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Old 09-18-06, 12:28 PM   #1
cyclintom
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Wobbles in Touring Bikes

It is pretty difficult to load a bike down with all of your touring gear and not have some wobbles in different speed regimes. Here are some ideas to eliminate or limit them:

1) Most really big wobbles are caused by the front wheel being crooked in the drop outs. This is something pretty easy to overlook since unloaded the bike handles fine and that tends to make you think that the problem is elsewhere.

2) Front racks must be centered over the front axle. If you allow your low riders to be rotated to the rear this will offset the weight behind the point of rotation of the front steering and the trail of the bike and the offseting weights will cause a wobble.

3) You can also get a wobble from unequal weights in the front panniers. Always try to equalize the loads from side to side.

Remember that all of this is assuming that the bike doesn't have any wobbles unloaded.

You can pretty much ignore slight wobbles as occur on most touring bikes between certain speeds as long as they never get out of hand and if they disappear as the bike moves through their particular speed.

If you were to build a bicycle that was so stiff that these wobbles didn't occur it would probably be too heavy for normal use. So you are pretty much stuck with at least some hint of wobbles. Strangely enough, some older steel tourers that feel as limp as a noodle often are the most stable bikes.

And of course you can also get wobbles caused because your panniers or rack loads are loose and swinging about.
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Old 09-18-06, 04:40 PM   #2
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I've also seen a case of speed wobbles from the rider holding the handlebars with a death grip. Loosening their hold on the handlebars fixed the speed wobble.
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Old 09-22-06, 02:03 PM   #3
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Quote:
Originally Posted by cyclintom
It is pretty difficult to load a bike down with all of your touring gear and not have some wobbles in different speed regimes. Here are some ideas to eliminate or limit them:
Missing from your list:

4) If the wheels are not perfectly in line and centered in the frame, wobbles will occur, and more so with increased loads. Bikes with horizontal dropouts are particularly susceptible to this. It is usually enough to adjust the rear wheel carefully so that it is exactly centered between the chainstays. If the wobbles persist, the frame and/or the fork may be out of alignment.
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Old 09-22-06, 03:44 PM   #4
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Originally Posted by Lotum
Missing from your list:

4) If the wheels are not perfectly in line and centered in the frame, wobbles will occur, and more so with increased loads. Bikes with horizontal dropouts are particularly susceptible to this. It is usually enough to adjust the rear wheel carefully so that it is exactly centered between the chainstays. If the wobbles persist, the frame and/or the fork may be out of alignment.
I'll take that under advisement. On an unloaded road bike misalignment of the REAR wheel doesn't cause any problems at all. I made a guy a Bianchi which had one chain stay almost a cm shorter than the other putting the rear wheel strongly out of alignment with the front and the only problem it caused was that the rider couldn't ride with no hands.

Of course loading a bike down makes a lot of difference.
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Old 09-22-06, 08:31 PM   #5
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It seems from the photos that the excellent Gordon low rack is not centered, and is actually to the rear of the axle. The ability to move weight around within the panier can make up for it's initial position. It does seem as though the more stable position would be behind the bolt, otherwise the bike itself would not be properly ballanced.

I also got rid of a front rack shimmy by getting rid of the perfect ballance with which I had initailly packed the paniers. What might really have been happening was an alteration in fore and aft loading, but either way ballance, within reason, is not all that big a deal.
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Old 09-29-06, 02:39 AM   #6
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Here is an interesting rack. the weight is placed well back on the front wheel and is claimed to allow hands free riding:

http://www.sandsmachine.com/a_arv_r1.htm
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