The dreaded shimmy

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glasgowcyclist

Charming but somewhat feckless
Location
Scotland
@Yellow Saddle Have you seen this Road.cc article?

Cyclist's death descending from Mow Cop could have been due to speed shimmy

Mooney had been descending from Mow Cop and his bike computer revealed that he had been travelling at about 30mph at the time of the crash.
Mooney's wife, Jennifer, said he had cycled on that road many times before and data revealed that he had ridden the stretch at similar speeds without any problems.

A passing motorist, Mark Hyde, said that he had been driving home from work shortly before 6pm when Mooney had come around the corner near the middle of the road.
He said that he had appeared to be wobbling on his bike “as though he was losing control and trying to get back to his side of the road”.
He said Mooney left the road on his bike and went into the verge where he hit something. The bike stopped and Mooney went over the handlebars into a tree.

Hyde said there didn’t appear to be anything in the road that would have been an obstacle or distraction to Mooney and added that he thought the cyclist had been trying to regain control of his bike before he’d come into view.

PC Rob Wilson, a collision investigator from Cheshire Police, suggested that Mooney could have been suffering from the effects of a “high speed shimmy”.
 
Location
Loch side.
@Yellow Saddle Have you seen this Road.cc article?

Cyclist's death descending from Mow Cop could have been due to speed shimmy

Mooney had been descending from Mow Cop and his bike computer revealed that he had been travelling at about 30mph at the time of the crash.
Mooney's wife, Jennifer, said he had cycled on that road many times before and data revealed that he had ridden the stretch at similar speeds without any problems.

A passing motorist, Mark Hyde, said that he had been driving home from work shortly before 6pm when Mooney had come around the corner near the middle of the road.
He said that he had appeared to be wobbling on his bike “as though he was losing control and trying to get back to his side of the road”.
He said Mooney left the road on his bike and went into the verge where he hit something. The bike stopped and Mooney went over the handlebars into a tree.

Hyde said there didn’t appear to be anything in the road that would have been an obstacle or distraction to Mooney and added that he thought the cyclist had been trying to regain control of his bike before he’d come into view.

PC Rob Wilson, a collision investigator from Cheshire Police, suggested that Mooney could have been suffering from the effects of a “high speed shimmy”.

No I haven't. Thanks for thinking of me (and death by shimmy in the same post).

It illustrates just how dangerous it is. This poor guy shimmied at the wrong time in the wrong place and went right into a tree. I like to practice my shimmy-recovery from time to time but really hope I never have to test it where I cannot veer off safely and come to a stop or safe sub-shimmy speed.
It is a pity the cop called it "high speed" shimmy. This no doubt has connotations of reckless riding or dangerous bicycles. I'm sure the guy just did what we all do.
 

ColinJ

Puzzle game procrastinator!
It is a pity the cop called it "high speed" shimmy. This no doubt has connotations of reckless riding or dangerous bicycles. I'm sure the guy just did what we all do.
I was thinking the same thing - 30 mph is not 'high speed'. There might be times when it is too fast but on most descents you would easily do that speed without even pedalling.

I just found THIS where a maths professor suggests that shimmy is NOT a resonance phenomenon, but an example of 'Hopf Bifurcation'!
 

Scoosh

Velocouchiste
Moderator
Location
Edinburgh
For those in the younger age bracket ...
3036.jpg
 

ColinJ

Puzzle game procrastinator!
And the other half of us are keeping quiet so we don't give away how old we are!
Speaking of which ... Dixon always looked like he should have retired about 30 years before he featured in the show! Dixon (actor Jack Warner) must have been near enough 80 but he was still walking the beat ... [I just looked it up - he walked the beat into his late 70s but was a desk sergeant until he was 81! :laugh]
 

Dirk

If 6 Was 9
Location
Watchet
...Truth is, counter-steering happens automatically. This is easily proven by riding no-hands. Yes, when you lean into a corner, the steering briefly swivels to the opposite direction, the bike leans, the steering returns and overshoots (the centre) and leans in towards the corner. This all happens without you knowing that it even happens or without you even thinking about it.

That's why I say the whole lore of counter-steering is BS.

I'm assuming that you've never been in a motorcycle road race and had to negotiate a quick 'flip flop' chicane?
 

nickyboy

Norven Mankey
I think I need to have a go at @Yellow Saddle "shimmy inducement" method mentioned upthread to understand better how to alleviate it.

On the one occasion it happened to me of course I gripped the bars even tighter, probably accentuating the shimmy. As a result all I could do was continue in a straight line, braking furiously. I ended up on the other side of the road and, had something been coming the other way, I suspect all I could have done was jump off and hope for the best, which isn't a great strategy
 
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