Probably didn't need to do a blog post about this but thought of the title and seemed a shame not to...
AHBART had slight vibration at certain speeds (at least two multiples of 45 km/h) from the rear, felt like, L/H side. After getting the tyres/balance checked turned out to be a slightly buckled rear wheel. There was no rim damage (as in a dent) but it wasn't quite round anymore. May even have been a legacy of last year's 3000km road trip as did have to get the front one fixed after I hit a pot hole. Seems 40 profile tyres and Kiwi roads sometimes don't get on.
With replacements well over a grand, and a very small chance of second-hand being available due to rarity, was glad the team at Wheelfixit (Wairau Rd) could do what they say and sort it out. AHBART's rolling smooth again.