Dished washers on Honda spokes ...what are they for?

[AshimotoK0]

My '69 CB350K1 was fitted with little dished or cupped washers under the spoke heads like in this pic of a genuine Honda spoke kit (i.e washer fitted between the nipple and the inner face of the rim). Anybody know the purpose? Was it to give a bit of extra tightening if the threads bottom out if using the spoke without them  or perhaps they were fitted  to form a better spherical  'swivel' between the inner face of the spoke head and  the  curved surface of the 'washer' than you would get with just the rim spoke hole? All credit to Allenchrome in Pocklington  for not losing any of these when included loose with a big batch of parts for barrel plating BZP.

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[Trigger]

Me thinks that these were use as a sealing washer. Think some brit bikes had them.

[Tomb]

I have some vague recollection that some rims of materials like ali or the later stainless rims caused fatigue cracks around the spoke hole, so washers like this were used to spread the load more.

Something else to google anyway 

[JamesH]

Interestingly my '67 CL77 rims had these washers as well Ash. Be interesting to understand why..J

[AshimotoK0]

I got this info from a post on HondaTwins.net by a wheelbuilder in the States

"Honda use domed washers to serve multiple functions, load spreading as well as friction reduction to prevent galling NOT to make up for oversized holes"

[AshimotoK0]

It just dawned on me that the wheels that had the dished washers on the spokes were actually from a CL350K1 not my CB model ( they came from DK) plus James says his CL77 has them . Perhaps Honda fitted them to street scrambler CL models (and possibly SL) because of the potential extra 'pounding' they would get when the bike is ridden  on bumpy surfaces and off-road.