Mar 13, 2002 9:24 AM
|I have a friend riding an old lemond 59cm steel frame, Campi hubs, and a carbon fork (cant remember what type). I've checked to see if there is any play in the headset or hubs and I couldn't feel any. This is the second time he's had this problem, the first time he was riding a pair of Spinergys and replaced this wheel set with a campi wheelset. He says that the problem starts out at around 30 mph start out kinda slow and then gets worse. He's a pretty big guy, 6'1", 189 lbs. I am wondering if there is anything i have overlooked or what can be done to fix this problem.|
|re: Speed Wobbles||ksfacinelli|
Mar 13, 2002 9:37 AM
|Where the tires the same both times?? I have heard of high speed wobbles with Axial Pros but never experienced this issue. Just an idea.|
Mar 13, 2002 10:59 AM
|It's my belief that all two wheeled bicycles and motorcycles have this inherent ability to exhibit front wheel wobbble at certain speeds when you let go of handlebars.
I've heard several theories why but my experience has been that your body position sometimes influences the degree or the possibility of wheel wobble. For example, if you're sitting upright pedaling with hands off the bars usually the bike tracks very well but try coasting at higher speeds on downhills where you can't sit up and the bike will wobble. Whether the bike is coasting or being driven has some effect, I believe.
Feeling a wobble when your hands are on the bars indicates a problem, wheel balance or headset adjustment, but hands off it's a common and incurable phenomenon.
|re: Speed Wobbles||rollo tommassi|
Mar 13, 2002 12:49 PM
|Check the frame - Did older LeMonds come with carbon or steel forks? If your friend bent the original steel fork, the head tube could be bent.
Also check to be sure that the steerer tube is not cracked at the crown.
Take it to a good shop and have them check the frame and fork.
|re: Speed Wobbles||Indiana Rider|
Mar 13, 2002 1:02 PM
|I'm still trying to go fast enough to get "speed wobble"|
|Clamp the top tube between your knees (nm)||Kerry|
Mar 13, 2002 6:04 PM
|re: Speed Wobbles||guido|
Mar 13, 2002 7:09 PM
|Yes, clamping the top tube between the knees is a sure way to absorb speed wobble. Also scoot back on the saddle. That takes weight off the front wheel and puts it over the rear. Short wheel based bikes do this more than long w-b bikes. Steep head angles and short trail also encourages wobble. But if the frame and fork are aligned, the headset is not too tight or brinneled, the wheel rims are round and true, no play in the hubs, and the rear wheel is in the same track as the front, only putting too much weight over the front wheel should induce wobble. A bicycle wheel stabilizes with speed, like a gyroscope. A large frame might induce wobble by flexing too much.
I think wobble can be eliminated, first by checking all the mechanical causes, then by positioning on the bike, fore-aft, relative to the front and rear wheels.