If you are a "fair weather" cyclist, you don't need fenders, but if you are a serious cyclist, and don't live in a desert climate, you really should have at least one bicycle with fenders.
Fenders make a tremendous difference when you are riding roads that are wet from drizzle, recent rain, or snowmelt.
In a hard rain, you may become wet with clean rain from above, but fenders will protect your body and bicycle from the mud and sand kicked up from dirty puddles and rivulets.
The British use the word "mudguards". In the early days of the bicycle when horses were common, that word only began to describe the advantage of fenders!
Rainproof clothing completes the picture of the well-equipped wet-weather cyclist. A rain cape
-- and if you need to keep your hair dry, a helmet cover -- allow free ventilation and maximum comfort. A jacket of Gore-Tex™ or other breathable fabric also can do the job, though it can get sweaty and hot in a warm rain. A jacket with a hood, or a conventional poncho, is not recommended, because it will interfere with vision when turning the head.
Photo: cyclist and bicyclefixation blog
author Richard Risemberg stays clean and dry with fenders, a rain cape and a helmet cover. Note that his headlamp is mounted below the hem of the rain cape. Photo by Gina Morey Risemberg.
Fenders Protect Your Bicycle
Many cyclists protect themselves from rain by wearing rainproof clothing, but they forget that their bicycles don't like dirty water any better than their bodies do.
The water kicked up by your wheels is much worse for your bicycle than the clean rain falling from the sky. If you ride in wet conditions without fenders, your chain, derailers and brakes will all get sprayed with sandy, muddy, scummy water, often mixed with gasoline residue. This is very bad for these parts.
Even more vulnerable is the lower section of your headset
. Headsets are designed to shed water like the shingles of a roof, and are basically rainproof...but the gritty spray from below has easy entry to the bearing surfaces of the heavily-loaded lower races.