Re: [CR]Silca Imperio questions and WTB

(Example: Production Builders:Teledyne)

In-Reply-To: <404E0D7E.804BCCF2@earthlink.net>
References: <19e.213d016d.2d7f696c@aol.com> <20040309190112.M68604@veloworks.com>
Date: Tue, 9 Mar 2004 22:52:52 -0500
To: chuckschmidt@earthlink.net, classicrendezvous@bikelist.org
From: "Sheldon Brown" <CaptBike@sheldonbrown.com>
Subject: Re: [CR]Silca Imperio questions and WTB


Steven L. Sheffield wrote:
> > But Silca's are a PITA pump to use compared
>to a Zefal ... but they're a lot
>> better looking, especially on a classic, lugged-steel frame.

Chuck Schmidt wrote:
>The Silca is built for lightness primarily, and all its limitations are
>a consequence of that. A racing part that might not be the best choice
>for riders not interested in lightweight racing parts.

Actually that's not quite it. The Silca is built for _speed_. A pump, like a bike, has a "gear" which is mainly related to the area of it's piston.

A large diameter pump like a Silca has a "high gear" and pumps a greater volume of air per stroke than a skinny one of the same length does. Being "geared higher" it does require more strength to compress the air to a given pressure.

Riders with weak arms and high pressure tires are generally better off with a skinnier, "lower geared" pump such as a Zéfal HpX...but a rider with strong arms can get back on the road quicker with a Silca.

Jobst Brandt has pointed out another key aspect of pump design, viz., that it is desirable that the air volume in front of the piston be as close to zero as possible when the piston is compressed all the way. Any airspace left between the piston and the valve is air that is compressed at some physical effort, but to no use. The Silca design (and also Zéfal) minimizes this wasted airspace, so as much of the compressed air as possible actually goes into the tube, rather than springing out when the pump handle is pulled out for the next stroke.

This is a big part of the superiority of direct-connect pumps vs those with hoses.
>The company started in 1917 making light weight pumps out of celluloid.
>
>Silca speecy, spicey, meataball:
><http://www.silcapompe.it//graficahome/silcahomeex3_r12_c19.jpg>
>
>Silca history:
><http://www.silcapompe.it/engl/pagine/storia.htm>

Neat links!

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