Fox TC Shock - spring rate question

[johnnySV]

howdy ya'll this a here is a spring rate question that only applies to Fox Twin Clickers on SV.

.... so i bought a twin clicker for an SV second hand and i am now looking for the proper spring to cater to my 140lb weight. According to Fox; their shocks are supplied w/ 1 of 3 or 4 different options (all weights are rider only.. the weight of gear is already factored into the equation).

a 500lb/in spring for a 90-140lb. rider
a 550lb/in spring for a 140-180lb. rider
and a 600lb/in. spring for a 180-230lb rider

so ya see, the problem i face s that i am right on the bubble of the two weight ranges. because of this, i am considering using a Hypercoil 525lb/in. spring.

the thing that F's up my equation is that when Traxxion sells a Fox.. it has already been re-valved and re-sprung per their specs... and they usually throw a 650lb/in. spring on it ! .. this seems to be a big difference from the manufacturer's recomendation.

i think im all set w/ Fox's recomended specs at 525lb/in. to cater to my street intermediate riding style. hopefully i will be good enough to move to the track soon, at which time i may require a stiffer spring.

im looking for spring rate advice as to what some of you guys are running based on your rider weights, and if you are track or street. spring rates on other manufacturer's shocks dont offer an apples to apples comparison.... so dont even try it foolz.

by the way, the 600lb/in. * 7in. long Eibach original spring is now for sale at $80 shipped. per fox's recomendation, this would be for a 180+ lb. rider. spring may also have other applications. email me for details at jptansey@cisunix.unh.edu

peace

[SUCATI]

Interesting comment. I was just discussing Fox Shocks with my riding buddy a couple of nights ago and he told me that his choice of springs that Fox recommended turned out to be too soft for him. (he rides a Hawk GT) He has since moved up one choice on the spring rate because he was unhappy with the softness.


Mike

[bwarbiany]

Well, since spring rate is probably independent of which shock you get, I'll put it this way... Aftershocks in NorCal recommended for me a 750 lb/in spring (this was when I weighed 240). It sounds like those recommendations are a little light.

But here's what you need to ask yourself. Are you looking for highest performance, or some comfort to? For performance, you'll want something stiffer than those recommendations. For comfortable riding and better performance, you'll be alright with those recommendations...

Brad

[dillweed]

The difference between 500 and 550 is only 10%, so I doubt you really need to go to the trouble of getting a special 525......I have installed 10% stiffer springs on a car, and the difference was not what I'd call significant......

And as for Traxxion Dynamics, they tend to favor high rates because of their bias towards racing......Witness how their fork spring recommendations are much higher than Racetech's.......

[Danny]

Depends on how you have, or plan to, set the fork up. Balance is crucial. Try the 600# first and see how it feels. Then call the guys at Traxxion for advice. Technically you should revalve the shock with a lighter spring, though 550# might work ok.

[johnnySV]

Mike,

I am interested to know where within the weight rage, for his chosen spring, your friend falls. do you know if he was on the bubble between two different springs like me ? ... and maybe he chose the lighter one and regretted it later ? .. or was he a solid weight within a rage (like, say he was 160lbs. in a range of 140-180) ... and did he still prefer the stiffer spring for street riding ??

Others....

Forks will obviously be emmulatore'd and sprung accordingly, and dropped 5mm within the triples. what is everybody running for increased ride height in the shock ? ... and have you'all experianced instability issues yet from too much of an extreme ride height adjustment ??

thanks,

[Dr. D]

Got a gsxr shock that raised the rear 1 inch and dropped the front 10mm. Pretty stable at road america. the sv is really conservative from the factory, as are most bikes. I'm currently running a 120/60 in front. In the spring I'll try a 120/70 and see how that works. I see a lot of racers use that size. Anybody here run a 120/70, how's it work for you?

[johnnySV]

your current setup strikes me as a bit extreme. (i am assuming you measured the unsprung length of ur gsxr shock vs. the unsprung length of the OEM sv shock; yielding a 1" length difference between the two). 1" up in the rear is more than twice the max ride height adjustment of the Fox TC (at 11mm max extension.... unless you add a lengthening kit), coupled w/ 10mm down in the triples must make the thing flick in unbelieveably quick. i have read though, that ramifications of such an extreme setup is instability. my question is, how did u arrive at your current setup.... and did u experiment w/ intermediary steps (like 5mm down in the triples, then 10mm) before deciding that this was right for you. was such a setup recomended by a reliable source and have you yet to experiance stability issues ?

[Dr. D]

Actually my set-up is not that extreme. As for the front end, 10mm down in the triple seems like a lot but the racetech springs raise the front by at least that much when loaded with me on it (200#). The rear, it's up an inch with a resprung 97 gsxr 750 shock. I never measured the shock from eye to eye but installed it's measures up 1 inch (actually more like 7/8). As for instability, so far so good. Factory engineers like to make things nice and safe for us. Reducing the rake and trail will almost always produce a better handling bike without instability. This is assuming you have the correct tire pressure, steering head is adjusted and so on. Remember there are bikes out there much more extreme than the sv. Try it for yourself. Experiment in small increments, worked for me.

[Dr. D]

Also eveything makes a difference, your weight, height, reach, body position, riding style, handlebars, tires (type, size, shape, pressure), chain slack, power delivery, smoothnes, road surface, seat height. What works for me will not always work for everyone else. I'm still finding ways to made my set-up right for me. There are just so many variables that have to be considered. By the way I don't race, its just a fun hobby and I test on track days and usually the same set of corners.

[bwarbiany]

Originally posted by Dr. D
As for the front end, 10mm down in the triple seems like a lot but the racetech springs raise the front by at least that much when loaded with me on it (200#).

Did you adjust your preload when you got the new Racetech springs? Sounds to me like you kept your preload the same, but dropped the forks in the triple to compensate. I'd suggest adjusting your preload to correct levels (assuming it wasn't done), and then setting your forks in your triples to a lower extent. It seems like you might be in danger of topping out your forks, or possibly not have enough travel.

All that being said, I could just be on crack. If you've set up your sag properly, disregard me. I do know that 10mm is about as extreme as most racers go on the forks, because it gets quite twitchy past that...

Brad

[Dr. D]

I set the preload per Racetech specs. The problem was the stock springs were so soft they sagged alot more than Racetechs. I could have set the preload on the stock springs to suit my weight, but then that would have also raised the front end ride height.

[dillweed]

I would say it's more important to get correct preload than it is to lower the triple clamp for better turn-in. Lowering the triple-clamp may make the bike turn in faster, but it doesn't compensate for a bike that bottoms out or tops out from bad preload. If your preload isn't right, you won't have any traction over bumps.

And which springs you're using doesn't matter ----- you can always get the bike to the correct preload by trimming or extending the spacers. And if by doing so, your ride height ends up being too high for your preferences, then sure, go ahead and lower the triple clamp. I guess what I'm saying is, there's no reason why you can't have both optimal preload and a triple clamp height that suits your preference.

[SV650R]

I am bringing this tread back from the death of time...

[mastashake72]

I just got a twin clicker that is kinda beat and I am sure it needs to be rebuilt. Fox can do it for $160, plus I dont know what rate the spring is. Anyone know of a place in the San Diego area who can measure the rate?