Sergii Gorieiev, a Ukrainian engineer, is the owner of a YouTube channel with millions of subscribers on which there are many inventions and gadgets.

One of The Q's specialities is on two wheels, specifically bikes (and bike parts) that break with the norms. We review some of the best.

Square wheels: it goes without saying that it seems impossible for this to work, but instead of turning the wheel, it turns the tyre.

Triangular wheels: these do turn, with a spectacular suspension that makes the bike functional.

Split wheel: the rear wheel is split so that there is no contact with the ground at any time and it continues to roll.

Shoe wheels: feel what it would be like to cycle in running shoes. With 12 running shoes, to be precise.

Invisible wheel: taking the spokes off a wheel and replacing with PVC glass makes it looks like it has no interior and the sensation is surprising.

Wooden bike: it took 200 hours to make this bicycle out of wood,  with a little metal in the chain  to make it more durable.

Walking bike: take your machine for an unexpected walk with a sort of bike/robot hybrid that looks like it has metal legs.

Snow and ice bike: Gorieiev replaces the usual mountain bike wheels with  circular saws to avoid slippage.

No-chain bike: it seems to be a fundamental element for a bike to work... but it can be replaced by another method.

World's smallest bike: the hardest part, more than building it (which is also difficult), seems to be riding on it. It can withstand up to 100kg!

Security bike: why carry an anti-theft system if the bike frame itself can be turned into a security device?