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1/21/2015
Location
Canton, GA
US
Edited Date/Time
12/21/2018 4:28am
Looking into 4cs upgrades and have read about every forum and review on the different options. Never been crazy about air forks so I think that's out. Spent time on the phone with both Corey at Protune and Cal at FTI. Both seem to be great guys and were very helpful. I think I've gathered the sss conversion is the way to go but I don't like the idea of buying KYB forks off ebay without knowing the history or true internals. Also, with this option I'm out the upgrade when I sell the bike. It's a 2016 so I'll probably move on to something different next summer. I can't seem to find much info or direct comparisons to the Technical Touch. Anyone have any experience in this?
I was messaging Cory (protune) on Facebook about doing the KYB switch into my WP and he thought the spheres are the better option and that is what he runs.
The Shop
KYB's tubing for the KTM/Husky comes from the Kawasaki. It seems as the WP upper tubes are more rigid to match up with the chromoly steel frame while the KYB tubes are more flexible as the aluminum frames have stiffer headstay areas, typically.
It's debatable whether this is better or not, buy our opinion is that the WP will be better. With more flex, you get more binding and the reaction loads at the bushings are greater on the KYB tubes as the bushings are a little closer together than the WP.
If you're looking for more flex (why?) there are better ways to achieve that which won't affect the suspension performance.
Oh, and the different internals will have negligible change in flex. The stiffness of the fork comes from the upper and lower tubes, the internals are so close to the neutral axis of bending that they won't make any noticeable difference.
But the flex characteristic that is most desireable/usable on the track is more the side to side loading (and all variations of direction) associated while cornering.
For that reason - I think flex is critical. I've said for ages - but the yzf feels like a yzf because of it's chassis - not purely it's suspension.
You can match the damping curve from the yzf into a kxf or crf - and have a totally different (stiffer) feel.
Lastly - I have no experience testing back to back on track with various clamp flexes and designs. But reading the reed two two honda article by racerX - where he said the honda factory clamps felt ultra plush vs what he had - was an eye opener. Just a simple clamp change having such a large influence on feel also makes you wonder if the yzf has an advantage there somehow.
From a fork lower tube standpoint, the flex direction that is affected by changing from WP to KYB (or vice versa) is in bending; vertical compliance difference is insignificant. And the bending stiffness of the fork tubes comes into play with lateral (side to side), longitudinal (front to back), and torsional (steering) forces. All of which will have an effect on suspension performance to my earlier point (negative effect for more flex).
So of the three loading directions mentioned above, longitudinal is arguably the most important as there are a lot of off-(fork)axis loads in that direction. There is no suspension action in that direction, so the flex is acting as the suspension (as an un-damped spring). The same can be said for lateral loads, but those are of a much lower magnitude. Torsional flex is rather different as it is entirely reacted by the rider (at the grips). And torsional is directly related to the amount of lateral and longitudinal flex, which are both directly related to bending stiffness.
Or in other words, by changing the lower fork tube flex, you're changing the response to lateral, longitudinal, AND torsional loading. Is that what you really want? What is the goal of changing the flex? Do you want more or less flex? And most importantly, is there another component you can change that only affects one of the loading directions and still achieves your goal (this is the right move, BTW)?
And it's important to remember that flex is not isolated to one component. It is the sum of all components from load application point to load reaction point. And that's different for various loads and situations. For example, cornering performance when it comes to flex is related to all components between the front and rear tires and the position of the bikes center of mass and the weight distribution. That's a lot of parts - tires, tubes, wheels, forks, swingarm, chassis, engine, etc... It's not possible to make a blanket statement that changing to different fork tubes will make the bike corner better without knowing what all the other parts on the bike are.
If you have two identical bikes, but they're running different wheels, say stock vs. Excel A60s (stiffer), changing the fork tubes to something with more flex may be beneficial to the bike with the A60s (it will bring the overall flex back into "balance"), but not to the bike with stock wheels. And that's a very simple example. Every other part along the way has an effect as well. So looking at Reed's bike, the overall flex characteristic is entirely different than a stock bike.
That said, I have my doubts that Reed ran KYB lower tubes with the setup that was mentioned earlier. If he was running KYB lowers that came from Technical Touch, why didn't they use DLC coated lowers? I'm sure they have piles of them lying around, and it's Chad Reed! The photos I've seen show stock hard-chrome lowers, which to me says that he was running WP lower tubes, not KYB. The two are nearly interchangeable, so it could be either one.
Finally, regarding clamp flex, the stock Yamaha clamps are quite stiff. Not sure what Chad was comparing the stock clamps to, but they would have to have been really stiff for him to feel a difference to stock. Very possible that this is all placebo effect. No one is immune to that, even top pros. Especially when they come in with per-conceived notions that stock cast/forged clamps are flexy (they're not).
Everything you stated is accurate - but having done a lot of testing between brands of bikes - using different forks mounted into different bikes - and matched the wheel damping rate between bikes to others with the shock...
My comments stay true to what I said. The whole characteristic of the bike is as you state - a sum of the design. But WHAT is the design we want? Too hard to know for mere mortals like us without huge budget - lots of track testing time with excellent riders.
Yamaha has NAILED the plush aspect and done so for a LONG time. Where the forces get directed, how they directed, and what the rider experiences is "plush".
They are the ONLY OEM to do so - and its NOT their damping curve.
The current yzf forks are STIFF vs anything yamaha ever produced years ago. The KTM forks of old - the ones people HATED for harshness, be it the old twin chamber, or the 4cs first year - were SOOOOFT. The old nitrogen twin chamber fork was less than half as stiff as the yzf of old. But its rider feedback was HARSH.
In fact the 2018 yzf came with fork oil that looked like honey in addition to being a super stiff valve stack vs older models - and yet people described it as....too soft.
And I've kept this a little quiet - but the ktm spokes are torqued very stiff vs other bikes. This undoubtedly has a massive influence on feel and precision - I PERSONALLY think it's lateral stiffness increases would help turning - of course the vertical stiffness increase is likely a large reason they have more harshness in a "slap down"
Reed ran a host of set ups
He ran kyb top to bottom
WP outers with KYB internals - converted
And a mix match of lowers and uppers with KYB internals which makes the swap easiest. You'd have to pick the week/day to know what was on the bike - and how accurate his feedback is - which can be questioned - but I know he had both back to back available side by side to test on test days.
His public comments were he needed as stiffer fork to offset the soft/loose chassis. Again - who knows how accurate that comment is to the enginerding of the ktm vs his former yzf or a crf he nearly raced.
His clamp comments at two two honda led me to believe it had nothing to do with the mental side.
He said they got to try the clamps - and he was interested in various offset changes on that day - but the clamp was so plush feeling vs what he had - he had to revisit all the testing over again because it was far more than an offset change..
It's been common place for years that the honda lower teams or riders who are doing "well" get kicked down factory clamps - and there must be reason for it.
On that comment - I always wondered where the factory bike could lose 10 lbs vs the reed bike - he had factory tranny and and access to full ti etc.
I've always said - it's cheating somewhere pretty seriously - good luck catching it though
Pit Row
When he was going over the KYB inserts, he said that Chad was running the KYB cartridges inside of WP outers and WP inners treated with DLC. The uppers were untreated.
He said that Chad switched from the KYB forks to KYB / WP because of the flex characteristics. I thought he said that the WP offered more flex.
One thing is for sure: The price.
Cartridge: 1750
R inner: 275 (KTM OEM)
L inner: 275 (KTM OEM)
R outer: 172 (KTM OEM)
L outer: 172 (KTM OEM)
DLC: 700
=========
$3346 -- that's buying new fork tubes, using your own makes it much less
(and I think you can buy DLC inners from TT for $350 each saving $344)
KYB Fork and Xtrig triples: $5400
Since my bike is a 2019, I wonder if less flex would be better. I am also considering Ohlins forks (not the cartridges).
It is interesting to understand what the top guys are using and try to judge it if helped, hurt or did nothing. To think that the same results would translate to me would be a mistake.
Or you could put Dal Soggio Spheres in for about $1500 and have a excellent set of forks...
I actually am currently using the Dal Soggio Sphere in untreated tubes and they do feel fine. I like how they go over braking bumps so smoothly. I would like to try something completely different so I can figure out what I like.
(Sorry for hijacking this thread.)
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