03 R6 - Can these spring rates possibly be right?

[ohio]

According to RaceTech, the 2003 R6 came with forks sprung for a 160# rider and a shock sprung for a 220# rider. Can that possibly be right?

I'm 165#... so should a really use the stock fork spring and a much softer rear spring? Or did RaceTech make a mistake? I have a hard time believing Yamaha got the spring rates so unbalanced from the factory.

Recommended Fork Spring Rate for Street: 0.853 kg/mm (use closest available)
Stock Fork Spring Rate: .850 kg/mm (stock)

Recommended Rear Shock Spring Rate for Street: 8.56 kg/mm (use closest available)
Stock Shock Spring Rate: 9.85 kg/mm (stock)

 

[MackeyStingray]

it's possible

the new ZX10 has an overly stiff front good for someone 200lb+ and pillow soft rear good for someone 120lb

 

[kxmike]

The first generation r6 was like that so I'm guessing it's possible Yamaha still fucked it up on the newer model.

 

[jraice]

Depends how fast you ride in the twisties and if its worth your money...

 

[ohio]

Well, my bike is currently sprung and valved for a silverback gorilla both front and rear (GP valve kits and springs for a ~225# rider), so I need to do the work anyway to try to keep the rubber on the road over anything remotely rough. I was trying to figure out correct spring rates, expecting to be about stock for both and confused to find recommendations for stock up front and more than 10% light in the rear.

Race tech is usually right, so I guess I'll run with it, but I can't do the rear myself (don't have a centerstand or jack) and don't feel like paying another $200 in labor when I find out the rear is now too soft.

 

[hayabusafiend]

Have you called Progressive Suspension yet? They can probably answer your questions.
http://www.progressivesuspension.com/

Didn't Calmoto partner with a suspension company?

 

[ohio]

Now I'm even more confused. Cross referenced with the Penske spring calculator, and THEY say a 600# spring for a 160-190# rider. 600# = 10.7 kg/mm which is MUCH stiffer than stock (though close to stock for the 2005).

So maybe RaceTech is just plain wrong? Penske and Yamaha seem to be in rough agreement...

edit: as does Ohlins who spec a 550#/9.8kg spring for a 120-150#rider.

 

[stangmx13]

all the street bikes ive owned have been sprung like yours when stock. its fine for normal riders that occasionally take passengers. id rather have the rear be quite stiff for normal use and then work well w/ a passenger (extra 110lbs min)... than bottom out the second a throw a passenger back there.

im 135lbs w/out gear and like the 95N/mm spring on my 600RR... but id bet the shock leverage ratio is completely diff on your bike, which would require a diff springrate.

 

[ohio]

all the street bikes ive owned have been sprung like yours when stock.

My bike is currently setup by GP suspension front and rear for a 225lbs rider, so it's definitely stiffer than stock. That's part of what makes it hard for me to judge just how much softer I should go...

 

[afm199]

Quite normal for Japanese bikes to be sprung up front for a single rider and in the rear for two. It's the compromise that allows both with some degree of safety.

 

[ohio]

Quite normal for Japanese bikes to be sprung up front for a single rider and in the rear for two. It's the compromise that allows both with some degree of safety.

Ah, suddenly it makes sense! Thanks for the help.

I left a message at RaceTech anyway, because it still seems odd that Penske and Ohlins recommend much stiffer springs but I least now it doesn't seem completely nuts.

 

[afm199]

I'd go with Traxxion recommendations on springs. Race tech is quite soft in their recommendation. .85 is probably a bit soft.