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Front wheel wash out in straight line

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On 9/18/2018 at 9:01 AM, Toughmudder said:

tire pressure in front around 18   and 20 in the back. This was  a rocky trail....   so i couldn't go lower than that

You could but if you don't have a musse or tubless you might pinch the tube. I have ridden in all sorts while competing in the SRT western hare scrambles. Key set up is the right tire pressure. A soft compound tire will help. I run 4 to 6 psi and have very little deflection on the front. Soft suspension setting too help if it is offroad only. If it is MX then the set up is way different.

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The OP was riding a WR250R dual-sport, 

at nearly 300lbs and travelling down trails at 30mph 

I can understand his interest in running higher than ideal trail pressures.

 

 

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On 9/18/2018 at 7:49 AM, Toughmudder said:

 

I was riding in a trail and i crossed a litle patch of mud/clay and i mmediately lost my front wheel and fall at around 45 km/h..I was lucky to not get hurt...There was a litle slope in the hole that was covered by mud/clay. I have agressive front tire . What can i do to prevent this???   Put more weight on the front?  less weight on the front.. Stay centerred on the bike. When i ride in the trail, i tend to bring my weight toward the back to keep the front light and skim over the rocks...
My sag is ok.  I removed my 2 inch handle bar riser after this incident. It seem the pro doesn't use that cause it change the bike handling... Any suggestions? Maybe i am wondering to much and i could have only go around that mud/clay patch....

Did you try to "wheelie" through the mud patch? this IS  viable solution. 

Otherwise, what air pressure are you running up front? Low enough to get a larger tire contact patch?

What was your body positioning at the entrance to the mud patch? Where was your weight? 

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On 10/29/2018 at 10:14 AM, Ktm200excrider said:

It sounds like the opposite of what you should do but yes I’ve found it much easier to go through it faster rather then slower. If you go to slow your tires collect mud rather then fling it off. Try not to fixate on the patch and look further ahead.that usually works for me. It’s when I stare at it and start thinking about it is when it grabs hold and slams me to the ground. Damn aliens!

Also known as "TARGET FIXATION"

Now that you know about target fixation, and that it's built into our predator DNA, let's use it to our advantage.

I have an exercise I want you to practice, the next time you're out on the trail/track. 

Instead of looking right AT an obstacle, I want you to look at the clear path around that obstacle. You go where you look. Doesn't matter if it's a tree stump/rock or guard rail on the street. See it? Hit it! So, consciously do not look at it. Look around it! 

Ride safe

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9 hours ago, NORTY said:

Also known as "TARGET FIXATION"

Now that you know about target fixation, and that it's built into our predator DNA, let's use it to our advantage.

I have an exercise I want you to practice, the next time you're out on the trail/track. 

Instead of looking right AT an obstacle, I want you to look at the clear path around that obstacle. You go where you look. Doesn't matter if it's a tree stump/rock or guard rail on the street. See it? Hit it! So, consciously do not look at it. Look around it! 

Ride safe

 I would describe it as looking past, rather than around, the obstacle. Sort a different way of thinking of the same thing, but frequently the best way to deal with an obstacle is to go over it, looking ahead to where you want to go can lessen the impact of the obstacle on the bike/rider.

Edited by motovita
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i don't think it is a tyre pressure issue here, but I ran 12-15psi for many years in terrain that was 99% rock or hardpack clay...never once had a puncture (nor friends with one). I never did any massive hits (rock ledges were done at jogging pace at most - usually much slower). I also often ran knobbies with only 2mm of knobbies left....So don't be afraid of trying a bit lower (or maybe I was just lucky)

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On 12/30/2018 at 12:40 AM, NORTY said:

Did you try to "wheelie" through the mud patch? this IS  viable solution. 

Otherwise, what air pressure are you running up front? Low enough to get a larger tire contact patch?

What was your body positioning at the entrance to the mud patch? Where was your weight? 

I don't have the skill to wheelie at that speed with this bike...   Wr250r is a heavy bike and not verry powerfull for this kind of stuff.. Maybe i should have slow down and clutch wheelie...  but all day i crossed water patches without a single problem.....   This mud patch was looking like a water patch like all the others.

Around 18 psi in the front. This was a verry rocky fast ride so i set the pressure accordingly.

Body position.  I always tend to put my weight toward the bike to keep the front light  specially when there is a lot of rocks.   

But the mud patch was located in in a sandy section.....  Again i always put my weight toward the back in sandy section too....

The guy in front of me was riding a KTM 1090 and he told me after the incident that when he crossed  that clay section, he feels to lose the front so he gave a bit of gas to correct everything....    This guy is a better rider than me....more experience..  but i am not sure if he took the exact same line as me ...

Maybe my mistake was caused  by shuting off the throttle just at the entrance of the patch.. this loading the front tire.... I don't recall if i crossed it with or without throttle......   

Thanks for your interest !!!!

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Maybe my mistake was caused  by shuting off the throttle just at the entrance of the patch.. this loading the front tire.... I don't recall if i crossed it with or without throttle......   



This is very likely the issue. Shutting the throttle at the entrance causes a forward shift in weight, made worse by the deceleration force of the mud. This causes the front tire to get “knifey” and catch ruts. Similar to sand, under these conditions your front end looses trail since it’s effective contact patch moves forward as it pushes the built up mud (or sand). This reduces front stability while the bike is also knifing.

You really have only two safe options.

1). Attack. Lighten the front as you enter and cross the obstacle. On low powered bikes preloading by pushing down on the handlebars and pegs, then moving your body back and applying throttle as the suspension begins to rebound will lighten the front.

2) Slow way down and slog through at a very low speed.

It’s far less safe to ride through at a speed in between these two options. Ask me how I know.

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Sounds like you know what to do, the next time this scenario rears it's ugly head. 

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