speed wobble

[flyingzonker]

I came across this on Youtube. If you watch the first 5 mins you will get the best of it.

Speed wobble,aka shimmy, is a really nasty phenomenon that anyone on a motorbike should be wise to. Too much speed is one of the causal factors. There are others; look them up on Wikipedia. Increasing the inflation in front tire seems to help prevent the problem.

I recall many years ago standing on the shoulder of an expressway. A guy, shirtless and without a helmet, went by on a cruiser of some make. Suddenly the front end started to shake powerfully. Something happened then that I have only experienced one other time in my life (which I won't go into): I saw waves coming off this rider, as though he were a rock that had been thrown into a still pond. I actually SAW the vibration of terror being emitted from this man. Happily he was able to dampen the steering and get the bike back on a steady course.

This vid is also a good reminder of how nice it can be to have a helmet strapped to your head if you happen to get thrown off at high--or any other--speed.

[chicaboo]

Poor guy, at least he seems relatively unharmed for how hard he hit the deck.

Speed wobble has always been a concern for me on the bicycle since it can happen at lower speeds.
The fastest I've been on the bicycle is about 64kph, and speed wobble can occur from about 70kph on.
You have a chance to catch it on a bicycle at least. Not sure what the recovery process is on a motorcycle?

[Mel46]

I have seen the "death wobble" on videos of bikes trying to break the 200 mph record. I know that they go through a lot to try not to have that but it does happen. I'm not sure what can be done to correct it once it starts. It happens very quickly.

[flyingzonker]

The fastest I've been on the bicycle is about 64kph, and speed wobble can occur from about 70kph on.
You have a chance to catch it on a bicycle at least. Not sure what the recovery process is on a motorcycle?

Grab the grips and strong arm the steering back to center--that at least would be the instinctive response. Need to be very quick and very strong.

[flyingzonker]

I have seen the "death wobble" on videos of bikes trying to break the 200 mph record. I know that they go through a lot to try not to have that but it does happen. I'm not sure what can be done to correct it once it starts. It happens very quickly.

I would think that at that speed when this condition comes into play all you can do is close your eyes and wait for the angels to come and carry you home.

[sendler2112]

The PCX doesn't tank slap or wobble. The CBR250R doesn't do it. The R3, Ninja20, Ninja650, Yamaha Majesty, none of my bikes do it. Don't worry about it.

[homie]

Good to know, I always wonder what a slide would be like at 90 but this is worse as he tumbled and survived. His injuries should have been the more typical squid rash if he slid. Note he remembers nothing during tumbling because the initial thump on the helmet spared him the rest. Unconscious rag doll effect is why relaxed drunks rarely get hurt in a collision. All around lucky kid from start to finish. Fall off, bump head, the rest is witness account. We all should be so lucky.

[you you]

The PCX doesn't tank slap or wobble. The CBR250R doesn't do it. The R3, Ninja20, Ninja650, Yamaha Majesty, none of my bikes do it. Don't worry about it.

Exactly.

[you you]

Good to know, I always wonder what a slide would be like at 90 but this is worse as he tumbled and survived. His injuries should have been the more typical squid rash if he slid. Note he remembers nothing during tumbling because the initial thump on the helmet spared him the rest. Unconscious rag doll effect is why relaxed drunks rarely get hurt in a collision. All around lucky kid from start to finish. Fall off, bump head, the rest is witness account. We all should be so lucky.

Kyle Minogue should write a song about it

[WhiteNoise]

Yeah, "Shake Your Booty" ^ that song lives already! just sayin' and...I'm done here

[WhiteNoise]

Oh and I never ever, never ever want to feel a Wobble I Pass!

*Thanks sendler for taking That Off my (our) minds

[flyingzonker]

The PCX doesn't tank slap or wobble. The CBR250R doesn't do it. The R3, Ninja20, Ninja650, Yamaha Majesty, none of my bikes do it. Don't worry about it.

These sound a lot like famous last words to me. You can shimmy on a bicycle.

Here's what can happen on an R6 (never happen,of course, on a Ninja 650):

[homie]

I would crush that piece of shit and use it for a coffee table like Eric Buell did with the Buell Blast inventory when Harley tried to claw them back. Heck you couldn't even sell that and live with yourself

[flyingzonker]

I would crush that piece of shit and use it for a coffee table like Eric Buell did with the Buell Blast inventory when Harley tried to claw them back. Heck you couldn't even sell that and live with yourself

I don't know anything about the Blast but we have swarms of Harleys around here. Speaking of that, have you ever heard the one about how you can tell a Harley from a Hoover? The Harley is the one with the dirt bag on top.

This joke would probably have more point in Hell's Angel territory than where I'm at.

[homie]

I would crush that piece of shit and use it for a coffee table like Eric Buell did with the Buell Blast inventory when Harley tried to claw them back. Heck you couldn't even sell that and live with yourself

I don't know anything about the Blast but we have swarms of Harleys around here. Speaking of that, have you ever heard the one about how you can tell a Harley from a Hoover? The Harley is the one with the dirt bag on top.

This joke would probably have more point in Hell's Angel territory than where I'm at.

Thanks FZ!
I was needing a joke to tell next Sunday on my 3 hour tour with mostly Harley owners... I think I will save it until after we get back home though.

[ScooterAddict]

I have witnessed many high speed wobbles, also saw crashes. One of them was a rider being bucked off at 80mph with helmet, leather jacket and no gloves. Worst road rash I have ever seen.

When you start to experience high speed wobble the worse thing you can do is abruptly close the throttle. Try to maintain the throttle or increase just a hair. At the same time leaving the throttle in place, start applying the rear brake progressively. Do not use the front brake. Closing the throttle will exaggerate the wobble. Look on YouTube.

Make sure your steering head bearings are adjusted properly. When tightening or loosening the bearing to set preload, make sure you loosen the forks slightly with the pinch bolts. Not to loose or the forks will fall out. You will need to raise the front end off the ground slightly, just enough to see daylight. Or touching the ground ever so slightly. While you are setting the tension on the bearing you may want to turn the forks from side to side. Doing this could help prevent brinneling. While suspended, the bearing is set properly when the steering will fall from side to side with just a little bit of tension. This is tricky and takes a gentle touch. Just a hair to tight and when riding it will fell like you are stuck in a giant rain groove that requires more effort to turn.

That is my $.02 and I hoped I explained my process of adjusting steering head bearing.

[flyingzonker]

[quote="ScooterAddict
That is my $.02 and I hoped I explained my process of adjusting steering head bearing.[/quote]

I'll say this: You gave it a hell of a good try.

[gn2]

Anyone ever adjusted the steering head bearings on a PCX or Forza, how much disassembly is needed to get at the adjuster and lock nuts?

When tightening or loosening the bearing to set preload, make sure you loosen the forks slightly with the pinch bolts.

Not required on most scooters because they are single clamp.

[you you]

Anyone ever adjusted the steering head bearings on a PCX or Forza, how much disassembly is needed to get at the adjuster and lock.

I think you start by removing the rear light...?