HathiTrust is a free online digital library containing over 17 million items. About 40% of the content (over 7 million items) are in the public domain and fully available online. The remaining items have an active copyright but the text may be searched.
The HathiTrust digital library is the product of collective effort by many academic, public and research libraries as well as museums (see list).
The Internet Archive has 35 million books and texts uploaded by libraries, archives, government entities and more.
In the left bar, enter search terms and select "Text contains" in order to search full text for words and phrases. (A search in the "Metadata" option will only look for your search terms in the titles and subject headings).
Google Books Advanced Search is definitely the best for "needle in a haystack" searches but not so great for reading online. Tip: try Google Books Advanced Search for discovery and then switch to HathiTrust for reading online. Books often show up in both databases.
PROS: On the results list, Google will rank highest those which have the search terms close together (for example, within the same sentence or paragraph, or on the same page)
CONS: The results lead to pages in books or periodicals, but it is not easy to see the titles or dates of the publications.
More bicycle travelogues, some of which are online...