to fit a tolerance at all (with castings the tolerances are very much open, believe you me).
And I never said it's hard. It's not. We can do tons of things. The thing is that making more components fit tight tolerances is time consuming and that makes it expensive. You mentioned 2k USD for a fork. Would you buy one that cost 3k? Or 4k? What if it ticked ALL the boxes?
11.) agreed. Plus, regardless of performance, I want my bike to work. A 4k USD fork is worth exactly 0 USD if you're waiting 2 months for a replacement part because the supplier is a small garagist who can barely handle the orders. I'm personally sticking to Rock Shox because it's easy to buy replacement parts and tools and all the service manuals are available over the internet, as opposed to FOX (it's getting better for FOX though...). A fancy fork with no service support doesn't help me much if I can't ride it.
As for the house of cards, I'd be happy for you to point out which part of the stiffness affecting parameters is wrong. Plus, if I'm not riding moto, does that instantly make me wrong in all points? I haven't ridden a steep seat tube bike until a year ago, but I knew I need one three years ago. And now I know I need a steeper angle still, if anything. I haven't ridden an upside-down-fork, but it's basic fact that, with the same sliding tube and bushing overlap configuration and the same axle, the torsional stiffness will not be as good. Or the weight will be higher. You can't have more stiffness with less material (well, you can, but not in the same form factor using the same material at the same weight). It's basic physics...
As for unsprung weight, scarface the USD fork has a lower unsprung weight. So, in that regard, it's much better. Yet there are hardly any on the market. And unsprung weight is less of an issue for a motorbike, since the sprung weight is also much higher than for an MTB.
Why does everybody try so hard to turn our mtb’s into moto’s? Parts that are missing from the equation, roughly 200+ lbs. then there’s the motor(obvious)so...
Why does everybody try so hard to turn our mtb’s into moto’s? Parts that are missing from the equation, roughly 200+ lbs. then there’s the motor(obvious)so unless your Steve Austin The Six Million Dollar Man you ain’t gonna ever be spinning those pedals ever at even 1hp, engine braking, the moto bikes are truly incredible but our bicycles are way more incredible at this point. The whole motorcycle industry is in a time of huge change sales are waaay down innovation has slowed with the exception of a couple of manufacturers have kept the lights on but times are changing. The days of internal combustion powered fun are coming to a end. Well partially at least as gasoline powered generators might be a big player going forward.
Against better judgement, I will jump in.
I'm not "wanting my mountain bike to be a moto". But I do want my mountain bike to work well. When it comes to "working well" there are so many things that crossed over from mountain biking with much success its absolutely incredible.
For fun, go look at a mountain bike around 2000. Now go look at a moto. Yes, there have been changes to both, but which one looks more like it did in 2000s trim? Hell the YZ250 is the exact same bike as it was in 2005 as it is now...and people still love it! (and rave about the suspension!!!!). Imagine people raving about a 2005 mountain bike. (I guess I kinda did with respect to the Dorado...but I digress!)
Dirt bikes have gone through fairly small changes when it comes to suspension, geometry and overall handling. Mountain bikes on the other hand went from 70 degree head tube angles, suspension that was more akin to something you'd find on a toy in a Lucky Charm's box, brakes that seldom worked, poor rider placement and suspension kinematics that were awful to something that has a whole hell of a lot in common with a modern dirt bike.
Head angle - 63-64 on most dirt bikes. Sound familiar? Only took us 20 years to get here across multiple bikes from DH to enduro to even trail settings.
Playing with offset - common in dirt bike world, just coming into vogue in mountain bike world.
Speed sensitive valving, suspension that actually works and is tunable - now commonplace in the mountain bike suspension world, this wasn't always the case however. The modern mountain bike damper in a lot of ways is a scaled down moto damper.
Progressive rear suspension - Again, this is what we all covet and has been commonplace (less KTM) forever in the moto world
Brakes - We don't think much of the modern mountain bike brake anymore, but 20 years ago, rim brakes were still a thing and hydraulic disks were a far cry from what they are today. Dirt bikes? Yeah, that shit was dialed.
Clothing - Palmer made us look cool. Where did he borrow the style!?
Engineered Flex - Still not too talked about, but its very well discussed in the moto world. Swingarms that are designed to flex the right amount, triple clamps that do the same etc etc. Cesar talked a lot about this in his designs. Zipp clearly is trying to do something similar. But yeah, this has long been a point of design in the moto world (road/dirt) to get the bikes to handle well
Handlebars - We were riding 600mm wide bars when moto had 800mm bars.
Inserts - Moto had bib mousses way before Kreft (yeah, a moto company) started putting inserts into our bikes
...and on and on.
If you can't see how heavily we've been influenced by moto, you are totally blind. I just find it funny, only because if we had gone further this direction, more quickly, we'd be further down the road than we are now. This is a lot of my philosophy behind someone jumping in and making a USD fork that rips sooner than later. It will happen. I'd rather just not wait 15 years for the future.
Fun side story, I remember riding some Avalanche suspension in 2004. To this day, its still the best rear shock I've ridden. Oh, and it was 100% a scaled down moto shock. LOL
As far as you suggesting moto is going away, eh. It won't. I can't wait for E-Moto to be a thing, but we're probably 5-10 years off as far as battery tech is concerned. Sales may not be crushing, but the sport is far from dying. Hell, hard enduro in the US is absolutely blowing up. SX doesn't appear to be hurting as far as viewership. Bla bla bla. Growth isn't the end all be all to suggesting if something is going to stick around.
Side note, I also ride sleds. Another power sport! Mountain sledding is actually getting *more* popular as skiing becomes more and more of a joke. E-Sleds? Yeah, its being tried and WAY off. Again, battery tech is far from being ready for mainstream use in these sports. Range is way too limited for the power demands. ICE will be around for a long, long time in the future.
EDIT; Great post for those who think ICE powersports days are quickly coming to an end...
There's an argument that moto went through the same process MTB is going through now (wheel sizes, looks like a session, geometry tinkering, different suspension designs, etc.) 30 or 40 years ago. So of course 2000 MX bike looks fairly the same as a 2020 one. And a MTB doesn't. Maybe a 2040 MTB will look similar to a 2020 MTB though. Who knows.
There's an argument that moto went through the same process MTB is going through now (wheel sizes, looks like a session, geometry tinkering, different suspension designs...
There's an argument that moto went through the same process MTB is going through now (wheel sizes, looks like a session, geometry tinkering, different suspension designs, etc.) 30 or 40 years ago. So of course 2000 MX bike looks fairly the same as a 2020 one. And a MTB doesn't. Maybe a 2040 MTB will look similar to a 2020 MTB though. Who knows.
I'd bet you are right. We are already seeing a fair amount of that (bikes becoming a bit homogeneous) .
I just see the most low hanging fruit to remain with respect to front fork performance and rider weight distribution between two wheels across all size runs. I also feel a lot can be borrow from moto on both of these fronts (clearly).
Is weight distribution actually a thing in moto? I mean, motorbikes come in one size only? Or am i missing something?
Bike shocks (and forks) are more demanding than moto stuff since they need to cover a wider spectrum of settings (due to the variations in sprung weight, percentage wise of least to most weight - lightest to heaviest riders) plus they need to handle a wider range of suspension movements (due to pedalling). Though that can be covered by suspension geometry a lot as well...
Besides all of that they need to be light. And, I still think that, cheaper than moto stuff... (And of course should work with no maintenance for 10 years. /s)
Agreed. But then you have the added issue, if you're looking at enduro bikes, that they have to work going up, seated and pedalling, and going down, standing 'up' and not pedalling (mostly). The weight distribution is more of an interest in the latter point, but i still think, for enduro bikes and down, that seated pedalling position and the efficiency of it is the most important part of the bike handling equation. Simply due to the time and energy spent in that part. But I think we've had a discussion about this before?
My post is of course not valid once it comes to lift assisted riding and/or DH racing and the like.
but to your point, i agree i don't think a dual crown 38 is in the cards. Just not enough demand to justify the production of it, especially if the single crown version is made stiff enough.
If you have a cantilever with a load applied to it on the end (which is what a fork is), ideally the cross section would increase from the point of the load (axle) towards the anchor point (crown). Inverted forks have more meat towards the anchor point so they gain stiffness in this regard. Plus their lubricated seals and all.
But yeah, torsion is a bitch... A "dual lefty" would probably solve those issues, but would bring aforementioned issues with it, some more weight and a lot more cost (facing off the tubes to accept the needle bearings must be a PITA to do accurately, plus to prepare the interfacing surfaces in the outer tube as well...
As for USD forks and moto, yeah, they can deal with more weight. That means thicker tubes with thicker walls, stronger clamps, a thicker (diameter and wall thickness) axle, more clamping area overlap, etc. Plus higher longitudinal stiffness is not a problem for them since they, firstly, hit obstacles with more energy (higher speed, double the weight of a MTB bike-rider system), secondly ride on, dare i say it, smoother tracks (the nature of MTB and MX riding is completely different, but by no means easier for MX!). The torsional stiffness does not incur such a difference between the two since it's still your arms dealing with most of the forces. So the change in torsional stiffness gives a 'linear gain' but a change in longitudinal stiffness is not so 'linear' (different system characteristics with different responses and different requirements). And when i mentioned smoother tracks, maybe the torsional stiffness, even if it's on the same level, is less of a problem for the 'smoother' riding of MX compared to MTB where you often need more precision to put the relatively thin tyre between two rocks, roots and the like?
As for standard forks in moto, they had them. But apparently the USD type works for them. Like we had and have USD forks in MTB, but have mostly the 'right-side-up' (RSU? Could it be DSU? ) forks in MTB. Because the benefits outweigh the negatives?
As for history, that point has already been made and is in full swing. We have a single speed consolidation of drivetrains, 'everything looks like a session' (just like MX bikes are indistinguishable between each other without graphics if you're not an MX nut), wheel sizes that you mentioned, etc.
As for dual crown vs. single crown, I think that wouldn't make much of a difference.
Speaking of putting money where your mouth is, i think a comparison analysis could actually be made with Ansys. It would be good enough for a comparison, just put a 'parking lot test' level of steering and fore-aft force into the system and see the response of a simplified (empty) fork that is either USD or RSU, has different slider diameters and thicknesses, different axle diameter, thicknesses and axle overlaps, etc. It might actually be a good learning project for Ansys
EDIT: anybody doing a service on a Boxxer, 40/49, etc. fork and could do some wall thickness and bushing position measurements and upper/lower/crown weighing?
EDIT2: another things to note is convenience. With an MX bike you know you'll have to put it on a stand and use tools to remove the (front) wheel to do anything to it. With MTBs, we have gotten used to toolless axles. While not the norm in DH, the Boxxer nevertheless uses the Maxle axle type. That thing only preloads the axle system int he axial direction and has some clearance in the mounting points in the lower, increasing torsional flex. But with an RSU system you can pay the penalty for that and not be worried while giving the user a lot more convenience when removing your front wheel.clamping the axle down with pinch bolts will help a lot. And that's exactly what DVO did with two pinch bolts spaced relatively far apart on their Emerald. Much more than wath the rest of the industry has done in this regard.
And i just thought of this, another benefit is the price. With a RSU fork you can clamp it on a nice, smooth surface of the slider, that is ground to a smooth finish and to a tight tolerance. The lower need to be somewhat precise in the axle clamp area, the brake mount and where you fit the bushings and seals. Otherwise it can be fairly rough, so casting works nicely. With an USD fork you need to have the uppers relatively precise in the clamping area and inside, where you mount the bushings and also need to make axle/brake mount blocks for the bottom of the sliders, adding components and work done to them. And regardless of the costs involved with MTB components these days, it's still a much more price sensitive application than MX.
A closer look at the new canyon sender. Looks like the shock moved down but other than that looks wise it’s pretty similar.
I never felt like the torsional flex was a big deal and I always theorized that a little flex that way could help especially in rocks and roots. By flexing, it didn't jerk the bike in a funny way if you caught a weird edge and less feedback to the rider.
Watch how well moto USD forks handle chunky awful slickrock type terrain. The bikes float (and they aren't even mega tuned or anything, pretty off the shelf if i remember right). Russell is a freak for riding this in under an hour.
...and because I can't help but post it. Mario Roman from Romaniacs a few years ago. This is bonkers.
Magnesium is pretty light...
0.) no, I do not ride MX. But a lot of my points were more general and did with the stiffness of the forks. And if you're looking at a certain structure, it doesn't matter what it's used for, it will have certain properties. Now...
1.) okay... So, they lowered their flex compared to their competition. But saying they have the same diameter of the axle as MTB forks do doesn't say much since you can have a different thickness of the walls (or a solid bar for that matter), you still have different fork lowers/upper, triple clamps, axle clamps, etc. The axle diameter is just one part of the story.
2.) I almost intentionally missed out hard enduro, but I am aware of it. They do charge, but to say they do it like we do it... With 100-ish kg under you the mechanics will be different to an MTB, you can't get around that. So regardless of the terrain, the riding style will be different. Plus, with the size of the tyres their precision levels (or the needed levels) will always be different. Plus, looking at the videos you posted (and I was aware of that before), MX/Enduro technical riding is mostly done uphill with the bike being lifted on the throttle a lot. They go down relatively slowly (even compared to going up) while we bomb down the hill. Mario even turned off his bike going down in some cases. It's only natural, it's harder to stop 150 to 200 kg of mass compared to 100 kg, plus if half of that mass is the thing between your legs compared to only 20 %, it's a big difference. The demands on the fork are different in these cases. And to be sure, I’m not saying MX or hard enduro is easier than MTB; far from it. It's just completely different. And it's also not like they're slow going down. I have been 'chased' and caught by MX riders on my local trails. They are fast. But still, it's not a direct comparison in either case.
3.) I think I covered this under point 2. A lot of lifting the front end over obstacles using the throttle, mostly going up, where the riding is 'high energy', going down the riding is more subdued.
4.) It’s about the same making a single crown upside down fork as a right side up fork. The triple trees will add stiffness, that is a benefit. But if that was the only reason, you could argue all dual crown forks would be USD. But are not. You could argue that it's platform sharing (Boxxers used to have the same lowers as the Lyrik) or familiar terrain for the designers, but I don't think it's only connected to that. Agreed about the handling though.
5.) agreed, any dual crown is better in this regard though. But that doesn't have much to do with upside down forks if you ask me. It's a single vs. dual crown fork debate.
6.) I didn't mean single and dual crown forks are the same. I meant it's the same in the USD vs. RSU debate. You can easily make a single or dual crown fork in either configuration. Yeah, the USD single crown fork will have a bit more of a penalty (one crown/bridge vs. 2 in single crown configuration, 2 crowns/bridges vs. 3 in dual crown configuration, crowns/bridges being linking elements) in regards to stiffness, but still, it's not like you can't do certain configurations. That's why single vs. dual crown conversation doesn't matter.
When you're mentioning bushing overlap, increased bushing overlap is, theoretically, only possible with dual crown upside down forks. Only there you have the possibility of having sliding tubes and outer tubes long enough to give you both overlap and travel. With any configuration of a single crown fork you're more or less set from the start and it's the same for an RSU dual crown fork, you can only go up to the clamps. With an USD dual crown fork you can go past a clamp (let's leave the debate about what happens when you overtighten the clamps, like it could happen with some old Boxxers, where the air piston could get stuck there).
7.) see point 6. The single crown upside down fork will do the same. And the RSU dual crown fork, since the bushings are the same distance apart. Only the uppers will flex a bit less. And if you have the same configurations of bushings in your USD fork, it will be the same. Except if you put the top bushing up in the clamp, like I mentioned above. You have to actually spread the bushings to get an effect from it.
There is the benefit of better bushing lubrication with an USD fork though... But yeah, I’m with you, I’d prefer my fork to move. I should introduce you to a friend of mine who is pissed at RS and FOX because they both make forks with a lot of play in the bushings, which can cause even more binding, can cause bushing edge wear on the sliders (he has this on his Lyrik since it was a couple months old and he's doing the servicing the way it is supposed to be done), hates the 'rattling' from oscillations of the fork due to bushing clearance when braking, etc.
8.) a lot of people have gone to bolt axles, yeah. That doesn't change the fact that Boxxers don't have pinch bolts. Which means your axle still is not clamped the way it could be, lowering the stiffness of the system. It's not quick release vs. bolt axle, it's axial bolting vs. pinch bolting. There's a world of difference between these two.
9.) I beg to differ. 10k bikes are essentially race bikes. Hell, 5k+ bikes are race bikes. How much does a race motorcycle cost? I do not doubt a 2k fork would sell, it already does. But how large is the market for it? In bikes, the market is OEM, not aftermarket. When it comes to OEM stuff, the conditions are different to aftermarket in regards to what the components can cost and what sells. How many OEMs are speccing said linkage forks? Would you buy a bike fitted with one?
10.) Please do. But it's not that the tolerances need to be tighter or better. It's that you need to handle more components to a tighter finish. You need to grind the sliders in a dual crown fork. If you clamp them, you have a perfect surface. You're not spending much more to have the clamping surface finely prepared. With an USD fork, you do need to spend extra to prepare that surface, because the outer surface of the upper is otherwise 'non-functional' or cosmetic. With an RSU lower that part is a raw casting with some paint over it. Cheaper and faster to make. That is my point. It's not about the tolerances and their level themselves, it's about how many components of a BOM you need to make to fit a tolerance at all (with castings the tolerances are very much open, believe you me).
And I never said it's hard. It's not. We can do tons of things. The thing is that making more components fit tight tolerances is time consuming and that makes it expensive. You mentioned 2k USD for a fork. Would you buy one that cost 3k? Or 4k? What if it ticked ALL the boxes?
11.) agreed. Plus, regardless of performance, I want my bike to work. A 4k USD fork is worth exactly 0 USD if you're waiting 2 months for a replacement part because the supplier is a small garagist who can barely handle the orders. I'm personally sticking to Rock Shox because it's easy to buy replacement parts and tools and all the service manuals are available over the internet, as opposed to FOX (it's getting better for FOX though...). A fancy fork with no service support doesn't help me much if I can't ride it.
As for the house of cards, I'd be happy for you to point out which part of the stiffness affecting parameters is wrong. Plus, if I'm not riding moto, does that instantly make me wrong in all points? I haven't ridden a steep seat tube bike until a year ago, but I knew I need one three years ago. And now I know I need a steeper angle still, if anything. I haven't ridden an upside-down-fork, but it's basic fact that, with the same sliding tube and bushing overlap configuration and the same axle, the torsional stiffness will not be as good. Or the weight will be higher. You can't have more stiffness with less material (well, you can, but not in the same form factor using the same material at the same weight). It's basic physics...
As for unsprung weight, scarface the USD fork has a lower unsprung weight. So, in that regard, it's much better. Yet there are hardly any on the market. And unsprung weight is less of an issue for a motorbike, since the sprung weight is also much higher than for an MTB.
https://www.vitalmtb.com/videos/member/Team-CRC-2020-Launch-New-Bikes-a…
I'm not "wanting my mountain bike to be a moto". But I do want my mountain bike to work well. When it comes to "working well" there are so many things that crossed over from mountain biking with much success its absolutely incredible.
For fun, go look at a mountain bike around 2000. Now go look at a moto. Yes, there have been changes to both, but which one looks more like it did in 2000s trim? Hell the YZ250 is the exact same bike as it was in 2005 as it is now...and people still love it! (and rave about the suspension!!!!). Imagine people raving about a 2005 mountain bike. (I guess I kinda did with respect to the Dorado...but I digress!)
Dirt bikes have gone through fairly small changes when it comes to suspension, geometry and overall handling. Mountain bikes on the other hand went from 70 degree head tube angles, suspension that was more akin to something you'd find on a toy in a Lucky Charm's box, brakes that seldom worked, poor rider placement and suspension kinematics that were awful to something that has a whole hell of a lot in common with a modern dirt bike.
Head angle - 63-64 on most dirt bikes. Sound familiar? Only took us 20 years to get here across multiple bikes from DH to enduro to even trail settings.
Playing with offset - common in dirt bike world, just coming into vogue in mountain bike world.
Speed sensitive valving, suspension that actually works and is tunable - now commonplace in the mountain bike suspension world, this wasn't always the case however. The modern mountain bike damper in a lot of ways is a scaled down moto damper.
Progressive rear suspension - Again, this is what we all covet and has been commonplace (less KTM) forever in the moto world
Brakes - We don't think much of the modern mountain bike brake anymore, but 20 years ago, rim brakes were still a thing and hydraulic disks were a far cry from what they are today. Dirt bikes? Yeah, that shit was dialed.
Clothing - Palmer made us look cool. Where did he borrow the style!?
Engineered Flex - Still not too talked about, but its very well discussed in the moto world. Swingarms that are designed to flex the right amount, triple clamps that do the same etc etc. Cesar talked a lot about this in his designs. Zipp clearly is trying to do something similar. But yeah, this has long been a point of design in the moto world (road/dirt) to get the bikes to handle well
Handlebars - We were riding 600mm wide bars when moto had 800mm bars.
Inserts - Moto had bib mousses way before Kreft (yeah, a moto company) started putting inserts into our bikes
...and on and on.
If you can't see how heavily we've been influenced by moto, you are totally blind. I just find it funny, only because if we had gone further this direction, more quickly, we'd be further down the road than we are now. This is a lot of my philosophy behind someone jumping in and making a USD fork that rips sooner than later. It will happen. I'd rather just not wait 15 years for the future.
Fun side story, I remember riding some Avalanche suspension in 2004. To this day, its still the best rear shock I've ridden. Oh, and it was 100% a scaled down moto shock. LOL
As far as you suggesting moto is going away, eh. It won't. I can't wait for E-Moto to be a thing, but we're probably 5-10 years off as far as battery tech is concerned. Sales may not be crushing, but the sport is far from dying. Hell, hard enduro in the US is absolutely blowing up. SX doesn't appear to be hurting as far as viewership. Bla bla bla. Growth isn't the end all be all to suggesting if something is going to stick around.
Side note, I also ride sleds. Another power sport! Mountain sledding is actually getting *more* popular as skiing becomes more and more of a joke. E-Sleds? Yeah, its being tried and WAY off. Again, battery tech is far from being ready for mainstream use in these sports. Range is way too limited for the power demands. ICE will be around for a long, long time in the future.
EDIT; Great post for those who think ICE powersports days are quickly coming to an end...
I just see the most low hanging fruit to remain with respect to front fork performance and rider weight distribution between two wheels across all size runs. I also feel a lot can be borrow from moto on both of these fronts (clearly).
Bike shocks (and forks) are more demanding than moto stuff since they need to cover a wider spectrum of settings (due to the variations in sprung weight, percentage wise of least to most weight - lightest to heaviest riders) plus they need to handle a wider range of suspension movements (due to pedalling). Though that can be covered by suspension geometry a lot as well...
Besides all of that they need to be light. And, I still think that, cheaper than moto stuff... (And of course should work with no maintenance for 10 years. /s)
My post is of course not valid once it comes to lift assisted riding and/or DH racing and the like.
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