"Twenty-five tyres, 12 bicycle chains and two saddles - that's how many times you can expect to change parts on a bicycle when cycling 86,000km (53,000 miles) around the world."
The cycling doctor is Stephen Fabes; I really like the story of the start of his journey.
For comparison, I go through six chains and twelve tyres a year. The conditions for cycling around the world are seemingly a lot less harse than for cycling in Aberdeenshire.