Planet Bike Eco Bike Rack https://www.amazon.com/dp/B000RYAKRC?ref=ppx_pop_mob_ap_share

This is what I use

I just got this one for my girlfriend. I think it's great and holds 50 lbs. Easy to install as well.

https://www.amazon.com/gp/aw/d/B000RYAKRC/ref=yo_ii_img?ie=UTF8&psc=1