shimmy

[niggle]

I can remember my fat auntie running down the street in her apron holding onto the saddle of my new bike on my birthday, just before my friends arrived for my party!

LOL, I remember the motivation for learning to ride was the promise of a new bike on my seventh birthday (which makes it September 1970 actually) and then seeing my first proper bicycle all wrapped up in the hallway with shiny bits sticking out. It was a Dawes Kingpin Junior in gold (without a hinge in the middle) and was totally indestructible and incredible quality for a kids bike, with Weinmann alloy brakes for instance, plus the frame design meant it fitted for ages until I got my next bike, a green Raleigh Hustler 3-speed with drops. It must mean something that these are the only childhood birthday presents that I remember much about....

[MikewsMITH2]

Hi Niggle,
I was 7 too. (in 1958) Mine was a "Hercules Jeep". A miniature version of the Raleigh All steel (which my dad reckoned was the only bike worth having), 24" wheels, single speed with roller lever brakes and a tiny saddlebag with a toolkit. It was dark red. I was rather annoyed that my sister got a new bike too as it wasn't even her birthday! Hers was my next bike until I got my Sun Snipe racer for passing my 11 plus... Never experienced the shimmy though!

[Phil_Lee]

*Thank you for this one,I can not remember if my arms were locked or not, but I did have a stiff sholder from a fall on the ice a month or so back, and i did wonder if this was affecting my grip maybe. The rest fits too, jolts from the road and such like. I had gone over the bike a few times and found nothing, so me being the cause was a good chance, and I like the thought that our two groups, cyclists/motor cyclists have a lot in common. Long may your wheels turn and the wind be at your back eddie

I had it happen after coming over the top of a hill on a coolish day, after a hard climb.
The wind speed cooled me rather more effectively than was entirely good, and I started shivering.
The knee on the top tube saved me there too, along with consciously relaxing.
From motorcycling I can say that tyre pressures, tyre wear, and load distribution can make a huge difference to susceptibility.

A very similar phenomenon happens to novice pilots, when trying to hold a steady airspeed/altitude (particularly if you haven't learned to trim the aircraft properly); It's known as PIO - Pilot Induced Oscillation.
It also has a similar cure - relax your hand on the stick/yoke.

[DavidT]

I've had this happen once to me, about 5 or 6 years ago. Most terrifying thing I've ever experienced on a bike. 40mph+. Not good.

Researched what the hell had happened afterwards. Thanks to Chris Juden at that time.

I can only reiterate what has already been said. Remove effect by damping with thigh against crossbar.

I lost descending confidence big time after this incident. Learning to relax the grip and just let the bike go is the best bet, and something I've really been working on to get speeds up again. The "Death grip" referred to above certainly just seems to make things worse - psychologically if not actually physically! Holding on for dear life, tense as anything, waiting for it to happen! Self fulfilling prophesy?

[eddie]

[quote][/quote]I lost descending confidence big time after this incident. Learning to relax the grip and just let the bike go is the best bet, and something I've really been working on to get speeds up again. The "Death grip" referred to above certainly just seems to make things worse - psychologically if not actually physically! Holding on for dear life, tense as anything, waiting for it to happen! Self fulfilling prophesy?
Hi David know just where your coming from,but at least were still here, and have learned from it, hope this all helps others out there too eddie

[PW]

I've only experienced it twice. On a 531C tourer, when I fitted low rider front panniers, it went away as soon as the rack was replaced by an old fashioned high one, and years later on the same bike, when it turned out that the downtube had developed a fatigue crack across the headtube lug.