Nice idea on the laser engraving, maybe we could use that inside the bottom bracket - thanks. We have considered the chain, trouble is both chains and chainrin

Nice idea on the laser engraving, maybe we could use that inside the bottom bracket - thanks. We have considered the chain, trouble is both chains and chainrings wear and often cranks/rings aren't terribly-well centred (as fixed gear bike riders know, from variations in chain slack). For the gravity part we've tested a range of accelerometers; vibration is quite an issue though. Thanks for the interest!