Inverted Forks

[Steven Conlan]

OK - so I see people saying "no question is a dumb question" .

so here goes : Why do I keep seeing reference to "inverted forks".
Educated guess - forks operate better upside down. If this is true - Why??
When did this become common practice? Who first tried this ? Has anyone invented a fork that operates best right side up ?

Any tidbit on this would be appreciated. Thanks Steve

[Pete Logan]

It's about sprung versus unsprung weight.

The bottom end of the fork is unsprung (directly attached to the road), the top end is solidly attached to the frame, above the springs (sprung).

For best handling, it's best to have as much weight sprung as possible, so the heavy end of the forks should be at the top end, above the springs.

Personally, I find if I say 'sprung', 'unsprung', 'sprung', 'unsprung' a couple times, the words lose all meaning :-D

[MelodicMetalGod]

Steven Conlan,

Thanks for asking that question. I don't consider it dumb, in fact I've been wondering the same thing but never remembered to bring it up.

[MelodicMetalGod]

Pete Logan,

Thanks for the explanation. Makes sense but the sprung/unsprung weight thing hadn't even occured to me. Well done!

[Mark M]

It's about sprung versus unsprung weight.

The bottom end of the fork is unsprung (directly attached to the road), the top end is solidly attached to the frame, above the springs (sprung).

For best handling, it's best to have as much weight sprung as possible, so the heavy end of the forks should be at the top end, above the springs.

Personally, I find if I say 'sprung', 'unsprung', 'sprung', 'unsprung' a couple times, the words lose all meaning :-D

While this is partly true, it is actually about stiffness. Inverted forks place the much bigger outer tube at the top, and maximum bending force occurs at the lower triple clamp. Thus, inverted forks are stiffer and offer more precise handling and a less flexy overall chassis. The lower unsprung weight is only a happy coincidence, the extra rigidity is king on motorcycles.

Mark

[TheCafeKid]

Having only ridden one bike with inverted forks ( my dads Vulcan 900) it certainly a different feeling having the suspension react that way, I mean its not really different in philosophy but the handling certainly feels different..not weird but different. Its actually alot more stable seemingly. I guess that would be due to the unsprung vs sprung...seems to come up at you more than the bike diving to meet it...

[Dink]

Tis actually due to both reasons mentioned above. Lower unsprung weight,and the upper tube could then be extended to further increase stiffness.

Dink

[Billy Ricks]

Tis actually due to both reasons mentioned above. Lower unsprung weight,and the upper tube could then be extended to further increase stiffness.

Dink

Yup, aluminum is lighter than steel.

[the_journeyman]

So this is why people put GSXR front-ends on their GS I'm assuming. My Monster has inverted forks and it feels completely different from a handling and simple steering standpoint. I had to get used to how the GS felt ~

JM

[80GS1000]

So this is why people put GSXR front-ends on their GS I'm assuming. My Monster has inverted forks and it feels completely different from a handling and simple steering standpoint. I had to get used to how the GS felt ~

JM

People put GSXR front ends on their GS bikes because they're lighter, much stiffer, have much better brakes, and let you run an aluminum front wheel with a radial tire.

Your Monster feels different because it has a much more aggressive steering geometry than the stock GS. A GS can be made to handle like a newer sportbike by revising its steering geometry. By raising the rear, I was able to steepen the rake on the 1000 from 30 degrees stock to 24.5 revised. 24.5 is comparable to a FZ1, for comparision a GSXR 1000/750 or R1/R6 are in the high 23 degree range. It turns much much faster now. Also gone is ANY fork flex, and modern GSXR brakes work much better than the old GS front brakes.

[Nessism]

Newer bikes have stiffer frames as well which allows the designers to run steep head angles without loss of stability when loaded in a corner.

Regarding the topic in general, there have been significant improvements in suspension technology since the day of our GS bikes. Just about any fork from 1990 onward will put our small diameter GS forks to shame - up side down, right side up, or any which way.

[Steven Conlan]

Thanks

Thanks for all the answers - Its starting to make sense. I have only owned a handful of bikes. Only 2 for any mentionable time. A 1967 Norton P-11 (650cc "scrambler") a bike aimed at on and off road rally's. Owned that for 10 years. And 12 yrs ago the newest bike I have ever owned, a 1985 GS 1150. I have road other newer bikes. My nephew always has to have the latest and greatest. So I have ridden a couple of Ninjas and a couple of V-Max's (now thats a quick bike). The 85 has wet my whistle for something newer. Maybe something built aroung 1999. The short rides I have done on some newer bikes really impress me with thier agility. Trouble --- you start to think that you could manuever out of almost any situation. Yea - just like when I was 20 and bulletproof. I have been looking but I am at an impass. When I see a potential buy - my wife says "so how much are you gonna sell the 85 for". SELL - what is she crazy. Who ever said anything about sell. Well so far, thats as far as we can get in the conversation. Again thanks.