this is a somewhat heated debate.
many different people have many different opinions on the subject.
My bottom line... not safe. risk vs reward is too great.
Plus I like to use my ride time a as a "personal mental vacation" (other than safe riding practices). me and my thoughts alone to work it all out and just be part of my surroundings as they zip by.
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2010 Kestrel RT900SL, 800k carbon, chorus/record, speedplay, zonda
2000 litespeed Unicoi Ti, XTR,XT, Campy crank, time atac, carbon forks