Very lucky motorcyclist escapes semi truck

Status
Not open for further replies.
I ride, not much, but whatever. What I don't understand about this guy is why he was just shifting to 2nd at the 75-80MPH speed of the traffic?

I ride a 1984 Yamaha XJ750RL (very rare and not sold in USA) I'm usually out of 1st before the intersection ends, and if really pouring it on, I might be going 75Km/h before shifting to 2nd. I know these new sport bikes love to rev, but he was in a 1000cc + bike ? IMHO he should have been in 2nd at 75MPH (120 Km/h) and shifting to 3rd. 1 litre bikes have some pretty good torque, no need to rev that high me thinks.

To be sitting too far back when he shifted is a symptom of just hanging on, and not being the master of the machine.

He was wearing keds ? not exactly the best foot protection! I always wear a boot that covers my ankle bone.
 
Originally Posted By: ZX11Rebel
At least the guy had on his safety gear! Helmet, Jacket, and gloves etc.


From the waist up maybe. Cotton pants and sneakers, just plain stupid.

Claud.
 
I still think he was doing something stupid/reckless and almost paid the ultimate price. Of course he is not going to admit it, hence the blurred out speedo.

Modern bikes don't go into a wabble out of nowhere. From the slow motion replay the road surface looks very smooth and there is no oil or other debris on it. You can also see another motorcycle pull over towards the end. Most stupid stuff is done in groups, not alone.
 
Originally Posted By: KrisZ
I still think he was doing something stupid/reckless and almost paid the ultimate price. Of course he is not going to admit it, hence the blurred out speedo.

Modern bikes don't go into a wabble out of nowhere. From the slow motion replay the road surface looks very smooth and there is no oil or other debris on it. You can also see another motorcycle pull over towards the end. Most stupid stuff is done in groups, not alone.


Light front tire due to hard acceleration, and the front end got into some strange oscillation for some reason. Some bikes are more susceptible to be triggered into front end oscillation than others, especially if there is no steering damper. I've ridden over 100 different cycles in my lifetime and have done all kinds of "stupid things" on them and have never had any crazy front end oscillation like that.

Also, if the head bearings were getting loose or something else not quite right with the front end it's possible that could have factored into the oscillation incident.
 
Originally Posted By: Astro14
Originally Posted By: 02SE
Yep, I've experienced it on numerous bikes. I believe the riders account of what happened. My aforementioned ZX-12 was a tankslapper, looking for a place to happen. I eventually installed an aftermarket steering damper, before finally selling it for other reasons.


If you don't mind - how does one get out of this? do you wait until it dampens out?

None of my motorcycles (all in the 70's, all dirt bikes) ever did anything like this...so, is it weight forward? weight back? what reduces it?

It just amazes me that motorcycles can be sold with insufficient stability, which I presume comes from the rake/trail specs...this didn't used to be a thing...did it?


I've found it depends on the bike, as to what works. On a lower powered bike I've let go of the grips, and as has been described, hugged the tank and tried to get my weight forward. On a high powered bike, I've fanned the clutch, gave it more throttle, and pulled the tire off the ground in a wheelie, which stopped the front end oscillation.

As to what causes it, can be attributed to several contributing factors, such as the steering geometry, chassis rigidity, and weight distribution.

A bike with more aggressive steering geometry, will inherently be less stable, but also has more responsive steering that improves the bikes ability to change direction quickly. Most sporty bikes are designed this way. Most manufacturers also install steering dampers to keep the propensity to tankslap in check. The bike in the video could've certainly used a steering damper.

Both of my sportbikes have steering dampers from the factory.

The video of the chopper that went out of control was likely the result of poor weight distribution, and a too flexible frame and forks.
 
I appreciate the responses.

I sold my last motorcycle (the RM-125) in 1982. Which doesn't seem that long ago, now... I've ridden a few times since then and I've got a few friends who have returned to the sport (with some pretty nice motorcycles, like a new K1600GTL), so, as I contemplate my own return, it's clear to me that I don't know enough about it...

Thank you for the explanations.

I think a MSF class is in my future...
 
A steering damper is a band aid to reduce an inherent problem with the bike. Some bikes have them, and need them, others don't. I used to take steering dampers off my bikes. Early BMW's had a friction damper, mine never came with one. Same basic frame, but a few small changes over the years, and the bike is a lot more stable than early models. I fitted an S fairing and stock narrow bars a few years ago (I had taken them off years before) and had bar shake at 50kph, nothing dangerous, but if you took a hand off the bars it would shake. No fairing, higher wider bars and a more upright position and it isn't there at all.
 
Originally Posted By: Silk
A steering damper is a band aid to reduce an inherent problem with the bike. Some bikes have them, and need them, others don't. I used to take steering dampers off my bikes. Early BMW's had a friction damper, mine never came with one. Same basic frame, but a few small changes over the years, and the bike is a lot more stable than early models. I fitted an S fairing and stock narrow bars a few years ago (I had taken them off years before) and had bar shake at 50kph, nothing dangerous, but if you took a hand off the bars it would shake. No fairing, higher wider bars and a more upright position and it isn't there at all.


The performance envelope capability of Motorcycles, has improved just a bit since 1987. Decisions are made as to the goals for a model when it is in the design and testing phase, and every aspect is a compromise. A low-powered bike with relaxed handling characteristics and low limits can be designed and built today. In fact there are several bikes with those characteristics available.

An S1000RR (one of the bikes I own) has nothing in common with an old boxer twin, with the exception of two wheels and the Roundel. The same could be said of the K1600GTL, Astro has expressed an interest in.

It all depends on what your priorities are.
 
A friend had a tank slapper at around 100 mph and said he did his best to hang on to the bars but he feels to this day that a power greater than him had something to do with him avoiding a terrible crash. Some tank slappers are so severe there is no way you could control it let alone feather the clutch or throttle because it happens so fast and so violently you can’t even hold on let alone do some of the moves described here. I’ve seen videos of tank slappers and riders crashing in AMA racing, and these riders are the best in the world.
 
Originally Posted By: gman2304
A friend had a tank slapper at around 100 mph and said he did his best to hang on to the bars but he feels to this day that a power greater than him had something to do with him avoiding a terrible crash. Some tank slappers are so severe there is no way you could control it let alone feather the clutch or throttle because it happens so fast and so violently you can’t even hold on let alone do some of the moves described here. I’ve seen videos of tank slappers and riders crashing in AMA racing, and these riders are the best in the world.
This is what I feared.
I'll pass on the motorcycle.
 
Status
Not open for further replies.
Back
Top