From:Steve Marks e-mail:steve@microdesign.ltd.uk
Subject:RE: RE: RE: speedo fiber gear Date:Thu Mar 27 04:49:19 2008
Response to:2007
All the answers you need are here - courtesy of Steve Blancard and Gene Harper

http://www.splitdorfreg.com/Blancard/corbin.html

Rather than making a caliper as Steve suggests, and then calculating the circumference of the tyre, I put a chalk mark on the tyre where it touches the ground and a corresponding mark on the ground. Rolled the bike forward until the tyre chalk mark had done one revolution then marked another chalk mark on the ground. Distance between the two marks on the ground gave the circumference of the tyre. I did my calculations using Excel so that I could change a parameter and see the results quickly. Same file also includes gear ratio calculations, engine revs for given road speeds in each of the gears etc for a variety of front/rear sprocket combinations and also the early /late Deluxe first gear ratios. Unfortunately I can't post an Excel file here but if anyone would like a copy, please email me direct and I'll send it on. Steve.

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Steve, have 18 inch on my KL. Have I believe a 27 on it, and a 28 on the shelf. Not sure which goes on 19 and which on 18. Has correct pitch. Definately not Indian.

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Marty, not only is the number of teeth important the pitch is important. Look at your ring rear, it will have a 9P on it. This is the pitch or the shape of the teeth. A 27 or 28 tooth gear will work. Indian gears are 8P I believe, also 27 or 28 teeth which are good for the wheels you mentioned.

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What is the correct number of teeth on the speedo fiber gear that engages the large Corbin rear sprocket for 18 inch and 19 inch wheels?