Axl Myk
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Bingo! Check the wheel bearings.My back tire had loose bearings, and did the wobble over 20mph.
Death wobble
- Thread starter Joast
- Start date
Joast
Active Member
I ran the same road a couple days earlier at 30 mph --the bike ran smooth as usual.
This wobbling came on without any notice at about 3/4 throttle.
The bike was already built when I bought it so it may have problems somewhere
to address. john
Arty
Well-Known Member
The death wobble does seem to be a bit of a mystery. - - I've had it on two machines - a'69 750 Honda, and a '75 Triumph Bonneville, as well as on a 12 speed Sekine bicycle, and another bike. All were in top mechanical condition, and all happened at - let's say a "quick" rate of speed.
I think they are a result of frame/fork geometry, torsional stiffness, and road conditions.
They aren't fun.
At any rate, please don't take this as advice - just information on my experience, but, to get out of it, I would definitely not jam on the brakes, just gently ease off the speed, and ride it out.
Again - this is not meant as advice - I don't want to be responsible for someone else getting hurt - - just relating my experiences.
I think they are a result of frame/fork geometry, torsional stiffness, and road conditions.
They aren't fun.
At any rate, please don't take this as advice - just information on my experience, but, to get out of it, I would definitely not jam on the brakes, just gently ease off the speed, and ride it out.
Again - this is not meant as advice - I don't want to be responsible for someone else getting hurt - - just relating my experiences.
Joast
Active Member
Yeah, I just let off the throttle some and then hit the kill switch and pulled in the clutch and coasted down to where it would pedal.
My 150 scooter did it twice a few years ago at about 45-50 mph but hasn't done it for several thousand miles since. Pretty spooky feeling.
Thanks for all the posts --will check over everything, John
Head shake can be caused by loose stem bearings, bad/loose wheel bearings, poorly seated tire beads, damage to a tire, old hard tires, improperly setup suspension, wheels out of true or damaged, and uneven weight distribution. Or any combination of the above. As also said above, it can simply be caused by hitting debris or a road imperfection at just the right speed or angle.
It really doesn't take much to allow it to happen. All it takes is the right amount of something to be off just enough to start it, and the right frequency to cause what is basically a feedback loop.
When you should start looking for issues is when it is a repeated/repeatable issue.
It really doesn't take much to allow it to happen. All it takes is the right amount of something to be off just enough to start it, and the right frequency to cause what is basically a feedback loop.
When you should start looking for issues is when it is a repeated/repeatable issue.
Joast
Active Member
I have been wondering about the reflectors on the wheels (which I just removed) causing a slight imbalance.
Road was a perfect newly-resurfaced blacktop. Lots of possibilities to look at. Thanks
Juicyjayocean
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Your reflectors should be 180° from the valve stem in order to counter balance it's weight if not it would be bouncing it high speeds
Heck, I have had road tires that did that too. It wouldn't be so bad if the grooves were straight, but it seems like the person driving the machine got 2 hours of sleep or had a few drinks before work.
The reflectors shouldn't be an issue, but maybe it is possible. Generally speaking MB's don't get the wheels turning fast enough for a small balance to really affect them, but I personally think checking the balance isn't entirely a bad idea. Especially if you are wanting to be one of the crazy people pushing their bike to 50+ mph. I have a truing/balancing stand I use for my motorcycle wheels. I used it to check and balance my bicycles mag wheels. I was able to dynamically balance the front by simply turning the tire on the rim until I got the wheel to be nearly perfectly balanced. (All tires have heavy spots). On the rear I did the same and then had to stick half of a 1/4 oz sticky weight on it. I balanced the rear with my rotor and sprocket installed.
