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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,
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.
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.
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.
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
Halson baby
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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?
Fair enough tinsey
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.
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?
I don't ever remember trying to ride my bike with the forks wedged between my knees so that 'stiffness' test is a nonsense!
Gheezz! What with my 29" wheels and my noodle forks I'm surprised I can ride at all 
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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).
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.
So.............my forks are rubbish? Mmmmmmm I still manage ok on them thanks.
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.
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.
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)
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.
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.
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.
maped, work of the devil them forks, cant possibly work.. 🙂
Lefty are different because they run on flat surfaces with roller bearings - just like the headshok
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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
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Twin wishbone / duolever
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lefty's run on needle bearings which means yor taking more advantage of the stiffness of the tube, in theory you could build a very expensive fork with two legs using the same needle bearing system, but it'd be just that, expensive.
I just bought some 160mm Manipoo Sherman
I love those forks, are they the TPC+ versions?
TINAS, Yes they have TPC compression and rebound adjust... Were they expensive in their day?
Sure the execution in Lefty is different, but they are still uppy-downy things in front of the bike that make it easier not to crash. Cannondale propably has the design pretty well patented, but I'm still wondering why other manufacturers haven't tried anything like it. To me it seems like a pretty smart design altogether and gets rid off some problems both USD and RWU forks have, mainly the ones brought by having to use round stanchions. Sure, it propably wouldn't work in motorcycles due to the speed of the movement (the [s]roller[/s] needle bearings couldn't keep up?) but for bicycle use it seems like an ingenious idea to get rid of stiction brought by multiple seals and bushings and the vulnerability of the stanchions to dirt and rocks.
no, but they were infinately better than the SPV ones that folowed, TPC+ has made a reapearance in recent years, its like conventional foks, USD and SPV are fancier systems, but the simple ones always work better.
Just remember to change the oil in the damper and lowers, manitou always seemed to go off quicker with old oil than other brands, probably becasue they use smaller dampers/less oil to save weight.
And theres a lot of plastic in them so easy does it with the torque when serviceing.
I was just going to bolt them on and ride it!!! guess I could run to a service, I have oodles of fork oil. At £80 I am not expecting earth shattering performance.
thisisnotaspoon - Member
I've ridden marzzochi shivers on a DH bike, even just riding down a set of steps the flex was disconcerting.
Well, I've got Shivers on my Session 10 over the page, and yes if you do the (utterly pointless) twist your handlebar with the front wheel in between your knees test then they twist quite a bit, but on the Black and Double Black trails on the North Shore that I've ridden with them so far I've not noticed flax to be a significant issue. I only notice it a bit on tight rocky switchbacks and on the road if you turn quickly from one direction to another while leaning back. In both cases, the fork would be fairly well extended. Once it gets into it's travel then there are no issues to me.
I think Jedi still rocks a Shiver on his Demo 9, and seeing the riding he does, if flex was really that bad, he'd have died years ago!
Anyway, I only got it because I think they look great, and it was 200 bucks in mint condition...
firstly, where can I get a new lambo for £70k? Dont drag it OT just to avoid the point.
With respect, I wasn't dragging it off-topic at all, I was drawing a direct comparison. The way ferrari do things is better, lighter and more performance oriented than the way ford do things. But it costs more to do it properly that way. It doesn't mean they're flawed in any way, just that they're not mass-market and not the cheapest way to make lightweight stiff forks. I think you're confusing market potential with performance, that's all. Most manufacturers abandon maveric designs when they realise that either they're naff or they're too expensive to make properly. It doesnt make them a bad design, just not an accountants design.