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Ate it on the S18 today!


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3 minutes ago, FLRocketMan said:

Wear that safety gear, it is a must at the speeds of the current wheels. Ride safe everybody!

Exactly!  Glad your ok.  Wheels can be repaired.

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On 1/20/2021 at 2:57 PM, FLRocketMan said:

Crashed the S18 today at about 30mph. Started with a wobble and none of the techniques that I have used on other wheels could stop the madness.  The S18 damage was fairly light considering the magnitude of the crash. Tolley handle and rods were destroyed and the rear panel was broken. The damage to my body was also light considering (a few cuts, bruises and scrapes). Wear that safety gear, it is a must at the speeds of the current wheels. Ride safe everybody!

wobbles caused by what? always wondered since they announced suspension wheels if that motion would make them more or less stable

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My S18 came with the Eakia tire. I think this tire tends to track lines in the surface a bit more than some other tires. The wobble started as the tire began to track imperfections in the road surface. The wobble very quickly became catastrophic. None of the techniques I have used successfully on other wheels to get wobbles under control made any difference, at all. I do feel that the suspension added to the rapid loss of control and severity of the wobble. The wobble seemed to have a “bouncing” component from the suspension that compounded the problem. My setup is directly by the Kingsong recommendations for upper and lower shock pressure. I did have the rebound (shock click wheel) set for quick rebound (5 clicks) and this will be the first thing I experiment with now that the wheel is repaired.

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16 hours ago, FLRocketMan said:

My S18 came with the Eakia tire. I think this tire tends to track lines in the surface a bit more than some other tires. The wobble started as the tire began to track imperfections in the road surface. The wobble very quickly became catastrophic. None of the techniques I have used successfully on other wheels to get wobbles under control made any difference, at all. I do feel that the suspension added to the rapid loss of control and severity of the wobble. The wobble seemed to have a “bouncing” component from the suspension that compounded the problem. My setup is directly by the Kingsong recommendations for upper and lower shock pressure. I did have the rebound (shock click wheel) set for quick rebound (5 clicks) and this will be the first thing I experiment with now that the wheel is repaired.

hmmm, yea i thought as much.. it just adds another layer of complexity that can compound any issues especially with something thats constantly balancing

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  • 1 month later...

I had the same wobble issue around 25 mph back in September. Ate it as well. Not sure if it was the 40 psi in the tire or the higher stance of the pedals. 
 

I am going to try the s18 again with this latest batch. 

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In my experience the high psi was a major contributor.  I started with higher PSI (38) and would get random wobbles in all sorts of situations.  I started bringing the PSI down and they disappeared.  I think the combo of high pedals, suspension and high psi causes feedback loops.  31psi ended up as the magic number for me but I would imagine it depends on the weight of the rider.

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1 hour ago, pkinpdx said:

In my experience the high psi was a major contributor.  I started with higher PSI (38) and would get random wobbles in all sorts of situations.  I started bringing the PSI down and they disappeared.  I think the combo of high pedals, suspension and high psi causes feedback loops.  31psi ended up as the magic number for me but I would imagine it depends on the weight of the rider.

A lot of factors for ideal tire in my opinion, weight, riding type, and personal preference.   I LOVE the feel of 40 psi on the road, wheel responds to the slightest command instantly.  Which takes getting used to I guess.  OFF road I lower the PSI a bit to get more rubber on the trail, for my weight, minimum safe pressure is 35 ish and it feels super grippy but not nearly as agile.  I can say from experience that Pea Gravel at 40 PSI is not fun!

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I'm  a new rider and chose the S18 as my first wheel.  I can definitely say that the Eakia tire is very finicky. I too have experienced the suspension compounded wobble, crash and all when first starting out.

Things I learned very quickly:

  • A soft suspension = wobbles at high speeds.
  • Low tire psi = wobbles at med to high speeds
  • High tire psi = awful line tracking
  • Gravel and the Eakia tire = weird unpredictable behavior usually with a bad result 

I sport a pretty stiff suspension with a slightly damped return. It makes for a noisier ride but more stable. I couldn't tell you the exact psi's as learned to go by the feel of the suspension by pushing down on the wheel with my hands. Same for the tire, I grab the tire with both hands and press down with both my thumbs looking for a slight give.

I pump my pos chamber to 210 but lose a bit during disconnect

I pump the neg chamber to 150 but lose a bit during disconnect

I've tried lowering tire pressure for off road and did not like it, it tended to track lines way too much. If I do lower for off road it is ever so slightly below my psi for road.

 

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My tire pressure was 35psi when I crashed. I have also found that higher tire pressures seem problematic on the S18.

Currently riding with a pressure of 28psi.

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  • 2 weeks later...

Ate it last night on my first day with a new Kingsong S18. Tire pressure was 35 psi which probably was too much for my weight of 68KG. Exactly the same problem, I was driving down a hill maybe too fast ( should be less than 40KM/Hour as I didn't hear any alarm) and it started to wobble. I tried to slow down immediately and it just threw me away. As I didn't wear any gear, there were multiple scratches across my elbows, hands and knees.

Luckily the wheel was still fine after bumping into a tree, with one side shell loosed a bit. I could still got back to my wheel and finished the trail with a swollen right knee.

Going to try 28-30 psi next time with knee and elbow protection gear.

Edited by zzzzzzzzZzz
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3 hours ago, zzzzzzzzZzz said:

As I didn't wear any gear, there were multiple scratches across my elbows, hands and knees.

You got lucky. Many others would have broken bones (usually a collarbone or wrist). And collarbones can't really be protected with any amount of gear so.....do whatever you can to not fall off in the first place ;)

ANY wheel gets twitchy the more pressure you run. As a result, I run the least I can get away with. Thats around 25psi in my MSX at 90kg weight, although its ok down to about 22. 35psi, even in a 16x3, sounds like an awful lot for 68Kg.

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25 minutes ago, Planemo said:

ANY wheel gets twitchy the more pressure you run. As a result, I run the least I can get away with. Thats around 25psi in my MSX at 90kg weight, although its ok down to about 22. 35psi, even in a 16x3, sounds like an awful lot for 68Kg.

@Planemo I totally agree with everything you stated here, most of those higher pressures quoted in this topic are always gonna make for a twitchy ride!  I too run the lowest pressure I can get away with on All three of my wheels, being as the Z10, S18 and the Sherman are All running around 20psi for my weight of around 85kg fully kitted up!

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  • 3 weeks later...

I am at 24psi now and for me this made the wheel a real joy. I find I am riding it much more. Not as much as the Sherman, but I do appreciate what it is at a new level.

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I am 220 pounds + 20 pounds of gear and run 27-30 psi in the S18 and MSX with no problems. 

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I ride at 40psi on my S18 & ya I do get the wobblies on a consistent basis. That said, it could be part of my riding style (or at least I treat it as part & parcel of riding) & its easily handled with a shift in body positioning. I have to admit it used to scare the bejesus outta me in the beginning but time on wheel have given me the confidence to ride it out so much so I consider it normal.

Frankly I think panic & what accompanies it is the main cause of crashes. IMO ofcos as its always gonna be a YMMV. For those riding on low psi's, don't forget to be careful hitting curbs & such as I've seen multi vids of bent rims as a result. Most of 'em says they wished they'd checked the psi so I gather a rim replacement isn't cheap.

Personally, I find low psi handling to be squishy ie. unpredictable other than going straight. Again its always gonna a YMMV.

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For my weight (fully geared 96kg) I found that 35psi both on the KS 16x and the V11, were just perfect for me. Both are 3" tires and I get a great mix of response, maneuverability and tire grip. I did try 32psi on the 16x and 3rd week learning it was comfortable, eSy to maneuver... But worse o. Cobblestone roads, which are really nasty and irregular in Portugal. In particular in my area's microclimate where these stones get covered with moss. So 35 psi is much better for these tricky roads... in my case. 

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I do about 38-41 on my V10.  I do about 35-38 on my Nik+.  I don't really have wobbles I've noticed but I barely ride 30km/h as it is, usually less.   Geared up I'm about 90kg

Edited by /Dev/Null
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Today I had proof of one thing due to having ridden my KS 16x once again for 31kms... and again under the very strong north winds, typical of my region: strong frontal winds cause wobbles, no doubt about that! I had to be extra careful today when the wind was hitting me frontally. 

 

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If your pressure dose not match your weight and activity it can definitely be a problem. I saw a V11 rim destroyed this weekend. The rider thought his pressure was at 35  (he said he had not checked it in while) and bent the rim badly on a curb. We check his tire pressure after the incident it was 18psi.

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  • 2 weeks later...

How is everyone getting accurate enough readings of their pressure to determine whether they are at 32 or 35 etc psi? I have a pump with a gauge but it lets so much air out when disconnecting that I then measure with another gauge, which also lets a little bit of air out. But I'm pretty sure neither could be accurate to within 1 or 2 psi. In fact, my Slime branded gauge only has marks for every 2 psi.

Are you all using some fancy expensive gauge that I don't know about? Are you inflating using a device with a digital gauge? How does anyone know whether their gauge is calibrated anyway? My 27 psi might be someone else's 30 psi yet you're all saying that a difference that large could cause wobbles or bent rims etc depending on weight and tyre size.

I'm on a KS 14D and I pump it up to something like 50 psi on my pump gauge, which results in somewhere just over 30psi when I disconnect and remeasure with the other one. Anything lower than that and I can feel bottoming out just crossing a driveway gutter. I'm around 70kg.

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consumer pressure gauges are pretty imprecise as you've observed, my 38 won't be your 38. But it's ballpark. After that, it's what feels good when riding that matters... I'd recommend picking 1 gauge to use after you're done pumping and disconnecting and using that as your measuring stick—don't switch it out between measuring sessions. Then you can have an idea of what the settings should be for that pressure gauge.

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