upside down forks? wots it all about?
 

Bit embarrassing really, being an engineer as well.

But i cant figure out why upside down forks make any any difference as opposed to right way up forks?

can anyone explain, i've googled and wiki'd it, stil none the wiser! :roll:

My very basic understanding is that with upsidedownies the "thick" bit of the forks are contained within in the yokes, thus helping rigidity and the thin bits are suspended, helping with, maybe, unsprung weight.

I'm sure someone will be along soon with the professional answer. :lol:

Simply put, USD forks usually have better internals ie catridge(as opposed to SVs' damper rod internals). RWU catridge forks work just as well.


Cheers
Ben

And they look better too 8)

They do look better, but often transmit more of an accident shock into the frame, plus don't they have a tendency to blow the seals more often?

But there is no reason RWU forks can't have the same internals? its just a tarty thing?

Your right Ben is a tart :lol:

Have a look at this months Performance Bikes mag. There's a GSXR 600/1000 that's got radial brakes on RWU forks, weird but kinda cool. The guy who built it says the forks are good enough as they are, I think he's changed the internals though.

Now that most bikes have USD forks, shouldn't they be called RWU? Or would that be too confusing?

& they are more expensive to change the oil.......by a shop

:shock: :lol: .

Hovi5, for a shop with the right tools/know what they are doing(....and some don't) etc, shouldn't add much more. To do most USD yourself you only need to invest about £30 for a basic kit.


Cheers
Ben

i suppose you'd nee to remove forks completely,

or, like in the good ol days, when i were a lad, put the bike on its saddle and handlebars (then spin the wheels up as fast as they can go and throw stones at the tyre see how far it flys- pref. at older brother)

:oops: or was that just me?

Close enough Pete, they're stiffer, but the thing about USDs on road bikes is that they're rarely lighter than a set of RWU forks, the design would allow lighter forks but simply the exotic materials needed to make them lighter would be prohibitively expensive for a run of the mill road bike.
Also the layout of something never ever ever guarantees it's quality, there are notable USD forks out there that are simply poorer quality than the RWU they sometimes replace.

The racer dudes put a lot into their unsprung weight efforts, that's th main benefit I think. The Ducati factory are over the moon cos they've just made the front calipers 20mm smaller on the 1098, wowee.

It's the unsprung weight that's the benefit here, not stiffness. The wheels tyres calipers axles and the lower part of the forks are all insprung and therefore have to track the ups and downs of bumps. At speed these unsprung masses all present a lot of inertia as they bounce over even the smallest bumps. If the unsprung mass can't track the surface bumps then they'll lose contact with the road...and that aint good for grip.

Like what was said above it makes the shocks more responsive.

F=MA and all that jazz I believe.

If there's a set of USDs fitted to road bike that's superior in terms of unsprung weight, I shall be deeply surprised.
Remember in the case of RWU forks the slider, (the unsprung part), is aluminium and light, the unsprung part of a USD fork is steel, the wheel, brakes and mudguard etc are fitted in similar ways and are thus to be added to the weight of the fork's moving parts weight in the same way.

I'm quite happy to be outed as a tart :) I would've fitted recent GSXR RWUs but fitment's easier with the USDs- much better interchangability between years as the upper tube sizes are fairly consistent, so you can swap yokes, clipons etc. This could be the same for RWUs, but isn't.

The more i look at northwind's bike in the avatar, the more i want USD forks on my curvy..

Matt

Do it you know you want to 8) 21QUEST is selling a complete front end ready to go in http://forums.sv650.org/viewtopic.php?t=49845

And once you have done the mod you will recoup most of the money you spent on selling the parts you removed 8)

And welcome to the mad house :wink:

I should be on commission :) 21Quest's set would be a dead easy fit incidentally, hint hint. Far and away the best mod I've done to mine, with the possible exceptions of the heated grips and the button that blows all the fuses.

Yeah all the shameless plugging he owes us a drink :lol:

Cheers

Give me a year and i'll give you a full answer to this question.

I'll hold you to that :lol:

Doing motor sports Eng in sept (took a gap year to get some money and do a bike test 28th of Feb :S), one of the lecturers has a CBR600 with a blower. I'll ask him lots of questions about it.

Well, the Hyosung 650 Comet has Usd forks...but the Rwu SVs are said to be better. Would the Comets Usd fit the SV?

Well, you could make them fit, no doubt, but they're No Good... And I bet it'd be harder than fitting SRAD or later GSXR forks, which are Good. The reason almost everybody doing a fork conversion uses GSXR isn't that they're particularily fantastic- though they're very good forks- but that they're easy. SRAD yokes in a curvy are very nearly a bolt-in, likewise many of the later yokes for pointies, and that's the hard part.

Is it more of a cosmetic mod?

No not at all you get improved suspension and awesome stopping power over the standard set up!

Not at all... It makes a massive difference to the way the bike works. Better and more usable brakes, better roadholding... No running wide in bumpy corners or squatting on the brakes, and I can happily run over road hazards that would upset the SV.

You can make SV forks work just as well, but it's more expensive than a front end swap by and large- something like the Matris cartridge kit for the pointy would give a very good front end, and you could upgrade the brakes to be as good as the GSXR ones...

But when I did my front end swap, I sold the SV bits, and the only reason I didn't make money off the deal was that I chose to pay for powdercoating, a new front tyre and a better master cylinder. Even then, it cost less than a set of emulators and springs for the SV forks.

Also, it looks good :)

On the Hyosang it's cosmetic, as they're still rubbish damper forks. I suppose you could say that on the GSXRs it's cosmetic too, since they could make a RWU fork work as well. But fitting a good USD front to an SV is about a million miles from cosmetic

Stiffness is the primary reason for USD forks, unsprung weight is a secondary reason

the reason you don't see many non cartridge USD forks is cause cartridges were an advancement in fork technology before someone decided to turn then upside down, they first appeared in the dirtbike arena before making theire way to the street

USD forks are stiffer but unsprung weight is increased because the dense part of the fork is now at the bottom.

Materials technology could overcome the stiffness advantage that USD forks have but manufacturers know that USD forks sell bikes due to the aesthetics so there is no incentive.

Exactly. Ride, say, a GSXR600 K2 vs a 750 K2 and you wouldn't get off thinking "Hmm, those RWU forks are much less stiff than the USDs", or for that matter "Wow, you can really feel the difference in unsprung weight!"... Perhaps if you were converting for race use, or a really, seriously demanding rider, but I guarantee most of us couldn't tell the difference. Both good, effective front ends.

Precisely, Curium well done I'm glad somebody else is aware of this too.

As said before: Any of the USD forks you are likely to fit to an SV, (any that you'll find on a road bike actually), do not have a better unsprung weight ratio.

I've had a think and can't see why usd is better than rwu. Surely quality and setup are far more important.

must be a fashion thing.

Absolutely. But it's sort of like radial master cylinders- fashion dictates that the best bikes have to have them, and so the most development goes into the fashionable part, and the best price is taken for the fashionable part. So, frinstance, Brembo don't make a commercially available top-end conventional master cylinder, even though it'd work perfectly well, because less people would buy
it. (most of the improvements that people put down to radial master cylinders actually come from the fact that they tend to be better built, and better designed.

So there's a sort of self-selection here, the fashionable parts do tend to be better than the unfashionable.

Not necessarily, USD do have some advantages, the design allows unquestionably better stiffness, (of course this is only any good if the chassis to which they're fitted is stiff enough to take advantage of that, not all are), however as a suspension medium they will have a poorer ratio of unsprung/sprung weight unless something quite exotic materials wise is used for the slider, and it never is.

Yes, but depends on the use to which the bike is put. Where stiffness is important, ie racing, there'll be USD.

Incidentally, the first telescopic forks were what we would now call USD, so really SVs have USD forks fitted as standard - Northy's fitted RWU forks to his bike... :lol:

Incidently...

Why the original switch from USD to RWU? My dad rode in his youth and all his bikes were USD apparently, then RWU came in, now back to USD...

Any idea's?

Stu