[CR] "Frame saver" forks (was: EVEN MORE info on NOS Flat crown front forks - Special offer)

(Example: Racing:Jacques Boyer)

Date: Sun, 14 Mar 2010 19:55:18 -0500
From: "John Thompson" <johndthompson@gmail.com>
Organization: The Crimson Permanent Assurance
To: classicrendezvous@bikelist.org
References: <8CC8E332EDAEB1F-2564-A331@webmail-m095.sysops.aol.com> <208865.44298.qm@web82306.mail.mud.yahoo.com> <9327C3B25BD3C34A8DBC26145D88A90717317B@hippy.home.here>
In-Reply-To: <9327C3B25BD3C34A8DBC26145D88A90717317B@hippy.home.here>
Subject: [CR] "Frame saver" forks (was: EVEN MORE info on NOS Flat crown front forks - Special offer)


Mark Bulgier wrote:
> Champion forks are strong enough for any but the heaviest riders, and
> stronger is not necessarily a good thing here. For instance on a
> classic lightweight frame, having a fork too strong could make the
> frame buckle and be ruined, in many real-world collisions where the
> frame would not have buckled if the fork had taken the impact by
> bending. I really like to see a bent fork after a crash, it shows
> the fork did its job. That's one reason I like steel forks over CF,
> which can't absorb crash energy by bending.

The first couple runs of 753 frames we did at Trek used what we called the "frame saver" crown -- an Ishiwata SCM crown with material milled out between the steer tube and blades. Before modification, the SCM looked sort of like the Cinelli MC:

http://www.velobase.com/VeloImages/FrameParts/A40A8DD9-0365-4722-BFC6-31BC535FC07C.jpeg

After modification it looked like this:

http://www.os2.dhs.org/~john/ishiwata-1.jpg

It was much easier and cheaper to replace a customer's 753 fork than to replace the frame.

Later runs were changed to a Tange crown that wasn't as malleable:

http://www.vintage-trek.com/images/trek/JohnSatory/Satory12_320.jpg

I'm not sure why the change was made.

--

-John Thompson (john@os2.dhs.org)
Appleton WI USA