[CR] Frame Alignment: Ugly scratches and Useful bike tools

(Example: Framebuilding:Technology)

Date: Fri, 30 Oct 2009 20:11:46 -0800
From: "verktyg" <verktyg@aol.com>
To: <Classicrendezvous@bikelist.org>, <freitas1@pacbell.net>
Subject: [CR] Frame Alignment: Ugly scratches and Useful bike tools


I started this new topic to avoid hijacking 2 divergent, converging threads: "Merckx bike ugly scratches" and "Useful bike tools"

RE: John Hurley - improvements in frame quality and Tom Sanders - Dropout alignment tools.

I agree completely with several posters that most American frame builders set a quality standard that has rarely been met by ANY of the European builders.

Many famous name European frames were (and still are) built without the benefit of a jig or any fixturing. Tubing fit was "eye-balled" and a lot of frames were assembled with main tubes that weren't even accurately mitered. After brazing, the frames were cold set to an approximation of proper alignment.

In a properly aligned frame the wheels should be parallel on a horizontal and vertical plane with the centerline of the bike. The dropouts should be equal distance from the centerline too. Head and seat tubes should be parallel. Fork blades should be equal length and have the same amount of bend and rake or trail. The front axle should be parallel to the front of the fork crown and the rear axle parallel to the bottom bracket.

A well aligned frame doesn't have any pull to either side and tracks well through corners especially when descending.

While there are other elements of frame geometry that come into play, a properly aligned frame will handle better than one that's out of alignment.

Anecdotal tale in reference to the growth of mail order sales in the 70s:

In 1977 someone brought a brand new all Campy Bob Jackson bike into our shop. It was beautiful, black and tan with crisp decals, pinstriping and a shiny clearcoat. It was one of the nicest finished frames I've ever seen.

The "customer" had just received it from mail order house in Southern California that was pushing a lot of Bob Jacksons, Colnagos and other well known brand frames.

He complained that the bike was "pulling". I took it out for a test ride and brought it back in less than half a block. It was pulling was an understatement! It wanted to go in circles!

I put it up on the stand and immediately saw that one chainstay was over 1/2" shorter than the other. I showed him the problem and politely sent him on his way.

The term "Hand Crafted" applies to many of the bikes that are the topic of the CR group. None were created by divine touch!

As such these creations are rarely going to be perfect but they should at least ride and handle well by intent not accident.

Chas. Colerich
Oakland, CA USA