Race tech calculator

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3/31/2018 3:27 AM

How accurate is the spring calculator on the race tech website? It says I need a 5.2 spring (which I now have) but when I go to set my sag the spring is completely loose and still only at 98 mm sag. Is there a better way to figure out what spring I need?

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3/31/2018 3:49 AM

Are you sure it is the original spring?

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2020 YZ450F
2018 KTM 450SXF FE
2016 YZ250F 2008 CRF450R
2015 YZ250F 2008 CRF250R
2001 CR250R
2010 YZ250 2012 CRF150R
2009 YZ125 2010 KX109.5
SSR Motorsports Dealer YCF Motorcycles
TAGMX Suspension & Graphics! www.tagmxsuspension.com https://www.liquidskinzdesign.com/



3/31/2018 5:14 AM

sgrimmxdad wrote:

Are you sure it is the original spring?

I bought the race tech 5.2 kg spring as the calculator told me

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3/31/2018 5:35 AM

What bike, what is your weight? Not trying to be funny but do you have experience setting sag? What method are you using? RaceTech rates are based on your weight w/o gear MX Tech rates are with gear on. What spring did you take off the bike and how close could you get to your desired sag setting with it?

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2020 YZ450F
2018 KTM 450SXF FE
2016 YZ250F 2008 CRF450R
2015 YZ250F 2008 CRF250R
2001 CR250R
2010 YZ250 2012 CRF150R
2009 YZ125 2010 KX109.5
SSR Motorsports Dealer YCF Motorcycles
TAGMX Suspension & Graphics! www.tagmxsuspension.com https://www.liquidskinzdesign.com/



3/31/2018 6:19 AM

I am a massive supporter of Race Tech products and have them in half a dozen bikes but I have had some conflicts with them over their spring rate guide. I'll just leave it at that. Mainly on some older bikes.

My opinion, use it as a "guide" and not gospel in stone. Make sure you know what stock springs came on the bike from the factory, compare that to the RT guide information, check around with other reputable suspension companies, and use it all to help make a decision on spring rates.

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3/31/2018 10:15 AM

sgrimmxdad wrote:

What bike, what is your weight? Not trying to be funny but do you have experience setting sag? What method are you using? RaceTech rates are based on your weight w/o gear MX Tech rates are with gear on. What spring did you take off the bike and how close could you get to your desired sag setting with it?

I have a 2017 KTM 250 SX. My weight is 220 with out gear. I set my sag about twice a month in riding season. I use the motion pro folding sag tool. I always measure by going straight up from the axle to the rear fender.

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3/31/2018 10:21 AM
Edited Date/Time: 3/31/2018 10:28 AM

Have you cleaned and lubed your linkage and swingarm pivot lately? Check to see that it all moves smoothly through the whole arc of the swingarm. Check torque on all the bolts on the linkage and shock. It sounds like you are binding somewhere. Does your manual recommend a spring for your weight?

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The older I get, the faster I was.

3/31/2018 10:28 AM

I bought a race tech spring for my fc450 and sent it back since the measurements it gave me were way off.
I would try the factory connection spring

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3/31/2018 11:55 AM

sgrimmxdad wrote:

What bike, what is your weight? Not trying to be funny but do you have experience setting sag? What method are you using? RaceTech rates are based on your weight w/o gear MX Tech rates are with gear on. What spring did you take off the bike and how close could you get to your desired sag setting with it?

Goulding wrote:

I have a 2017 KTM 250 SX. My weight is 220 with out gear. I set my sag about twice a month in riding season. I use the motion pro folding sag tool. I always measure by going straight up from the axle to the rear fender.

I set up a 250SX 2 weeks ago for a guy @218lbs with 5.0kg and got 35mm static, 105mm race sag with 7mm spring preload.

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3/31/2018 6:53 PM

I would have to agree that the RaceTech calculator seems to be incorrect. At least one spring rate out for my calculation.

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3/31/2018 6:57 PM

Any online calculator is only as good as the input from the original information. I would not trust it in a saggy situation at all. Trust the basics of static sag and riders sag.....

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Germany 1975 250 CZ Centerport, laydown shocks, mikuni with reed valve, Marzocchi forks with me as the motopilot

3/31/2018 7:35 PM

I have had good luck with it... as long as you are honest with your weight without gear and your actual riding ability.... maybe you fibbed a little when you said you were a national pro when I reality you are a local novice?

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Don’t piss off the old people - the older they get the less “life in prison” is a deterrent for them!

2020.5 KTM 450 SXF FE
2006 KX250

3/31/2018 7:40 PM

Dang It wrote:

I would have to agree that the RaceTech calculator seems to be incorrect. At least one spring rate out for my calculation.

I too have seen this issue on a few of there spring rate calculation over the years, but by in large they are right most of the time. If you think it is incorrect, contact them and I am sure they will resolve the issue.

Paw Paw

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3/31/2018 9:08 PM

Bruce372 wrote:

I bought a race tech spring for my fc450 and sent it back since the measurements it gave me were way off.
I would try the factory connection spring

I have heard that Cannon Racecraft (http://www.cannonracecraft.com) in Oklahoma City, OK makes a majority of the springs for the aftermarket suspension companies. Not sure how accurate that rumor is, so don't quote me...althouth I think a start a few sentences a day with "I read on vital _____."

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3/31/2018 9:25 PM

Goulding wrote:

How accurate is the spring calculator on the race tech website? It says I need a 5.2 spring (which I now have) but when I go to set my sag the spring is completely loose and still only at 98 mm sag. Is there a better way to figure out what spring I need?

It's accurate enough that we're willing to guarantee the rates if you use it and order springs from us and they aren't right.

I will do some checking for you. My email is chris@racetech.com, but I'll post back here.

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Race Tech Director of Marketing
www.racetech.com
Proud supporters of VitalMX. Ask me about the VitalMX Discount!

3/31/2018 9:25 PM

crt32 wrote:

I have heard that Cannon Racecraft (http://www.cannonracecraft.com) in Oklahoma City, OK makes a majority of the springs for the aftermarket suspension companies. Not sure how accurate that rumor is, so don't quote me...althouth I think a start a few sentences a day with "I read on vital _____."

Maybe true, but I know they don't make the Race Tech or Factory Connection ones.

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Race Tech Director of Marketing
www.racetech.com
Proud supporters of VitalMX. Ask me about the VitalMX Discount!

3/31/2018 9:38 PM

Goulding wrote:

How accurate is the spring calculator on the race tech website? It says I need a 5.2 spring (which I now have) but when I go to set my sag the spring is completely loose and still only at 98 mm sag. Is there a better way to figure out what spring I need?

Riesenberg448 wrote:

It's accurate enough that we're willing to guarantee the rates if you use it and order springs from us and they aren't right.

I will do some checking for you. My email is chris@racetech.com, but I'll post back here.

I spoke with our Head of R&D.

The rate is what he'd recommend, and he said it would have 3-4mm of preload on it. On the stand he'd expect it to be just the on cusp of being loose because it has a soft top out spring and the it'll grow.

Rob's recommendation was to check to make sure chain isn't too tight or axle isn't slammed forward and that you're following correct procedure checking sag.

If you don't feel comfortable with the recommendation and the spring is still new/un-used and you'd like to swap out for a 5.0, use my email and I'll get you taken care of.

Here is a quick guide for setting sag.

Hopefully that helps! Let me know if I can be of assistance any further.

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Race Tech Director of Marketing
www.racetech.com
Proud supporters of VitalMX. Ask me about the VitalMX Discount!

3/31/2018 9:51 PM

The problem with the new Austrian bikes is the linkage ratio is a lot different from the Japanese bikes and it makes setting sag a little tricky.

Imo, getting the right spring on these bikes is more critical than the others.

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4/1/2018 3:53 AM

Riesenberg448 wrote:

I spoke with our Head of R&D.

The rate is what he'd recommend, and he said it would have 3-4mm of preload on it. On the stand he'd expect it to be just the on cusp of being loose because it has a soft top out spring and the it'll grow.

Rob's recommendation was to check to make sure chain isn't too tight or axle isn't slammed forward and that you're following correct procedure checking sag.

If you don't feel comfortable with the recommendation and the spring is still new/un-used and you'd like to swap out for a 5.0, use my email and I'll get you taken care of.

Here is a quick guide for setting sag.

Hopefully that helps! Let me know if I can be of assistance any further.

Chris, can you clarify that last sentence in the first paragraph? Are you saying that over time the spring will lengthen a little with use? I have a 6.3 on my 17 crf450, and to get to 104 I had to back it out to the last thread on the shock. Not comfortable with the lack of preload and threads on the 2nd ring.Photo

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4/1/2018 4:51 AM

The calc was accurate for me.

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4/1/2018 5:19 AM

I was kind of an idiot and didn’t listen too it and went up one harder spring than recommended. Too hard except for a super hard hit. Also had an FC revalve done. Obviously balance between I assume a new shock spring and fork spring is important. Like the saying, “you can’t have one without the other”.

Go with what it says, and better yet, make a phone call to confirm. And don’t exaggerate your riding ability.

It was strange to me, but after a while the springs seemed to lose diameter and bind on the slide.

Put the stock back in, problem cured with the binding. Plus now I’m old and slower and the tiny bit of plushness I can get out of the worst forks ever is kind of nice. 06 KTM, but the old girl is pretty cherry, and paid for.

I’m just an off-road weekend warrior but at 250 I thought I needed something.
I did, and it was the best motorcycle accessory I ever bought, a Scott’s Damper.Viola, like a new bike.

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In my 60’s and still loving dirt scoots up here in the frozen north.

2021 Husky 501s

4/1/2018 6:17 AM
Edited Date/Time: 4/1/2018 6:18 AM

I'm surprised to see the number of folks here who bring up riding ability as a factor when choosing a spring for mx. Choosing a spring is all about setting up race sag in relation to free sag and has nothing to do with the rider's ability.

I've used the RT calculator for a half dozen bikes in the recent past and it's worked out fine.

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4/1/2018 6:35 AM

Bruce372 wrote:

I bought a race tech spring for my fc450 and sent it back since the measurements it gave me were way off.
I would try the factory connection spring

crt32 wrote:

I have heard that Cannon Racecraft (http://www.cannonracecraft.com) in Oklahoma City, OK makes a majority of the springs for the aftermarket suspension companies. Not sure how accurate that rumor is, so don't quote me...althouth I think a start a few sentences a day with "I read on vital _____."

Riesenberg448 wrote:

Maybe true, but I know they don't make the Race Tech or Factory Connection ones.

Am I correct in saying Eibach makes your springs? I remember ordering an oddball (very stiff spring rate) spring for a customer with a KTM PDS shock. When the spring came it was in an Eibach box with either an FC sticker, or race tech sticker. I cannot remember. Either way, Eibach stuff is top notch.

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Tomac and/or Anderson for 2020.....