[wayne]

Was riding this morning and had a pretty scary experience on the Stryker and wondered if anyone else had experienced this. Was cruising along a straight stretch of road at about 70 mph by the speedo which considering room for error puts me at about 65. Hit a couple of studder bumps, small consecutive bumps in the road and the front end began to shake violently for a second or two. Now as an experienced rider I was able to hold on to it and ride it out but I could see a newer rider panicking and a pretty horrendous crash taking place. I am familair with head shake on dirt bikes and the appropriate measures (usually fork height adjustment) to take to remedy it and wondered if anyone has had the same experience with the Stryker. I'm thinking that the lowered rear (I have soupy's links) is throwing off the weight distribution enough to lighten the front a bit. any thoughts?

 

[SmokenJoe]

Sounds like a"tank slapper"........could be rake and trail numbers are off. Do a search on google and will tell you if you need to check it..

 

[toby]

Ohh tank slappers, head wobblers, I can relate to that. Not that what I experience causes excessive front end shake, but we have road ripples everywhere from heavy truck and unstable ground shifting, especially in corners and they seem to be right where my line is. Always something new every day. With a light hand on he bars it's not that bad and goes away quickly especially at speed, but deffenetally gives the pucker effect.

 

[BrettRTR]

I looked up some vids on YouTube after I read this yesterday. Good thing you handled it like you did Wayne, scary stuff. What is the right thing to do if it ever happens?

 

[wayne]

Sounds like a"tank slapper"........could be rake and trail numbers are off. Do a search on google and will tell you if you need to check it..

Tankslapper indeed. In 40 years of riding I don't think I've had a (street) bike that exhibited this as violently as this. Probably due to the exaggerated rake that gives the Stryker it's stylish profile.
Correct me if I'm wrong but the rake and trail are set by the bikes geometry i.e. head angle and offset. The only "adjustment" available would be the fork tube length by sliding the forks up in the triple clamps. By spec the Stryker has 40 degrees of rake and 4.3" of trail with 6 degrees of trail being in the triple clamps and 34 in the steering head. I will double check all the front end components, head bearings etc but don't think there should be an issue there as the bike is basically new with just over 1000 miles on the clock. This particular stretch of road is a tad bit rough with a series of undulations from frost and truck traffic but not particularly bad and I travel it almost daily and this was the first time I had this reaction. Must have hit it just right to set up the shake. It was truly a "pucker" moment!

 

[wayne]

I looked up some vids on YouTube after I read this yesterday. Good thing you handled it like you did Wayne, scary stuff. What is the right thing to do if it ever happens?

Brett. In my experience it's usually over before you can really react and if you don't panic and let the bike have it's head it will straighten out itself. If you try to fight it and over-steer that can put you in a bad situation. Stay off the front brake and as Toby said, a light but firm hand on the bars. The gyroscopic effect of the wheel will want to bring it back to straight. Letting off the gas to slow down will also usually help, again staying off the front brake so as not to lock up the front wheel. The phenomonon is a combination of suspension geometry, speed and the spacing of the terrain irregularities which set up a kind of resonance in the front wheel. Changing any of the factors will break the pattern. In my case letting off and slowing just a bit took care of it. (and of course going home and changing my shorts!)

 

[11Stryker]

I found my front pinch bolts for the forks where not torqued properly after I had about 600 miles on bike. May want to check them Wayne.

 

[wayne]

I found my front pinch bolts for the forks where not torqued properly after I had about 600 miles on bike. May want to check them Wayne.

Will definitely take a look. I'm still thinking the issue is probably the fact that it is lowered in the rear which would have a tendency to lighten the front a bit. I'm down probably close to 2 1/4 - 2 1/2 " so I might bring the back up just a bit. After doing a bit of research on the main causes of head shake this was the one thing that really makes sense. The fact that I was riding fairly aggressively and the type of road conditions combined with the change in the bikes attitude due to the lowering are a perfect scenario for what happened. Or maybe I just need to slow down a little bit LOL.

 

[Strom]

This is some really good info Wayne - thanks for posting it. I never have experienced head shake -nor had I heard of it - before this post. I'm gonna check my fork bolts and try to remember your advice if it happens to me.


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[wayne]

This is some really good info Wayne - thanks for posting it. I never have experienced head shake -nor had I heard of it - before this post. I'm gonna check my fork bolts and try to remember your advice if it happens to me.


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I hope you never do but it's best to be prepared for anything! Most important thing is not to over-correct and not to let it pull the bars out of your hands.
I've experienced head shake a few times riding motocross on a dirt bike and seen it take riders down. Happens when the front end is light and the tire hits a bump slightly turned. The impact pushes the tire sideways while the gyro effect and rider input want to go in a straight line. Sets up a back and forth oscillation which really gets the adrenaline pumping.

 

[11Stryker]

Had this happen riding my dad's bicycle when I was 7 years old. Was being smart with the handle bars not realizing what was about to happen. I could not hold it and went down. Great learning experience and got er done at an early age when I healed quicker! LOL

 

[wayne]

Had this happen riding my dad's bicycle when I was 7 years old. Was being smart with the handle bars not realizing what was about to happen. I could not hold it and went down. Great learning experience and got er done at an early age when I healed quicker! LOL

I hear ya bout the "healing quicker" That's why I quit riding MX this year. My neighbor is still healing from a knee injury from our last trip out last year and he's 10 years younger than me.
I did check the pinch bolts and the tops were not up to torque spec. The bottoms were pretty close. Good idea for anyone with a Stryker to check these as there seems to be a pattern here. Thanks for letting me know about those 11Stryker.

 

[11Stryker]

Here's a thread I started 1-1/2 years ago. http://www.yamahastarstryker.com/21...all-might-want-check-these-proper-torque.html