Bicycle chain confusion

General Discussion about electric bicycles.
Post Reply
12-C
100 W
100 W
Posts: 122
Joined: Oct 14, 2016 9:22 pm

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 http://www.gizmology.net/sprockets.htm 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. http://www.gearseds.com/files/design_dr ... 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?

User avatar
amberwolf
100 GW
100 GW
Posts: 24240
Joined: Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

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:
http://www.idleamusements.com/?page_id=54
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
http://www.cnczone.com/forums/mechanica ... tware.html
has some info (though it's a decade old so I don't know how many links still work).

Post Reply