The best places will be north of the aforementioned cattlegird, where the Templar Way path is, https://goo.gl/maps/x25E4NrtEH3u2JTn9
There's a few places in the trees lower down the climb, but as it's not a closed road event it'll be too narrow/dangerous in a lot of it for spectators.
As dbr says, Haytor Vale is probably the best place. Although best gurns might be seen at the start of the trail in that link. There are a small few carparks off the main road. Also avoid Cafe360 in bovey, expensive and slow. The brookside has been friendly to cyclists for years.
The best places will be north of the aforementioned cattlegird, where the Templar Way path is, https://goo.gl/maps/x25E4NrtEH3u2JTn9
There's a few places in the trees lower down the climb, but as it's not a closed road event it'll be too narrow/dangerous in a lot of it for spectators.