RoadBikeReview.com's Forum Archives - General


Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )


No hands = front end shimmy(15 posts)

No hands = front end shimmylaffeaux
Oct 30, 2002 1:49 PM
Yesterday I tired riding with no hands on my morning commute. I do it often on my MTB, but I guess I never have on my road bike. Anyway, when I sat upright the front wheel starts to shimmy back and forth, and after 3-5 seconds got to the point where it was nearing uncontrollable. I tried several times with the same effect.

I checked the headset and front hub, and both seem tight. Any ideas what causes this? Again, I have no trouble riding hands-free on a MTB.
re: No hands = front end shimmyNo_sprint
Oct 30, 2002 2:01 PM
That is pretty much standard procedure if you're a real tall person on a tall bike going pretty fast. If you're not any that, it shouldn't be happening. Also happens more with less stiff bikes. I recently saw Zinn make a Litespeed Ultimate wobble a bunch!
6'0" on a 59cm frame (nm)laffeaux
Oct 30, 2002 2:10 PM
I also saw that...Bruno
Oct 30, 2002 2:54 PM
and he mentioned that it shouldn't happen. I'm 6'3" and have no shimmy while riding without hands which I enjoy and do frequently. I have no idea what can cause shimmy. I ride an entry level specialized that has a very stiff frame but a soft CF fork.

P.S. Have you ever tried to steer a car with your knees?
Try it one more time. (nm)onespeed
Oct 30, 2002 2:06 PM
Pitted headset? Headset too tight?SnowBlind
Oct 30, 2002 2:25 PM
Headset too tight can cause this, quickly becomes pitted too.
Unbalenced rims, oddly worn tires, can do this as well, just like a car.
This topic came up a couple of years back ...Humma Hah
Oct 30, 2002 2:27 PM
... and one rider reported correcting the problem by balancing the front wheel. Evidently you roadies with your wussy little featherweight wheels can get out of balance, side-to-side, by such insignificant things as having your cyclocomputer magnet located close to your stem.

This has never been a problem on the Schwinn cruiser, which can be ridden for miles at a time, no-hands, uphill, thru turns, taking jackets and backpacks on and off .... Has something to do with a front wheel and tire weighing 7 pounds, I guess.
also...dave woof
Oct 30, 2002 3:37 PM
the frame could be out of alignment side to side - do the string check ... or one wheel could be skewed a bit in the drops, or the drops out of alignment. I had a Colnago that did that - wasn't the wheels or headset

Dave Woof
re: No hands = front end shimmyHeron Todd
Oct 30, 2002 3:43 PM
Read the shimmy FAQ:

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

Todd Kuzma
Heron Bicycles
LaSalle, IL 815-223-1776
http://www.heronbicycles.com
Thanks for that linkBreakfast
Oct 30, 2002 9:36 PM
I once heard a Giant dealer make the comment that Giant builds their high-end road bikes so well that they don't shimmy. Then I knew it was B.S., all bikes are subject to these forces and Giant or any other maker is not exempt. I never believed that the best, most perfectly aligned, adjusted, and wheel balanced bicycle could avoid the oscillation because of the variables involved. I got shimmy only at a certain speed range on slightly downhill sections when my hands were off the bars. The info on the link page only confirms my idea of this phenomenon.
thankslaffeaux
Oct 30, 2002 11:12 PM
The article makes me feel better. The shimmy on my bike was worse while traveling down a small hill. I'll try to lean my knee against the top tube and see if it goes away.
re: No hands = front end shimmyMariowannabe
Oct 30, 2002 7:15 PM
I had the same experience on a previous bike of mine, and it got worse after I added a tri-bar extension. It was a popular bike with a crit geometry. The bike would also shimmy when desending at speeds over 44 m.p.h.- with my hands on the bars. Scary!!
look momFrith
Oct 30, 2002 8:04 PM
mountain bikes are definitely alot easier to ride no hands. A couple of months ago i wowed myself by taking off my backpack, opening it up pulling out a fresh t-shirt changing into it and putting away the sweaty one, zipping up and putting the backpack back on, all without getting off the bike or touching the hanlebars.
re: No hands = front end shimmydivve
Oct 31, 2002 4:10 AM
In hindsight the cause of the shimmy on my bike was rather obvious. I solved the problem by truing my front wheel, even though it was well with-in spec. I guess it was just an unfortunate combination of the wheel being slightly out of true, in addition to the always present in-balance of tires.
re: No hands = front end shimmyxxl
Oct 31, 2002 7:30 AM
Glad to see you caught your problem. I had a similar situation, and was going to suggest true/dish (since you'd mentioned the usual suspects in your initial post). I'd have also looked at the alignment of the dropouts (as well as the frame alignment), esp. if your shimmy got worsened at speed.

In my case, I drove myself half-crazy, trying to fix the problem, until I discovered the "self-dishing feature" (and any of my wheels, natch) of my truing stand was off a few mms.