Re: [CR]Calculating fork rake?

(Example: Production Builders)

From: <OROBOYZ@aol.com>
Date: Thu, 16 Oct 2003 15:46:54 EDT
Subject: Re: [CR]Calculating fork rake?
To: aphillips9@mindspring.com, classicrendezvous@bikelist.org


In a message dated 10/16/2003 2:19:16 PM Eastern Daylight Time, aphillips9@mindspring.com writes:

<< ....helping my neighbor, Jenna, put together a nice little steel 1980 Rossin she got. We are totally unable to insert any stem, - and I had a lot of stems to try - in the steerer tube. I had my local frame repair resource check it out and Tamara is convinced that the tube is either slightly bent or deformed in some way and it would be best to replace the entire fork.

Now I can get a pretty inexpensive chrome fork from QBP, thats just fine. Question is, this is a very small frame, like a 48 cm and I want to measure the fork rake on the existing fork. It looks like it has a lot of rake, to avoid some portion of toe clip overlap. Obviously I'd want to compare the original fork to the one in the QBP catalog.

Is this something I can do without engaging a mechanical engineer? With you know, tools at home, like a tape measure and a calculator? >>

If you were in Greensboro, we would certainly try using a correctly size ream to see if that steerer had a goober or two inside it (certainly before throwing the fork out!) It's a shame you don't have a well equipped old school bike shop nearby (Tell your boss Fred I said that! Ha!)

Measuring the offset can be done (not exactly but close) by:

- laying the fork down, tips up on a flat surface, making sure that the steer tube in parallel to that surface. - From the flat surface, measure up to the center line of the steerer (A) - From the flat surface, measure up to the center of the drop out. (B) - subtract A from B.

A small Italian bike like that is likely to have a whole bunch of offset...way over 50 mm.

Dale Brown
Greensboro, North Carolina