As a number of folks have expressed, it depends. I kept the rear fender on this Spaceliner because I felt obliged to save the cool rear rack and the rack mounts to the fender. I did bob the fender because the rear brace was mangled. Fenders definitely add weigh and rattling noises, but sometimes the coolness is worth it.
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You can keep the rear rack and still lose the rear fender on a Spaceliner. I couldn't get the mangled ones on mine to work with the wider tires I wanted to use.