Re: [CR] Brakes and Flex


Example: Framebuilders:Masi

From: "Andrew R Stewart" <onetenth@earthlink.net>
To: "KO Kevin" <kko@springfield-or.gov>, <classicrendezvous@bikelist.org>
References: <C1E1D2BFD0E40040BA644474C38411A605B6C0DD54DA@spifs030.Springfield1.net>
In-Reply-To:
Date: Wed, 5 Jan 2011 15:55:01 -0500
Subject: Re: [CR] Brakes and Flex


Kevin- I do very much like using non instrumented methods to test theories. But a few points about your suggestion. It might be hard to localize the cable tension increase from any lever or tube stop flex (especially lever movement or flex). Second, with the cable effectively touching the casing/stops at the entry/exit points wouldn't that tend to just dampen the cable in housing portion of the tonal changes. Third, couldn't the same be done for the housing? (Although it might not have much "ring" to it's being plucked, it's tension will definitely be different under tension). Seems to me that your experiment has too much "noise" in it (sorry but couldn't help making that pun).


----- Original Message -----
From: "KO Kevin"
To:
Sent: Wednesday, January 05, 2011 3:38 PM
Subject: Re: [CR] Brakes and Flex



> Elastic stretching of the brake cable is easy enough to verify or refute
> for those of you who have a bike with a length of exposed cable along the
> top tube. Take up the slack by moderately squeezing the brake lever.
> Then start plucking the cable like a guitar string as you increase the
> force on the brake lever. As a guitar player and builder, we know that
> you cannot increase the pitch of a string without either shortening it or
> elongating it to increase the tension. So, if the pitch of the brake
> cable increases as you squeeze the brake lever, the tension of the cable
> is increasing and the cable is stretching. If the frequency doesn't
> change, the "stretch" is in the housing, shoes, calipers, etc.
>
> Kevin Ko
> Eugene, OR USA