Hypothetical Scenario Thoughts

[Freddy Snottgrass]

So the past couple of days I've been commuting and having this persistent question. I hope it isn't a premonition...

Say someone (not me) is doing his normal 22 mph cruise and his chain suddenly loosens and binds up in the drive sprocket (proper name?), what is going to break?

A: His chain?
B: His wheel?
C: His head?

 

[wheelbender6]

In most cases, the wheel.

 

[Frogslayer]

By drive sprocket do you mean the small sprocket on the engine? If so, you should check your alignment between the sprockets and the tensioner. Also make sure your chain is tensioned enough but not too tight. It's possible your sprocket and or chain are wore out of spec and may need replacing as well. That's all i can really think of. I'm sure posting some pictures of your set-up would help to try and see what's going on.

 

[mark20]

So the past couple of days I've been commuting and having this persistent question. I hope it isn't a premonition...

Say someone (not me) is doing his normal 22 mph cruise and his chain suddenly loosens and binds up in the drive sprocket (proper name?), what is going to break?

A: His chain?
B: His wheel?
C: His head?

well, ive had that happen, (chain went right into the case)

i got flung forward, but stayed on the bike, wheel had a few broken spokes, my tire was f***ed (it wore it to the belts!)

the wheel was repairable (ill be it, a pain in the ass)

had to replace the chain (i just didnt trust it anymore)

but thankfully i was not hurt (my balls were though)

 

[Freddy Snottgrass]

By drive sprocket do you mean the small sprocket on the engine? If so, you should check your alignment between the sprockets and the tensioner. Also make sure your chain is tensioned enough but not too tight. It's possible your sprocket and or chain are wore out of spec and may need replacing as well. That's all i can really think of. I'm sure posting some pictures of your set-up would help to try and see what's going on.

No this is just some made up situation I go through on my ride home. I have a 7+ mile commute and with that, three stretches over a mile. I'm just riding along, impressed with myself and my creation and the defeatist in me kicks in and says, "Man, Zak, you built this. Something's gotta eff up." and this is just my most recent 'final destination' movie that plays in my thoughts. Hope you found humor in that...

But those thoughts get my mechanical thoughts going... "Hmm I wonder where the weak point is"

 

[bakaneko]

rear wheel locks up and you will skid; depending on your agility. you will just have an abrupt stop or maybe lose your balance and fall. happened to me; i guess it depends on rider weight too; my rear wheel was fine; no broken spokes.

 

[CrazyDan]

I find a chain issue causes a rear wheel lockup. That doesn't fling you over the handlebars, ride it like you did as a kid dragging a 20 foot skid with your coaster brake for fun. The lockup that is usually serious is the front wheel, and that's from slamming the front brake too hard or a front fender dropping into the wheel.
The scariest moment I've had on my motorized bike was a few years ago, was riding between a city bus and 18 wheeler. My rear fender decided it wanted to turn into a burrito between my rear wheel and rack. I was going 35-40 mph and skid to a halt between these monstrosities with about 2 feet on either side to skid safely. The whole time I was just staring at them big ass tires doing my best to not go under. I skid so far about a half inch was ground off my rim. Never ran a fender since.
I honestly think that if I never challenged neighborhood kids to a skid contest when growing up, I would have went under and died then. Man it was so fun to get the longest skid mark without getting skid marks in your pants... That day on my MaB, the skid marks were oh so real.

 

[extremeodd]

The following things can happen:
1: The wheel will simply lock up and you will skid to a stop
2: The wheel will lock up and the force of you + the bike + the speed bends/destroys the wheel
3: The wheel will lock up momentairly until the force of you + bike + speed overcomes the tensile strength of the chain and it snaps
4: All of the above

I've had all 4 happen for various reasons. #4 happened when my chain jammed in the engine (buy the damn $12 anti chain lockup kit!) which caused a sudden reversal of power traveling through the drivetrain and in the span of about 250ms the chain jammed in the motor, the sprocket and hub adapter start to rotate bending the spoke/wheel which increases its resistance to rotation which causes the tension on the chain to spike up which proceeds to snap in 2 spots and go flying off to the side.

From my point of view I was riding, there was a sudden clattering/bang in the drivetrain causing the bike to jerk and I was instantly on the clutch and brakes as hard as I could. I was somewhat surprised to see how much damage there was from a rather anticlimactic event.

 

[FurryOnTheInside]

What's the front brake doing during this 40mph skid?
Surely, and I have not had to try this, if the rear wheel was to lock up you would use your front brake to stop safely and quickly, rather than grind through the rear wheel as you skid uncontrolled down the road?

 

[gary55]

Usually it ends up with a trashed chain, and either a flat spot on the rear tire, sometimes worn through with blown tube. If the chain derails to the inside it's usually trashed spokes as well. The fact that you're thinking of these scenarios makes it far less likely to happen.