Why pin your number to your favorite $20 technical shirt and risk putting a hole in it when you can pin it to a race belt instead?? Just place the belt with the pinned number next to your shoes and you can strap the number to your waist while you're running.
Rather than picking black like everyone else, pick from red, white, blue, or - if you must - black. Remember a colored belt will stand out better in the transition area and tends to keep people from picking your belt up by accident.
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