You have to be patient waiting for Google to re-cache a page and, even after they do, your rankings still might not improve with just onsite changes. You need backlinks too. Also, more internal links from blog posts can help too.
In terms of the type of content to write for the Alsace Bike Tours page, we'd recommend looking at the top ten ranking pages and get ideas from their content. Also, include any information that someone might want to see if they are searching for that phrase.
We looked at https://www.digngo.com/tour/alsace-bike-tour/ and think that you did a great job talking about Strasbourg and Colmar. Since those cities are the beginning and ending of the bike route it makes sense to talk about what someone can do in those cities.