Fork spring help
#2
Race Tech has a calculator to answer your question...
http://old.racetech.com/evalving/Spr...pringType=Fork
http://old.racetech.com/evalving/Spr...pringType=Fork
#3
One source of information about spring rates is www.race-tech.com.
#6
Greg always asks what your weight is while wearing full gear - what ever you have. The suspension on the bike is very sensitive and at its very best when it's properly tuned. 15 pounds DOES make a difference. A good adjustable shock is an important part of this package and absolutely required for two-up riding.
#8
FWIW - Here is a little chart showing rider weight vs. fork spring rate. Please note that the weights shown are without gear i.e. in street clothes:
VTR1000F Fork Spring Rate Chart
115-150lb = 0.80kg/mm
150-180lb = 0.85kg/mm
180-215lb = 0.90kg/mm
215-250lb = 0.95kg/mm
250-300lb = 1.0kg/mm
As you can see, mhaisten is on the bubble between 0.95 and 1.0. For these cases I round up.
VTR1000F Fork Spring Rate Chart
115-150lb = 0.80kg/mm
150-180lb = 0.85kg/mm
180-215lb = 0.90kg/mm
215-250lb = 0.95kg/mm
250-300lb = 1.0kg/mm
As you can see, mhaisten is on the bubble between 0.95 and 1.0. For these cases I round up.
Last edited by JamieDaugherty; 11-26-2009 at 08:27 AM.
#9
Don't forget to account for weight lost from the bike from aftermarket stuff. Hell, you can lose 15# just from slip-ons, of course that's mostly in the rear though.
Spring rate also depends how you ride. If you're doing a lot of track days and braking hard then you'll want to go up in rate .05 to .10 kg/mm. For just street the table Jamie posted is perfect.
Spring rate also depends how you ride. If you're doing a lot of track days and braking hard then you'll want to go up in rate .05 to .10 kg/mm. For just street the table Jamie posted is perfect.
#10
Don't forget to account for weight lost from the bike from aftermarket stuff. Hell, you can lose 15# just from slip-ons, of course that's mostly in the rear though.
Spring rate also depends how you ride. If you're doing a lot of track days and braking hard then you'll want to go up in rate .05 to .10 kg/mm. For just street the table Jamie posted is perfect.
Spring rate also depends how you ride. If you're doing a lot of track days and braking hard then you'll want to go up in rate .05 to .10 kg/mm. For just street the table Jamie posted is perfect.
That's a good point. I should have put the caveat on that table that the rates are for street riders. These are reasons why it helps to get with a suspension tuner who can help sort out these kinds of variables for you.
#11
Hi everyone. New to forum today.
Got 8,000 miles on VTR I purchased one year ago. Immediately (within 500 miles), largely based on this thread, I chose "180-215lb = 0.90kg/mm" springs to replace the stock jokes. (( I weight 178 lbs without gear )). As soon as I let the VTR down off the jack I knew immediately the springs were too soft. They are definitely preloaded correctly as I was precise with the required cuts ( also I can only tolerate the preload adjuster about halfway in. After that the tire gives too much rumble feeback on the road. a good indicator that preload is correct). So, last week, after 7,500 miles I went with the next spring "215-250lb = 0.95kg/mm". The feel of this spring (also a racetech) is a huge improvement. Bike actually has a smoother ride too cause I run a bit less preload. Its much less prone to that dive/knife when doing a quick flip into a turn. Its also less prone to wallow and wag a bit when encountering minor asphalt rolls in high G banked turns. I'm actually kind of elderly (just a few months shy of 65) but have quite a bit of motocross and supermotard experience but I really don't think that matters that much. The .90 KG is just a bad choice for a 178 lb VTR rider who occasionally scrapes the pegs on the street. Just some feedback for future fork spring swappers. Oh, and it has stock fork valving. Later...
Got 8,000 miles on VTR I purchased one year ago. Immediately (within 500 miles), largely based on this thread, I chose "180-215lb = 0.90kg/mm" springs to replace the stock jokes. (( I weight 178 lbs without gear )). As soon as I let the VTR down off the jack I knew immediately the springs were too soft. They are definitely preloaded correctly as I was precise with the required cuts ( also I can only tolerate the preload adjuster about halfway in. After that the tire gives too much rumble feeback on the road. a good indicator that preload is correct). So, last week, after 7,500 miles I went with the next spring "215-250lb = 0.95kg/mm". The feel of this spring (also a racetech) is a huge improvement. Bike actually has a smoother ride too cause I run a bit less preload. Its much less prone to that dive/knife when doing a quick flip into a turn. Its also less prone to wallow and wag a bit when encountering minor asphalt rolls in high G banked turns. I'm actually kind of elderly (just a few months shy of 65) but have quite a bit of motocross and supermotard experience but I really don't think that matters that much. The .90 KG is just a bad choice for a 178 lb VTR rider who occasionally scrapes the pegs on the street. Just some feedback for future fork spring swappers. Oh, and it has stock fork valving. Later...
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