Had an email from alpkit and mentioned a mullet build bike. Had to Google to work out what was as couldn't work out how a bike could be work on top and weekend at back
Turns out it has a 29" wheel front and a 27 5" rear. I've heard of this before but this was probably before 27.5 so had a 26 one end and a 29 other so was more suggestively named a 69er