[CR]RE: Now: Two-speed track bike

(Example: Framebuilding:Brazing Technique)

Date: Thu, 6 Mar 2008 19:31:32 -0800 (PST)
From: "Fred Rednor" <fred_rednor@yahoo.com>
To: Classic Rendezvous <classicrendezvous@bikelist.org>
In-Reply-To: <477311.21944.qm@web55905.mail.re3.yahoo.com>
Subject: [CR]RE: Now: Two-speed track bike

> My understanding of the dual drivetrain setup is that it had
> a lower gear on a freewheel attached to one side of the hub,
> and a higher gear fixed cog on the other side. The fixed cog
> is started on the thread but still several revolutions from
> being seated against the hub. The difference in ratios means
> that the fixed cog is screwing itself on as the rider starts
> in the lower gear and once the fixed cog seats on the hub it
> takes over and the freewheel begins to freewheel (as
> freewheels sometimes do) due to the lower ratio relative to
> the fixed side of the drivetrain. Clearly this would require
> some left-hand threaded parts for the left side drivetrain.
> I think the rider coudl find tune the time/distance that it
> took to engage the high gear using ratio difference and the
> extent to which the fixed cog is started on the hub thread.
> The benefit is a lower gear for a faster start in a track
> TT event (kilo, as I recall).

It's an interesting mechanism. But one major disadvantage is that it is not legal for sanctioned track racing competion. Fred Rednor - Arlignton, Virginia (USA)

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