Joined: May 2008
Posts: 10,106
Likes: 2,757
From: Fredericksburg, Va
Bikes: ? Proteous, '65 Frejus TDF, '73 Bottecchia Giro d'Italia, '83 Colnago Superissimo, '84 Trek 610, '84 Trek 760, '88 Pinarello Veneto, '88 De Rosa Pro, '89 Pinarello Montello, 'Litespeed Catalyst'94 Burley Duet, 97 Specialized RockHopper, 2010 Langster
Others more knowledgeable or experienced will pipe up.
First, it isn't 10mm extra, it is 5. you need to split it for both sides.
Likely the hub width isn't much different as rim dishing will keep the block closer to the chain line. The difference will be small enough not to matter too much.
Run whatever count of sprockets you want. I would space the block as close to the hub flange as the RD will allow without getting into the spokes in the lowest gear. Match the chain to the number of sprockets on the block.
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