Suspension history of USDs?

**haydes55** · 18th January 2014, 08:26

Originally Posted by manxkiwi

Back to the subject of forks for a moment. Robert, when you say USDs have a slight advantage in racing, are you meaning to work on? From a sus. tech. point of view.

As I said earlier in this thread, I don't think there's a massive performance/rigidity benefit over RWUs. Does it have anything to do with unsprung weight? Would love to hear your wiewpoint on them.

My understanding with USD forks, is the lighter, skinnier part of the forks are now the parts moving, so move faster, easier.

**Ocean1** · 18th January 2014, 18:33

Originally Posted by husaberg

My 1954 James captain has them too......

My first store-bought (second hand) bike was a James. 250 scrambler. Forks were conventional though.

Fuck I'm old...

**husaberg** · 18th January 2014, 18:36

Originally Posted by husaberg

I will post an article as it appears i are getting usurped in the Anorak stakes.

I am surprised you guys spend so long on the net without posting this though (will add later)

http://world.honda.com/MotoGP/history/NR500/
You can hear it as well on the site same as the NSR and the RC166 etc etc great site
scanning story as i type.
As you will see in the article the origional was a V8 and was legal because it had only 4 combsution chambers honda wouldn't race it even though it was legal as they didn't want to be accused of being dodgy........
The 250 twin Turbo they built for Freddy was also oval pistoned and made more power i posted some stuff about it a while back can't remeber where but i will link it later.The rule allowing its use never evenuated so it was shelved.

Originally Posted by Ocean1

My first store-bought (second hand) bike was a James. 250 scrambler. Forks were conventional though.

Fuck I'm old...

they went to FB AMC forks later. i think the usd "grease dampened" forks only were up to 53 or 54 they we almost exactly the same as Bantam likely same gaiters and all....

**Ocean1** · 18th January 2014, 19:02

Originally Posted by husaberg

they went to FB AMC forks later. i think the usd "grease dampened" forks only were up to 53 or 54 they we almost exactly the same as Bantam likely same gaiters and all....

Don't know what year mine was, I bought it in bits and there was no indication anywhere. Was the later frame they made for scramblers (the non-Cotswold one?) but it had the Villiers which I don't think was usual for the 60's scramblers.

The forks were shit of course, but everything was shit compared to current stuff. And the tracks weren't anywhere near as aerial, so I was quite happy. Was surprisingly quick when you got it right.

**gavinnz** · 19th January 2014, 00:28

Moto Guzzi used upside down forks on their singles from about 1948 until 1967.
I think Scott might have had the first? I remember reading a "first" article in Classic Bike years ago and the first telescoping fork was on a Scott in about 1908 and it was USD.

Check out this picture of a 1913 Scott....

http://en.wikipedia.org/wiki/File:Scott_550_1913.jpg

Regards
Gavin

**ktm84mxc** · 19th January 2014, 08:23

Didn't Honda's CB350F have USD forks or was it just they looked like modern USD's ?
There have been many a design to MC front ends Earls, Springer, Canta lever, BMW's para system etc. Almost as many as rear suspension designs.

**husaberg** · 19th January 2014, 08:26

Originally Posted by ktm84mxc

Didn't Honda's CB350F have USD forks or was it just they looked like modern USD's ?
There have been many a design to MC front ends Earls, Springer, Canta lever, BMW's para system etc. Almost as many as rear suspension designs.

nah they were the rwu same as these twins (one with shouds the other with rubber gators for the SS look)
they had shrouds either to cover the external springs or the unplated sliders or sometimes both (ie Norton BSA etc) like a lot of other bikes mentioned....
the Z50s and so forth plus a lot of Scooters were also USD.....or Male Slider because they could be made cheaply as a fabrication exactly like the James USD fork.
A lot of the early 90 forks were about looking hi tech and they were no better then the conventional forks they replaced most were not even cartridge.

Originally Posted by haydes55

My understanding with USD forks, is the lighter, skinnier part of the forks are now the parts moving, so move faster, easier.

with the slider mounted below they can be made with less unsprung weight
they can aslo be stiffer as the most stress is in the area below the fork yoke. Which is why those 80's fork braces were just a fashion accessory, what you needed was a deeper yoke.

**TLDV8** · 5th June 2014, 18:42

Originally Posted by Crasherfromwayback

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.

Off topic but it seems a lot of those parts in general are spendy these days.
I brought a RM125S new from Colemans in 1976 (in box's now) some time in the 1990's (iirc) I was at Mount Eden Motorcycle Wreckers when you could just wander around looking for parts (H2 parts) and what did I find,a mint DG radial head for said model RM125 asking price $15.
I could probably double my money.

The BSA (DKW) Bantam had a USD of sorts but its a stretch,based more on cost and ease of manufacture perhaps.

**Crasherfromwayback** · 6th June 2014, 00:21

Originally Posted by TLDV8

Off topic but it seems a lot of those parts in general are spendy these days.
I brought a RM125S new from Colemans in 1976 (in box's now) some time in the 1990's (iirc) I was at Mount Eden Motorcycle Wreckers when you could just wander around looking for parts (H2 parts) and what did I find,a mint DG radial head for said model RM125 asking price $15.
I could probably double my money.

The BSA (DKW) Bantam had a USD of sorts but its a stretch,based more on cost and ease of manufacture perhaps.

Nice find mate! And double your money? Fuck me...a mint DG head for your RM would fetch around 4-5 hundred US on Ebay I'd think mate.