gunderwood
New member
Summary
I've learned a lot from this thread, specifically because it made me curious enough to really investigate the topic. Thanks to the OP for starting it. I've provided references where possible, but as always, there is some interpretation of the information and I'm not infallible, so please feel free to ask questions and challenge the statements.
The theory of "autobalance" isn't new and certainly devices have been designed, built, and sold which utilize this mechanism for achieving dynamic balance. However, they are few and far between in practice and there's several very good reasons for that.
I'm surprised no one has bothered to really look it up...there are plenty of theoretical, analytical, and experimental papers out there on the subject. In fact the first theoretical reference I could find was from 1904 and the first real reference nearly everyone cites is Thearle in 1932. The first patent appears to be from 1916, but one of my references says Thearle showed it couldn't work as he proved that an autobalancer mechanism requires discrete weights and the patent used a liquid; i.e. the liquid in tires to make an autobalancer appears to be BS as far as I can tell (more on this later). I've narrowed it down to three papers as I feel they adequately address the Dynabead physics, but it's important to note that none of them actually address the Dynabead product. However, they convinced me to not use Dynabeads...YMMV.
Let's cut to the chase. IMHO the basic physical theory which Dynabeads uses is sound. The theoretical, analytical, and experimental physics all back up the concept of an autobalancer. The fact that you can do it and that it can work very well is not at all in question. However, if you look deeper it becomes obvious IMHO that their particular implementation is lacking as it appears to violate several key assumptions and worse still, autobalancers have well documented issues which are exactly why engineers (like myself) have not built them into many products. These issues, IMHO, so far invalidate the usefulness of an autobalancer, particularly a suboptimal one like Dynabeads, on a motorcycle.
Please note that I have not totally convinced myself yet that no autobalancer design can work well on a motorcycle, but simply that Dynabeads isn't it.
There are several different ways to build an autobalancer, but they all suffer from increased instability if they aren't spinning supercritical (i.e. until it reaches an RPM which is "fast enough," aka supercritical) and really don't like being perturbed (e.g. bumps, acceleration, turning, certain dampening states, etc.). The problem isn't that autobalancers don't work, it's that they only work well within particular set of parameters and if you violate them they actually make the imbalance much worse. This is exactly why engineers generally only use them in relatively static environments or they make them active balancers (sensors, actuators, etc. to actively change the balance...i.e. not an autobalancer). I also think this is why some people have success and others don't. It's a fragile system and even minor things can upset it.
In my next post I'll present my case, but I wanted to summarize it here because it's a bit long.
I've learned a lot from this thread, specifically because it made me curious enough to really investigate the topic. Thanks to the OP for starting it. I've provided references where possible, but as always, there is some interpretation of the information and I'm not infallible, so please feel free to ask questions and challenge the statements.
The theory of "autobalance" isn't new and certainly devices have been designed, built, and sold which utilize this mechanism for achieving dynamic balance. However, they are few and far between in practice and there's several very good reasons for that.
I'm surprised no one has bothered to really look it up...there are plenty of theoretical, analytical, and experimental papers out there on the subject. In fact the first theoretical reference I could find was from 1904 and the first real reference nearly everyone cites is Thearle in 1932. The first patent appears to be from 1916, but one of my references says Thearle showed it couldn't work as he proved that an autobalancer mechanism requires discrete weights and the patent used a liquid; i.e. the liquid in tires to make an autobalancer appears to be BS as far as I can tell (more on this later). I've narrowed it down to three papers as I feel they adequately address the Dynabead physics, but it's important to note that none of them actually address the Dynabead product. However, they convinced me to not use Dynabeads...YMMV.
Let's cut to the chase. IMHO the basic physical theory which Dynabeads uses is sound. The theoretical, analytical, and experimental physics all back up the concept of an autobalancer. The fact that you can do it and that it can work very well is not at all in question. However, if you look deeper it becomes obvious IMHO that their particular implementation is lacking as it appears to violate several key assumptions and worse still, autobalancers have well documented issues which are exactly why engineers (like myself) have not built them into many products. These issues, IMHO, so far invalidate the usefulness of an autobalancer, particularly a suboptimal one like Dynabeads, on a motorcycle.
Please note that I have not totally convinced myself yet that no autobalancer design can work well on a motorcycle, but simply that Dynabeads isn't it.
There are several different ways to build an autobalancer, but they all suffer from increased instability if they aren't spinning supercritical (i.e. until it reaches an RPM which is "fast enough," aka supercritical) and really don't like being perturbed (e.g. bumps, acceleration, turning, certain dampening states, etc.). The problem isn't that autobalancers don't work, it's that they only work well within particular set of parameters and if you violate them they actually make the imbalance much worse. This is exactly why engineers generally only use them in relatively static environments or they make them active balancers (sensors, actuators, etc. to actively change the balance...i.e. not an autobalancer). I also think this is why some people have success and others don't. It's a fragile system and even minor things can upset it.
In my next post I'll present my case, but I wanted to summarize it here because it's a bit long.