one-eyed_jim
Old School Grand Master
...and "eccentricity" would be a serious marketing liability.GeoffApps":3eg7serw said:
Egg chainrings, who remembers them?
- Thread starter mattbrown
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At the risk of being written-off as a total up-yor-ass pedant:
I get what you mean regarding the use of 'eccentricity', but I don't think it would apply anyway; the chainwheel mounting is dead-centre of the ellipse, whereas eccentricity would imply that the mounting is off-centre.
Hmmm, now there's something to think about...
I get what you mean regarding the use of 'eccentricity', but I don't think it would apply anyway; the chainwheel mounting is dead-centre of the ellipse, whereas eccentricity would imply that the mounting is off-centre.
Hmmm, now there's something to think about...
one-eyed_jim
Old School Grand Master
GeoffApps wrote:
http://en.wikipedia.org/wiki/Eccentricity_(mathematics)#Ellipses
(I can't make that link clickable - you'll have to cut and paste. Or click here:
http://en.wikipedia.org/wiki/Eccentricity
and read the second article on the list)
The executive summary: eccentricity is a mathematical term that describes the departure of an ellipse (or other conic section) from the circular. I think Highpath probably use a simpler definition based on the ratio of major and minor axes, but the concept is similar.
Well...
http://en.wikipedia.org/wiki/Eccentricity_(mathematics)#Ellipses
(I can't make that link clickable - you'll have to cut and paste. Or click here:
http://en.wikipedia.org/wiki/Eccentricity
and read the second article on the list)
The executive summary: eccentricity is a mathematical term that describes the departure of an ellipse (or other conic section) from the circular. I think Highpath probably use a simpler definition based on the ratio of major and minor axes, but the concept is similar.
I think Mavic tried that on some early models of their 637 mtb crank: the granny ring had several sets of holes to allow non-concentric mounting. I can't think why they thought that was a good idea...
one-eyed_jim
Old School Grand Master
The answers to most of those question are here:cyfa2809":3bdh7lo6 said:
http://www.highpath.net/cycles/ovals.html
Ah, wonderful Wikipedia!
I was thinking more on the lines of Eccentricity (Mechanical), rather than (Mathematical). However, we are both right, though you'd win on points.
Yes, Chris uses the ratio between the major and minor axis, and presents it as a percentage. As an example, I had Chris make me a 100% EggRing. I can't remember the exact number of teeth, but I seem to recall that the minor axis gave a rough equivalent of 18 teeth, and the major about 29, it was fitted to a trials machine and worked extremely well at very slow speed. Anyway, the point is that 100% ovality (as Chris refers to it) gives a major axis twice the length if the minor.
I seem to recall discussions on eccentric (mechanical) fitting of chainrings, but it quickly became obvious that the idea was hopeless.
Large and successful manufacturers are perfectly capable of taking a cock-up from conception through to design, prototype, manufacture, marketing, supply, press and publicity, before eventual product withdrawal after selling lots of said items to the gullible, leaving some of us wondering how it all happened...
I was thinking more on the lines of Eccentricity (Mechanical), rather than (Mathematical). However, we are both right, though you'd win on points.
Yes, Chris uses the ratio between the major and minor axis, and presents it as a percentage. As an example, I had Chris make me a 100% EggRing. I can't remember the exact number of teeth, but I seem to recall that the minor axis gave a rough equivalent of 18 teeth, and the major about 29, it was fitted to a trials machine and worked extremely well at very slow speed. Anyway, the point is that 100% ovality (as Chris refers to it) gives a major axis twice the length if the minor.
I seem to recall discussions on eccentric (mechanical) fitting of chainrings, but it quickly became obvious that the idea was hopeless.
Large and successful manufacturers are perfectly capable of taking a cock-up from conception through to design, prototype, manufacture, marketing, supply, press and publicity, before eventual product withdrawal after selling lots of said items to the gullible, leaving some of us wondering how it all happened...
cyfa2809":2dt9wlpn said:ok thanks. i understand more now than what i did yeterday but i keep finding things, reading them 5 or 6 times and thinking what?! nothing sinking in
Well done! Stick at it Cyfa
It took me ages to figure out how and why these things work.
It will eventually fall into place inside your head, and then you'll be an 'expert'!
Yep... exactly.
I like your phrase "assisting you at the wrong part of the pedal stroke"
How's that for a useless bit of kit?
You've got that bit.
You're well on the way to becoming an expert! You now understand more about the subject than the majority of other cyclists.
I like your phrase "assisting you at the wrong part of the pedal stroke"
How's that for a useless bit of kit?
You've got that bit.
You're well on the way to becoming an expert! You now understand more about the subject than the majority of other cyclists.
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Elliptical Chainrings
I have mentioned before that elliptical EggRings feel strange for about two minutes before your legs and brain get used to them. This feels like the rear wheel is slipping, as if on ice, but only as the pedals pass through the deadspots.
If I rotated my 4 bolt EggRings 90 degrees (Biopace orientation). Now the slipping sensation would now be during the power stroke, just like you would experience if you were cycling on ice. The reality is that Biopace rings are not oval enough, and actualy feel little different from round rings.
I have mentioned before that elliptical EggRings feel strange for about two minutes before your legs and brain get used to them. This feels like the rear wheel is slipping, as if on ice, but only as the pedals pass through the deadspots.
If I rotated my 4 bolt EggRings 90 degrees (Biopace orientation). Now the slipping sensation would now be during the power stroke, just like you would experience if you were cycling on ice. The reality is that Biopace rings are not oval enough, and actualy feel little different from round rings.
