would you recommend a chest mount or head mount?

Chest every time! Much more interesting with your arms and bars in, than what appears to be a flouting camera on the helmet!
Take a look on dx.com, loads to choose from and way cheaper than the official GoPro stuff!
I got a aluminium bar mount which i use to mount to my seat post and forks (with a bit of inner tube) for like £3! with those sort of prices, you don’t mind buying and never using!

I like some of the footage ive had from the helmet mount on my Full facer,and the chesty is great when set up right,my 1st shoot was mostly of bike frame and no trail 😳

I’d go chest mount, but the angle of viewing is pretty critical and easy to get wrong.

I’d go chest mount, but the angle of viewing is pretty critical and easy to get wrong.

Not if you go into settings and set it to film upside down, then mount it upside down in the harness.

Think about a fork mount as well. I have a shoulder mount and a rear-facing mount near the rear axle, & am going to buy a fork mount next.
Wheel-angled shots give a great sense of speed & ‘lean’ & mixing up the viewpoints in the edit makes the vid much more interesting (mine are still dull but not quite as dull!)