I know that cassette wobble on bicycles is nothing new. It's not a bent axle (seems like most like to blame that for starters). So, I ran an experiment.
I had a set of wheels that had varying degrees of cassette wobble and one that had none. I put them in the truing stand and spun the wheel, while keeping the cassette mechanism (no actual gears) still, and watched the wobble. I then took the best cassette mechanism and put it on the worst wobbling wheel and the worst wobbling cassette mechanism and put it on the best wheel. The result was the wobble followed the rim and not the cassette mechanism. I even went as far as to switch the steel washers around and rotated them to new positions to verify that it's not the washers.
My question is does anyone know what is causing the hub to behave like it's mis-aligned when mated to the cassette mechanism? Is it possible that all hubs start out true and lose that truness when a wheel is build and stress relieved (do the hubs bend slightly - road bike hubs especially)? Is it possible that all hubs start out with varying degrees of truness based on machining and thermal aging cycles? Any other possibilities?
I know this is a don't care. It's more of a technical curiosity for me.
I know that cassette wobble on bicycles is nothing new. It's not a bent axle (seems like most like to blame that for starters). So, I ran an experiment.
I had a set of wheels that had varying degrees of cassette wobble and one that had none. I put them in the truing stand and spun the wheel, while keeping the cassette mechanism (no actual gears) still, and watched the wobble. I then took the best cassette mechanism and put it on the worst wobbling wheel and the worst wobbling cassette mechanism and put it on the best wheel. The result was the wobble followed the rim and not the cassette mechanism. I even went as far as to switch the steel washers around and rotated them to new positions to verify that it's not the washers.
My question is does anyone know what is causing the hub to behave like it's mis-aligned when mated to the cassette mechanism? Is it possible that all hubs start out true and lose that truness when a wheel is build and stress relieved (do the hubs bend slightly - road bike hubs especially)? Is it possible that all hubs start out with varying degrees of truness based on machining and thermal aging cycles? Any other possibilities?
I know this is a don't care. It's more of a technical curiosity for me.
Thanks, GM
it's almost certainly optical illusion. the ramps on the cassette sprockets are sloped depending on position to assist shifting. this gives the teeth tips the appearance of sloping one way at one part of the circumference, the opposite at another. if you hold a pointer [like a dead spoke] /between/ sprockets as they rotate, you'll see that the sprockets themselves rotate true.
I know that cassette wobble on bicycles is nothing new. It's not a bent axle (seems like most like to blame that for starters). So, I ran an experiment.
I had a set of wheels that had varying degrees of cassette wobble and one that had none. I put them in the truing stand and spun the wheel, while keeping the cassette mechanism (no actual gears) still, and watched the wobble. I then took the best cassette mechanism and put it on the worst wobbling wheel and the worst wobbling cassette mechanism and put it on the best wheel. The result was the wobble followed the rim and not the cassette mechanism. I even went as far as to switch the steel washers around and rotated them to new positions to verify that it's not the washers.
My question is does anyone know what is causing the hub to behave like it's mis-aligned when mated to the cassette mechanism? Is it possible that all hubs start out true and lose that truness when a wheel is build and stress relieved (do the hubs bend slightly - road bike hubs especially)? Is it possible that all hubs start out with varying degrees of truness based on machining and thermal aging cycles? Any other possibilities?
I know this is a don't care. It's more of a technical curiosity for me.
Thanks, GM
it's almost certainly optical illusion. the ramps on the cassette sprockets are sloped depending on position to assist shifting. this gives the teeth tips the appearance of sloping one way at one part of the circumference, the opposite at another. if you hold a pointer [like a dead spoke] /between/ sprockets as they rotate, you'll see that the sprockets themselves rotate true.
There is no cassette installed (no gears) and the mechanism is not spinning - only the wheel is spinning. The splined cylinder is wobbling. When you're home, lift up the rear wheel and crank the pedals a few times to get it spinning at a good rate. Then stop the pedals and watch the cassette (it's not spinning at this point). You'll see what I'm talking about. If you don't, you've got a hub without a wobble.
I'm just trying to understand the origin of this wobble. Whether it's a manufacturing process that's not easily controlled, or a characteristic that shows up after the wheel is built up.
<[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
<snip>
Quoted message said:
Quoted message said:
it's almost certainly optical illusion. the ramps on the cassette sprockets are sloped depending on position to assist shifting. this gives the teeth tips the appearance of sloping one way at one part
of
Quoted message said:
Quoted message said:
the circumference, the opposite at another. if you hold a pointer
[like
Quoted message said:
Quoted message said:
a dead spoke] /between/ sprockets as they rotate, you'll see that
the
Quoted message said:
Quoted message said:
sprockets themselves rotate true.
There is no cassette installed (no gears) and the mechanism is not spinning - only the wheel is spinning. The splined cylinder is wobbling. When you're home, lift up the rear wheel and crank the pedals a few times to get it spinning at a good rate. Then stop the pedals and watch the cassette (it's not spinning at this point). You'll see what I'm talking about. If you don't, you've got a hub without a wobble.
I'm just trying to understand the origin of this wobble. Whether it's a manufacturing process that's not easily controlled, or a characteristic that shows up after the wheel is built up.
Thanks, GM
I've seen it frequently in cheap old freewheels too. They seemed to work Ok so I never took the time to figure out what the cause was.
I know that cassette wobble on bicycles is nothing new. It's not a bent axle (seems like most like to blame that for starters). So, I ran an experiment.
I had a set of wheels that had varying degrees of cassette wobble and one that had none. I put them in the truing stand and spun the wheel, while keeping the cassette mechanism (no actual gears) still, and watched the wobble. I then took the best cassette mechanism and put it on the worst wobbling wheel and the worst wobbling cassette mechanism and put it on the best wheel. The result was the wobble followed the rim and not the cassette mechanism. I even went as far as to switch the steel washers around and rotated them to new positions to verify that it's not the washers.
My question is does anyone know what is causing the hub to behave like it's mis-aligned when mated to the cassette mechanism? Is it possible that all hubs start out true and lose that truness when a wheel is build and stress relieved (do the hubs bend slightly - road bike hubs especially)? Is it possible that all hubs start out with varying degrees of truness based on machining and thermal aging cycles? Any other possibilities?
I know this is a don't care. It's more of a technical curiosity for me.
Proving that there's nothing new on r.b.t, here's a thread on the exact same subject from 1996:
There is a certain amount of play between the cassete and the hub. If you loosen the bolt joining the two and then tighten it back up you will have to retrue your wheel. The worse hubs for this are the XT series they have a steel insert where the bolt goes in.
