from the Nashbar customer service rep i emailed, because i saw a 15% off bikes/frame and the 20% coupon for one item

"The coupon for 20% off is not valid on bikes. Please click on the exclusion link on the coupon.

We do have a 15 price protection policy. However, it is only valid on actual merchandise pricing, not coupons or promotions.

Regards,
Kimberly
Customer Service"