Re: [CR]Why normal reach calipers on short reach frames?


Example: Component Manufacturers:Avocet

Date: Fri, 11 Jan 2002 17:22:50 -0800
From: Brian Baylis <rocklube@adnc.com>
To: Sheldon Brown <CaptBike@sheldonbrown.com>
Cc: classicrendezvous@bikelist.org
Subject: Re: [CR]Why normal reach calipers on short reach frames?
References: <3C3F666E.52AEF5F7@ventoux.com> <v04210102b8651bfeb477@[10.0.1.13]>


Sheldon,

Pin a silver star on Mr. Sheldon Brown! That is exactly the reason for minimizing the brake reach on a racing bike. The same principal applies to track frames and tire clearance between the fork crown and the seat stay bridge.

That Sheldon, such a fountain of information!

Brian Baylis
>
> Lee Berg wrote:
> >I have noticed a number of '70s bikes, whose frames appear to have been
> >made for short reach calipers, sporting normal reach calipers with pad
> >holders in the tops of the slots. Were normal reach calipers installed
> >due to some desired mechanical property of this arrangement?... or due
> >to a some extended shortage of short reach calipers?... or was it just a
> >fashion of the time?... Or...???
>
> Short reach calipers generally have a reach range of 39-49. Long
> reach is usually 47-57. (Talk of "normal" reach is likely to be
> confusing, and I'd urge everybody to purge this ambiguous term from
> their vocabulary.)
>
> A caliper brake has its greatest mechanical advantage when the pads
> are high up the arms, close to the pivot. Back when long reach was
> the "norm" a conscientious frame builder building a high performance
> bike would locate the bridge and crown to maximize the braking
> mechanical advantage. Especially, the old Campag single pivots had
> such poor braking that this was a very nice touch.
>
> You may also see this on bikes made to work with both 630 mm (27
> inch) clinchers and 622 (700c) tubulars. When the larger wheels were
> installed, the shoes should be near the tops of the slots.
>
> Sheldon "Stop!" Brown
> Newtonville, Massachusetts
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