Complex sentence: Circulation leapt from 25,000 before the Tour to 65,000 after it; in 1908 the race boosted circulation past a quarter of a million, and during the 1923 Tour it was selling 500,000 copies a day.
Split into simpler sentences: Circulation leapt from 25,000 before the Tour to 65,000 after it. In 1908, the race boosted circulation past a quarter of a million, and during the 1923 Tour, it was selling 500,000 copies a day.