Classic & Vintage - Front end vibration...out of the blue.

I was on a group ride with my Maza Prestige (TSX tubing). At one point, we were doing about 24MPH on the flats and the front end of my bike started resonating. I could hear it and feel it in the bars. It only lasted about 20 seconds. We slowed down for a road hazzard and it stopped, and never returned. I have over 50K miles on this bike and this is the first time I've ever experienced this. I checked the frame, fork, wheel and headset and found nothing wrong. The only difference with the bike is: I usally use Vittoria Rubino Pros, but I put Open Corsas on about a week ago. Was this just a case of the right speed on the right road surface? Or, is there something I should be watching out for?

are the tyres out of true-when you spin them can you see anything odd?

Picked up a piece of gum or road tar on the back tire - it rubbed itself off after a while.... ?

I think, if it were me, I would dismount the tire and tube and inspect both closely. While I was at it, I'd put the wheel on the truing stand and give it a once over as well. Could have been a fluke of harmonics, but then, I'd hate to be riding along at speed and have a catastrophe. You know what they say about an ounce of prevention !!


Ive ridden a lot on Rubino Pros and never had a problem. Have not tried the Corsas.

Good luck and let us know if you find the glitch.

Joe

This kind of thing is hard to diagnose, especially if you can't repeat it. Possibly you were just going over a section of pavement that had a slightly washboarded surface, in which case the only way to replicate would be to ride the same section of road again. At the same speed, same tire pressure, etc.

I've had more than one bike shimmy one day and not shimmy the next day. Since most of my bikes don't have dropout adjusters of any kind, in such cases I have suspected the problem might be that I've installed the rear wheel at a slight angle to the natural angle of the fork; so the solution might be to redish the wheel... how much, and which direction, to be guessed. I hate that, 'cuz I'm not a gambler.

Then again, Southpawboston recently told me that he had traced a front end shimmy to a loosely mounted saddle bag. Oy.

Good luck! And if this post helps not at all, my apologies.

I've had a similar sensation from a brake rubbing at low speed. I don't know that it would apply at high speed.

Possibly high-speed shimmy.

-Kurt

Make sure wheel is squarely in the dropouts. Put it on the ground, then tighten QR.

This is a common and scary problem. Next time it happens, put a knee against the top tube to dampen the vibration. Unexpected culprits can include a mis-dished or misaligned rear wheel.

Was it vibration or shimmy? If the answer is vibration, have you checked to make sure the headset hasn't loosened a little bit?

That has happened to me a few times, when cranking hard in top gear and later down a fast decent (full on speed wobble). One time it was the headset, another the front tire/wheel slightly out of true, lead to uneven wear. Something is not right there.

Pb

This type of thing is usually caused by the curvature of the earth combined with the Coriolis effect.

Don't be alarmed.

If it happens again and you don't believe in science you can get a St. Christopher statue to glue on the top-tube. That will stop if if you have enough Faith. If you are not Catholic, and instead follow one of the pagan traditions, you can try a Gremlin Bell (http://www.gremlinbells.com/) instead.

This type of thing is usually caused by the curvature of the earth combined with the Coriolis effect.

Don't be alarmed.

If it happens again and you don't believe in science you can get a St. Christopher statue to glue on the top-tube. That will stop if if you have enough Faith. If you are not Catholic, and instead follow one of the pagan traditions, you can try a Gremlin Bell (http://www.gremlinbells.com/) instead.

I actually wear a Madonna di Ghisallo medal at all times.

Well 200 more miles and I can't recreate it. I won't call it a shimmy. It felt more like riding over a steel-grated bridge, but front end only. Just weird.

Front brake got off center, was rubbing on a strange angle, and corrected itself when you hit the brakes.