Inverted forks, why?

[bargovic]

So i was drooling over the truimph speed triple again, as i read about it in cycle world this weekend.  It has inverted forks, which i think look awesome.  But whats the benefit of having them over a regular fork ? more travel ? And has anyone put them on a GS?

[Egaeus]

Less unsprung mass.  There is less weight on the wheel side, so there's not as much inertia.  That allows the wheel to move faster, causing it to respond to the road surface better.  Or at least that's my understanding.

Edit: unsprung....  Don't want to confuse anyone over the argument.

[brembo]

Inverted forks are more rigid so are less prone to deflection compared to a same-sized conventional fork. The main drawbacks to the USD forks are their higher cost and greater weight.

[makenzie71]

Less sprung mass. There is less weight on the wheel side, so there's not as much inertia. That allows the wheel to move faster, causing it to respond to the road surface better. Or at least that's my understanding.

Umm...unsprung weight is the same no matter which way the skinny end points.

Inverted forks are more rigid so are less prone to deflection compared to a same-sized conventional fork. The main drawbacks to the USD forks are their higher cost and greater weight.

Partially right...they are less prone to flex.  More of the shock is "thick" and the the assembly as a whole is beefier.  But my 41mm TL forks weight the same as my 41mm Bandit forks.

[Phaedrus]

Because "Upside down forks R kewl" 

[corndog67]

I'm buying a set of GSXR 750 forks from a road racer guy that I work with, with the 6-piston calipers, front wheel, master cylinder, brake hoses, everything, that I am going to put on the little GS500E.  I will probably have to make a steering stem, or swap the GS stem into the GSXR triple clamps, figure out a headlight bracket, and a way to mount the gauges.  I am also going to put some standard handle bars on it.  As it is now, my stock forks suck.  They bottom out on grains of sand.  I checked out the weight of the GS, and the GSXR, and they are pretty close.  The spring rate should be about right.  We're talking 2 finger stoppies.  I will let you know how it works out.  I am a machinist, so it isn't going to be a hack job. 

[werase643]

better brake calipers
better brake pads
better rotors
3.5x17 rim...better tire selection

[makenzie71]

I'm buying a set of GSXR 750 forks from a road racer guy that I work with, with the 6-piston calipers, front wheel, master cylinder, brake hoses, everything, that I am going to put on the little GS500E. I will probably have to make a steering stem, or swap the GS stem into the GSXR triple clamps, figure out a headlight bracket, and a way to mount the gauges. I am also going to put some standard handle bars on it. As it is now, my stock forks suck. They bottom out on grains of sand. I checked out the weight of the GS, and the GSXR, and they are pretty close. The spring rate should be about right. We're talking 2 finger stoppies. I will let you know how it works out. I am a machinist, so it isn't going to be a hack job.

You need a bearing kit...it'll cost about $75 as a whole for good bearings if you have a later GS.  The earlier 500's have ball bearings iirc...the newer E's should use rollers.

Bikebandit and ronayers both carry headlight mounts that stick an SV style 7" light to the GSXR inverted forks.  Sign up on TLzone and PM DRZDoug about how he mounted the guages...not too sure.

Oh yeah...and it's "inverted" forks.  There's nothing "upside down" about them.

[The Buddha]

If you are buying inverted forks though ... get the 90-95 I believe GSXR 750 ones ... the newer ones were made thinner and thinner and thinner ... as in ... you bump into somehting and they break ... Of course the oldies are heavy as a mofo ...
Cool.
Srinath.

[fettcols]

With the older ones you'll probably run into less problems with the speedo...

[Kasumi]

The inverted forks on my new bike seem to give me alot better handling than conventional ones - yes they are heavier but they're stiff and hard and give a better feeling and i don't feel any touch of flex on long open fast corners. Theyre wonderful. Plus they look the dogs gonads. Im only talking from a riding perspective i am unsure of the physics of inverted forks.

[Wrecent_Wryder]

[5

[fettcols]

The inverted forks on my new bike seem to give me alot better handling than conventional ones - yes they are heavier but they're stiff and hard and give a better feeling and i don't feel any touch of flex on long open fast corners. Theyre wonderful. Plus they look the dogs gonads. Im only talking from a riding perspective i am unsure of the physics of inverted forks.

Exactly... heavier without the squish/nosedive factor.       One bad thing about them... It's a little more expensive on the labor to replace the seals.. And when they go bad you get fork oil on your brakes...

[makenzie71]

That's an unusual opinion. The rest of the world pretty much thinks that having the "big end" bouncing up and down with the wheel, as opposed to the "skinny end", really does increase the unsprung weight.

I'll try wording it a bit differently:

The skinny end of my TL1000S forks weighs the same as the big end of my Bandit forks.  Does that help?

[red_phil]

yeah, still for overall mass of forks, the Inverted forks has less unsprung mass.
so you get more stiffness without the extra unsprung mass.

[makenzie71]

But my 41mm TL forks weight the same as my 41mm Bandit forks.

The skinny end of my TL1000S forks weighs the same as the big end of my Bandit forks.  Does that help?

Then...

yeah, still for overall mass of forks, the Inverted forks has less unsprung mass.
so you get more stiffness without the extra unsprung mass.

Read a bit, mate.  In the few instances there may be a difference in weight...it's neglegible as a whole or at either end.  The heavy stuff is inside the fork and is "unsprung weight" and remains pretty constant regardless of fork design variety.  The only forks made that are lighter over all are springers and telelevers and that's because all the springy shaZam! is bolted to the bike.

[dgyver]

I'm buying a set of GSXR 750 forks from a road racer guy that I work with, with the 6-piston calipers, front wheel, master cylinder, brake hoses, everything, that I am going to put on the little GS500E.  I will probably have to make a steering stem, or swap the GS stem into the GSXR triple clamps, figure out a headlight bracket, and a way to mount the gauges.  I am also going to put some standard handle bars on it.  As it is now, my stock forks suck.  They bottom out on grains of sand.  I checked out the weight of the GS, and the GSXR, and they are pretty close.  The spring rate should be about right.  We're talking 2 finger stoppies.  I will let you know how it works out.  I am a machinist, so it isn't going to be a hack job. 

When I did a 96-99 GSXR750 f/e, I had the gix stem turned to fit the GS. The GS stem is 0.5mm smaller in diameter than the gix and would not press into the gix lower triple. You can weld the GS stem and turn it to fit. The gix stem is very easy to turn to fit but you will need a lathe that can cut metric threads. One thread is 25x1.0 and dies are not made. Luckily I have access to a tooling shop. Also, I have a drawing of the stem if you need it.

[corndog67]

Thanks dgyver, but I am a machinist in what I consider the baddest ass machine shop in the state.  We've got the machinery to do almost anything.  Metric threads included.  I will let you guys know when I am done.  It's going to be a  little while, we are way behind at work, so it's overtime for a while, then I will be able to do it. 

[makenzie71]

The stem really needs to be turned down?  I thought it fit through the stock steering head...?  I know two people who've got GSXR forks (late 90's 750 on one, K4 1000 on the other) and I could have sworn they said they only have to get a different bearing set.

[corndog67]

I will let you know what it needs when I get in there and start measuring.