Jump to content
Sign in to follow this  

KTM Rear Spring Choice

Recommended Posts

Which type of rear spring (Prog. or Straight wound) works best for 2 Stroke MX applications with the PDS setup? I have an 2011 SX...thanks.

Share this post


Link to post
Share on other sites

Straight rate always works best on the PDS . Set your sag properly to pick the correct spring rates and you will be shocked on how well the PDS system works. You want about 37-40mm static sag and less than 5mm preload on the spring. Rider sag should be about 115mm (+-2mm).

Front forks need about 40-45mm static and 75mm rider sag.

Pick the springs that give you these numbers.

Share this post


Link to post
Share on other sites

I put the pds 6 on and works much better than the straight on my own personal 250sx 2011 . Im 200 with gear on .This bike will never be as good as the link bikes I know I rode one this weekend a 350sxf no comparison on rear suspension . I run my sag 108 to 110 .Not 115.

Share this post


Link to post
Share on other sites

115 is correct for the amount of travel the bike has. If you run a progressive rate spring you have to run too much preload to make it work and it will infact be harsher than if you have the correct straight rate spring with minimal preload. That is the trick to making the KTM PDS work. The stock bike has too light a spring for even a 165lb rider. I weigh about 180lbs and had to go up 2-3 sizes on my spring. Actually went down one in the front. Had to , to get the correct sag.

Share this post


Link to post
Share on other sites

My preload on the pds 6 is about 3mm . I went up on front to .46 . to each there own I guess but every big tuner recomends the progressive .My free sag is about 35 to 38 bike doesnt squat anymore coming out of corners . only downfall to this spring is they are quite heavy . If I had to do it over I would spend the extra money and get the DSP ti spring .

Share this post


Link to post
Share on other sites
My preload on the pds 6 is about 3mm . I went up on front to .46 . to each there own I guess but every big tuner recomends the progressive .My free sag is about 35 to 38 bike doesnt squat anymore coming out of corners . only downfall to this spring is they are quite heavy . If I had to do it over I would spend the extra money and get the DSP ti spring .

Check your front sag, I bet you are way heavy on the front. I ran .42kg on my 525EXC and 530 KTMS . I ran .40 on my 250/350XCFW. I weigh about 180lbs. You may need a .44kg or so. The sag numbers tell. Every Big Tuner is trying to sell you their EXCLUSIVE progressive spring. Not because it works better. It has been proven that the progressive spring provides a harsher ride due to having too much preload. If you are running a heavy enough progressive that you don't have too much preload, you are now too heavy halfway through the stroke. I personally have tested the progressives and quickly went back to straight rate. All the really savvy tuners agree.

Share this post


Link to post
Share on other sites
Probably right for offroad But I ride motox .

Correct sags are the primarially the same for offroad and MX. Mxers may run on the less sag side of the variance. Only damping is different. Your springs are wrong. You have too much static sag on rear. Don't you think if KTM found that a progressive spring is better it would be a simple thing to start using them on there bikes ?

Share this post


Link to post
Share on other sites

If ktm was smart enough they never wouldve used a non linkage to begin with nuff said I rode the linkage bike on sat no comparison . Ps how can I have to much static when you reccomend more than I have ? I'm sure you're very good at what you do offroad but honestly your reccomendations are wrong . I will say my bike is much better now than it was from factory with changes I've made . You seem to go against the grain on your reccomendations and I fear you're misleading alot of guys on this board . I know what has worked for me simple as that .

Share this post


Link to post
Share on other sites
If ktm was smart enough they never wouldve used a non linkage to begin with nuff said I rode the linkage bike on sat no comparison . Ps how can I have to much static when you reccomend more than I have ? I'm sure you're very good at what you do offroad but honestly your reccomendations are wrong . I will say my bike is much better now than it was from factory with changes I've made . You seem to go against the grain on your reccomendations and I fear you're misleading alot of guys on this board . I know what has worked for me simple as that .

You don't have enough rider sag. I miss stated that point. This is not a board for just MXers. Those in the know who have check my recommendations , concure. If you reset your rear to have the correct rider sag you will have too much static sag. You are having to compensate for too heavy a fork spring if you are having to run 108mm instead of the more correct 115 (113-117mm). I have ridden both PDS and linkage suspension and my setup on the PDS is as nice as any Honda Linkage suspension that I have ridden. Even nicer than my linkage Husky. You haven't tried my recommendations so you can't honestly say that I am wrong. I have been around long enough to not be a Lemming on using the same old set that is not correct or just passable. I have also had enough AWFUL suspension setups from those BIG NAME suspension tuners not to believe everything they say or do. You can't setup someones suspension from a distance. You have to do the final setup with you and your bike. Using my formula gives you the tools to not have to guess and how to check your springs to make sure they are correct for you . The basic formula has been around for many years. I did fine tune it so you can use it for any long travel bike.

Share this post


Link to post
Share on other sites

Dwight ktm have used progressive springs and straights, but what ktm do isnt that relervant as they have never made a truely good mx suspension....you say peoples sags are wrong unless its 75mm , but thats your opinion and you wont accept anything thats not exactly as you think it should be, its very frustrating you tell everyone you are correct but all the big companies are wrong and we should beleive this because....you dont race mx or ride mx bikes very often....i dont tend to direct people on woods as i know people like davej , you and russ are much more inclined to give good advice, would it not be fair to ask you to direct your advice at your speciality? would it not be better for everyone involved.?

Share this post


Link to post
Share on other sites

i have a ohlins rear shock for it if any of ya's are interested just sold my 2011 sx250 shock has about 1.5hr on it comes with 6.8 7.0 spring $ 750 for all shipped to your house!

Share this post


Link to post
Share on other sites
Dwight ktm have used progressive springs and straights, but what ktm do isnt that relervant as they have never made a truely good mx suspension....you say peoples sags are wrong unless its 75mm , but thats your opinion and you wont accept anything thats not exactly as you think it should be, its very frustrating you tell everyone you are correct but all the big companies are wrong and we should beleive this because....you dont race mx or ride mx bikes very often....i dont tend to direct people on woods as i know people like davej , you and russ are much more inclined to give good advice, would it not be fair to ask you to direct your advice at your speciality? would it not be better for everyone involved.?

Most top long time suspension tuners recognize that 25% of available travel is what you should be looking for in rider sag on the front forks. That is what I have been told it should be for all disiplines. With what I have seen over the years there is no reason to doubt that. Static sag is just as important(front 14%). The same tuners also say you should be looking for 33-34% in rider sag on rear suspension. Static sag =11% on the rear. These percentages should only be varied in rare instances very far from the recommendations for riders whose riding styles demand it or to compensate for frame design flaws. So my recommendations are for most riders.

It is frustrating when someone posts something like "4 inches of sag"

and that is supposed to work for all long travel bikes regardless of actual travel. With my recommendations the bike should carve corners much better and be more stable on straights. With adjustments to damping they will work great on big jumps too.

Share this post


Link to post
Share on other sites

how can it carve corners better(it will up to a point with more weight and fork angle) but then also be more stable, thats crazy, all tuning is a compromise, if bikes turned better and got more stable with soft fork springs all OEM would fit it.

I dont believe most long time suspension people believe 25% of fork travel is correct for modern bikes on modern tracks, you discount all the big names and all the small ones on this forum, but you say most long time tuner do xyz....they just dont...you need to get a fast rider, put your springs in and let him hammer some whoops and g outs, break his wrists or neck going over the bars and then you will see your obsession with cornering is ill placed....

You live by numbers, the rest live by tuning, i dont set my bike at a specific number, i set it where it handles the best, and that maybe 20mm out from your magic number generator, i dont care to be honest, no tuner lives by numbers, they tune each bike for each rider, if the tuner cant do that, the rider has to.

Share this post


Link to post
Share on other sites

The KTM needs some sort of progression ovr what the rising rate gives it . The progressive spring gives it some needed progression.

I personaly think KTM has used the straight rate spring for the stock application because , when the numbers (money) to build the bike are viewed by the acounting dept the opt for the straight rate spring because of cost to build it (lower cost) and it is easier to produce the same ( quality control) straight rate spring .

This has been debated many many times -- do a search . I do not intend to launch another debate . Go out and test -- see what you like .

Share this post


Link to post
Share on other sites

You get the progressive "Feel" from the correct spring rate and minimal preload. The bike actually has a mild progressive angle on the shock. It is not linear and not degressing. ALSO, The shock has a progressive damping system. (PDS). So if properly setup the shock works great. Granted you must be much closer on spring rate to get that feel.

Share this post


Link to post
Share on other sites
http://s619.photobucket.com/albums/tt278/PetePayne/?action=view&current=linkagesnapshot.jpg&jwidget_action=album

This is a snap shot of a few linkage curves/ratio's .

You might find them interesting.

Thanks, About what I expected. It shows there is progression on the linkless KTM suspension. KTM has also progressive damping to further inhance the effect. :thumbsup:

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×