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The route I'd take is trying to fit a second disc to the CM400 wheel, aren't most Honda wheels drilled right through so a disc can be fitted to both sides? even if they ain't I'd do it, the CM400 has a cover over the non-disc side, I wouldn't take that off coz it'd mean removing the pegged nuts but the centre of it could be machined out and the hub drilled and tapped, and the disc spaced out with spacer disc.