Quote:
Originally Posted by Mr Gazza
I'm going to contend the gyroscopic effect that you mention in a playful way, as I don't fully understand the details of the principle.
Does the weight of the gyro have an influence or is it the speed of rotation?
Motorcycle steering is initiated by interference to the gyro's procession and if the effect was reduced by weight then I think you would have noticed more effort required to initiate a turn and overcome the bike's mass? Whereas I think you have said the reverse in the past?
I would also posit that the effect has been increased, (or remains the same?) if the major weight is now at the periphery (the tyre) relatively speaking, The central part, (the wheel.) having a lesser effect? That brings diameter into the equation too come to think of it.
There's a nice think for you if you fancied a think and couldn't think of a think..  |
Ha !
Back down the rabbit hole we go.
I've never yet found my way out.
Anyway, let's have another go.
And joke on you, mate, cos I'm now going to clutter your thread with goodness knows how much ramble.
But first, I might say (and here I quote Jefferson Airplane in paraphrase) ...
Well I thunk and thunk.
Couldn't think of anything better.
I tried so hard.
But thinking ain.t doing me no good, people.
Thinking ain't doing me no good.
https://www.youtube.com/watch?v=JRNRVe0kgC0
Though maybe I'm wrong ... it probably helps keep the Alzheimer's at bay.
I have some notes in the attic from my days as an engineering student in the mid 1970's ... but I'm going to leave them there and instead try and reason my own way through the warren .. cos that's more fun.
I'll get stuff wrong, probably, but it won't be the first time.
So...
Lets say that gyroscopic forces arise from the angular momentum of a rotating mass.
The two variables here are 1) the mass and 2) the radius of rotation .. and 3) the speed of rotation (nobody expects the spanish inquisition) ... but lets rule the latter out by assuming a constant speed.
The mass is distributed over the whole radius, from wheel spindle to tyre periphery (and across the width of the wheel too, but ...)
Lets resolve that mass distribution to a single centre of mass ... imagine a rotating wire hoop of infinite density and thinness (although I use the word infinite loosely here otherwise it would disappear up its own black arsehole, but I digress).
So we now have a single hoop of infinitely thin mass rotating at a single "effective radius".
And here I can say "yes", it seems obvious that lighter wheels would not only reduce the magnitude of the mass but also its distribution and hence the effective radius, both of which contribute to reduced angular momentum.
Since gyroscopic forces arise from angular momentum then those gyroscopic forces must be reduced if the wheels are lighter.
Here is where words start to play tricks ... well on me at least (if they haven't done so already).
But in for a penny .....
So ...
Less angular momentum (from lighter wheels) should mean less force necessary to overcome said angular momentum (Newton's laws of motion). Hence easier steering.
But at the same time I can see your argument, Gary, that if there are more gyroscopic forces acting (from heavier wheels) then there are grounds for saying that there would be a greater tendency for the bike countersteer. Hence easier countersteering ???
I remain somewhat baffled and perplexed by all this.
And there I'm going to leave it, for now.
Capo would have said that only calculations will provide the answer, but that would mean a good rummage in the attic for my 50 year old notes.
I might just go out for a nice relaxing ride on my old Raleigh bicycle instead.
Trouble is, I think there's something wrong with it.
Every time I steer left the bloody thing turns to the right.
Which isn't great on the canal towpath.
By the way, no substances other than tea were used in the production of this rambling.