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Old 08-23-2010, 06:15 PM
Creative Engineering Creative Engineering is offline
Join Date: Sep 2008
Location: Clearwater, FL
Posts: 1,668
Default Re: reduced tire size

Originally Posted by worksmanFL View Post
Jim (and justin)

RE: Post #11

I have a falcon hub 1.539 - 1.548", measured with a micrometer in 2 places, while trying to keep micrometer straight.

My friends falcon hub measures 1.533 - 1.543", measured in 2 places.

a. Why the difference, and
b. will the worksman sprocket adapter work?
c. what is the measurement of the new worksman adapter?

Thank you.
a. The outer shells for the coaster brake hubs are produced by a process called swaging. The wall thickness of the blank...the temper, (annealed state), of the blank...and the press set-up, (from one production run to another), can cause a variation in the diameter of the finished product.

As you have discovered, this is the reason why I ask that that an accurate measurement be provided when ordering. Two different hubs from the same manufacturer can be .005"-.010" different. The sprocket adapters are made to precisely fit the hub. On hubs that are out-of-round I make the adapter to the nominal size, (split the difference). This has an added benefit of eliminating brake pulse. If you ride the bike, and lightly apply the brakes you will feel the .010" out-of-round condition. The sprocket adapter makes the hub round again.

b. No...the previous release of Falcon hubs measured 1.528"-1.531". I was not aware that the Falcon hub dimensions had changed when I included them in the group. I will have to let Justin and Robert know that it is no longer assumed that a CB-110 adapter will fit a Falcon hub. This same thing happened with the Huffy Cranbrook bikes...for about a year they used a no name hub that measured 1.507"-1.510". Then they switched to a Hi-stop which has the same measurements as the CB-110. I replaced quite a few adapters, (free of charge...including back shipping), because my website had "Cranbrook" as a roll-out option.

c. 1.528"

From your measurements I'm going to say that the manufacturer of the Falcon hub; has changed the tooling. They may have had to replace the tooling after the last production run of hubs...who knows.

This is the very reason that it is impossible to inventory adapters for most hubs...custom orders, with wait times were just the necessary evil for this application.

The Shimano coaster brake hubs have been around forever...and knock on far they have been VERY consistent dimensionally. 1.526"-1.528"

I did, in the beginning, design an adjustable sprocket adapter. It would have cost $175.00 to produce, and I knew this market wouldn't bear that custom made one-off's, made to the size supplied by the customer was the only answer to keep costs in-line.

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