Major Wobble at high speed - didn't expect it

Al st1100 said:

Wow an honest and fair minded thought !!!! Watch MotoGP they (with all their engineers and money still get a weave) not all the time but a condition happens to cause it. Think about it, take a gyroscope and spin it, sometimes its good but it just takes the smallest thing to throw it off and it wobbles. On a bike you have two gyroscopes. Just because you have not experienced the weave before doesn't mean you have hit the condition the can cause a weave.

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Absolutely, motorcycles are by their very nature inherently unstable. It seems to me that the manufactures problem is finding the balance between stability and handling. A long wheelbase and raked out fork will give a more stable motorcycle but it won't be spritely around the corners, give it a short wheelbase and a steep fork and it'll want to fall over! I bought a new Fireblade in '93 and nearly fell off at my first roundabout, I put it into the roundabout and it went over so quickly I nearly got caught out.
I suspect those MotoGP bikes are so quick to steer that they are incredibly unstable, put a bit of weight high up (top box) and I bet they would be all over the place!
But that instability is what makes motorcycles such fun to ride. I don't believe that the Pan is a dangerous motorcycle unless you do something silly, the same could be said of any vehicle two wheels or four.

jazzkat said:

Absolutely, motorcycles are by their very nature inherently unstable.

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Umm.. really.... then why do they seem to move along just fine without a human on board to supposedly stabilize them? Probably because the human is the most unstable thing there is on-board the ship.

T_C said:

Umm.. really.... then why do they seem to move along just fine without a human on board to supposedly stabilize them? Probably because the human is the most unstable thing there is on-board the ship.

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Yes, but only when momentum is applied, without speed they just fall over! Even if they are travelling at speed it only takes a slight bump in the road or a gust of wind and they go off course and then fall over, unless someone is on board controlling it with small (or large!) inputs to keep it going where they want it.

jazzkat said:

Yes, but only when momentum is applied, without speed they just fall over! Even if they are travelling at speed it only takes a slight bump in the road or a gust of wind and they go off course and then fall over, unless someone is on board controlling it with small (or large!) inputs to keep it going where they want it.

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Even with a human on board you still need forward movement for the bike to help you keep it stable. Unless you are one who can balance stationary for an hour. Not me.

Let's just say for academic purposes that motorcycles were inherently unstable, how often would you see kids standing on the gas tank?
Okay, bad example. They would anyway.
Bikes are inherently stable which is why you have to force it to make a turn. Take your hands off the bars and the bike won't care. Hit a bump, it'll bounce, maybe change course a bit, but it's still stable. The rider maybe knocked off, but the bike obeys the laws of nature.

Around 1989 I used to run some radio control motorcycles (1/12th scale) that were pretty darn stable with no rider on board. We did try to keep them from going off course, but we did it for fun and it cost more money to fix them then I wanted to spend.
Here's some newer generations (gas vs electric): [video=youtube_share;ZwMY1ODNJB0]https://youtu.be/ZwMY1ODNJB0[/video]

But you have never seen ghost rider bikes? As long as there is rake and trail a front wheel will stabilize itself. Physics takes care of it all, from steering angle to lean.
Going on or off road with a full size bike does not matter. It takes more then a little bump or gust of wind if the clutch is released and it's in gear.

[video=youtube_share;KSVgweZ8BwA]https://youtu.be/KSVgweZ8BwA[/video]

[video=youtube_share;wwQUkHize8k]https://youtu.be/wwQUkHize8k[/video]

[video=youtube_share;KEGihH-Mo50]https://youtu.be/KEGihH-Mo50[/video]

The RC bikes are amazing, I've never seen them before! I once fancied having a go at RC aircraft until I realised that I would never be able to afford to rebuild them after every crash, ha ha.

I'm not being argumentative for the sake of it, I can see what you are getting at but in those videos where the motorcycle doesn't have steering input they all go randomly out of control. Turning in various directions and the vast majority going into a fairly serious tank slapper. The speedway bike was violently out of control even if it was still up on it's two wheels.

If you get out of a four wheel vehicle whilst moving, it will generally continue on a straight line until it hits something and stops, probably still on it's four wheels, unless there is a high speed collision. It won't attempt to turn as it slows down, which a motorcycle will - as demonstrated in the video.

I think we can both agree that it is a very complex system with lots of variables that affect the handling of any motorcycle, as shown in the videos you have posted.

I am no engineer and cannot speak with any authority about wobbles and weaves but I am surprised that the issues revealed in this article do not seem to enter into discussions about the st1300 handling issues more frequently. This 2012 article has been posted on st-owners before and many of you have seen it but I felt it worthy of re-posting given the subject of this thread.

excerpt from an article about Dave Hancock, head of product planning and business development at Honda Motor Europe:

"Hancock, who did development riding for the bike, knew about this weave. The day before the world press launch in France, he called the European national sales manager and expressed his concern that since work was still being done to resolve the stability issue, it might not be a good idea to let journalists ride the bikes, telling his European counterpart, “If they ride it on the road they’ll all complain about the stability.”Hancock was told it was too late to do anything about it, and was even accused of being “too critical”. The following day he got a phone call telling him he was right, and that every journalist who had ridden the machine had complained about its instability. The solution was specific to each individual bike and required shimming the swingarm pivot bearings and then take it out and test ride it to make sure the weave was corrected. Every ST1300 produced since has been test-ridden before leaving the factory"

The article can be found here:

http://canadamotoguide.com/2012/11/16/interview-dave-hancock-head-of-product-planning-and-business-development-honda-motor-europe/

The article does not mention if the engineers experimented with a CT to see if it exacerbated (or alleviated) the problem

beeker said:

The solution was specific to each individual bike and required shimming the swingarm pivot bearings and then take it out and test ride it to make sure the weave was corrected. Every ST1300 produced since has been test-ridden before leaving the factory

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There is a problem in the article.

So if every ST1300 was test ridden before going to dealerships, it follows that a new ST1300 would have a few miles/kms on the odometer. Unless they test them without the gauges connected.