twentysomething

Have a new Trek Madone 4.5. Took it for a ride and it started shimmying (?) on downhills.

Hopefully, this doesn't sound too weird.

I looked at it later and the front wheel seems like it is 'out of round'. When I spin the wheel, it doesn't rub the brake pads, so it seems true from that standpoint. But its like it is weighted more on one side.

Does this make sense and does anyone know what it might be?

Jeff Wills

Consult the gurus: https://sheldonbrown.com/brandt/shimmy.html

reddog3

Tighten up that QR skewer.

wmodavis

If the wheel 'seems' like it is 'out of round', have you done anything about it? Don't know if it has anything to do with the shimmy problem but 'out of round' is easily verified by measurement and likewise easily corrected by proper wheel truing techniques.

twentysomething

Have not done anything about it. Just noticed the problem last night. I'm guessing whenever it was true'd, one side of the wheel was tightened too much?

jimc101

New bike, take it back to the shop, they can check it better than a guess on here with no one being able to see it.

wrk101

+1 You pay a premium for a new bike, part of that premium goes towards addressing/solving problems like this.

fietsbob

+ 1 + here, that is anything, for 6 months, as needed, that is even the modest priced bikes.

gmt13

And don't let them tell you that "they all do that"

twentysomething

I know. Not an issue (don't think) taking it back to adjust. Just a pain in the you-know-what, particularly since I'm not sure I'm keeping the bike or not but that's another forum.
Thanks guys.

cranky old road 

Perhaps the tire is poorly mounted or defective?

FastJake

Almost sounds to me like the wheel was not properly mounted. Loosen up the QR, and when you install the wheel make sure the bike is on its wheels so the weight of the bike is pushing the front wheel into proper position. If it's not centered at that point, you have a problem.

You know how to properly tighten a QR skewer, right? (Not trying to insult your intelligence if you do, but lots of people don't.)

gmt13

This is probably the first thing that I would check. My guess, though, is that if you have an out-of-round wheel, you would notice it at slower speeds as well. How fast were you going down hill when this happens? If you sit back in the saddle going downhill, the weight on the front wheel is reduced. This tends to enhance the effect. Does the headset seem to be adjusted right?

-G

Trakhak

By "out of round," do you mean that the wheel is vertically out of true (i.e., that the rim seems to move up and down when viewed at the brake pads while spinning)? Or do you mean that the wheel is unbalanced in terms of weight distribution around the rim?

BikeWise1

These bikes generally ride exceptionally well. I would treat this as a safety issue and get it dealt with. In order of liklihood: wheel(s) not seated and fully secured in dropouts, front wheel spoke tension not optimal, tire pressure too high, something actually broken somewhere. Don't mess around with this! Get it fixed. It's what warranties are for.

mconlonx

Out of true, radially. Wheel truing side to side is lateral truing -- getting a wheel round is radial truing.

Have the shop where you bought it fix it or replace it under warranty. Otherwise, you'll be passing the problem along to a second owner, who will have no warranty recourse and it will be on them to have it fixed...

Nerull

The side which seems to have 'more weight' wouldn't happen to be the side with the valve, would it?

Death wobble on downhills can be caused by a lot of things other than wheels.

ScottieDog

I'd be interested to know the "proper procedure". Just incase. Lol

ScottieDog

That's very interesting information. Thanks for the link Jeff.