speedometer magnet holder

I have got an old BSA motorbike and the speedometer is a bit dodgy.
so I purchased a wifi one as used on pushbikes. the spokes on the motorbike are 1/8th inch (3.2 mm) diameter so the original magnetic holder would not fit. so designed a holder so i could fit 4 small magnets in and would fit the spokes.
magnet are 5mm dia x 2mm thick, glued in