We always ask "where are you riding said bike" Personally I would rather have a bit more clearance between my tire and fender. Coming to a complete, unexpected halt due to something getting caught between a fender and a tire isn't fun. So keep in mind where you are riding and how much stuff - twigs, leaves et al are on your path. Of course, I also hear the concern about looking a bit silly if there is too much space. we have found the 10mm rule of thumb to work well, thus the post.
Sky King
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Gilles Berthoud "Bernard"
Surly ECR "Eazi"
Empowering the Bicycle Traveler
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