Despite others saying this item does not work, if you follow the instructions and apply a bit of logic the item actually does securely fasten to a bike. The instructions are very vague, but the product itself works very efficiently and securely on my bike - because of the vague instructions, this product gets a 4 star rating. All you have to do when you receive this item is criss-cross the velcro and run it to the back of the product. Then, loop the velcro (still criss-crossed) through the two slits in the back. After this, criss-cross them again and they will attach to the other velcro very securely, it won't fall off at all. I've tested this on a real road for an hour and I can confirm it didn't move at all! Great product. :-)