You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
Nope.
x1000.
When will it stop?
Loved my Girvin vector linkage forks, shame some robbing so and so decided they liked them more and took them while attached to my stumpjumper 🙁
In the single-sided version it looks weirdly tempting. Otherwise it's just a shinier version of Whyte's PRST-4 design, right?
Shouldn't it be Agauche?
Oh, bravo! Bravo!
Sublime.
Conkers. Loving your work. 😁
Otherwise it’s just a shinier version of Whyte’s PRST-4 design, right?
Exactly my thoughts. Reinventing the wheel. Again.
To me, it looks like a step in the right direction.
all the clever/ ££££ parts of a regular telescopic fork are in the damper cartridge thingy.
if the lefty design is no longer patented, it lets the bike manufacturers free to put their own lefty/ linkage fork on their bikes and leave the fork manufacturers to concentrate on the damper cartridges?
i never got on with telescopic forks ...the maintenance requirements were always a bit vague and not suited to the 95 percent hamfisted population who would struggle to replace the disc pads on their car.
What would be the downsides to a linkage fork like this?
What would be the downsides to a linkage fork like this?
Other than the pivot bearings, 2 shock bearings, need for proprietary frame, possibly stem and headset, cost of shock, and higher CofG?
Very little I'd have thought. Sign me up.
if the lefty design is no longer patented
As far as I know, the patent applies to the use of a flat sided stanchion and roller bearings. Otherwise, the Lefty is just a telescoping fork. I don't think there was anything preventing someone making a one sided linkage fork (surely "tine" is the correct word, not "fork").
It will be interesting to see how the Adroit forks compare, but I certainly won't be an early adopter. Can't see that the benefits will be big enough to outweigh the potential problems, let alone the cost.
Shouldn’t it be Agauche?
Depends on your point of view?
There has to be a benefit to any new design either in weight reduction and/or performance. The conventional fork design, though it has been finessed and developed over the years, is technically flawed...it's just a crap design, but it's lightweight and works well enough. I like that this uses a rear shock so separating the suspension/damping bit out of the actual suspension mechanism, that is a superior design, but unless you can make it lighter and/or perform better then it's just an interesting technical exercise. In order to make it better then it needs development which means investment of ALOT OF £££££££££££££££. The problem is who's going to do that? Especially with so many luddites around who just wouldn't be open about new innovations like this. Conventional forks in the early days were properly crap...heavy, flexy, crap performance, but over the decades they were developed and finessed to something that does the job today....any new fork design has to go through that same development curve before it's a mature product delivering all the benefits it can.
Not sure it needs proprietary frame though, the head tube above looks pretty standard to me. Linkage bearings are not a problem so long as they're easy enough to replace and cheap enough. Certainly easier than the prescribed service schedules on conventional forks (assuming you actually follow them). Bring on the technical innovation I say, conventional forks are crap.
Mechanically my lefty was far superior to any conventional fork I've had, I miss it, but the damping and airspring were not as good because you're trying to squeeze too much into the single lefty leg, and things got more difficult with longer travel, but separating things out like this solves that problem. You can't get more stiff than ditching the telescoping legs and replacing with a single shaft.
proprietary frame...a lot of frames seem to incorporate that kind of kink where the top and down tubes meet.
different headset...we've been through the one inch threaded to 1.1/8 to tapered to angleset. Another standard won't hurt?
shock bushings/ pivots...no one complains when they're on the rear of the bike.
higher c of g? I've got long legs as a proportion of my body, so a higher front end at least is ok by me.
I think my only concern would be with regard to the longevity of the moving parts, though I recall how Marin offered a lifetime warranty on the bushings/ bearings.
and I'm wondering what they're like in real-life. Any BMW motorbike owners?
People in the motor cycle world have been saying the telescopic fork is a dead and useless for all kinds of reasons, for years and yet most modern motorcycles still use it. BMW are the exception and I have owned a telelever GS which was fine and handled very well but to be honest I don't think I would have noticed the difference if I hadn't have known it wasn't tele forked.
I certainly have no objection to alternative fork designs and would fancy one of those Adroits but while tele forks are so much cheaper and reasonably refined, I'm out. When the price comes down and reliability is proven, I will definitely take another look. The inertia of conservative buyers who will buy what they know must surely be against all forms of new fork design.
shock bushings/ pivots…no one complains when they’re on the rear of the bike.
There are plenty of complaints about their longevity if you spend a few seconds searching. Also, having a small amount of play at the back is a different thing to having it between the front wheel and handlebars.
The conventional fork design, though it has been finessed and developed over the years, is technically flawed
All engineering is a compromise. The telescopic fork seems to be a reasonable compromise between performance, weight, and cost. I'm not into moto-x, but AFAIK, they use telescopic forks so the compromises can't be too severe.
people still buy buy bikes with rear suspension and factor in (put up with) the maintenance.
afaik, front end stiffness isn't the be-all.
ive heard some people say that a flexy front end helps the front wheel sniff out the path of least resistance.
as for motorbikes, they're carrying considerably more weight (sprung/ vs unsprung) which makes the suspension work better.
its amazing how supple even the crappiest suspension can feel on a motorbike.
even looking at fully sus e-bikes on YouTube, the extra weight seems to make the suspension work better.
maybe the industry will go for linkage forks on unpowered bikes and telescopic forks on the e-bikes?
ive heard some people say that a flexy front end helps the front wheel sniff out the path of least resistance.
ROFPMSLOL
"All engineering is a compromise. The telescopic fork seems to be a reasonable compromise between performance, weight, and cost."
Correct - engineering is the art of compromise and some compromises are better than others. Conventional forks are not a reasonable compromise, they've been the only compromise really. It's the only option that has had any reasonable development. The Lefty has had some development over the years, but a fraction of the development compared with conventional forks and they are lighter, stiffer with less stiction, so show alot of promise in almost all of the key areas, and if they suddenly took off and everyone wanted them, then there would be more development in them to iron out those areas where they are not perceived to perform as well as conventional forks. But it is unlikely they will ever get that chance.
Humans are a very poor judge of whether one product is better than another. There are plenty of failed products out there that were the better technical solution, but for subjective human reasons never took off....VHS vs. Beetamax springs to mind.
I had a BMW with the telelever front end and I could tell the difference easily - lovely soft suspension for bumps with no dive under braking and the suspension still worked when braking.
the issue with this on cycles is that to get the full benefits of a funny front end you need a frame redesign. Doing it so it fits a standard frame you lose much of the benefits. BMW have two different systems and on both the suspension components like the shock do not move with the steering and the forces into the frame are separated out across much wider areas and braking forces do not act thru the suspension.
a girder fork like this the shock moves with the steering and braking forces go thru the suspension meaning a lot of the advantages are lost.
also the very short links compromise the path of the front wheel movement on bumps
There still remains the advantage of being able to tailor the front wheel path to alter how it handles under braking ie increase trail under compression if you want more stability over bumps if that is what you want.
good answer!
though for me, the advantage would be in not replacing and entire fork once the moving parts are worn out.
For me, It rains too much around Glasgow to shell out on a pair of telescopic forks.
i could send a pair off to be serviced and next time I venture out there could be a months worth of rain falling in one day.
would they need another service?
Come back a week later they could have seized solid.
though it seems like they haven't used a radically different frame in the pics above.
I done a bit of sick in my mouth
As for the braking forces, surely a Bluetooth speed sensor mounted inside the hub could relay to the fork and compensate for such forces?
greatbeard - they have used a stock frame hence the design is badly compromised. The suspension turns with the steering and forces are still concentrated all on the headtube. Both BMW designs the main forces act on the frame around the height of the top of the wheel not a foot above it and most importantly the suspension does not turn with the steering so the steering bearings do not take suspension loads so much less stiction
greatbeard - if you do that you acan only sreduce the effect of the forces by increasing damping under braking leading to a fork that skips over bumps when braking. Motorcycles have been thru a lot of this over the years and "antidive" done by increasing the damping is an idea found wanting so is no longer used
very good answers (again!)
seems like I'll be sticking with a thudbuster, rigid fork and 29+ for the foreseeable future:)
people still buy buy bikes with rear suspension and factor in (put up with) the maintenance
my LBS just changed the bearings in my frame after 2 years, so I've not had to "put up" with any maintenance.
For me, It rains too much around Glasgow to shell out on a pair of telescopic forks. might be a months worth of rain falling in one day. would they need another service?
They did my forks (RS Pike) at the same time, it's the first time they'd been serviced I live in W Yorkshire, so it's about the same weather. They didn't need much doing, so just lubed the wiper seals, refreshed the oil and put them back together. I think you're under estimating the longevity or seals and bearings.
I agree. I have ten+ yr old conventional forks on two bikes used a fair amount. I simply change the oil every year. Never needed anything else. Ok sunny leith is not the west coast but even so.
Other than the pivot bearings, 2 shock bearings, need for proprietary frame, possibly stem and headset, cost of shock, and higher CofG?
Very little I’d have thought. Sign me up.
Add to that, non linear wheel paths that make steering unpredictable and poorer damping as you have less oil flow.
There's a reason why in MotoGP or WSBK - Honda, Ducati and Yamaha haven't tried to beat each other by getting one up on each other by moving to a modern girder fork.
lovely soft suspension for bumps with no dive under braking and the suspension still worked when braking.
Why you'd want a motorbike that doesn't load up the front tyre by shifting CoG forward when braking is completely beyond me.....
with reference to the maintenance of rear suspension, I meant that potentially they require maintenance, but its obviously not a deterrent to people buying them.
Though, there have been people on the forum enquiring about the longeivity of their recently overhauled rear bearings/ bushings.
still reluctant to splash out on a 'proper' set of pikes/ rebas etc.
my ridgeback came with a pair of rst m29's. Great forks, but I found that the thudbuster was doing most of the work.
And until you actually open them up, there's no real way to assess the condition of a pair of telescopic forks.
some kind of warning light would be handy!
Rayban - you completely fail to understand - quelle suprise
Non linear axle paths can be tailored to give the characteristics you want. Increasing trail, decreasing trail, increasing rake, decreasing rake or you can have a linear ( well almost) axle path if you want. Which is better in a car? double wishbone or sliding pillar (* like on old morgans)
No motorcycle changes its COG. Its fixed ( well it gets a bit lower fork compresses more than the rear extends. )
Even with the antidive geometry of the BMW you still get exactly the same weight transfer. Its just that the loads do not compress the suspension as the load path does not go thru the suspension but striaght thru the wisdhbones to the frame.
On racing motorcycles you actually want the reduction in trail that a telescopic fork gives under braking - they don'[t care about instabilkity and like the fast turn in reduced trail gives. they also have much shorter suspension travel than a tourer like the BMW - the road versions have 7 inch of travel, the GS a foot!
You get better damping with a shock under leverage than a telefork as its a much easier setup - one reason why open bath forks are dno longer common. a rear shock has much more sophisticated damping than a tele fork. You can also alter geometry of the shock to get rising rate if you so desire.
ever ridden anything with a funny front end?
Also racing motorcycles are on smooth surfaces so the fact you have almost no suspension under braking does not matter. Would you not like an MTB that you could use the front brake over braking bumps without it skittering across the top because the suspension is effectively used up by dive?
I should expand on what I said, the axle path of a telescopic fork and dive under braking alter the CoG of the rider+chassis in relation to the front wheel. Whilst you can tune a girder fork to behave in the same way, what's the point?
On off road motorcycles, historically, girder forks have run into packaging, weight and axle path issues in long travel applications.
The GS has 190mm of travel at the front, actual offroad bikes eg motocross bikes have upto 330mm of fork travel.
When Hossack tried to do MTB suspension, all he could get out of his lumpy, heavy design was a measley 100mm. Whooo for progress!
https://thekneeslider.com/norman-hossack-builds-a-mountain-bike-suspension/
In regards to damping, top end motorcycle tele forks have just as sophisticated damping as the rear - but they displace more oil.
Still not getting it. Girder forks are a horrid compromise because they use the standard steering head and do not separate the various forces out and also they turn the suspension. mcpherson strut type ( bmw =telelever) or true double wishbone ( BMW duolever) have huge advantages in separating out the forces and allowing tailored axle paths and in allowing suspension to continue to work under braking. also hugely increased stiffness both laterally and longitudinally and also much better small bump compliance due to reduced stiction.
Plenty of motorcycles use funny front ends of various types including leading and trailing link, hub centre, mcpherson strut, double wishbone and funny front ends have been succesfully raced at a high level. amin advantage for racing is the braking performance
still wrong about the COG as well - it does not move bar a tiny bit of reduction in height and a tiny bit of shortening of the wheelbase. not enough to make any significant differnce and for road motorbikes the instability generated by the decreased trail because of dive is a bad thing
again this is a topic I have been interested in for years. From the hub centre steering of jack <span class="st">Difazio</span> and the various subsystems built by tony foale and Royce Creasy to the hossack and mead and tompkinsons nessie to the elf racers.
Wrong on the travel on a GS as well.
Its difficult to get your head around I know but the advantages in properly designed funny front ends are huge.
Problem for MTBs is that a prperly designed front end cannot be fitted to a standard frame
I suggest reading tony foales book if you would like to learn more
still wrong about the COG as well – it does not move bar a tiny bit of reduction in height and a tiny bit of shortening of the wheelbase. not enough to make any significant differnce and for road motorbikes the instability generated by the decreased trail because of dive is a bad thing
Read what I said again. Yes, it alters trail and steering geometry - it does alter the wheelbase though to a point that I wouldn't consider it to be insignificant.
But Moto GP and Superbike riders the world over, beg to differ.
You know more than they do, though, don't you TJ?
Plenty of motorcycles use funny front ends of various types including leading and trailing link, hub centre, mcpherson strut, double wishbone and funny front ends have been succesfully raced at a high level. amin advantage for racing is the braking performance
Yeah, 50 years ago. With the odd weirdo trying and failing at them since.
Wrong on the travel on a GS as well.
BMW are wrong?
Basically, when someone manages to produce a long travel linkage fork, that doesn't dive, doesn't have a compromised axle path (the ones in the OP look like they have a vertical....hell maybe even a forward axle path either of which is ****ing horrific), doesn't weigh a **** tonne, doesn't have the axle to crown length of a 200mm dual crown 29er fork and is reliable......maybe.....maybe I'll buy one.
But no ones made one.
Not one in all the decades of bicycle hipsters the world over whispering about the death of telescopic forks.
I certainly know a damn sight more than you about this topic. Basic errors in physics and understanding. Still I should know better than to debate with you given you are worse than I am for dogmatic and arguing with a lack of knowledge
check BMW for wheel travel on GS - they have reduced it on the 1200 ( compared to the 1100) from 290- mm to 220
Check world endurance racing. check all the mottorcycles that have non telescopic front ends including current racers.
But then - 40 years of reading everything I can on the subject and many years of riding bikes with non tele front ends is obviously trumped by you
~Ever ridden a bike with a non tele front suspension? Bicycle or motorbike?
Check world endurance racing. check all the mottorcycles that have non telescopic front ends including current racers.
You're making it sound like there are loads, there aren't. The only one that I know of is Team Mettis - all the top teams in the rankings are running telescopics.
Spring travel, front/rear210 mm / 220 mm https://www.bmw-motorrad.co.uk/en/models/adventure/r1200gsadventure/technicaldata.html#/section-technical-data
how on earth you can think that telelever has a vertical path is beyond me. basic geometry fail. Its clear yu have no understanding of how it works.
Ever ridden a non tele front end bike? I have ridden several different designs over many years
Well I think we have stunk up this thread enough
Huh, guess they lowered the Ralleye then by dropping the travel - that runs 190mm.
Still, it's a long way off being a "foot" isn't it. MX bikes run suspension setups measured in feet - I have yet to hear of any link forks being measured in feet.
As for the vertical axle path, it could well be - based on looking at that video. They have certainly had issues with axle paths in the past - as Vorsprung have alluded to in their videos, a path following the current trends in steering angles gives good bump absorption.
The wheel base of the telelever bike is much more stable under fork compression than the telescopic, which tells me that the axle path is probably pretty damn vertical.
Presumably without the braking dive, the steering under braking would be more predicable as the head angle doesn't change?
Also presumably better traction if the fork stays in the supple part of its travel.
correct retro also you can use a much lower spring rate as the spring does not have to absorb the braking forces. riding one its uncanny how the suspension still works under braking.
Also presumably better traction if the fork stays in the supple part of its travel.
Bit mute though if you can't get the travel of an equivalent telescopic fork, with a useful axle path.
If not, you're trading traction off the brakes for traction under braking - and you''re arguably not even doing that if you have to run a fork with considerably less travel.
The telelever works pretty well on the road, but GS bikes don't usually have to deal with multiple square edged hits like MX and mountainbikes have to.
Again with the lack of understanding - one advantage of funny front ends is you tailor the axle path to give the characteristics you want - like the BMW does with its j shaped axle path
And the Ribi forks have been done to death on the moto forums in the past - eg
Decoster raced with the twin shock Ribi Quadrilateral forks a few times.
He influenced Honda to buy the rights / licence for them. You can find many pictures of Works Hondas with them on - twin shock and single shock. I do hope Ribi got a good amount of money from them for his design(s). They are totally different to the leading link forks you find on Sidecars - all of the extra links / pivot points were to give the wheel travel a path similar to Telescopic forks, where std leading links travel in a single arc. Though, there are some that use a wheel mounting system that has the wheel mounted to a plate (think Kawasaki's Foo Bar / Lawwills system, but on the front of a leading link fork) that can change the axle path from a strict arc.
Cagiva tried them on both 125s and the 500s, around the same time that Decoster tried them. Villa did too, but in machined aluminium, rather than welded tubular steel, well before Honda went to Aluminium, .
A fair few others tried them - Eric Cheney made a few bikes with them, and plenty of small frame makers and private individuals made copies of the Ribis.
Now, most Engineers will tell you that Telescopic Forks are an engineering abomination. And that's certainly true - my Engineering brain tells me just that.
But, they've been developed intensively over the decades, and work bloody well.
No matter how light the components of the various Ribis were made, they have quite an inertia / Polar Moment problem, not just by the weight of componentry, but the varying amounts (of PMI) that are created during their travel.
And the amount of individual components to them is substantial.
Then, you get into the huge amount of pivot points they can have - you'll find, at least, on that front end pictured, 20 pivot points (don't forget the brake torque arm and backing plate pivot at the axle, people), not including the steering head bearings. That's a lot of bearings, a Lot of potential for bearing slop. Just check out your average linkaged rear end, for bearing slop - most would be shocked at the amount of 'free movement' at the rear wheel, from slop in linkage bearings - even on new bikes. Then think about that being on a front end. Cripes, the money I spent on high enough quality rose joints on some of my bicycle suspension systems was frightening - thinking of the costs of bearings for a Ribi type front end makes my bank account twitch in fear.
Despite all of this , I do love 'funny front ends' (and weird rear ends, such as the Boyesen Link) . So I'm not slagging the Ribi at all - just putting forward some problems / potential problems that exist with 'funny front ends'. Hell, one of my long term projects Is / are a couple of 'funny front ends', just because I can make them.
rayban have you ever ridden a bike with a funny front end. Its clear you don't even understand the basics So have you any experience or are you an armchair expert. I have ridden several different types of funny front end and understand how they work
Putting a funny front end on a conventional frame does not work as I said early on and as that quote agrees. thats the barrier to having them on MTBs
so what is your personal experience or are you just an armchair expert?
There have been plenty of forks that have failed that have had links attached to the frame, the packaging issues exist even with those types in long travel applications.
Bimbling around on a few funny forks doesn't make you an expert, listening to the majority opinion amongst motorsports engineers is probably the sensible thing to do though.
And at the moment, the entire industry is still on the fence about linkage forks and yet the motorsports world gets to take liberties with weight, spend bonkers money on fancy materials and R&D and have less packaging issues.....and yet they still haven't done it.
There have been plenty of forks that have failed that have had links attached to the frame,
Really - name one? the whyte - hopelessly compromised by the top linkage being too short
this is one of the bits you don't understand - to do this properly its not just a fork - its a whole frame design like the whyte but unfortunatly the compromises made in that design made it flawed
so you actually have no knowledge of this topic just a load of frantic googling. I thought so
raybanwomble
...And at the moment, the entire industry is still on the fence about linkage forks and yet the motorsports world gets to take liberties with weight, spend bonkers money on fancy materials and R&D and have less packaging issues…..and yet they still haven’t done it.
A properly designed linkage fork is no problem. The problem is building it with long enough links so that the wheel path does not do strange things. Using short links means there is only a limited amount of the arc of travel that is usable, hence short travel has been the rule.
Short travel isn't necessarily a problem. If your braking doesn't induce fork dive, then you don't need to provide the extra travel needed for the fork to still have reserve travel for any bumps it meets under braking.
The telescopic fork is an enormous kludge that imposes many compromises on bike design, eg head angles. However it is a highly refined kludge now, and a whole generation of riders are skilled in its use.
The problem the racing teams have with linkage forks isn't the hardware, but the wetware.
A skilled racer takes years to hone their reactions to suspension movements, so they are starting almost from scratch in the learning curve when you put a linkage fork on, and are at an immediate disadvantage, no matter how good it is. It costs time and money and quite a few lost races before they are back on equal terms with their previous level.
It would be better to start with talented newbies or folk who have ridden rigid.
Short travel isn’t necessarily a problem. If your braking doesn’t induce fork dive, then you don’t need to provide the extra travel needed for the fork to still have reserve travel for any bumps it meets under braking.
That depends on how much time you are spending in the air, whether you need that travel to absorb landings....and also how much braking you actually do. There's no point gaining .5 of a second on a track under braking if you lose .75 seconds on the straights.
But yes, building with long enough links has been the problem, even in the motorcycle world. The Ribi also had to use a crazy amount of pivot points to do it.
The problem the racing teams have with linkage forks isn’t the hardware, but the wetware.
I'd wager money that it's the hardware that they see as the main challenge.
this is one of the bits you don’t understand – to do this properly its not just a fork – its a whole frame design like the whyte but unfortunatly the compromises made in that design made it flawed
So where is the non fatally flawed design then TJ? I know building a frame around the front suspension makes it easier, but has it been done properly yet? It's all theory till someone does build one with the same axle path, same amount of travel, same cost, same weight, same stiffness and same reliability.
hols2
I’d wager money that it’s the hardware that they see as the main challenge.
The wetware would say that though, wouldn't it? 🙂
very interesting.
Will hopefully feed back with some real world experience in the next few months. Using some different shocks, also expecting some differing links to tune axle paths and leverage curves.
Always open to seeing if this kind of thing works or does indeed fall short but after trying it.
It will be fitted to a std frame but with a slack head angle which does cause a noticeable increase in maintenance and stiction to maintain performance (experience not theory)
It will be interesting to see how compatible the frame, designed to be very effective with a std tele fork, is with different characteristics, how hard it is to adapt and if the advantages and performance are worth it.
I have had a number of girder fork, leading link fork and BMW 'system' forks. lefty etc. so am open minded.
Should be interesting.
Good to read some of the knowledge on here, helps to stimulate the testing process...
Should have made it clear "It will be fitted to a std frame but with a slack head angle which does cause a noticeable increase in stiction with a std tele fork like the 36 or lyrik (less so with a Fox 40), and an increase in servicing to prevent a significant, and rapid, drop off in performance (experience not theory)"
It has been possible to extend maintenance periods noticeably for normal trail riding using a 40 and stiction is much less of a problem to the point I don't notice it.
I would be super happy with a tele fork that performs like the 40 does but with 20% less weight.
Stiffness in regard to the tele. vs an unconventional fork is also a point.
The tele suffers from significant fore/aft friction/binding (again reduced significantly with a 40 for me; although a god like Minaar noticed it at 62HA) which the unconventional alternative shouldn'
Love me a Lefty but the only really weird front suspension I ever tried was a Difazio front end on my old bosses Laverda Jota.
Most impressed.
Front page in "catching up with the forum" SHOCKA!
😉