The teenager, who is well-known from his appearances on Our Yorkshire Farm with his mother, visits Hertfordshire at the British championships, where he finds out about the sport, which is becoming increasingly popular.
He said: ”I’ve always wanted to have a go at this before I try and build my own lawnmower racer.”
Reuben finds out that the lawnmower racers can go up to 55 miles per hour on a big track.
After having a go, the 17-year-old - who has been working as an apprentice mechanic helping to fix tractors, says :”That was great, I’m going to go away and build one and come back next year and take part.”
Presenters Jules Hudson and Helen Skelton also try out the lawnmower machines in the show.
Farmers Rob and Dave Nicholson visit The Penistone Show where it's a big day out for the Cannon Hall Farm team - and some of their best-looking animals - as they aim to impress the competition judges and bag some rosettes.
Regulars Rob and Dave go to collect their beloved shire horse Orchid from the stud farm. The duo are re desperate for a foal, but will there be the pitter patter of tiny hooves next spring?
The show also catches up with one of Britain’s youngest farmers, nine-year-old Joe Trofer-Cook, as he attempts to buy his first sheep at auction, while Cannon Hall Farm head chef Tim Bilton travels to Jersey to visit the largest oyster farm in Britain.
This Week on the Farm is on Channel 5 tonight (Oct 13) at 8pm.