I guess I'll have to start putting the source in again, especially for poor Motley. The 30% loss of cyclists in Eugene since 2009 comes from the US Census American Community Survey. It tracks mode of commuting, a reasonable stand-in for overall cycling. In 2009, 10.8% of all workers living in Eugene used their bikes to commute. In 2015, the latest year of data, that had fallen to 7.6%.

It's a little difficult to get to the data if you haven't played with it before, so here's some help. Go to American Fact finder, scroll down to American Community Survey, click on "get data". In the new page, click on geographies, select "place", choose your state, select the city you're interested in and then close the geography window. In the data choices, click on "commuting characteristics by sex" (one year data, not 5-year smoothed) and you will see the various modes broken down by numbers, percentages and genders. To see other years, select one from the list on the left.