Spoke angle difference between a disc and drum brake SF

71Laverda750SF

71Laverda750SF

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Replacing the front rim on a SF2 that was crunched in an accident. The spoke angles look different than the drum brake rim, illusion or reality? If reality, anybody have a SF2 front rim they don't need (or want to swap).

Clay
 
'71 SF said:
If reality, anybody have a SF2 front rim they don't need (or want to swap).

Clay
Click to expand...

Hi Clay, pretty sure they're different: what's the Borrani rim # on the SF2? I think there might be a couple on the 'Bay presently (not sure of condition though).

AndyW 8)
 
You only need to compare the different size hubs to see that the drum spokes are way shorter therefor a shallower angle.
New Butteronis are now available for a pretty reasonable price.
 
Drum brake rim is 4446.
Disc brake rim is different but not sure of the number. Will be same rim as on 3C if anyone can advise.
 
Thanks for the confirmation and comments, I'll have to do some more research on the rim. While looking at the two the angles look different (as Rob points out), but maybe the rim I have was buggered up when they laced it since there is a pretty good amount of play to move the spokes around. I was pretty sure the holes should have been set at specific age with a little play but this old rim seems to be more than what I would expect. Let the search start.

Clay
 
motoddrob said:
You only need to compare the different size hubs to see that the drum spokes are way shorter therefor a shallower angle.
New Butteronis are now available for a pretty reasonable price.
Click to expand...

The spoke pattern also differs from front to rear.  Laverda used a rare (and un-loved by wheelwrights) 3-cross pattern to increase possible loads on the rear rims.  This is difficult to copy with todays rims, as dimples are often too shallow to allow the flat exit angle of the spokes, the drillings generally overlap into the centre of the rim.  Normal practise is to have the spokes cross only twice between rim and hub with a steeper spoke angle, as in Laverda front wheels.

WTF are Butteronis??

piet
 
That lace pattern I have seen referred to by some wheelwrights as a Super Lace, some do it to wheels to take extreme offroad work on the heavyweight Adventure Bikes around these days.
 
The rear rims (drum ) have a steep single crossspoke pattern so the nipple drillings are a different angle to the disc front rims.
Thats the difference in the 4446 rim and the 4761 rim although I have seen the incorrect lacing on a rear rim haven't I Brett.
 
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