If the bike shop or mail order company that you purchased the product from can't answer your question, you can e-mail your question to customerservice@profile-design.com, or call (888) 800-5999 ext 161, and ask to speak with someone on our Customer Service team.  Office hours are Monday through Friday, 8:30 AM - 5:00 PM Pacific Standard Time. Our staff of cyclists know every detail of the product line, what products work best and size-related specifics.