Race tech spring Calculator

TW85
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TW85
Edited Date/Time 12/21/2015 6:23pm
I've got my 2014 KX250f tore down to do some maintenance before storing the bike for the winter. One of the things that I need to do is service the forks and shock so at the same time I'd like to spring the bike for my weight/skill level.

I'm 140lb intermediate vet rider and the race tech calculator is telling me I need a .84kg front spring and 5.0kg rear spring, down from the stock springs of .98 front and 5.4 rear. Now the reason I'm posting, that seems like a huge jump down in rates so I'd like to hear from you guys that have purchased from race tech before and get your feedback on how accurate you found the suggested rates to be? Are the springs fine by themselves or does the calculator want you use gold valves with those suggested springs?

I'm going to be doing my gf's bike as well so for the time being I don't think I can afford to do the gold valves or send the suspension out for a revalve/respring. I figure with just doing the springs and fresh fluids I should be pretty happy.

Thanks!
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mattyhamz2 12/12/2015 11:59am
12/12/2015 11:59am
I've always found their calculator to be spot on for me as well as customers at the shop I worked at for 4 years. Always used it to find out what spring rate each customer needed and never heard a complaint.
Spagina767
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Spagina767 12/12/2015 1:02pm
12/12/2015 1:02pm
I told m my suspension guy what the race tech calculator said for me, and he said it was way stiff, so who knows. I believe spring rate should be calculated based off of sag measurements.
pCp 252
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pCp 252 12/12/2015 1:10pm
12/12/2015 1:10pm
I'm pissed. I used their calculator to order fork springs for my 14' KX250F as well. I weigh 160 Amateur MX and they recommended a .88! So then I call Factory Connection and order up the .88 spring which I later found out is WAY too soft for me.

They also recommend a 5.0 shock spring, which I knew was WAY too soft. I won't use their calculator again.

Are you interested in a never used or mounted .88 spring? This should be the correct rate for you. I'd call Factory Connection.
Paw Paw 271
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Paw Paw 271 12/12/2015 5:28pm
12/12/2015 5:28pm
Over the years that calculator was a proven item, but over the past couple of years I have also found many flawed calculations on several bikes. I just don't trust it much any more. I have called them and received different spring recommendations than the on line calculator showed, so I know there are some issues in the online unit.

Paw Paw

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mb
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mb 12/12/2015 6:37pm
12/12/2015 6:37pm
Be very cautious of your terrain/riding level selection as it does make a significant difference. Just because you don't race A/B doesn't mean you don't jump the same jumps they do.
TW85
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TW85 12/13/2015 8:49am
12/13/2015 8:49am
Thanks for the feedback guys. I'm glad I asked instead of ordering up some parts, looks like I'll make some calls to few suspension shops this week and see what's recommended.
murph783
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murph783 12/13/2015 7:10pm
12/13/2015 7:10pm
Spagina767 wrote:
I told m my suspension guy what the race tech calculator said for me, and he said it was way stiff, so who knows. I believe...
I told m my suspension guy what the race tech calculator said for me, and he said it was way stiff, so who knows. I believe spring rate should be calculated based off of sag measurements.
This was basically the same response I got when I told the guy I go to for suspension advice. I think they're pretty close generally but not spot on. 2014 YZ250F for reference
lumpy790
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lumpy790 12/13/2015 8:28pm
12/13/2015 8:28pm
140 is pretty light and will require a lighter shock spring to get the sag in the proper working range. Remember the spring and valving have to work together.
ReinV
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ReinV 12/15/2015 12:24pm
12/15/2015 12:24pm
In my experience they gave right number for the front but too stiff for the rear. Trust your sag measurments! In my case they offered 0.2kg stiffer rear spring. I have got down these 0.2kg and then the rear of the bike was ok. Did it with my honda, kawasaki, ktm and now with suzuki and it always worked. But I have to note, all my bikes where 450-s. I´m sure it all same with 250-s - RIGHT SAG numbers.
c0ncEpT
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c0ncEpT 12/17/2015 11:51am
12/17/2015 11:51am
When talking to my suspension guy he told me that pretty much every bike that comes threw his shop gets a lighter fork spring(s). Unless they are Lorettas type fast or overweight than they almost all go lighter.
mb
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mb 12/17/2015 1:44pm
12/17/2015 1:44pm
What is your definition of overweight? 180lbs?
TW85
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TW85 12/21/2015 3:15pm
12/21/2015 3:15pm
For what it's worth I ended up calling them them last week and the tech guy went through his notes and said that they've started to use .88 springs instead of .84 for someone my size/riding level. So that's what I ordered.

I've got another kind of silly question. I stopped by the local shop today to grab some fork oil and got Motul 5w expert.. At the time I didn't realize they made two types the "expert" and "factory line", I haven't found much online about either but it appears the factory line is better stuff. Am I okay to use what I have or should I find a higher quality oil?
slipdog
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slipdog 12/21/2015 4:35pm
12/21/2015 4:35pm
It will work fine. The Factory Line is a higher quality 100% synthetic and the Expert is a semi synthetic that is a hair lighter weight and lower viscosity index, but within the acceptable range of a 5wt fork oil

Expert data

Factory line data
DuroTools
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DuroTools 12/21/2015 5:38pm
12/21/2015 5:38pm
Are there any markings or visual differences on or in the springs or is the only way to tell one from the other is to compress them and measure the force or something like that? I have a used bike with Race Tech suspension and this thread has sparked my interest about what the springs are exactly. I have no clue about the owner before me cause it was bought from a dealership, for all I know he could be 280 lbs and I'm 140!
TW85
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TW85 12/21/2015 6:23pm
12/21/2015 6:23pm
Thanks for the info and tech sheets Slipdog.
ttg953
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ttg953 6/30/2016 1:59am
6/30/2016 1:59am
TW85 wrote:
I've got my 2014 KX250f tore down to do some maintenance before storing the bike for the winter. One of the things that I need to...
I've got my 2014 KX250f tore down to do some maintenance before storing the bike for the winter. One of the things that I need to do is service the forks and shock so at the same time I'd like to spring the bike for my weight/skill level.

I'm 140lb intermediate vet rider and the race tech calculator is telling me I need a .84kg front spring and 5.0kg rear spring, down from the stock springs of .98 front and 5.4 rear. Now the reason I'm posting, that seems like a huge jump down in rates so I'd like to hear from you guys that have purchased from race tech before and get your feedback on how accurate you found the suggested rates to be? Are the springs fine by themselves or does the calculator want you use gold valves with those suggested springs?

I'm going to be doing my gf's bike as well so for the time being I don't think I can afford to do the gold valves or send the suspension out for a revalve/respring. I figure with just doing the springs and fresh fluids I should be pretty happy.

Thanks!
Do you still want to sell that .88kg kx250f fork spring?
Sheriff245 6/30/2016 5:26am
6/30/2016 5:26am
TW85 wrote:
I've got my 2014 KX250f tore down to do some maintenance before storing the bike for the winter. One of the things that I need to...
I've got my 2014 KX250f tore down to do some maintenance before storing the bike for the winter. One of the things that I need to do is service the forks and shock so at the same time I'd like to spring the bike for my weight/skill level.

I'm 140lb intermediate vet rider and the race tech calculator is telling me I need a .84kg front spring and 5.0kg rear spring, down from the stock springs of .98 front and 5.4 rear. Now the reason I'm posting, that seems like a huge jump down in rates so I'd like to hear from you guys that have purchased from race tech before and get your feedback on how accurate you found the suggested rates to be? Are the springs fine by themselves or does the calculator want you use gold valves with those suggested springs?

I'm going to be doing my gf's bike as well so for the time being I don't think I can afford to do the gold valves or send the suspension out for a revalve/respring. I figure with just doing the springs and fresh fluids I should be pretty happy.

Thanks!
I have had the same experience. 2-3 rates to hard in the rear and spot on in the front. 2016 YZ450F
MXD
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MXD 6/30/2016 8:06am
6/30/2016 8:06am Edited Date/Time 6/30/2016 8:08am
I plugged my info into their calculator for my 16 KX450 rear spring and it spit out 5.972. Basically a 6.0. I had a 5.8, 5.9 and 6.1 in my basement so I tried them all. I couldn't get it right with the 5.9 and 6.1 but the 5.8 fell exactly on 105/34, perfect. So yeah, it was a bit off for me too. I chalked it up to the bike being brand new and maybe there wasn't a ton of info on it yet.

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c0ncEpT
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c0ncEpT 6/30/2016 1:46pm
6/30/2016 1:46pm
TW85 wrote:
I've got my 2014 KX250f tore down to do some maintenance before storing the bike for the winter. One of the things that I need to...
I've got my 2014 KX250f tore down to do some maintenance before storing the bike for the winter. One of the things that I need to do is service the forks and shock so at the same time I'd like to spring the bike for my weight/skill level.

I'm 140lb intermediate vet rider and the race tech calculator is telling me I need a .84kg front spring and 5.0kg rear spring, down from the stock springs of .98 front and 5.4 rear. Now the reason I'm posting, that seems like a huge jump down in rates so I'd like to hear from you guys that have purchased from race tech before and get your feedback on how accurate you found the suggested rates to be? Are the springs fine by themselves or does the calculator want you use gold valves with those suggested springs?

I'm going to be doing my gf's bike as well so for the time being I don't think I can afford to do the gold valves or send the suspension out for a revalve/respring. I figure with just doing the springs and fresh fluids I should be pretty happy.

Thanks!
Sheriff245 wrote:
I have had the same experience. 2-3 rates to hard in the rear and spot on in the front. 2016 YZ450F
Same here. I just ran the numbers and they called out 46kg for the front and I am currently running a 47kg which is what the stock spring tested so we kept it. 2016 YZ250F.
MaxPower
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MaxPower 7/1/2016 5:17pm
7/1/2016 5:17pm
Dive found the Race Tech spring chart to be a huge help. I thought the spring recommended was going to be entirely too stiff. Instead it made my bike way more fun to ride
Eddie_E
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Eddie_E 7/6/2016 7:30am
7/6/2016 7:30am
I have found the RT calculator to be right on for my YZ's. I tend to be in the 190 lb range most years.
I seem to like the higher of the 2 options when rounding the numbers, though.

My reason for that is that I find the heavy spring with less pre-load feels like is has less bounce in breaking bumps when I stand and unload the bike to brake late.
I don't know if this works with the scientific theories, but it's what I feel. I can hit the rider sag numbers with either size.

What are you guys who find it too stiff feeling in the bike?

I don't use the old guy numbers yet, even though I am getting old. FC usually recommends a size lower than that when I show up in person. I nearly had a full blown argument with FC to get .49 fork springs for my old 450 SXF, LOL.

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