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I'm workin' on it....
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Discussion Starter · #1 ·
I've got an '07 Orca and am having a horrible front end shimmy problem with it. It happens pretty much any time I go over 35mph. It feels like it's starting around the fork or head tube. I do the "lock your knees on the top tube" trick, and it does help, but I want it to not happen at all. I've done a bunch of research on the archives of RBR , and also read Zinn's stuff on Velo News. I am aware of all the riding form stuff, and have been very careful about that-keeping my hands loose in the drops, weight forward enough (I just had a professional fitting done). I don't think it's road surface or wind related. I've experienced it on really smooth roads and bad ones too, and windy and calm days. I'm becoming convinced it's the bike. On Zinn's Velo News site, he quoted Craig Calfee as saying that the fork can be the culprit if it's not perfectly straight (as in; the dropouts are not aligned perfectly). The other typical equipment suspects such as the front wheel hub and spoke tension, and headset have been checked. Anybody have any advice? I love the bike, but I didn't buy it to keep it under 35mph. This is really stressing me out-any help would be great.
 

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Wheels OK? Skewers locked down properly? I've got to say, the high speed stability is a trademark of Orbeas. So something must be seriously wrong with yours. Maybe you can break out the tape measure and see if everything is the same. Has it always done this?
 

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I'm workin' on it....
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255 Posts
Discussion Starter · #3 ·
Wheels and skewers seem fine. Pretty much every time I've had the bike over 35mph it does this. I am going to try a few different things; I might try to ride another Orca and see if it happens on a different bike, and I may start to switch out parts one by one and see if I can get it to not happen. I may also try to get someone else to ride my bike fast and see if it happens to them, in another attempt to see if it's me or not.
 

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Tire pressure?

You didn't mention anything about tire pressure. If it is too low you may experience tire flex or squirm that would cause the front end to wobble at speed. I have the same bike and it's rock solid up to 44 mph -(according to my Garmin Edge)- the highest speed I've seen on it so far.
 

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Batteries not required
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Arginine said:
I've run Michelin Pro Race 2's and Conti Force/Attack, both sets at 100psi. Do you recommend going higher?
100 psi is probably fine but it wouldn't hurt to experiment. Try increasing the pressure in increments of 10 psi up to the max recommend by the manufacturer and see what happens. I'm sure your tires can hold more that 100 psi. I have Vittoria Rubino slicks and run 120 psi with no shimmy at all.

Someone else mentioned that their rear wheel was not completely aligned in the drop outs and was causing the front end to feel unstable. You may want to check that too. It seems like you've checked out every thing in the front already.

I hope you get it fixed. Good luck.
 

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I'm workin' on it....
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255 Posts
Discussion Starter · #11 ·
No. I was due to try a different set of wheels, to see if that would fix it, when I had what I thought was a minor crash on my commute. I had the shimmy thing happen on a hill, and I had scrubbed most of the speed off, and was watching the front end instead of the road, and I hit a soda bottle that was in the bike lane. I went down fast, but it was a pretty slow speed crash-under 20mph. I got a little scraped up, but nothing serious. Bike is fine, except for the dime sized dent in the top tube. Don't really know what it hit exactly; maybe a rock or something on the ground. In any event, the frame is toast.
I'm going to take advantage of Orbea's crash replacement policy to buy another Orca frame at somewhat of a discount. I'll report back when I get the new frame set up and rolling. I've been agonizing over changing to another manufacturer, but, other than the shimmy thing, I've really liked the Orca frame. So I'm gonna get another one and see what happens.
 

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For what it's worth, I have an 05 Mitis, and I'm not exactly thrilled by the front-end stiffness, but the only time I've picked up a genuine speed wobble was sitting up with my hands off the handlebars.

That said, I can easily INDUCE one if I wiggle the bars back and forth too quickly; if you have a death grip on the bars, or you have too much weight on the front that is fatiguing your arms, that could also cause such a problem.

I think. Good luck!
 
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