Upside Down Forks

[cameron_15]

I don't think i'll ever ride one of those forks. and for that matter i don't even know why anyone would use them. there way too expensive and i could never trust that my hub wasn't going to buckle in and that i would get slingshotted like 50 meters.

Those forks would be more suited to mild xc, (i'd say)

and anyway, why did they have to make something so stupid, why couldnt they ust stick to the conventional fork design.

They remind me of those forks that are like rigids but they have a shock below the steerer tube.

They are probably good forks, but i could never trust them and would never like to do a jump on one.

 

[Ham]

I don't think i'll ever ride one of those forks. and for that matter i don't even know why anyone would use them. there way too expensive and i could never trust that my hub wasn't going to buckle in and that i would get slingshotted like 50 meters.

Those forks would be more suited to mild xc, (i'd say)

and anyway, why did they have to make something so stupid, why couldnt they ust stick to the conventional fork design.

They remind me of those forks that are like rigids but they have a shock below the steerer tube.

They are probably good forks, but i could never trust them and would never like to do a jump on one.

you probably shouldn't jump them they are xc based forks, i was dubious about them to begin with however once i rode one i could see what the fuss was about.

 

[Viv92]

you probably shouldn't jump them they are xc based forks, i was dubious about them to begin with however once i rode one i could see what the fuss was about.

It's actually not that bad. Lefty max (which aren't made anymore) jump pretty well. I have a mate with a prophet and you can do some decent stuff on them. They are actually a lot stronger than a lot of conventional forks of their class (except fox) and stiffer than almost anything except DH forks. Cedric Gracia used to race 4X on them and they seemed to handle it alright.

 

[Viv92]

Is there a reason why normal USD forks can't run splined stanchions and axles and even uppers/crowns?

I'm not 100% on this but I remember reading something on MTB dirt saying that Cannondale did try it once. The fork weighed heaps more than any other DH forks which made it handle terrible. Maybe if you could make it lighter somehow...

A lefty is pretty heavy for a single leg, so if you stick 2 together you aren't gonna have a very light fork for a little gain in strength.

 

[toodles]

Is there a reason why normal USD forks can't run splined stanchions and axles and even uppers/crowns?

While it would work it makes sealing a PITA, and increases the surface area of the stanchion making drag an issue.

Upside down forks have many benefits on motorcycles, but these benefits just aren't realised on MTBs as we can afford to get away with different technologies.

As for the sprung/unsprung weight issue - Boxxer lowers weigh 676g + ~200g for foot bolts, oil bath and damper rod.

Dorado lowers weigh 815g on their own. On top of that there's another 180g of oil to factor in.

 

[M1$T@ M1]

Upside Down Forks/Lefty

The reason you can trust Lefty forks guys is because (1)the axle/arm of the fork is Ti.(2) The design for the single leg was "borrowed" off the A-10 Warthog ("Tankbuster") because the 30mm GAU/8 A Avenger cannon which neccesitated the gear be "offset" or single-sided . BTW the A-10 weighs 11322 kg "clean" or 22680 kg loaded .So if an object with that kind of weight and a build date of 1972 does not have failure(s) due to weight or age ,do you think that anyone would not try and emulate those kinds of specs?

 

[McSweeney]

Bit off the initial topic this thread is,
But i rode my new(Not new, but new bike) 2004 Manitou dorado's on the weekend at illinbah. For a year, ive thought all the time, i hate USD forks, they are so dodgy, i don't trust them and they suck.

I can honestly say they are insane, they handled everything Illinbah threw at them, were EASILY the plushest fork ive ever ridden and i didn't notice any flex.

USD Forks are beautiful, i know it isn't exaclty what you were asking, but i thought i'd say it anyway.

 

[b_S]

what is the deal with the lefty?

Cannondale, being different for the sake of it... (again).
Actually they are decent performing forks all things considered, and damn stiffer than you'd expect. But FFS, achieving what they did given the complications is commendable but I'd say that effort would've been better spent elsewhere.

 

[benwilson1]

Yep...there are indeed alot of cons to USD forks...but there are alot of pros. USD forks are often renowned for being some of the most plushest forks out there...too bad the copious amounts of oil needed to make them this way. This oil indeed exerts pressure on the seals so they need to be serviced regularly...less for say Marzocchi Shivers but for Dorados, well lets just say you will be seeing the insides alot. Their weight and flexiness means they are often outclassed by the standard forks we see out there...
Motos dont have to worry about weight as much for the rider isnt pedaling it...manufacturers have to make the fork not only light but beefy enough to eliminate flex. In the end, the flex still remains and comparitivly, the forks are heavy...

USD forks just arnt feasable in the long run because of their associated costs for little performance gain...both Marzocch and Manitou have realised this I reckon...thats why we dont see the Shivers/Dorados around...

hey ango, im not saying your wrong. i just disagree with a few things that you mentioned.

The avalanche USD forks stand out to pretty much disprove alot of what you said.

Despite being a USD fork, they do not need servicing a whole lot. Avalanche says on the service and parts page, that you only need to service the forks every two years. I think my 888"s will probably be service 3 or 4 times in the same amount of time.

Ive never ridden the DHF or MTN range of forks so i cant comment on the flex.

I know these things are overbuilt like a bomb shelter, and they arent exactly light. but i think they may be simmilar, if not better than a conventional fork!

http://www.downcycles.com/store/2008-avalanche-downhill-racing-p-100.html

 

[sebbyreddan]

Cannondale did try an upside down fork with a brace or arch, the Moto FR.


Jut a bit heavy compared to todays forks.

 

[b_S]

I was going to mention the Moto FR but didn't want to confuse things... it uses square legs like the lefty, so you could imagine it'd be damn stiff. But yeah, stupidly overbuilt for a 4" fork

 

[stinkybigmacc]

Depending on how you look at it the flex inherent in a USD fork is great on a moto and could be great on a MTB for helping the front wheel track laterally, lessening the feedback through the fork and helping it to track straighter. A stiffer design would tend to skip when being deflected by an object. On MTB's however it could be argued we have more flex in the front wheel than a moto due to rim size and a significant difference in tyre construction.

Has anyone come across any testing on the subject?

 

[Shredden]

Maybe this has been said, and maybe it is a stupid comment, but wouldent the weight be higher, therefore giving a higher centre of gravity?