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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!
😉