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Shimmy  

post #1 of 6
5/28/03 at 6:30pm
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When going fairly fast front wheel shimmies (wheel turns a bit left and = right fast back and forth)
when taking hands off handlebars. May be = dangerous at speed. What causes it and how can it be
fixed (other than = not taking hands off ;-) )? Thanks! --=20 Steve Juniper
(snijuniperremovethis@attbi.com)

"Invading Iraq to get rid of Saddam Hussein is like using a hand grenade = in a crowded schoolyard
to get rid of a bully."

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6.00.2800.1170" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=3D#ffffff>
<DIV>When going fairly fast front wheel shimmies (wheel turns a bit left = and=20 right fast back
and forth) when taking hands off handlebars. May be = dangerous at=20 speed. What causes it
and how can it be fixed (other than not taking = hands off=20 ;-) )?</DIV>
<DV>Thanks!<BR>-- <BR>Steve Juniper (<A=20
href=3D"mailto:snijuniperremovethis@attbi.com">snijuniperremovethis@attbi= .com</A>)</DIV>
<DVI>&nbsp;</DIV>
<DVII>"Invading Iraq to get rid of Saddam Hussein is like using a hand = grenade in=20 a crowded
schoolyard to get rid of a bully."<BR></DIV></BODY></HTML>

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post #2 of 6
5/28/03 at 7:00pm

Re: Shimmy

> Steve Juniper wrote:
>
> When going fairly fast front wheel shimmies (wheel turns a bit left and right fast back and forth)
> when taking hands off handlebars. May be dangerous at speed. What causes it and how can it be
> fixed (other than not taking hands off ;-) )? Thanks!
> --
> Steve Juniper (snijuniperremovethis@attbi.com)

First, please turn of the HTML. It is inappropriate for USENET.

Second, an answer to this question can be found in the FAQ
http://draco.acs.uci.edu/rbfaq/FAQ/8h.5.html
post #3 of 6
5/28/03 at 7:00pm

Re: Shimmy

Steve Juniper writes:

> When going fairly fast front wheel shimmies (wheel turns a bit left and right fast back and forth)
> when taking hands off handlebars. May be dangerous at speed. What causes it and how can it be
> fixed (other than not taking hands off.

http://draco.acs.uci.edu/rbfaq/FAQ/8h.5.html

Jobst Brandt jobst.brandt@stanfordalumni.org Palo Alto CA
post #4 of 6
5/28/03 at 8:00pm

Re: Shimmy

Many things can cause shimmy. Frame alignment (mis-alignment, actually), poor frame material, an out
of true wheel, Badly loaded panniers (if touring), loose bearings (either headset or wheels), even a
lopsided tire, etc. And/or any combination of the above.

Check these things, or have them checked, and corrected, where necessary.

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": http://www.geocities.com/czcorner
post #5 of 6
5/28/03 at 8:30pm

Re: Shimmy

> Many things can cause shimmy. Frame alignment (mis-alignment, actually),

You had it right the first time, in a peculiar sort of way. A frame that's perfectly aligned is more
likely to shimmy than one that's out of whack. The bike, by itself, desires to turn only in one
direction. You're constantly applying force to make it go straight, and damping out its desire to
shimmy. Much easier to create a shimmy in a system where the bike wants to turn in either direction
with little effort.

I'm sure Jobst can put it more accurately than that, but he probably won't be as nice.

--Mike-- Chain Reaction Bicycles www.ChainReaction.com

"Chris Zacho "The Wheelman"" <ChriszCorner@webtv.net> wrote in message
news:7482-3ED5371E-33@storefull-2353...wson.webtv.net...
> Many things can cause shimmy. Frame alignment (mis-alignment, actually), poor frame material, an
> out of true wheel, Badly loaded panniers (if touring), loose bearings (either headset or wheels),
> even a lopsided tire, etc. And/or any combination of the above.
>
> Check these things, or have them checked, and corrected, where necessary.
>
> May you have the wind at your back. And a really low gear for the hills! Chris
>
> Chris'Z Corner "The Website for the Common Bicyclist": http://www.geocities.com/czcorner
post #6 of 6
5/30/03 at 10:30am

Re: Shimmy

audaxrex snipes anonymously (in new English, no less):

> have i got this straight? you took a front wheel, checked to make sure it was out of dish, put it
> in a frame and fork you knew to be straight, took it up to a good speed - and had no problems?
> Think about it - if the front wheel is not tracking in the same line as the rear, it will try to
> pull so that it DOES track - yanking the fork over. Then the rear wheel goes back to where the
> frame wants it to track - and the front wheel tries to follow THAT - but then the rear... you see
> what I mean? SHIMMY SHIMMY SHAKE SHAKE. Ъ×

On bicycles that double track (leave two separate wet tracks after riding through a puddle) I found
no propensity to shimmy. The same goes for a front or rear wheel with a broken spoke (substantially
out of alignment). From what you say, and how you say it, I take it you are hypothesizing about all
this; common fare for wreck.bike.

"Think about it!"

Jobst Brandt jobst.brandt@stanfordalumni.org Palo Alto CA
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