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I have a trek Allant 7+. When I set the pre-load to minimum I got a terrible shimmy. It seems OK when pre-load is set to max. I weigh 195 lbs. Could the pre-load affect the shimmy like that? It is pretty scary when it happens, even as slow as 20 mph.

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    The current answer is based around wheel hub pre-load, but are you asking about the pre-load on the fork? some forks have this on the cap on the top of the stanchion
    – Swifty
    Aug 3 '20 at 20:15
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    I have to concur with Swifty, I think that the OP was indeed asking about the suspension pre-load. It's not obvious how to alter the pre-load on many hubs, and I think it isn't even obvious to newer cyclists that this is even a thing that can be done. Also, it might help to clarify when the shimmy occurs - when riding straight, when descending, some other times? And unfortunately, I only know about road bike speed shimmy, which some frames may encounter on descents, so I'm unable to contribute much more than asking for some clarity.
    – Weiwen Ng
    Aug 3 '20 at 21:15
  • fair point....clarification is necessary.
    – moscafj
    Aug 3 '20 at 23:38
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If you can move your front wheel side to side with your hand when the bike is on a stand, you should adjust the pre-load so that the wheel doesn't move (side to side). Too much tightness, and you will increase bearing wear...not enough, and your wheel potentially moves side to side. Be gentle with the mechanism, it's usually plastic with a small allen screw.

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  • An overly lose or stiff steering makes the bicycle also prone to shimmy, it follows the Goldilocks principle. Read the shimmy related article on wikipedia.
    – Carel
    Jul 5 '20 at 11:57

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