bikaso

hi,
could you you help me with right size fender for my bike, the tire size is 700x38c ?
thank you

JohnDThompson 

Measure the distance between the seat stays at the brake bridge and the distance between the fork blades at the fork crown, and that will tell you the widest fender you can fit. There's really no downside to getting a wider fender than strictly necessary, and too narrow a fender will not be effective.

bktourer1

Take a look here, Bike Fenders - Front & Rear Bicycle Fenders - Planet Bike some pretty good info

maddog34

To sum up... in your case, Frame size and Capacity matters, not tire width... and i've seen some creative trimming done to fit too-wide fenders into a frame.

grumpus

Increased weight and aerodynamic drag. These things are important to some people.
That depends on the tyre and where it's used - with a smooth tread on a clean surface most of the water is flung off the centre portion of the tread so a mudguard that doesn't cover the full width is still quite effective.

JohnDThompson 

Such people are unlikely to consider mounting fenders in the first place.