[CR]TA Cranks, threads, etc.

(Example: Production Builders:Tonard)

From: "Mark Petry" <mpetry@bainbridgeisland.net>
To: <classicrendezvous@bikelist.org>
Date: Mon, 7 Jul 2003 15:31:18 -0700
In-Reply-To: <CATFOODUicYPij7uA0E00000dc9@catfood.nt.phred.org>
Subject: [CR]TA Cranks, threads, etc.

In re the current discussion on pedals threading in "hard" or easy, here is my thought. The thread forms used for ISO standard vs. old style BSC / italian / french threading for FREEWHEELS had some differences not only in the diameter and pitch of the threads, but also the the thread forms and the finishing of the thread crowns and valleys.

Memory has faded (anybody else have this problem) but seems to me the Italian hubs had 55 degree threads, and the french threads were radiused in the crowns and grooves (others were flat). Current ISO standards dictate a 60 deg thread andgle and the crowns and grooves finished with a flat. An italian freewheel, if you recall, would fit on a BSC hub with a "class B fit" that required some lubrication and more than normal torque, because the diameter and TIP were the same, but the thread forms slightly different.

Is is possible that the TA pedal spindles, even tho threaded to an ISO standard 9/16 X 20 size, may have slightly different thread forms "from the old style" and therefore cause slight interference (but no shavings) when threaded into "modern" crankarms.

===================================================== Mark Petry 206.618.9642 Beautiful Bainbridge Island, WA mpetry@bainbridgeisland.net

===================================================== "Never be afraid to try something new. The Ark was designed by amateurs. The Titanic was designed by professionals."

R. Buckminister Fuller =====================================================