Death wobble

[Joast]

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.

These are just newer 2.125" by 26" balloon tires with road tread. Not knobby or slicks. I always pitch the reflectors on the wheels of my road bikes, but just didn't think of it on this thing. I am wondering if a fairly strong side wind hitting the reflectors could cause some uneven force of some sort at speed.

Thanks, John

 

[DAMIEN1307]

I am wondering if a fairly strong side wind hitting the reflectors could cause some uneven force of some sort at speed.

What DOES happen, I found out some years back...When your bike is cruzin along at 30 to 35 MPH, the reflectors like to creep upwards on the spokes on the rim that they are attached to because of centrifugal force...The pressure aginst the plastic tabs holding the reflectors to the spokes just snap and that sucker is lost on the street and run over by the car right behind ya...lol...End of wheel mounted reflectors...lol...lol.

 

[ImpulseRocket]

What DOES happen, I found out some years back...When your bike is cruzin along at 30 to 35 MPH, the reflectors like to creep upwards on the spokes on the rim that they are attached to because of centrifugal force...The pressure aginst the plastic tabs holding the reflectors to the spokes just snap and that sucker is lost on the street and run over by the car right behind ya...lol...End of wheel mounted reflectors...lol...lol.

This is why I love tires that have reflective white-walls

 

[weefek]

Can't really speak for 50mph-ish but it seems to be the balance of the crank / rotating assembly is the main source of vibration, not tires/rims. Unless your engine is supremely balanced and your tires/wheels are not, which I suppose is possible, but seems rare considering how light bicycle tires/wheels are in general.

I know people want to push 50+ mph but tbh I feel sketchy enough as it is as my max of 35. I stay below 30 , 25 to 30 is where I cruise and I would never want to go any faster. Personal preference.

It never leaves my mind how different this hobby is vs the automotive.

 

[weefek]

These are just newer 2.125" by 26" balloon tires with road tread. Not knobby or slicks. I always pitch the reflectors on the wheels of my road bikes, but just didn't think of it on this thing. I am wondering if a fairly strong side wind hitting the reflectors could cause some uneven force of some sort at speed.

Thanks, John

To be fair, any cross wind is hitting you and your bike is by far more adding force to your body than the reflectors. A few inches squared vs many ft. I've noticed it as top heavy, being near the sea (off-shore breezes can be intense). The reflector is making up for a very minimal amount of wind resistance compared to you yourself in that case.

 

[DAMIEN1307]

A few inches squared vs many ft. I've noticed it as top heavy, being near the sea (off-shore breezes can be intense).

This always makes me laugh a little...The reason why I laugh is last year someone saw where my motor was mounted and said it was too high up on my bike frame and said this was throwing off the "center of gravity" of my bike...I just couldn't stop laughing...lol...80 pounds of bike and motor and then add my fat butt sitting on the very top at 217 pounds and this yutz was telling me about my "center of gravity"...lol...lol.

That was blown a long time ago, just like the diet and my waist line...lol.

 

[weefek]

I mean completely talking about wind factors , specifically 90 degrees to the direction your traveling. Your body makes up a bigger 'sail' then the damn reflectors in your wheels. If there's a 30mph cross wind for example, your body is taking the brunt of it, making that force 'top heavy' if you know what I mean.

 

[ImpulseRocket]

Can't really speak for 50mph-ish but it seems to be the balance of the crank / rotating assembly is the main source of vibration, not tires/rims. Unless your engine is supremely balanced and your tires/wheels are not, which I suppose is possible, but seems rare considering how light bicycle tires/wheels are in general.

It's not just about felt vibration. It can also cause a slight issue with alternating contact patch/grip with the tires at a certain level. This is why misbalanced tires on a motorcycle can cause steering wobble in the right conditions. While the effect may be reduced some at lower speeds you would be surprised at how low of a speed it will affect large diameter wheels like those found on bicycles. Made even more noticeable with skinny tires... like those on a bicycle.

There are other physics forces at work beyond simple mass as well. A concept known as moment of inertia really comes into play. A Bicycle wheel may be relatively light but the majority of the mass is located the furthest away from the axis. A best example I can give that is familiar to people would be the flywheel on a car engine with a manual transmission. A heavier flywheel generally means the engine revs and down more slowly. I can make a flywheel that weighs the same that revs up and down more quickly by shifting the mass closer the axis of rotation. I can also make a lighter flywheel that revs up and down just as slow by keeping the mass as far away from the axis of rotation as possible. In real layman terms just think rotational leverage.
In this case the further the imbalance is from the axis of rotation the more force it exerts and the more exaggerated the effect can become. For a bike being pedaled up to 20-25mph I agree that it shouldn't matter. I just prefer not to take any chances since I know for a fact my bike can easily top 40mph if I choose to do so. I usually don't because I don't care about top speed on my Kent. 30-35mph is my happy place on road. I just learned a long time ago to always plan for the worst case scenario.

 

[BrainPain]

I know others have answered about your wobble problem I have a Schwinn siesta cruiser I just destroyed the motor on it after the clutch messed up I cooked the rings I guess making it home after trying to adjust the main spring I have hit 30 mph and never got any wobble and the front rim is not perfectly true and the Schwinn nylon tires have 1240 miles on them the rims to. I put a new motor on the bike it's a 50 cc.

 

[redneckracing674]

ive found out that weight and small tires do this. if i stand on the foot pegs of my scooter that are about 6 in behind the tire, it will death wobble at low speeds. steering andle, and geometry play a huge part. razor e3oos will death wobble at 17 mph, due to the speering being straight up and down, and the tire being dead center in the forks. it is called gt2 geometry i believe