PDA

View Full Version : Brakeless gear hubs


Adam Rush
May 9th 04, 01:11 PM
When a gear hub is manufactured without a coaster or drum brake, what
is it usually made to do when back-pedalled? Does it freewheel for
all eternity or does it go a few rotations before going no further?

Zog The Undeniable
May 9th 04, 01:41 PM
Adam Rush wrote:
> When a gear hub is manufactured without a coaster or drum brake, what
> is it usually made to do when back-pedalled? Does it freewheel for
> all eternity or does it go a few rotations before going no further?

Usually freewheels for all eternity; at least, that's what
Sturmey-Archer ones do.

Werehatrack
May 9th 04, 04:16 PM
On 9 May 2004 05:11:02 -0700, (Adam Rush) may have
said:

>When a gear hub is manufactured without a coaster or drum brake, what
>is it usually made to do when back-pedalled? Does it freewheel for
>all eternity or does it go a few rotations before going no further?

All of the Sturmey-Archer, Shimano and Sachs non-coaster gear hubs of
my experience simply freewheel if back-pedalled. If there's no
coaster brake, the freewheeling sprocket on the hub should not care
whether the speed mismatch is due to backpedalling or not pedalling;
it will simply ratchet freely in either case.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

Adam Rush
May 9th 04, 06:53 PM
Zog The Undeniable > wrote in message news:<409e27a6.0@entanet>...
> Adam Rush wrote:
> > When a gear hub is manufactured without a coaster or drum brake, what
> > is it usually made to do when back-pedalled? Does it freewheel for
> > all eternity or does it go a few rotations before going no further?
>
> Usually freewheels for all eternity; at least, that's what
> Sturmey-Archer ones do.

Where I live, "Sturmey-Arch" is translated to "Sachs." Anybody with
info on the Dreigang?

A Muzi
May 10th 04, 01:25 AM
Adam Rush wrote:
> When a gear hub is manufactured without a coaster or drum brake, what
> is it usually made to do when back-pedalled? Does it freewheel for
> all eternity or does it go a few rotations before going no further?

Single and multiple speed hubs with no backpedal brake just
coast. You may indeed backpedal forever just as you could
with a Record cassette hub. Or a freewheel hub. Or a Profile
Racing flatland single speed hub.
Hubs which allow coasting by one means or another
incorporate a one-way device which engages the hub shell
when pedaling forward. That mechanism, usually a pawl in a
ratchet ring, just does not engage the other direction

Coaster ( backpedal) brake hubs have two mechanisms, one to
engage and drive the hub shell (for example, a clutch
that's pulled tight against the hub shell or a series of
rollers which run up ramps and jam against the hub shell)
and another to press a stationary component against a moving
one to provide braking ( either an expanding cylinder
against the hub shell or a series of discs engaged
alternately to the hub and axle which all press together or
some such). The default position, achieved by turning the
hub but not one's pedals, is disengagement of both mechanisms.

Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Google

Home - Home - Home - Home - Home