I must say that my O.T. tandem uses roughly the same amount of cable housing as my road bike, but the cable is almost 2X longer... and the rear brake is so mushy that I had to add a "brake amplifier" to make it useable. Granted, this comparison is not all apples to apples, since the canti brakes and lever on the tandem are different than those used on my road bike, amongst other things... but this example makes me believe that steel cables do stretch a bit, (within their elastic range), when you really squeeze the brake lever... Best regards,
Tom Royce in San Diego
> From: onetenth@earthlink.net
> To: kko@springfield-or.gov; classicrendezvous@bikelist.org
> 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" <kko@springfield-or.gov>
> To: <classicrendezvous@bikelist.org>
> 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
> >
> >
> >
> > _______________________________________________
> Andrew R Stewart
> Rochester, NY