I used this product
"I have used this product several times on rides, in particular to pull my 5 year old son up complicated climbs for him. The product is as described and works as shown in the video. It fitted my bike and my son's bike perfectly. I'm waiting to see over the long term whether the winder and rope will hold up over time. I find the price a little excessive for the item so I hope it lasts but it's a great idea for a product that has changed my latest rides and created enthusiasm in my child."