Author Topic: Nomad shimmy  (Read 2398 times)

chauser

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Nomad shimmy
« on: March 17, 2006, 12:08:01 AM »
I have a Nomad, and it exhibits a disturbing shimmy on downhills.  I'm curious if others have experienced this and how they resolved it.

I first experienced it on a tour of NF a couple of years ago.  Bike was loaded w/ ft and rear panniers and a handlebar bag (camera +snacks).  I played w/ weight distribution and found no real solution.  Was using 1.5" tires at the time.

I experience it unloaded as well, and usually end up braking to control it.

Headset does not appear loose.
No frame damage.

Suggestions?

 

john28july

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Re: Nomad shimmy
« Reply #1 on: March 17, 2006, 10:12:07 AM »
You must have some kind of inbalance somewhere. I have owned a early horizontal top tube Nomad and now the Compact frame style. The bike is on rails downhill or anywhere. Something is in the wrong place with you/luggage or whatever.
John.
www.pbase.com/john28july

Eric

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Re: Nomad shimmy
« Reply #2 on: March 18, 2006, 08:23:13 AM »
It's just an imbalance thing. The old trick to stop it was to bring your knees in to touch the top tube, but that might be a trifle difficult on modern 'compact' frame designs. Try it.
 

chauser

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Re: Nomad shimmy
« Reply #3 on: March 18, 2006, 04:25:28 PM »
John,

Do you have any suggestions how to identify/locate the source of the 'imbalance'.

I can send pics of bike, me on bike if helpful.

thanks
charles


quote:
Originally posted by john28july

You must have some kind of inbalance somewhere. I have owned a early horizontal top tube Nomad and now the Compact frame style. The bike is on rails downhill or anywhere. Something is in the wrong place with you/luggage or whatever.
John.
www.pbase.com/john28july


 

john28july

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Re: Nomad shimmy
« Reply #4 on: March 19, 2006, 10:36:59 AM »
As I think that the Nomad runs on rails, I guess you must be 'Top heavy' or something like this. Such as leaning very heavily on the bars (drop?) going fast downhill. Otherwise I find this a real mystery as in my own and I am certain, others experience, the Thorn Nomad is a heavy and very stable bike.
I hope this is at least of some help.
John.
www.pbase.com/john28july

stutho

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Re: Nomad shimmy
« Reply #5 on: March 20, 2006, 02:31:49 PM »
Have the forks being replaced at any point?  Sounds like you may nead more trail / less rake.

chauser

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Re: Nomad shimmy
« Reply #6 on: March 20, 2006, 10:53:11 PM »
Thanks,

You may be on to something: I am taller from the waist up than from the waist down, and probably do put more weight on the bars.  Not sure how to address this.  I'll experiment this weekend.

Charles


quote:


I guess you must be 'Top heavy' or something like this. Such as leaning very heavily on the bars (drop?) going fast downhill.

 

john28july

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Re: Nomad shimmy
« Reply #7 on: March 21, 2006, 10:06:43 AM »
Raise the bars!
John.
www.pbase.com/john28july

stutho

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Re: Nomad shimmy
« Reply #8 on: March 21, 2006, 10:30:37 AM »
If you are convinced that there is too much weight on the bars try checking you saddle position.  Too far forward and you will place more weight on the bars and hurt your knees. Too far back and you will be 'pulling' on the bars and still hurt your knees.  (NB Saddle position should be set relative to the BB NOT the bars)

If saddle is in the correct position then you need to change the height / reach of the bars probably by changing the stem.