washer with a little hook in rear fork tracks

[Emanuel Berg]

Many times I've seen washers with a little hook
to be used in rear triangle dropout tracks.
Those (the washers) are pretty big.

E.g. the Shimano Nexus 3 has them, often in
some bright color like yellow. They are between
the dome nut and the rear fork tracks.

What is the purpose of the little hook or
protruding part, and how is it different from
a regular washer with a rough pattern, pointing
into the frame?

We assume both are pulled 28Nm.

[Frank Krygowski]

Post by Emanuel Berg
Many times I've seen washers with a little hook
to be used in rear triangle dropout tracks.
Those (the washers) are pretty big.
E.g. the Shimano Nexus 3 has them, often in
some bright color like yellow. They are between
the dome nut and the rear fork tracks.
What is the purpose of the little hook or
protruding part, and how is it different from
a regular washer with a rough pattern, pointing
into the frame?
We assume both are pulled 28Nm.

Internally geared hubs exert torque on the bike frame or dropouts in
certain gears. If the axle has flat surfaces and the washer's inner hole
has matching flats, I think the washers you describe are a way the hub
transmits that torque to the frame.

[Emanuel Berg]

Post by Frank Krygowski
Internally geared hubs exert torque on the
bike frame or dropouts in certain gears.
If the axle has flat surfaces and the
washer's inner hole has matching flats,
I think the washers you describe are a way
the hub transmits that torque to the frame.

Okay...?

The surfaces are flat! But there is also the
hook! Perhaps the hook is just a way of putting
it (the washer) there so the flats align
easily? But somehow that sounds unlikely!

And what happens with the torque if there is an
ordinary washer?

[John B.]

Post by Emanuel Berg

Post by Frank Krygowski
Internally geared hubs exert torque on the
bike frame or dropouts in certain gears.
If the axle has flat surfaces and the
washer's inner hole has matching flats,
I think the washers you describe are a way
the hub transmits that torque to the frame.

Okay...?
The surfaces are flat! But there is also the
hook! Perhaps the hook is just a way of putting
it (the washer) there so the flats align
easily? But somehow that sounds unlikely!
And what happens with the torque if there is an
ordinary washer?

Washers with the little "hook" are used in a number of devices as an
anti rotation system. The "hook" fits into a hole, or in the case of a
bicycle the rear dropout slots.

Do a google search for "anti rotation washer". There are literally
hundreds of different types.

[Frank Krygowski]

Post by Emanuel Berg

Post by Frank Krygowski
Internally geared hubs exert torque on the
bike frame or dropouts in certain gears.
If the axle has flat surfaces and the
washer's inner hole has matching flats,
I think the washers you describe are a way
the hub transmits that torque to the frame.

Okay...?

To further explain the torque:

With a derailleur hub or a single speed hub, the torque applied to the wheel
by the chain and sprocket is the same value as the torque applied by the
tire's friction force acting on the tire+wheel radius. Of course, the dirctions
are opposite. We engineers would say the sum of the torques must be zero, at
least for constant velocity situations.

When you shift an internal gear hub to a lower gear, the gear hub applies more
torque to the wheel than is applied by the chain and sprocket. That must be
generated by a reaction torque from the dropouts (or on some hubs, from a
reaction arm attached to a chainstay, etc.).

Post by Emanuel Berg
The surfaces are flat! But there is also the
hook! Perhaps the hook is just a way of putting
it (the washer) there so the flats align
easily? But somehow that sounds unlikely!
And what happens with the torque if there is an
ordinary washer?

I think there may be no problems with an ordinary washer, provided the nuts
holding the axle in place are tight enough. In that case, the torque will be
transmitted to and from the dropouts by the friction forces between the nuts and
dropouts.

With the washer, the axle flats transmit torque between the axle and the washer,
and the washer's tabs transmit torque between the washer and the dropouts,
helping the axle nuts transmit torque.

- Frank Krygowski

[Emanuel Berg]

We engineers would say [,..]

We long-ears would say, that while there are
many internally geared hubs w/o non-turn
washers (e.g., Duomatic and Dreigang/Triplex),
it is possible that development has moved
forward and that the Shimano Nexus 3 has them
(non-turn washers) to counteract the increased
torque, compared to a single speed hub.

BTW Nexus 3 has a break arm to.

[AMuzi]

Post by Emanuel Berg

We engineers would say [,..]

We long-ears would say, that while there are
many internally geared hubs w/o non-turn
washers (e.g., Duomatic and Dreigang/Triplex),
it is possible that development has moved
forward and that the Shimano Nexus 3 has them
(non-turn washers) to counteract the increased
torque, compared to a single speed hub.
BTW Nexus 3 has a break arm to.

Fichtel & Sachs Duomatic has a brake arm. Torpedo Dreigang
has a flatted axle with no-turn washer.

[Emanuel Berg]

Post by AMuzi
Fichtel & Sachs Duomatic has a brake arm.
Torpedo Dreigang has a flatted axle with
no-turn washer.

Ha ha! :)

Torpedo 3 has no-turn washers in the
flat axle/washer sense but not with the little
hook that the Shimano Nexus 3 no-turn
washers have.

And Dreigang has a brake arm as well! :)

[AMuzi]

Post by Emanuel Berg

Post by AMuzi
Fichtel & Sachs Duomatic has a brake arm.
Torpedo Dreigang has a flatted axle with
no-turn washer.

Ha ha! :)
Torpedo 3 has no-turn washers in the
flat axle/washer sense but not with the little
hook that the Shimano Nexus 3 no-turn
washers have.
And Dreigang has a brake arm as well! :)

There are several ways to extend axle flats with a no-turn
washer. None work any better than the others. It's a very
simple problem, as Frank clearly explained.

[Emanuel Berg]

Post by AMuzi
There are several ways to extend axle flats
with a no-turn washer. None work any better
than the others.

The reason to do it is

1) to keep it all together

and

2) if it gets loose, it won't get *that* loose?

[AMuzi]

Post by Emanuel Berg

Post by AMuzi
There are several ways to extend axle flats
with a no-turn washer. None work any better
than the others.

The reason to do it is
1) to keep it all together
and
2) if it gets loose, it won't get *that* loose?

23 April, in the first reply of this thread, Frank Krygowski
wrote:

"Internally geared hubs exert torque on the bike frame or
dropouts in certain gears. If the axle has flat surfaces and
the washer's inner hole has matching flats, I think the
washers you describe are a way the hub transmits that torque
to the frame."

With the patience of a saint, Mr Krygowski expanded on that
in his reply 24 April:

"With a derailleur hub or a single speed hub, the torque
applied to the wheel
by the chain and sprocket is the same value as the torque
applied by the
tire's friction force acting on the tire+wheel radius. Of
course, the dirctions
are opposite. We engineers would say the sum of the
torques must be zero, at
least for constant velocity situations.

When you shift an internal gear hub to a lower gear, the
gear hub applies more
torque to the wheel than is applied by the chain and
sprocket. That must be
generated by a reaction torque from the dropouts (or on some
hubs, from a
reaction arm attached to a chainstay, etc.). "


People have devised different styles to do that:
Loading Image...

Loading Image...

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and of course the original design:
Loading Image...


the exact shape doesn't matter except where axle-to-frame
position is critical, such as inside-cable designs like this:
Loading Image...

which are color-coded for various angles.

[Emanuel Berg]

Post by AMuzi
https://www.bicyclehero.com/media/catalog/product/cache/image/650x/bcf7ce64d63d93f1f374273bba74938d/8/4/8475.png
http://images.modernbike.com/256/main_2126212142.jpg
https://fasterbikes.eu/738-thickbox_default/axle-nuts-for-mxus-3k-5k-16-mmmotor-spare-parts.jpg
http://www.ucycle.com/merchant/2856/images/small/Capture47.PNG
http://i.ebayimg.com/17/!BnNUOswCGk~$%28KGrHqUOKicEtluYLPB6BLio-KnEdQ~~_35.JPG
the exact shape doesn't matter except where
axle-to-frame position is critical, such as
http://cdn.modernbike.com/Product_Images/large_49040.jpg
which are color-coded for various angles.

They look mostly the same to me. Partly flat
axle hole, sometimes with a protruding part
as well.

[Emanuel Berg]

Post by Emanuel Berg
They look mostly the same to me. Partly flat
axle hole, sometimes with a protruding part
as well.

So the answer to my original post would/could
be, "the reason for the little hook is to hook
into the frame's dropout track in order to
further hinder the washer from rotating/falling
out, should the dome/axle nut come loose.
However to this end the hook is a second-rate
feature because the most important thing is to
have a flattened axle and no-turn washer, with
or without a hook, but always with a flattened
axle hole"?

[Tosspot]

Post by Emanuel Berg
Many times I've seen washers with a little hook
to be used in rear triangle dropout tracks.
Those (the washers) are pretty big.
E.g. the Shimano Nexus 3 has them, often in
some bright color like yellow. They are between
the dome nut and the rear fork tracks.
What is the purpose of the little hook or
protruding part, and how is it different from
a regular washer with a rough pattern, pointing
into the frame?
We assume both are pulled 28Nm.

Anti rotation washer. The lug sits at various angles to the axle flats.
The colours indicate the angle. I have used white, red and green in
the past.

They work if the axle nut comes loose.

[Emanuel Berg]

Anti rotation washer. The lug sits at various
angles to the axle flats. The colours
indicate the angle. I have used white, red
and green in the past.
They work if the axle nut comes loose.

Amazing!