Bicycle chain confusion

General Discussion about electric bicycles.
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Bicycle chain confusion

Post by 12-C » Dec 30, 2017 2:02 am

For curiosity sake I'm trying to design a sprocket in CAD, partly to pass time and learn and partly for the fun of it.

I have precision calipers that I have used to measure brand new KMC chains I own.

The obvious mistake that has made is mixing up the with/without derailleur headings as geared bike chains have inner plate widths of 3/32 (<9sp) or 11/128 and it is only the outer plate widths that differ between 9/10/11sp.

The thing that is also in conflict with my measurements is bicycle chain roller diameter stated as 5/16 or 0.3125" which is at odds with my measure of 0.306" or rather in agreement with a size 41 ANSI chain in that respect but differs in others....

Everywhere I read about bicycle chains it says conflicting info, most incorrectly quote 3/32 as the standard for anything geared.... totally oblivious to 11/128.

I'm inclined to use this guide to fashion a sprocket. ... cket_5.pdf

I was hoping the web could be a resource for confirming my measurements but rather it seems more like a circular argument citing other incorrect references.... No shit the idea of a flat earth became a thing despite evidence supporting the contrary as far as 2000 years back...

Anyone have any evidence based and supporting measurements?

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Re: Bicycle chain confusion

Post by amberwolf » Dec 30, 2017 2:21 am

I don't know what the measurements of a brand new chain would be, and have nothing accurate enough to measure, so can't help with that.

But there are sprocket designer programs out there to generate a template for you, if it helps:
It saves as DXF if you like (or gcode for CNC). You could then import DXF into something else to alter tooth profiles, etc., if necessary.

and this thread ... tware.html
has some info (though it's a decade old so I don't know how many links still work).

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