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So, two questions for an Old Skool Bloke:
1) If the sides of the teeth on a thick-thin chainring don't actually touch the insides of the chain plates, how do they achieve what they claim to achieve?
2) If you have a clutch mech to take up the chain slack, do you need a thick-thin chainring anyway?
1) magic
2) not always, clutch only on my 1x10 HT has never dropped the chain.
The thick and thin teeth reduce the clearance so that it's very difficult for the chain near but not on the ring to move sideways enough to miss the ring when it drops on because the chain that is on the ring can't move sideways.
It's working with the idea that in order for the chain to drop off the ring (as it'd do if you were running 2x and trying to shift at the front), there always has to be a point where one link is on the ring and then the next one along is not yet on the ring but is far enough misaligned sideways to go to the side of the teeth. If you take the sideways play away for the chain that is engaged on the ring, there isn't enough play for the chain to move that far in the length of one or two links, so even when it does bounce it is guided back down into the right place.
It can't actually grip the chain, that'd cause massive chain suck.
1) they do but since there's some play, there's not significant friction
2) depends. I was getting very occassional drops with a non NW chainring and clutch mech. None now I have a NW chainring.
The chain is a natural oscillator. It wants to oscillate not just up and down but sideways and rotationally (like a guitar string). Oscillation energy moves between all three directions of oscillation. The thick sections of the chainring cut off / damp the rotational and lateral oscillations so keeping the chain from developing a resonant pattern with sufficient kinetic energy to jump off the chainring.
That's my theory anyway!
natural oscillator
I like that ,I think that shall become my new job title.
I consulted the gurus, and they've informed me that there's magic everywhere in this bitch.
I agree with the groove guru. Ideal name, too, for discussing the minutiae of rhythmic oscillations. I had similar thoughts although I was unable to translate them to text so eloquently.
Northwind - MemberI consulted the gurus, and they've informed me that there's magic everywhere in this bitch.
Have you considered a career in marketing NW?