If you go back a few pages, I posted a few shots from my recce ride of the route. https://www.lfgss.com/comments/14785886/
It's road/tarmac until Epsom, then we cross the race course - its chalk/flint at that point, then leads to clay/sand and into woodland, after that it's road again, then fine gravel (a managed trail). The Downs link itself is gravel. After Stan's Bike Hut it's rougher gravel/clinker then fine gravel (managed trail).
It's all rideable on 28c light touring tyres. I probably wouldn't want to take 25c or 23c tyres unless you need some fillings removed and thin sidewall race tyres would probably be a mistake.
If you go back a few pages, I posted a few shots from my recce ride of the route.
https://www.lfgss.com/comments/14785886/
It's road/tarmac until Epsom, then we cross the race course - its chalk/flint at that point, then leads to clay/sand and into woodland, after that it's road again, then fine gravel (a managed trail). The Downs link itself is gravel. After Stan's Bike Hut it's rougher gravel/clinker then fine gravel (managed trail).
It's all rideable on 28c light touring tyres. I probably wouldn't want to take 25c or 23c tyres unless you need some fillings removed and thin sidewall race tyres would probably be a mistake.