Nobody said that going green was going to be easy, and if you live in San Francisco, the hilly areas might just prove too much for your calf muscles to endure cycling up and down those killer hills each day. Why not get a little bit of outside help with the Ego-Kits E-powered Downhill Bike Kit? Whenever you’re heading downhill, your electric-powered mountain bike will use that golden opportunity to generate enough juice to power you over the next hill – giving your calves a much needed time break time. Capable of being compatible with up to 70% of commercially available downhill bikes, this little engine that could will turn your standard bicycle into a true uphill machine. Of course, there is always the issue of the battery pack weighing you down by some, but we think that at is a small price to pay for a whole lot of assistance uphill.