Scan books on the run

I'm a university student and cyclist so I need to scan books on the run, so sheetfed is pretty much out of the question, and it has to be lightweight as I'm already carrying an assortment of things which makes it strenuous biking for long distances.

I thought of something like Casio FREEDIO Portable Handheld Scanner but its reviews got me doubting that kind of product then (avoiding sheetfed) found the nice review Best Portable Scanner for College for Books and Photos but I don't know how much those weight.

A concern that seem to be completely unimportant in scanner detailed specifications is its weight and my premise mentioned that it's important to me. Is there some kind of rule of thumb when I'm looking into scanner weight ? I'm interested with portable scanner pointers as well, some general things that I should look for.

Thank you kindly