Inverted Forks

[akreider]

I have a 81 GS1100E and I am looking to swap on an early 90s GSXR forks. I have seen that some people invert them, what is the benefit of doing that?

 

[mlaalm]

Classic made modern - mostly for the looks
With a set of progressive springs and heavier fork oil your bike would be fine
I did my 1150 mainly for the looks . . . . . I confess

 

[RJ]

I respectfullu disagree. Changing my '82 1100E forks over to a GSXR unit made for a vast improvement in handling and ride quality over stock units that were rebuilt with Progressive springs, fork brace, brand new Bridgestone Battlax tires. Not only did the suspension action improve, I was able to mount six piston calipers that blow the old calipers into the weeds. There simply is no comparison to the old setup. Yes it does look kinda bitchin' too.

 

[fat_sac]

I respectfullu disagree. Changing my '82 1100E forks over to a GSXR unit made for a vast improvement in handling and ride quality over stock units that were rebuilt with Progressive springs, fork brace, brand new Bridgestone Battlax tires. Not only did the suspension action improve, I was able to mount six piston calipers that blow the old calipers into the weeds. There simply is no comparison to the old setup. Yes it does look kinda bitchin' too.

I was listening until you said Battleax's. Those things are complete ****.

 

[mlaalm]

I agree to dis-agree. My stock GS1150 brakes with steel lines totally smoked my GSXR six pistons with braided lines. The GSXR six pistons even on newer bikes like the Hayabusa still suck. Even with the GSXR 1100 usd forks, by having to go with lower profile rubber (120/70) I have lost enough ground clearance to where I have to go over speed bumps in parking lots and my sub-division with caution.

Yes you do get a better selection in rubber but the GS's are touring bikes by nature. Giving them better forks and rubber in my mind made it a modern looking touring bike but by no means turned it into a sport bike.

If I could do it again I would have just coverted my GS1150ES to a GS1150E.

The GS's are built so long that to me going with GSXR front and rear rims and rubber actually takes away from the 'lean' agle you would have if you would keep it stock with the taller profile rubber front and back.

Just my .02 cents . . . . .

 

[mlaalm]

BTW, six piston calipers are for looks as well . . . . four pistons stop much better

 

[Guest]

Ouch!!!!!!

 

[jhw84]

Back to your question, Akreider, to invert the forks keeps them from twisting as much. It is a dirtbike thing that somehow got conveyed to the street. Very unnecessary in my opinion, because the reason dirtbikers started doing it is because their forks twisted too much when landing a long jump... something that I would pay good money to see any streetbike do.

 

[graymulligan]

Back to your question, Akreider, to invert the forks keeps them from twisting as much. It is a dirtbike thing that somehow got conveyed to the street. Very unnecessary in my opinion, because the reason dirtbikers started doing it is because their forks twisted too much when landing a long jump... something that I would pay good money to see any streetbike do.

I was wondering when someone would bring up the dirtbike thing. 100% correct (as I've read at least).

For the most part, the "inverted fork" idea isn't a bad one, but its more sales pitch and less real world performance unless you're riding near the limit, which most of us don't really do.

Now, on a 900RR on the track at Watkins Glen, yeah, I see some benefit. But storming the backroad twisties, not a ton of help there for folks who don't push toward the edge of the envelope.

 

[Guest]

There are a couple of reasons I went with inveted forks...

1. the bike goes WAAAAAAY FASTER
2. nice to get rid of that chopper front wheel
3. nice to have a thick foot print and some pirelli's
4. the bike goes WAAAAAAY FASTER!
5. can get way nicer fenders, wheeeeeels
6. nice to get rid of the anti dive nonsense and the spungy lever
7. I kind a like a valved fork too
8. I don't even want to mention those UUGLY heavy 80'S BRAKES (so I won"t)
9. 320 full floating rotors???? nice (but I am sure they don't stop any better)

Other than that and they look WAY KOOL! they are USELESSSSSSSS..........

just might be me though

i SAY go for it dude and enjoy.

 

[makenzie71]

holy cow...sportbikes went with inverted forks because of dirtbikes? hahahahahahaahha How do you figure? Just about every manufacturer that adopted inverted forks introduced them the same year...most actually popped out dirtbikes the next year.

The development and placement of inverted forks had nothing to do with dirtbikes or streetbikes. It was entirely about structural rigidity. They're sturdier...beefier...heavier. They don't flex as much, which equates to better road handling in the curves. Also, the travelling end is shorter, reducing the amount of leverage against the road, making bending more difficult.

Oh and just for kicks:

Anyone want to tell me what dirtbike had inverted forks from the factory in 1988?

 

[Nerobro]

first off, you can't "invert" forks. Forks must always be installed "proper side up" or else they won't work.

Installing inverted forks on your bike, is not hard. You just need to find a suzuki with inverted forks, buy them, and install them.

The reason companies went with inverted forks is that it places the stronger part of the fork (the larger diameter part) closer to the highest stress aeras. It also reduces the unsprung weight.

 

[QuaiChangKane]

FWIW - the initial reason for using inverted forks on a street bike was to reduce unsprung weight, not to reduce twisting.


Dirt bikes have longer forks, so the tubes are longer on standard forks, and are more prone to flexing.

Either way, though - inverted forks provide both less unsprung weight and shorter tubes for less flex. But with street bikes, even standard forks are beefier now and have shorter tubes than they used to, so are less prone to flex by design now.



-Q!

 

[jhw84]

Damnit, now Im going to have to test-ride something with inverted forks to see what all the fuss is about. I think the "regualr" forks on my bikes work fine.

 

[bwringer]

Back to your question, Akreider, to invert the forks keeps them from twisting as much. It is a dirtbike thing that somehow got conveyed to the street. Very unnecessary in my opinion, because the reason dirtbikers started doing it is because their forks twisted too much when landing a long jump... something that I would pay good money to see any streetbike do.

How much money?

I can take you to a certain public road in a certain secret location where you may witness the sheer wrongness of a fully loaded GS850 landing an impressive jump and wheelie.

Of course, I pretty much needed new underwear the first time it happened unexpectedly, but I've learned to anticipate and enjoy it.

 

[bwringer]

Back to the topic at hand, are there any handling problems created by lashing super-stiff "new style" inverted (or conventional) forks to the flexible "old style" GS frame? As it is now, both the frame and the fork have similar "matching" limits.

Also, it is possible to easily perform such a fork transplant on a shaftie, where you're pretty much stuck with a 130/90-17 rear tire? IOW, would you be able to retain the stock 100/90-19 front tire and rim while transplanting the newer stiffer forks?

Anything's possible with a machine shop and plenty of time, but I didn't know if anyone's found a way to do this less painfully. I know most fork/front wheel transplants also involve a swingarm/rear wheel transplant to fit wider rubber, and that isn't an option on a shaftie.

Just random thoughts...

 

[morthrane]

Of course there's the potential for problems. The chassis, much like an engine, is a system that is more than the sum of its parts. Changing one part of that system will invariably bring out the shortcomings in other parts, or introduce new problems (e.g., ground clearance); if you're not careful, the whole system just won't work well at all. The best analogy I've heard is that of baking a cake-- the finished product does not resemble the ingredients, and major changes to the quantity of ingredients can make an otherwise tasty cake totally unpalatable. This isn't to say you can't tweak and tune, just that its apparently very easy to reach a result that won't fit your tastes as a rider.

For example, most of the "serious" chassis upgrades made to Katanas involve bracing the frame in addition to upgraded brakes/forks/wider wheels/swingarm/shock(s).

Another point to consider is that wider tires are actually detrimental to handling. Wider tires are a method of coping with horrendous horsepower outputs; does a shaftie put out that much power to really need wider tires?

Unless you're willing to go the whole route and upgrade the entire chassis, it doesn't seem like its really worth the effort when you can spend a small sum of money to make what you have work better. Different brake pads, Racetech Emulators, different springs, some cheap shocks that aren't 20 years old...

 

[morthrane]

FWIW, I've had a chance to put some miles in the mountains on my 82 1100-motored Katana. It doesn't actually handle that badly for a 550+lbs bike, it just can go way too fast and overwhelm the pitiful OEM brakes.

The chassis definitely is a flexiflyer, as I found when a bad mid corner bump essentially levered the front wheel into the air momentarily, the Yoshimura 4-1 left a chunk of itself embedded into the asphalt, and a piece of the seat vanished into a black hole.

I'm looking right now at how I can make an extra 01 R1 frontend fit on the Katana....

 

[Dink]

FWIW, I've had a chance to put some miles in the mountains on my 82 1100-motored Katana. It doesn't actually handle that badly for a 550+lbs bike, it just can go way too fast and overwhelm the pitiful OEM brakes.

The chassis definitely is a flexiflyer, as I found when a bad mid corner bump essentially levered the front wheel into the air momentarily, the Yoshimura 4-1 left a chunk of itself embedded into the asphalt, and a piece of the seat vanished into a black hole.

I'm looking right now at how I can make an extra 01 R1 frontend fit on the Katana....

TO fix the brakes flush with Methylated spirit and refill with Castrol SRF brake fluid, it isn't cheap but it will then pull two finger stoppies. Remove anti-Dive lines if not already done.
Dink

 

[Guest]

and remove the garden hoses and go with s/s lines