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Possible to absorb big hits and still have usable suspension?

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Mediocre air.jpgBottom Out.jpg

 

I provided two pics.  The forks on this bike are 2015 KTM 450 sx-f (compression turned to the max).  Rear suspension is an enduro shock rebuilt to be stiffer.  I find it hard to believe that you motocross guys are ok with suspension this soft and more likely on a softer settings than this. (oh ya...I weigh 200lbs with all my gear on)  Is there a way to land properly so that I can soften the blow?  I landing the front tire and rear tire at the same time.

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You have correct springs/valving for your weight?

 

To soften the landing it helps when you land rear wheel first, and with full throttle.

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Huck valves in the forks would help

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It's impossible to tell what is happening in those pictures.  Landings aren't just about how "big" you go, they're about the shape of the takeoff, the shape of the landing, the terrain, etc.  It looks like a flat landing in your picture, which is worse than the shape of most MX track jumps.

 

A fork (or shock) is generally going to feel crappy with the bleed fully closed (comp all the way in) than with the bleeds partially open and the valving stiffer to compensate.

 

Lots and lots and lots of MX guys run bikes like the SX-F, or (fairly plush/soft YZs) with stock or near stock valving, so yeah, start believing that they are ok with suspension that soft.

 

I think you should experiment with revalving your suspension significantly stiffer, or having it revalved stiffer.  You have made multiple posts arguing that people run suspension too soft, but it doesn't seem like you've bothered to see if going stiffer works for you.  You aren't going to find your optimal setup from asking other guys online, you need to try stuff, especially in what seems to be a non-standard application.

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No fast MX guy would be happy with the fork setting on that bike. The mid needs to be stiffened and closed up to keep the fork up in the stroke and stop it from diving. I also change the valving on the base piston a whole bunch as well. For going fast and jumping big suspension needs to be stiffer but dont confuse that with being harsh, it can and must still be compliant and have traction.

I support a rider who has won National MX2 races on a Husky FC250 with the same suspension that you have and its way stiffer than stock 450 settings.

Its all relative to the speed of the rider and type of riding

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Ok...the full truth.  Those pics were before my last revalve but I don't have any recent photos for reference. My forks are incredibly stiffer now but I still managed to bottom the suspension on a big cliff (15ft: 30ft from take off to landing...maybe a tad bit more).  Yet, I still think that is not big compared to you motocross studs.  Check out this youtube video.  I highly doubt these guys did a complete revalve just for this one moto race.  Can landing properly really give you the ability to do this?  If not...what am I missing when it comes to the suspension revalve...how do I explain to my tech that I want to be able to catch this much air? 

 

https://www.youtube.com/watch?v=BFd-Z4_ArCI

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what am I missing when it comes to the suspension revalve...how do I explain to my tech that I want to be able to catch this much air? 

 

 

Gotta say "bro" and "sick" a lot when explaining.  That equates to "I go huge" in tuner-speak.

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I've hit that on 165' on a stock yz450f, and at 180lbs the springs were much too soft. The landing isn't harsh at all, less then dropping 4 or 5 feet to flat. If your jumping to flat, nothing is going to lessen the blow. You have to find a down side to land on. No one is setting up their suspension for the jumps. If it's working well and stiff/plush enough everywhere else, jumping isn't an issue.   

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Exactly.  They're landing on a downslope, HUGE difference.

 

What spring rates are in your bike?

 

I don't get why this is such an ongoing issue for you.  If you bottom more than you like, and you think your fork are too soft, go stiffer on your springs and stiffer on your valving.  Eventually it'll be too stiff, and you can dial it back to the point where they were still ok.  :excuseme:

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Exactly.  They're landing on a downslope, HUGE difference.

 

What spring rates are in your bike?

 

I don't get why this is such an ongoing issue for you.  If you bottom more than you like, and you think your fork are too soft, go stiffer on your springs and stiffer on your valving.  Eventually it'll be too stiff, and you can dial it back to the point where they were still ok.  :excuseme:

Yep.

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Yep.

 

Exactly.  They're landing on a downslope, HUGE difference.

 

What spring rates are in your bike?

 

I don't get why this is such an ongoing issue for you.  If you bottom more than you like, and you think your fork are too soft, go stiffer on your springs and stiffer on your valving.  Eventually it'll be too stiff, and you can dial it back to the point where they were still ok.  :excuseme:

The jump in my example above - it isn't that flat.  Unless you never leave the moto track.  This is an ongoing issue because I cannot find someone who rides outside a motocross track and likes to jump.  I will start another topic about the spring rates I have, specific suspension mods, my clicker settings, etc.  Maybe someone out there has my fancy WP/Kreft Moto suspension too and can provide expertise that I can relate too.

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I guess I don't get it.  If you bottom more than you want and your suspension isn't harsh, have your tuner valve it stiffer.  It sounds like you're on stock SX forks and a revalved enduro shock, which is probably not extreme at all, but without knowing what settings are in there nobody but your tuner can say.  Asking question after question isn't going to make your bike work better.  If you don't like it the way it is, have your tuner fix it, or find another one who can.

 

You're never going to know what level of stiffness is right for you, or too much, until you try it.

 

I don't see the benefit of all these threads talking about it.  :excuseme:

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PJ, if you already have a susp pkg from Kreft why are you not asking him these questions? He is an enormously respected tuner and not cheap. And everyone I know who has used him says he is exceptionally helpful in dealing with issues. ???

Edited by YHGEORGE
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PJ, if you already have a susp pkg from Kreft why are you not asking him these questions? He is an enormously respected tuner and not cheap. And everyone I know who has used him says he is exceptionally helpful in dealing with issues. ???

you are so very correct...Adam is amazing. I appreciate others information and enjoy getting worked over by you all :). Adam says the bike would be unrideable at the stiffness I need. I'm thinking he may not be factoring in the weight of my bike. Didn't think to mention it...260lbs dry I bet.

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The two pics seem to show you jumping perpendicular to the slope of the hill.  This is pretty much a flat landing, but this is over a fairly small jump which shouldn't be a problem.  If you land correctly, on the rear wheel, on the gas and with your legs extended and ready to absorb the landing it shouldn't be bottoming.

 

To answer your question specifically, you can absolutely have compliant and comfortable suspension that does not bottom.  I don't have any experience with those forks specifically but there are always the same basic adjustments.  You have spring weight which will correspond to the weight of the rider and rider preference.  The oil level will primarily effect bottoming resistance toward the end of the stroke.  The valving will effect the damping characteristics with the base valve having the greatest effect at low speed and the mid valve coming into effect as the speed of the impacts increases.  The suspension on these bikes is speed sensitive and uses different circuits to control different types of impacts, so you can change one thing without necessarily effecting another.

 

If the amount of sag indicates the springs are too soft you can increase the rate.  If the spring rate is okay you can try increasing the oil height.  If the oil height doesn't solve your problem you would want to stiffen the mid valve stack or reduce the float if applicable.  This is assuming the forks are performing satisfactorily everywhere else and the only thing you dislike is the tendency to bottom out.  For my KX the mid valve did the trick.  You definitely don't want to run the compression adjusters all the way in.  This will only make the suspension feel harsh and stiff while doing pretty much nothing to prevent the bottoming. 

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You need to bring bike up to an acceptable mx level. Valving and appropriate spring combo will do the trick.

Tracks are groomed, and stiffer valving wouldn't be a bad choice. Off road is some nasty stuff; in terms of the obstacles you may encounter at lower speeds.

Springs are a consideration as well. I prefer the correct shock spring for the rider's weight, while i like a rate stiffer on fork springs. Oil height and spring preload are a large part in making a bike work as well.

All of the 4cs tunes i've done on 14 fe and 15 bikes have been mx based.

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Adam says the bike would be unrideable at the stiffness I need. I'm thinking he may not be factoring in the weight of my bike. Didn't think to mention it...260lbs dry I bet.

 

I highly doubt that a guy who is well regarded as one of the best in the business of KTM suspensions forgot how much a motorcycle weighs.

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