2018 ktm 450sxf rear spring rate

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2/26/2019 8:53 AM

i bought a spring a while back for a 16 250sxf and it is listed as 252.51 n/mm, i never installed it and now i have a 2018 ktm 450sxf and cant find where the calculator was that i used for the 250sxf over a year ago

so long question short will this spring work ok for my 18 ktm 450sxf i am 190ish without gear and just a out of shape 35 year old midpack c rider


2/26/2019 10:27 AM

Those numbers don't make any sense. I would guess that that is lbs/in which would make it 4.5kg or basically 44n/mm.

That is softer than your stock spring and I wouldn't recommend going that way, but you can give it a try. I use 48n/mm for people 190lbs on a 450.


2/26/2019 10:49 AM

part number i ordered from rockymountain was 131307011550

its weird and i think its a messed up listing when i go to my order history because it appears the part numbers have been superseded


2/26/2019 10:56 AM

never mind i am retarded it is 51 n/mm

for some reason the listing has spring252 51n/mm

but when i look it up for a 2018 ktm 450sxf it is listed as spring 260 51n/mm

will a 51n/mm be to stiff? thanks for the help


2/26/2019 11:33 AM

Right now I test some different spring rates, I ran 45n/mm with my sx-f 350, after I change for 450 and I thought for my weight (195lbs with gear) the 48n/mm will be the right based on KTM chart.

Finally no, the 48n/mm was definietly too stiff, I could not setup the sag either, I recommend to try firstly the 45n/mm spring.


2/26/2019 11:41 AM

I think so. I've used that for 210-215lbs a lot. It will be stiff with very little spring preload

The 252 is a weird number, 260 means the spring length


2/26/2019 12:29 PM

well dang, anyone need a good deal on a fatboy rear spring lol


2/27/2019 12:47 AM

46nm would be optimal but 48 is ok.


2/27/2019 4:46 AM

i ordered the 48 n/mm and will give it a try, thanks for the help guys