in their modern form i remember production mx and enduro bikes having them from 1989 onwards...mostly the 125's and 250's. i remember the 'new at the time' rmx250 had them
Forum whore
in their modern form i remember production mx and enduro bikes having them from 1989 onwards...mostly the 125's and 250's. i remember the 'new at the time' rmx250 had them
'the stickiest situation since sticky the stick insect got stuck on a sticky bun'
Cpt Edmund Blackadder
Forum whore
and of course they became de rigueur throughout the '90s, their main advantage being the lack of underhang below the front axle...although i cant recall the last time i was thrown over the handlebars due to my rwu forks snagging me to a halt in a rut
im sure dr robert could fill us in on any technical advantages of them over rwu's
'the stickiest situation since sticky the stick insect got stuck on a sticky bun'
Cpt Edmund Blackadder
one placenta
...my earlier bikes all had upside down forks at some point in their lives...nearly always ended up with broken ribs or shit like that, just after they turned USD..
FUN LOVIN CRIMINAL
Originally Posted by Blackflagged
WP in 1983 1st mass supplier of USD for KTM
No8 Wire Extraordinaire
Suzuki FA50 std fitment from 1980, but heaps of examples before that. The woeful Bantam has been mentioned before, and there's not much arguing that wasn't mass produced. Can't be bothered to check if the DKW the design was stolen from was usd.
Don't you look at my accountant.
He's the only one I've got.
Fully qualified Sifter.
Yep. Simons UDX60's. Worth big money now. Was a new set on TM a while back. Similar to the sort of money Fox Factory Forx fetch..sometimes more.
Forum whore
henderson fours went to usd's before WW1
Hardcore Biker
I'm under the impression that the main difference is that USDs have a slightly lower unsprung weight. I don't think there's much in it with regard to rigidity. Would be interested to hear if that's not the case and/or what else there might be.
Do us all a favour, by bringing yourself up to speed, before pulling onto the motorway.
No8 Wire Extraordinaire
Why would you think that?
What are the differences in the tube sizes comparatively? & would you think that would make a difference?
Don't you look at my accountant.
He's the only one I've got.
Hardcore Biker
Just the impression I was under, I did say 'unsprung weight'. I would have thought an USD lower was lighter than a RWU lower. They're normally quite chunky cast aluminium (RWUs). I think USDs might well be lighter overall too. They're like eggshells on wall thickness. RWU stanchions are usually pretty heavy walled steel. Though there is the caliper mounting system difference too to consider.
Just my thoughts, I don't know if it's actually the case. As I said I'd be interested to hear if this is correct or myth.
Do us all a favour, by bringing yourself up to speed, before pulling onto the motorway.
No8 Wire Extraordinaire
Just like frames. Bigger tubes = more rigidity. The smallest diameter tube is also the shortest instead of the longest.
As with monoshock rears (the increased size helped), but they conincided with proper shimmed damping.
Don't you look at my accountant.
He's the only one I've got.
FUN LOVIN CRIMINAL
Bantams and a few other makes at the time were direct copies of the DKW RT125 and the Royal Enfield flying flea was a copy of the RT100 but with rigid suspenders
mmm nah they had two variants of a springer front end either trailing or leading linkage even when Schwinn brought he brand in 1917 they stuck with the same design; even the 1925 1300cc De Luxe was springer front end
Forum whore
Bigger diameter upper tube means more contact area between tube and triple clamps, which apparently means a more rigid assembly.
Among other reasons.
it's not a bad thing till you throw a KLR into the mix.
those cheap ass bitches can do anything with ductape.
(PostalDave on ADVrider)
Forum whore
Being that I am of the suspicious type, I'll ask the question of "why do you you need to know?" Are you you specifically asking for your own general interets and furthering your knowledge base, or given the date you have noted in the your post above of "before say 1990", are you heading in a pre 89 race bike legality question?
If the later, you'll want to pay particular attention to the the specific pre 89 rules around forks that can be used, and when. It's very much a case of just because USD forks existed pre 1990, doesn't mean that any USD fork can be used. Period Ohlins and WP forks can be used where there is proof they were used on a specific model (ie Olins on Bimota YB4, 888 Corsa OW01, YZR500), or appropriately old enough WP's on say a AF1 250 Aprilia GP bike. ZXR400 are the only obvious USD fork /OEM production model and the rules are such that these are allowed, but only on a ZXR400. Essentially to stop every bike arriving with a set of ZXR400 forks on them.....
Last edited by malcy25; 3rd October 2013 at 11:51. Reason: spulling!
No8 Wire Extraordinaire
Sweet! Due to this post I can now pull out my Ex Lawson YZR & legally use USDs in Posties.
Now it was around here somewhere. . .
What's under this sheet? Drat an XZ400.
Hmm. . .CX500 Custom, no. . .
MVX250, no. . . .hmm.
Ohh, GPz305, but no,
Hey I didn't remember this Hesketh,
bah,
it'll show up I'm sure.
Don't you look at my accountant.
He's the only one I've got.
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