Both my pairs of maverick sc's are soooo flexy that i can't ride my bike in a straight line. NOT 
Bike Forum
[closed]
USD forks ! Why not ?
-
Posted 2 years ago #
-
thisisnotaspoon - Member
A motorbike has a minimum weight limit for competition.
Not in my days of motocross and enduro riding they didn't, and AFAIK they don't now either.
Anyway, tinsy has hit the nail on the head - the big advantage of USD forks was that you could achieve long travel with sufficient slider/stanchion overlap without having the end of the sliders practically dragging on the ground.
Posted 2 years ago # -
RWD vs USD on motorbikes IS mostly fashion
That may be so. But, even you admit it's MOSTLY fashion, so there's no doubt there is some performance advantage, even if it's only a bit. And that's how technology progresses - Bit by bit, slowly. If it didn't, we'd all still be riding round on noodly things that needed an extra brace like those in the pic above. Can you get braces for modern bikes? Do they need them? I think not!
And what's wrong with fashion anyway? My Monster would have looked bloody stupid with RWU forks
http://farm4.static.flickr.com/3421/3742709337_3b454be555_b.jpgPosted 2 years ago # -
Mainly fashion on motorcycles anyway
TJ, as usual you're talking pure bull.For the majority of motorcycles tho its purely for fashion as I said. Hyosung 650 with USD?
Fashion and Hyosung together in the same sentence? Why not?
Posted 2 years ago # -
I remember back in the day (probably about 2000) Marzocchi announced a 1000g USD XC fork, the RAC, which IIRC (just to get another TLA in there) was 'Reversed Advanced (or Action) Composite.
Unfortunately they could never make it work properly, and the production version of the RAC was a short travel fork which ended up weighing quite a bit!
These:
Posted 2 years ago # -
Hairchested as I said and others agree - its mainly fashion. Are you really trying to say that the hyosung has usd forks for a performance advantage? If they had spent the money on a better pair of RWU forks it would handle better.
Posted 2 years ago # -
I am struggling to see why USD are any more expensive to make than RWU, and I have worked in a production engineering enviroment for over 20 years, the cost as ever will be down to the numbers produced, materials used, & what you can make common parts with other derivatives etc, etc, the part count in either fork must be very similar.
I have had this moan about MTB forks before, the manufacturers make a travel adjustable fork so it suits lots more applications, this adds cost and complexity to the fork that we pay for, what in most cases we really need is a simpler fork with a lock down feature for climbing, but why produce that when the end user is still happy to pay for lots of tech he rarely if ever uses.
My mav's lock down its a great feature when your running forks that are at or over the upper limit of travel for your frame.
Posted 2 years ago # -
what in most cases we really need is a simpler fork with a lock down feature for climbing
Sounds just like the Maverick SC/DUC32
Posted 2 years ago # -
Supersport certaily has a weight limit, no idea about anyone else, in MX it would be unenforceable with all the mud!
On the flexiness point:
OK the two owners of USD mountainbike forks up there ------------^ on the last page.......
Maverick - you can flex them between your knees, this is true for all USD forks, from shivers through to dorrados, they all flex horrfificaly.
Avalanche - if you crashed they had to be re set in the cowns as they had bent out of shape.
Take a set of fox f120's with 15mm axel and compare their stiffness against the maverick SC32's, if you find the fox is less stiff I'll eat my own trillby.
USD forks are flexier than their conventional counterparts for a given weight. On motorbikes weight is less of an issue, so they go with USD. On mountainbikes we rather have a stiff and light fork.
on the weight point:
An MX bike has 60hp+ pushing it allong, adding 1lb to the fork uppers makes no noticable difference, and the lower stiction of USD forks is more of an advantage.Take a DH bike, if you added 1lb of unnececary weight you'd never sell a single one! And if youve ever taken a set of forks appart, youd know the lowers are magnesium and weigh SFA anyway, it'd be hard to get much lighter with big aluminium tubes and machined dropouts.
Posted 2 years ago # -
Tinsey - with rwu forks the sliders can be left as cast except for a few areas for mountings - with USD forks more / all of the upper leg needs to be machined.
Posted 2 years ago # -
One last point.............
Motorbikes use (or did last time I checked) 1" steeres, becasue they aren't so bothered about the weight saving, they could use a solid bar in there if they liked. Mountainbikes are lighter therefore we almost addopted 1.25, then setteled on 1.125 and 1.5 steerers,
Posted 2 years ago # -
And....................
Look at the lower tiers of moto gp, the 125's.
Much more weight concious as they have 50bhp rather than 250bhp pushing them allong, conventional forks IIRC are still fairly common as they can be made stiff enough without throwing weight at them.
Posted 2 years ago # -
TINAS, your right of course I covered that in my first post, but in real terms and whilst riding that flex just doesnt manifest itself as an issue, the for and aft flex is probably a bit less than conventional forks, the worst area for flex on either type is the crown thats where all the load is, also covered in my first post.
Did you see the guy the other day with the bent steerer tube after a crash? thats where most of the flexxing is going on, hence the slow move to 1.5 and tapered steerers..
But they did add an extra 1lb into DH forks as they got longr and longer, thats what the dual crown is all about to stiffen the flexy area of the crown and steerer tube. Dual crown is loads heaver but hugely stiffer, even with the old skinny legged Boxxers, still loads stiffer up top where the leverage is. If that are dual crown USD fors they are even stiffer still as the large tubes at the top are stiffer.
TINAS, again your right about the tiddler classes still running conventional forks, but your forgetting its not just the power they have lots less of, its also the weight, it takes a lot less to stop a light weight than a big bike so you dont need that stiffness.
Posted 2 years ago # -
One of the big things, for me, is check out the amount of scratching around the axle of a normal fork - they regularly get beaten on rocks/trees, rested on the ground etc. Even with guards the only USD forks I saw on MTBs (couple of local riders brought them into the shop) had scratches all over their vital bits - that put me off to begin with, I'm not sure it's the best sport for them TBH, except maybe at race level. I think it's hard to draw a line under X is more stiff than Y, it depends totally on the materials, shapes and techniques used - sure one may tend towards more noodleyness but that doesn't mean it is impossible to design it out.
PErsonally I've always wanted a set of ~2000 Jnr Ts, seemed like the ideal compromise really.
Posted 2 years ago # -
Lever / wishbone forks would be better for MTBs imo - no vulnerable sliders, geometric effects for play with for dive. Separation of steering and braking forces, less unsprung weight. Hossack type I think
Posted 2 years ago # -
Halson baby
Posted 2 years ago # -
TJ you would gain that back because the casting cost would be reduced, especially in the MTB design with an arch, its a lot mor complicated to cast the 2 loweres together than seperate.. pretty sure we could go on all day pointing out why one fork would be cheaper to produce but at the end of all that I stick by my comment the cost would be very similar as long as they have the same features for either.
TJ you on about Leading link forks? Like the USE sub for example?
Posted 2 years ago # -
Fair enough tinsey
Posted 2 years ago # -
I've ridden marzzochi shivers on a DH bike, even just riding down a set of steps the flex was disconcerting.
I've ridden shiver SC's again, though big rocks (stanage casueway and the beast) they felt horrible. On a par stiffness wise with my old manitou minutes which were utter pap.
Yes DH forks weigh more than conventional forks, but look at the marzocchi shivers and the original 888's, both made at the same time, both used a similar damper, the 888's were much stiffer, and much lighter, and the shiveres thankfully eventually dissapeared.
The original dorrado's were nicknamed flexarado, nuff said.
Posted 2 years ago # -
TJ, you mean like on the prst-4? With it's "J" axle action that everyone said felt like the wheel tucked under as you turned and it compressed. Obviusly could be tuned with different bone lengths, but it also had issues with shock getting covered in junk. Not sure if it was lighter, anyone got any figures?
Posted 2 years ago # -
I don't ever remember trying to ride my bike with the forks wedged between my knees so that 'stiffness' test is a nonsense!
Posted 2 years ago # -
Gheezz! What with my 29" wheels and my noodle forks I'm surprised I can ride at all
Posted 2 years ago # -
Posted 2 years ago # -
I don't ever remember trying to ride my bike with the forks wedged between anything so that 'stiffness' test is a nonsense!
Ever time the forks hit a rock not quite straight on thats exaclty what happens, they twist.
Every time you brake the fork twists
Every time you turn the bars, the fork twists
Every time you go round a corner, the fork twists.
If stiffness isn't apparent, why is there a trend towards bolt through lowers?
Look at it this way, if it was actualy any good, why does no one make them for the mass market (i.e. i'm excluding £3000 dorrados and foes forks).
Posted 2 years ago # -
Look at it this way, if it was actualy any good, why does no one make them for the mass market (i.e. i'm excluding £70000 ferraris and lamborghinis).
Just because they're not good for mass production doesn't mean they're inherently not good.
Posted 2 years ago # -
So.............my forks are rubbish? Mmmmmmm I still manage ok on them thanks.
Posted 2 years ago # -
One day they will be.. For now I will stick with my Mavericks USD mass produced twisty things..
When Fox make USD forks and one day they will, perhaps opinion will change.
To be honest its just a push bike, ride it and enjoy it.
Posted 2 years ago # -
Look at it this way, if it was actualy any good, why does no one make them for the mass market (i.e. i'm excluding £70000 ferraris and lamborghinis).
firstly, where can I get a new lambo for £70k? Dont drag it OT just to avoid the point.
Secondly, the fact no one outside a couple of niche manufacturers uses(even whyte abandoned maverick forks) has to prove something. If they were better, racers would demand them, consumers would demand them. Theyr not, and we dont.
People want stiff forks
People want light forks
People get conentional forks as it fourfills both those requirements better than USD designs.By all means keep using them, but I dont bleieve for one moment they are better in any way than being more niche than the current generation of conventional designs.
Posted 2 years ago # -
If stiffness isn't apparent, why is there a trend towards bolt through lowers?
Because the marketeers have convinced everyone that they need it?
Either for stiffness (because everything previous was near unrideable because of the flex) or for safety (because all QRs come undone so YOU'LL DIE)
Posted 2 years ago # -
I just bought some 160mm Manipoo Sherman flicks (conventional) to build a budget alps bike, no doubt their will be lots of better forks for the job USD OR RWU, but none of that will be going through my head when I am caning Plenny run.
For now conventional forks fulfil all the requirments you want TINAS stick with them as thats where the R&D is right now for MTB, but one day it will change, it will take FOX to have a swipe before genral opinion is changed.
Posted 2 years ago # -
Surely with USD forks its all about the tube diameter. Increasing the tubing cross section will incresase the strength exponentially...MX bikes can use larger tubing so are much stiffer hence they can use USD forks. Look at the foes xtd f1 fork, it uses a 30mm axle and users have no problems with stiffness and dont weight too much either.
Posted 2 years ago # -
How about Leftys? Theyre USD and I have been led to believe they're stiff, light and work quite well. Sure, price has been a problem in the past but pretty much on par with the competition now, and and you can get adapters (Project 321) to fit pretty much any bike.
For me they seem like a pretty smart design that tackles most of the problems off both traditional fork types. Mind you, I havent ridden one, so they could be utterly horrible.Posted 2 years ago # -
maped, work of the devil them forks, cant possibly work..
Posted 2 years ago # -
Lefty are different because they run on flat surfaces with roller bearings - just like the headshok
Posted 2 years ago # -
Alternative forks - I was meaning like the whyte - altho that is comprimised in lengths of the wishbones as it uses the top wishbone as the steering link.
The sub and the lefty both turn the suspension - a true alternative front end separates the steering from the suspension. - suspension componenets do not turn with the steering. Requires specific frames tho. Has real advantages in that you can tune resonse curves with the location of the wishbones and pivots and you can make them stiffer for the same weight.
A few motorcycles use them - BMWs mainly
singlewishbone / mcpherson strut / telelever
Twin wishbone / duolever
Posted 2 years ago #
Topic Closed
This topic has been closed to new replies.
