NewGen Fork Spring Rate Chart

[InvisiBill]

Here's a chart of ideal weights for different spring rates from RaceTech's calculator. This is just a quick reference so you can get an idea of what spring rate you should be looking for. Don't take RT's numbers as gospel, and different people may prefer slightly softer or stiffer springs, but this will give you a rough idea of the rate to match your weight.

RATE (kg/mm)	STREET (lb)	RACE (lb)
0.44 (PreGen)	<30        	<30
0.585 (EX500)	53         	34
0.60        	63         	44
0.65 (NewGen)	96         	76
0.70        	129        	107
0.75        	163        	139
0.80        	196        	171
0.85        	229        	203
0.90        	263        	234
0.95        	296        	266
1.00        	329        	298

(Note that the NewGen and 300 share front ends, so these numbers are the same as the 300's.)

[wardie]

thanks Bill that really helps size the springs to my weight.

[Ralgha]

Why different weights for street and track?

[Floki]

^Street riders have a softer spring

[InvisiBill]

Yup, you generally want a softer spring for the street. Hopefully you're not dealing with potholes, speedbumps, etc. on the track, and you're generally concerned more with performance than comfort in that situation. The extra squish in softer springs makes for a nicer ride on rough surfaces, but may sacrifice some precision on the track.

[Somchai]

Please let me make three remarks since there is more than only springs.
- Oil height is part of the spring component.
- The correct spring is the softest spring available, that is able to support the bike and rider under the hardest of braking/accelerating while still leaving some room for the system to travel if a bumb is encountered in this state.
- Race Tech also sells fork springs. The labeled rate of the Race Tech springs have been called into question by many sources, although they are still fine quality springs. I rated some 0.85kg/mm labeled springs that I have and they were actually 0.90kg/mm.

Please read all this and more about that here: http://www.peterverdone.com/archive/springs.htm

Just remember that Kawasaki already changed the oil level from 108 +/- 2mm of the Ninja 250 to 100 +/- 2mm in the front fork of the Ninja 300, what made the front to be stiffer.

[InvisiBill]

That's good info. This was in no way meant to be a definitive guide to forks. I've just seen a lot of people here who seem to have no idea whatsoever on what they should be looking for in springs. This is just a quick reference chart so you don't have to put a million numbers into RT's calculator (I did that for you) to see different results for different weights.

It gives you some idea of the scale of spring rates for different weights, which gives you an idea how far off your spring is. You gained or lost 10lb since last year, so you know your springs are no longer perfectly matched to your weight, but how big a deal is it? You weigh 110lb, so just how bad are the stock springs for your weight? That's the sort of thing I was getting at.

I frequently find myself tossing numbers in RT's calc to get an idea on spring rates. Making this chart once saves me from constantly putting similar numbers in the calculator. Hopefully it gives people a rough idea of how rates and weights match up too.