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Are SA hubs X-SD 70mm side specific ?

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stormbird View Drop Down
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    Posted: 25 May 2019 at 5:50pm
Hi there

On a pair of new hubs back plates I have one of my back plates has a R cast in it ? the other has a F ?

So I bought a s/h wheel/hub & back plate that came from a well known tadpole trike the back plate has an F cast in it and a hand written ' right ' on the back plate ? 

regards Paul
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MatthewLR View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MatthewLR Quote  Post ReplyReply Direct Link To This Post Posted: 03 June 2019 at 9:08pm
The cast F and R refer to front and rear respectively for the standard bicycle application, the hand written right indicates that the well known trikes intended this to be used on the right hand wheel. The difference between left and right only being the orientation of the lever that moves the pads. The hubs themselves have no orientation at all.
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stormbird View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote stormbird Quote  Post ReplyReply Direct Link To This Post Posted: 04 June 2019 at 10:13pm
Matthew

Thanks for this.

Originally posted by MatthewLR MatthewLR wrote:

The cast F and R refer to front and rear respectively for the standard bicycle application, the hand written right indicates that the well known trikes intended this to be used on the right hand wheel.


I though that at first except I could not understand how the 'rear' one was driven ?


Quote The difference between left and right only being the orientation of the lever that moves the pads. The hubs themselves have no orientation at all.


Thanks muchly.

regards Paul


Edited by stormbird - 04 June 2019 at 10:13pm
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Brucey View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brucey Quote  Post ReplyReply Direct Link To This Post Posted: 11 September 2019 at 4:32pm
FWIW single cam drum brakes always have one leading shoe and one trailing shoe. However they are also sensitive to the rotation direction of the actuating cam; because of both cam geometry and friction on the cam, the force exerted on the brake shoe varies with cam direction.   Thus the brake plates need to be 'handed' (i.e. perfect mirror images of one another if the brakes are to work identically on each side.

The stub axle brake plates are indeed normally meant for Front (LH) and Rear (RH) fitment; the idea is (I think that the shoes wear slightly more evenly if the cam rotates in the wheel direction as the brake comes on.  The difference between the stub axle brake plates and the bicycle ones is also (of course) the shape of the reaction arms, which are rivetted on to the brake plate itself.

cheers
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Post Options Post Options   Thanks (0) Thanks(0)   Quote stormbird Quote  Post ReplyReply Direct Link To This Post Posted: 12 September 2019 at 8:11am
Brucey

Thanks for this

regards Paul
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brucey Quote  Post ReplyReply Direct Link To This Post Posted: 12 September 2019 at 9:31am
oops I meant the other way round of course; for stub axle use the 'front' style plate goes with RH brake and the 'rear' goes with the LH brake, if the cam rotation direction is to be as per a bicycle front brake.

cheers
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