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My front wheel wobbles at high speed and it's scary!

post #1 of 7
Thread Starter 
Is this normal? I've always enjoyed riding downhills pretty fast, but when I tried it on my new and first road bike (Specialized Allez Pro), the front seemed to wobble. I'm not sure how else to explain it.

I don't have a computer, but I was probably going 30 to 40. I was so scared that I had to slow down a little. Does this happen to anyone else? I must admit that my bike can get going pretty darn fast without much effort on level ground. This was my first long downhill on this bike and as much as I was looking forward to it, it kinda scared me.
post #2 of 7

Re: My front wheel wobbles at high speed and it's scary!

Quote:
Originally posted by wolfgang
Is this normal? I've always enjoyed riding downhills pretty fast, but when I tried it on my new and first road bike (Specialized Allez Pro), the front seemed to wobble. I'm not sure how else to explain it.

I don't have a computer, but I was probably going 30 to 40. I was so scared that I had to slow down a little. Does this happen to anyone else? I must admit that my bike can get going pretty darn fast without much effort on level ground. This was my first long downhill on this bike and as much as I was looking forward to it, it kinda scared me.
High Speed wobble is not unusual, but it can often be minimized by holding the top tube between your knees. You are experiencing a physical oscillation.
Check to make sure that hub bearings, headset, and everything is properly adjusted. Also try unweighting the saddle a little.
The experience can be scary. Normal human response is to hold the handlebar tighter, but this usually makes it worse.
post #3 of 7

Re: My front wheel wobbles at high speed and it's scary!

Quote:
Originally posted by wolfgang
Is this normal? I've always enjoyed riding downhills pretty fast, but when I tried it on my new and first road bike (Specialized Allez Pro), the front seemed to wobble. I'm not sure how else to explain it.

I don't have a computer, but I was probably going 30 to 40. I was so scared that I had to slow down a little. Does this happen to anyone else? I must admit that my bike can get going pretty darn fast without much effort on level ground. This was my first long downhill on this bike and as much as I was looking forward to it, it kinda scared me.
I've always wondered if this is a balance problem involving the unsymmetrical weight distribution of cheap tires, tubes, and the valve stem.

I wonder if taping some weights on the opposite side of the valve stem would help.
post #4 of 7

Re: Re: My front wheel wobbles at high speed and it's scary!

Quote:
Originally posted by Mr_Potatohead
I've always wondered if this is a balance problem involving the unsymmetrical weight distribution of cheap tires, tubes, and the valve stem.

I wonder if taping some weights on the opposite side of the valve stem would help.

I'd take a new bike back to the dealer and complain....no reason a new road bike should wobble at 30-40 mph.

Agree tires/wheels with a wobble (lateral runout) could be a source of the problem. If the tire isn't built straight, or if the bead isn't seated correctly on the rim, that would do it.

I don't think high-speed wobble is caused by unbalanced wheels, but I like to balance them anyway to make the bike smoother at high speed. If you spin up the rear wheel on a stand to a decent speed, and the bike starts hopping vertically, you may want to add balance weight. The Velomax wheels I've got now were a good bit heavier opposite the valve stem, due to the rim splice there.

I balanced them just by wrapping wire solder on the spoke next to the valve stem. Wrap on just enough weight to stop the high-speed hop.

Of course, adding weight to the rim will make the wheel a bit slower to spin up, but eliminating the high-speed vertical bounce should make the bike faster downhill, as well as giving better roadholding and a smoother ride.
post #5 of 7
I'm an inline (skate) racer who recently started riding. Speed wobble is a common problem on skates at high speed. One thing we do to reduce the problem is to keep our weight back on our heels during fast descents.

On my bike, I found that I'm able to induce speed wobble by bringing my weight forward. It was an experiment and once is enough.

To stop the speed wobble, you may try sitting back further or even going behind the seat a little.
post #6 of 7
My old trek wobbled above 40mph on tighter turns. When I tweaked the rear wheel on some railroad tracks and bought a Cosmos wheelset, the wobble went away. After I did a lace-over on the old wheelset with a new rim, I took both wheels in and had them retensioned. It cost me $10 a wheel, but 80-90% of the wobble disappeared. If it's a new bike and there is a good wheelbuilder working there, it might pay to ask.
post #7 of 7
Hi speed wobble during decent is all too common and there are a variety of causes. The culprit - assuming you have perfectly good wheels and a good bike (meaning there is nothing wrong with your frame, fork and alike) - is the gyroscopic effect of the front wheel with an unstable steerer like what we have on our bikes.

Motorcylces are also prone to high speed wobbles but nowadays they are equipped with a steering damper. But dont fret cause there's a remedy or two that you can try and it's used by pros when they encounter such. Try these:

1) Relax your grip on the handlebars as well as your arms and support your torso with you back instead of your arms. or...

2) If the above does not work, try gripping the top tube with your knees.

Most often one of the above will fix the problem.
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