Front wheel wobble

Richard tea

Someone was looking down on me today:o 99% of the time I dont take a chance whilst on the bike. Ill only overtake if im sure its 99.9% safe to do so. Heading home from work today I came upon a slow moving 4x4. I decided to gun it over a section of road that has white diagonal stripes. I passed the 4x4 no problem but all of a sudden the front wheel/handlebars went into a violent wobble.

I genuinely thought I was a goner. As soon as i passed the white diagonal stripes the bike straightened up & I relaxed my bowels:P The wobble lasted for about 4 seconds & I was probably doing about 80 kph.

So that's me done with and stupid maneuvers. Im going back to plane Jane riding.

Has anyone experienced this front wheel wobble before?

Any do's or donts?

LookBehindYou

Richard tea wrote: »

Someone was looking down on me today:o 99% of the time I dont take a chance whilst on the bike. Ill only overtake if im sure its 99.9% safe to do so. Heading home from work today I came upon a slow moving 4x4. I decided to gun it over a section of road that has white diagonal stripes. I passed the 4x4 no problem but all of a sudden the front wheel/handlebars went into a violent wobble.

I genuinely thought I was a goner. As soon as i passed the white diagonal stripes the bike straightened up & I relaxed my bowels:P The wobble lasted for about 4 seconds & I was probably doing about 80 kph.

So that's me done with and stupid maneuvers. Im going back to plane Jane riding.

Has anyone experienced this front wheel wobble before?

Any do's or donts?

Keep off those Painted Stripes.You got a Tank Slapper cos of the bumpy painted lines on the road, which would have caused your front to move from side to side very quickly and then more voilently.
Best way to get out of one of those is to rev the bike more to lighten the front (if you can)

Richard tea

LookBehindYou wrote: »

Keep off those Painted Stripes.You got a Tank Slapper cos of the bumpy painted lines on the road, which would have caused your front to move from side to side very quickly and then more voilently.
Best way to get out of one of those is to rev the bike more to lighten the front (if you can)

Tank slapper - I knew there was a name for it alright. Will do mick:)

AgileMyth

Happened me a while back. Was pulling out to overtake three cyclists taking up the whole road. Was moving quite slowly so it was fairly bad. You need the momentum to pull you back in line.

Idleater

I don't think that was a tank slapper, which is essentially oversteer on a bike. What most likely happened was the gyroscopic effect of the wheels was upset by the constant moving of the suspension going over the white lines at a certain frequency.
Similar instability can happen under braking going over those yellow lines that they used to paint on slip roads. The suspension compresses a little bit more each time but there's insufficient rebound and your steering can start to wobble.

LookBehindYou

Idleater wrote: »

I don't think that was a tank slapper, which is essentially oversteer on a bike. What most likely happened was the gyroscopic effect of the wheels was upset by the constant moving of the suspension going over the white lines at a certain frequency.
Similar instability can happen under braking going over those yellow lines that they used to paint on slip roads. The suspension compresses a little bit more each time but there's insufficient rebound and your steering can start to wobble.

I called it a Tank Slapper to make it it simple.
It happened because he went over the bumpy painted lines.
To avoid it, keep off those bumpy painted lines.

Its a scary thing for a rider, and can cause accidents.
I prefer to explain things simply, because its understood better.

Hotblack Desiato

You were unlucky OP. The speed you were going and the spacing of the lines were just right to 'stimulate' the front end at a frequency it will oscillate at. If you were going a few km/h faster or slower, or if the spacing of the lines had been slightly different, it probably wouldn't have happened.

The best reason IMHO to keep off those sort of road markings is that they're often full of debris and you could pick up a puncture.

You need never take a chance to overtake on a bike. There are always going to be safer opportunities, if you are in any doubt at all just wait.

Hope when your bowels relaxed, they didn't relax too much :eek:


You might have leaky forks (or fork oil that needs a change, if it's a few years old) or perhaps your head bearings are too loose. These would make it easier to upset the front end.

Wonda-Boy

Perfect opportunity to go out and buy a new bike with a steering dampner Joe....tell the missus its a safety device!

Richard tea

Ninga900 - I just had the fork seals done less than 1000 miles ago so I say they are fine.

Wonda - I cant imagine getting a new bike. When my insurance was due for renewal in June I decided the bike was going. Only for the missus said that I should renew it for one more year I would have given up on the old biking game. What ill try to do is apply for the test and at least ( with a miracle ) pass it for a full license. Ive 3 months to try and iron out some issues on the bike & with baby number 4 due next week its gonna be tough.

As for the wheel wobble - If the white strips had of lasted another 2 seconds I would say I was off the bike. Anyway lesson learned.:)

bladespin

Idleater wrote: »

I don't think that was a tank slapper, which is essentially oversteer on a bike. What most likely happened was the gyroscopic effect of the wheels was upset by the constant moving of the suspension going over the white lines at a certain frequency.
Similar instability can happen under braking going over those yellow lines that they used to paint on slip roads. The suspension compresses a little bit more each time but there's insufficient rebound and your steering can start to wobble.

Pretty sure the term tank slapper covers a multitude, anything that would make the bars 'slap' the tank, oversteer is just one reason.

rat_race

What should you do in this situation? Hold on tight and try to straighten the bike up, or loosen off the bars and let the bike straighten itself (which I presume it will as long as it has speed)...

I'd say the latter is the best option, but I doubt anyone can fight their instincts and not hold on like crazy, in that situation.

But I would think that if you try to straighten the bars too much, it'd only make the wobble worse...

Stainless_Steel

I believe it's best to lessen your grip on the bars rat_race...but I'm not experienced enough to be sure.

Hotblack Desiato

I have heard that the best thing to do is loosen your grip on the bars and power out of it.

AFAIC confidence in the front end is all-important on a bike, I don't care too much what the rear suspension is doing but I do like a well damped front end, and I hate cruisers, too much weight bias towards the rear, and looks should never dictate the steering or suspension geometry.

serious3

why were you overtaking on the diagonals anyway?

Richard tea

rat_race wrote: »

What should you do in this situation? Hold on tight and try to straighten the bike up, or loosen off the bars and let the bike straighten itself (which I presume it will as long as it has speed)...

I'd say the latter is the best option, but I doubt anyone can fight their instincts and not hold on like crazy, in that situation.

But I would think that if you try to straighten the bars too much, it'd only make the wobble worse...

Hold lightly seems to be the best option. To be honest there way no way you could hold on tightly. The wobble was to strong.

Richard tea

serious3 wrote: »

why were you overtaking on the diagonals anyway?

Moment of madness. Sun shining and getting carried away with myself. It wont be happening again I can tell ya.

arybvtcw0eolkf

Best to wheelie out of it

Wonda-Boy

Richard tea wrote: »

Moment of madness. Sun shining and getting carried away with myself. It wont be happening again I can tell ya.

Just jump off like on the BMX's years ago....and watch the bike going down the road in a straight line :pac::pac::pac::pac:

Richard tea

Wonda-Boy wrote: »

Just jump off like on the BMX's years ago....and watch the bike going down the road in a straight line :pac::pac::pac::pac:

Ill soon run out of underwear:p Prob best to go commando.