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LeMond Steel frame shimmy, Yikes....(21 posts)
|LeMond Steel frame shimmy, Yikes....||J.S.|
Apr 13, 2001 8:09 AM
|While watching Paris-Nice last night (OLN rules) I noticed that Mercury riders Jan Koerts and Fabrizio Guidi, when they won their stages took their hands off the bars to celebrate, but not for long as their steel Lemond framed bikes began to shimmy wildly forcing both riders to quickly grab the bars to keep from crashing. As a previous owner of a Lemond Zurich I know this feeling all to well, it seems that the compliance people rave about in small tubed steel frames can lead to shortcomings in other areas.|
|They probably had loose wheel bearings right??????????||JImbob|
Apr 13, 2001 8:26 AM
|re: LeMond Steel frame shimmy, Yikes....||TF|
Apr 13, 2001 8:29 AM
|I don't know what others think, but I will avoid lemond bikes. I have ridden $25 bikes hands off and they didn't even shimmy like that...|
|Lemond knows how to make great bikes. These are custom frames..||Jimbob|
Apr 13, 2001 8:43 AM
|that are flexing like this. They are probably just trying to get them too light. They are switching to Ti soon I heard.|
|that was after their 6th champagne :-)||ET|
Apr 13, 2001 8:44 AM
|Usually shimmy is attributed to high-speed (50+ mph) instability, not celebratory finishes. What you describe sounds more like a balance issue. Sometimes riders use a smaller stem for some stages to get crit-like turning capability at the expense of stability. What stage was it? And did you get a look at the frame and stem sizes? :-)|
|Uhhh, like I think their hands were in the air dude!? Stems dont||Beavis|
Apr 13, 2001 8:57 AM
|change a bikes stability. A short stem doesnt change fork rake/ geometry nor does it change frame stiffness. SHort bus??|
|maybe it was I on my 6th champagne :-)||ET|
Apr 13, 2001 9:04 AM
|I'm not talking about changes in the frame. I'm almost certain I read somewhere that a longer stem is better for no hands, a short stem being too twitchy.|
|ET, your logic is really making me wonder!!!!!!!!! If youre not||Beavis|
Apr 13, 2001 9:10 AM
|touching the stem/bars, how could it have an affect?????|
|shifting body weight and uneven terrain (nm)||ET|
Apr 13, 2001 9:15 AM
|Maybe . . . .||Fiver|
Apr 13, 2001 9:28 AM
|With a shorter stem, the weight of your handlebar, levers, etc., is slightly farther behind the front wheel, making it less stable?|
|grz mnky, any help?||ET|
Apr 13, 2001 9:34 AM
|Or are you gonna let me wither here all by myself?
I have a source. This is a quote from Performance Cycling: How to Get the Most Out of Your Bike, by Stuart Baird, 2000., pps. 117-118, under the heading "Effect of Stem Extension on Handling":
"A shorter top tube gives a shorter wheelbase, the effects of which were discussed above [quicker handling]; but (for a given size of rider, to retain good fit) it must be counteracted with a longer stem. A longer stem extension increases the length of the lever arm effecting steering corrections, which makes the steering more stable [note his word], or (viewed another way) more sluggish. Minor road jitters trasmitted to a long stem cause only small changes to the steering angle, and a given steering angle change requires a physically longer sweep of the hands. Conversely, a long top tube may require a short stem extension, which could seem responsive or nervous, depending on one's point of view."
I just changed the stem on my hybrid to one longer. I can definitely feel a more "stable" ride and more inclined to try no hands than before. And stock Lemonds have rather longish top tubes, possibly necessitating somewhat shorter stems.
Maybe I'm not so drunk after all.
|I'll offer help.||Jimbob|
Apr 13, 2001 9:54 AM
|Yes, a short stem requires less "sweep" or turn of the bars to get a given turn. So if you hit a bump and your hands get jarred 3mm to the right with a short stem it will make slightly more of a turn than if you had a long stem. Making it more jittery or responsive. THis is only a very slight difference. BUT like Beavis said, if your hands are off the bars it no longer has an affect. THis is the same concept of a big steering wheel or long stick shift. Both require more movement to get the desired result than their shorter/smaller counterparts. Am I wrong??|
|I had the same problem... I tryed to ride no hands & ate crap!!||Beavis|
Apr 13, 2001 10:26 AM
|Now I have a custom Titanium 3 foot stem and now I can do centuries with no hands. Its unreal. Its so easy on your lower back. Its terrible for aerodynamics though.|
|Are you sure that C+ doesn't have a review of...||boy nigel|
Apr 13, 2001 10:27 AM
|these exact same Lemonds in next month's issue, ET? Can't see how they can't cover something like this. Maybe something on thin-tubed "audax" bikes? Hey: What does "audax" MEAN, anyway? I got a few issues of C+. All over the place was the word "audax." It's obviously a Brit/European term for some sort of cross-country, touring, or commuting type of bike. I never found it being described or defined ONCE, though. Any light shed on this is appreciated. |
By the way, one's front wheel doesn't KNOW that it only has a short stem on it, so riding no-handed shouldn't be affected by this. When riding WITH hands on the bars, however, a big difference can be felt with a longer vs. shorter stem.
|stem length affects stabilty with or without hands||LBS Guy|
Apr 14, 2001 4:57 PM
|Ok beavis your obviously not very bright, a longer or shorter stem is going to change the placement of the weight of the stem/bar/controls of the bike, thus introducing the problem of the twitchy front wheel even without hands. but also what will play into the fact of having a shorter stem will be the saddle position, the riders center of gravity will be further back redusing weight on the front wheel, which increases chance of the front wheel being less stable on the ground, hence this is also part of the reason y bikes with longer stems control better yet are more sluggish because there is more weight on the front wheel. but yes that little amount of weight in the control area of the bike moved further in front of the wheel axis or behind the wheel axis affects the stablity of the bike with or without hands. In my personal opion i think Beavis should change his name to brickhead|
|LBS guy obviously rode the short bus & thats why he works in LBS||Beavis|
Apr 16, 2001 7:55 AM
|Your logic does not even deserve a response nor anybody's time since you are obviously beyond help.|
|re: LeMond Steel frame shimmy, Yikes....||dug|
Apr 13, 2001 9:22 AM
|You don't suppose it could possibly have anything to do with the fact that they were adrenalized/euphoric/fatiqued/overwhelmed and had others within inches of them in excess of 40mph do you??
obviously it was that small tubed steel frame.
Apr 13, 2001 9:35 AM
Apr 13, 2001 10:14 AM
|You said |
had others within inches of them in excess of 40mph do you??>
I'm not sure what this would have to do with someone raising their hands in victory and having the bike shimmy wildly. Also, my Zurich did the same thing just riding down the street with my hands off the bars, not winning a stage of Paris-Nice.
|re: LeMond Steel frame shimmy, Yikes....||dustin|
Apr 13, 2001 9:45 PM
|hell, i can't ride with both my hands off the bars. never learned how to do it.....or never tried, actually.|
|re: LeMond Steel frame shimmy, Yikes....||not an idiot|
Apr 14, 2001 5:21 PM
|If its really that bad here's what to do:
Threadless steerer bikes:
Loosen the stem bolts, tighten the stem cap down 1-2 turns, make sure can still turn fork fairly easily, make sure stem is straight, retighten stem bolts, make sure stem bolts are ass tight.
Threaded steerer bikes:
Tighten headset with a big cone wrench about 1/4-1/2 turn, make sure fork can still turn.
There problem solved, if not solved then here's what to do:
Take bike completely apart, so there's nothing left but bare frame, take bike and ram it as far up your ass as possible, repeat as much as necessary or wanted, rebuild bike, then make the stem as tight as possible, take bearing out of stem if wanted(it will shave weight), check stem bolts. now you can ride without hands as long as far as you want as long as you can balance through a turn and lean well, and always remember, stupid people have to wear signs stating they are stupid, and people with those signs are not allowed to ride with a group. thank you have a great day