speed wobbles
in [Motorcycles]
|
From: BrianNZ on 5 Feb 2010 16:22 Went for a spirited ride the other day with some mates and for the first time in a long time the urge for more 'go' and wind protection crossed my mind.Since it was a hot day, it was jeans and a nylon 'bomber' jacket to keep the sunburn at bay, but the jacket flaps in the wind....the faster I went, the more it flapped until the bike started to get a weave/wobble.....not what I want at speed. To make the wobble disappear I just had to let go of the handlebar with my left hand. The bike instantly settled and more power could be wound on....if I touched the bars, it would wobble again. Meanwhile my mates had accelerated into the distance. As soon as the roads tightened up and top speed meant nothing, I was happy again.....I must stay away from long, straight boring roads, 'cos to make them exciting invites trouble. :) My workmate who brought the 1198S Ducati managed to run off the road three times in the first 300km!! :) he will learn....one way or the other.
From: Lew on 5 Feb 2010 17:10 On 05 Feb 2010, BrianNZ wrote in news:4b6c8fe1$1(a)news.orcon.net.nz > Went for a spirited ride the other day with some mates and for the > first time in a long time the urge for more 'go' and wind > protection crossed my mind.Since it was a hot day, it was jeans > and a nylon 'bomber' jacket to keep the sunburn at bay, but the > jacket flaps in the wind....the faster I went, the more it flapped > until the bike started to get a weave/wobble.....not what I want > at speed. To make the wobble disappear I just had to let go of the > handlebar with my left hand. The bike instantly settled and more > power could be wound on....if I touched the bars, it would wobble > again. Meanwhile my mates had accelerated into the distance. As > soon as the roads tightened up and top speed meant nothing, I was > happy again.....I must stay away from long, straight boring roads, > 'cos to make them exciting invites trouble. :) > > My workmate who brought the 1198S Ducati managed to run off the > road three times in the first 300km!! :) he will learn....one > way or the other. > High speed wobble should be taken seriously; I wouldn't assume it was the jacket. As for your hot day, it's rainy and 30s here. :-( -- Lew
From: S'mee on 5 Feb 2010 17:15 On Feb 5, 3:10 pm, Lew <no...(a)notmindspring.invalid.com> wrote: > On 05 Feb 2010, BrianNZ wrote innews:4b6c8fe1$1(a)news.orcon.net.nz > > > > > > > Went for a spirited ride the other day with some mates and for the > > first time in a long time the urge for more 'go' and wind > > protection crossed my mind.Since it was a hot day, it was jeans > > and a nylon 'bomber' jacket to keep the sunburn at bay, but the > > jacket flaps in the wind....the faster I went, the more it flapped > > until the bike started to get a weave/wobble.....not what I want > > at speed. To make the wobble disappear I just had to let go of the > > handlebar with my left hand. The bike instantly settled and more > > power could be wound on....if I touched the bars, it would wobble > > again. Meanwhile my mates had accelerated into the distance. As > > soon as the roads tightened up and top speed meant nothing, I was > > happy again.....I must stay away from long, straight boring roads, > > 'cos to make them exciting invites trouble. :) > > > My workmate who brought the 1198S Ducati managed to run off the > > road three times in the first 300km!! :) he will learn....one > > way or the other. > > High speed wobble should be taken seriously; I wouldn't assume it was > the jacket. As for your hot day, it's rainy and 30s here. :-( I dunno. I seem to recall that discussed elsewhere and loose jackets and improperly packed gear (stuff flapping in the wind) apparently contributed quiet a bit. To be fair the only speed wobbles I've experienced were a known wobble in high speed sweepers on the GL1000 and twitchy little RD that likely was caused by poor maintinence. <shrug>
From: 府寺 on 5 Feb 2010 18:25 On Feb 5, 1:22 pm, BrianNZ <br...(a)itnz.co.nz> wrote: > Since it was a hot day, it was jeans and a nylon 'bomber' jacket > to keep the sunburn at bay, but the jacket flaps in the wind....the > faster I went, the more it flapped until the bike started to get a > weave/wobble.....not what I want at speed. To make the wobble disappear > I just had to let go of the handlebar with my left hand. The bike > instantly settled and more power could be wound on....if I touched the > bars, it would wobble again. 1. Do you Kiwi duffers even *know* the difference between a weave and a wobble? 2. How was the traction of the surface you were riding on? A speed weave and a speed wobble are two completely different modes of oscillation and the frequencies are different. A speed wobble involves only the front forks and wheel. The chassis behind the steering head is not involved in the wobble, so the motorcycle stays upright. A speed wobble occurs when the front tire cannot get enough grip to keep from oscillating at a frequency of 5 oscillations per second or more. You cannot even hold onto the bars when you're in a speed wobble/tank slapper. In a speed weave, the rear tire has less traction than it needs, and the front tire is gripping adequately. The whole chassis can become involved in a speed weave, with rolling and yawing, but not a lot of movement on the pitch axis. The frequency of a speed weave is 2 to 5 cycles per second, with the possibility of running off the road, since the rolling of the chassis also steers the motorcycle in undesired directions. *Every* motorcycle has a critical speed at which it begins to weave. Big sportbikes just do it at over 120 mph. Big dual sport motorcycles will begin to weave around 80 to 90 mph if they have tires which are mostly pavement oriented. Dual sport motorcycles also have a high center of gravity which lowers the critical speed at which speed weave begins. If the rider is rather porky, as I remember you to be, just take your left foot off the foot peg and lower your leg to get the motorcycle to stop weaving. But don't run over your foot. That hurts. DAMHIK... Alternatively, lean forward over the gas tank, or tap the rear brake pedal to get weight to transfer to the front and stop the weave.
From: BrianNZ on 5 Feb 2010 19:04
Lew wrote: > On 05 Feb 2010, BrianNZ wrote in news:4b6c8fe1$1(a)news.orcon.net.nz > >> Went for a spirited ride the other day with some mates and for the >> first time in a long time the urge for more 'go' and wind >> protection crossed my mind.Since it was a hot day, it was jeans >> and a nylon 'bomber' jacket to keep the sunburn at bay, but the >> jacket flaps in the wind....the faster I went, the more it flapped >> until the bike started to get a weave/wobble.....not what I want >> at speed. To make the wobble disappear I just had to let go of the >> handlebar with my left hand. The bike instantly settled and more >> power could be wound on....if I touched the bars, it would wobble >> again. Meanwhile my mates had accelerated into the distance. As >> soon as the roads tightened up and top speed meant nothing, I was >> happy again.....I must stay away from long, straight boring roads, >> 'cos to make them exciting invites trouble. :) >> >> My workmate who brought the 1198S Ducati managed to run off the >> road three times in the first 300km!! :) he will learn....one >> way or the other. >> > > High speed wobble should be taken seriously; I wouldn't assume it was > the jacket. As for your hot day, it's rainy and 30s here. :-( > My hot day was late 20's C (your mid 80'sF?). Heading to town at 7.30pm the other day it was 32C...by 11.30pm it was down to a comfortable 17C. I don't miss the cold but don't like the heat...hard to please some people. :) The bike doesn't wobble when I'm wearing my proper bike gear. I blame the jacket 'cos the wind really gets the top of the sleeves flapping around my shoulders and as soon as I took my input to the bars out of the equation, the bike was happy. It wasn't a scary wobble, just noticeable. The upright riding position of the SuperMoto doesn't cut it when I'm trying to keep up with a pair of Aprilia's and a Ducati (in a straight line). |