3/8. Can 40-year-old mountain-bike instructor Tony Griffiths from North Wales realise the ultimate mountaineering feat? It's a gruelling month of climbing in freezing temperatures and biting 200mph winds before a final push for the top. Add to that the depressing odds - only one in eight reaches the summit of Mount Everest, while one in ten of those does not make it back at all - Griffiths faces an uphill battle, literally. Producer Ewen Thomson : Series producer Richard Sinclair (AD)