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Front end wobble

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Front end wobble

Old 12-22-09, 10:02 AM
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jco1385
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Front end wobble

On my commute today, i noticed that when i have both hands off the bar (water, adjust gloves, etc) the front end wobbles pretty bad. I wasn't going fast at all (15mph TOPS) and i have never noticed it before. The only difference today from usual is that i added a rack on the back and it had maybe 5-8lbs of stuff (clothes) on it. (i also swapped on a better derailleur, but i'm sure that has nothing to do with this....) I pulled off and checked to see if there was any play in the axle or the headset and they both seemed fine. the wheels are true also. I did a quick search on here and it was suggested to check and re-adjust the headset. well, since mine looks/feels fine, any other suggestions i can check out? i plan to take it to the shop today and see what they say but i thought i'd ask here first.

here is a shot of what she looked like this morning:



could the weight on the back cause this? could the smaller front wheel (700c) and the larger back wheel (27") have this effect?
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Old 12-22-09, 10:05 AM
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Remove the clothes and water bottle and test ride it.
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Old 12-22-09, 10:07 AM
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Does the rack wiggle when you put your hands on it?
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Old 12-22-09, 10:31 AM
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Originally Posted by 10 Wheels View Post
Does the rack wiggle when you put your hands on it?
nope. i just went and checked. it's pretty solid.
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Old 12-22-09, 10:40 AM
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this is normal. also research the dreaded: "death wobble" which occurs to bicycles and motorcycles. there's nothing wroing with your bike - it's just a phenomenon. you can lower your center of gravity by standing on your pedals and grabbing the top tube with your knees. you can add a small front rack to add back and redistribute the weight, you can keep your hands on the bars, you might even be able to change your fork to something with less reach or whatever they call it. I have one bike that does this more than the others and it's really annoying. I just keep my hands on the bars
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Old 12-22-09, 10:50 AM
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hmm. i thought that was at higher speeds (death wobble)? and why would it not do it, then do it? i'll try and test it w/o the weight on it, but i cant until after work. i'm thinking it's the weight on the rear. idk how or why, but thats what i'm thinking, as i never had this issue before the rack (afaik).
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Old 12-22-09, 11:46 AM
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That rack sits pretty high. If it is weight on rack causeing it and you still want to use it,i"d lower that rack some.
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Old 12-22-09, 11:49 AM
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If removing the weight on the rack doesn't fix it then do me a favor - lift up your handlebars, grab the wheel and try to rattle it side to side. If there's play then adjust your hub bearings.
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Old 12-22-09, 11:51 AM
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the rack is high. i didnt even notice. i need to lower it anyways. and as far as the hub bearings, i already did that this morning en route. they are fine. i also clamped the front brake and rocked back and forth to check the headset. everything is snug. thanks for the suggestions.
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Old 12-22-09, 12:24 PM
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this is the bike I get it on
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LeTour seatpost rack.jpg (58.7 KB, 12 views)
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Old 12-22-09, 12:59 PM
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Originally Posted by jco1385 View Post
On my commute today, i noticed that when i have both hands off the bar (water, adjust gloves, etc) the front end wobbles pretty bad. I wasn't going fast at all (15mph TOPS) and i have never noticed it before. The only difference today from usual is that i added a rack on the back and it had maybe 5-8lbs of stuff (clothes) on it. (i also swapped on a better derailleur, but i'm sure that has nothing to do with this....) I pulled off and checked to see if there was any play in the axle or the headset and they both seemed fine. the wheels are true also. I did a quick search on here and it was suggested to check and re-adjust the headset. well, since mine looks/feels fine, any other suggestions i can check out? i plan to take it to the shop today and see what they say but i thought i'd ask here first.

here is a shot of what she looked like this morning:



could the weight on the back cause this? could the smaller front wheel (700c) and the larger back wheel (27") have this effect?
I think the weight on the luggage rack could indeed have caused it. I've had the same thing happen on my Woodrup with a lightly loaded rear trunk bag. It's worse going downhill.
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Old 12-22-09, 04:18 PM
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Death wobble, or speed shimmy or whatever the hell you call it is a pretty mysterious condition that can be caused by a number of things. Weight distribution is indeed important, although I've found front loading makes more of a difference than rear. I'd try without the water bottle first, then ditch the clothing in back, see if that helps.

Oddly, sometimes more weight is the answer. When I attach my trailer, my bike has speed shimmy like mad, and my 'speed' I mean 15 mph. However, this goes away as soon as the trailer is loaded. Why? I haven't the foggiest, but at least now I know not to ride no handed with an empty trailer.
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Old 12-22-09, 06:18 PM
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Is your headset tight?
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Old 12-23-09, 08:49 AM
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well, with nothing on the rack it is fine. the water bottle has always been there, and never a problem. and of course i checked the headset. i've said that 3 times. anyways, problem/mystery solved. thanks for the suggestions.
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Old 12-23-09, 08:54 AM
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The rack may wiggle some with the weight on it.
Secure everything very very tight to the rack.
The connection to the chain stays looks weak.
But that could not be true.
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Old 12-23-09, 09:01 AM
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It could just be the weight distribution, or it could be that your load wasn't very secure.

Adding the 700c front wheel would prolly have exacerbated the issue by steepening your head angle and reducing trail, something you didn't have much of to start with given all the rake on that fork.
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