In regards to Sunnyday, they are extreamly made now. They are a Korean made (not Chinese) scooter. not only is it a pain to peddle but they drilled the holes the wrong and the left peddle has a tendency to loosen as you peddle it. there is no form of locking mechanisms on the bikes structure which allows bolts and nuts to loosen as you ride your bike. I do put strong reguards to the term NOW though because the older bikes (like pre 2010ish) were better built and didnt have as many problems. also the bike handles well with a 250 LB man and his 180LB GF on it. (although they not rated for more then 300) the other problem with them isthe center of balance on the bike is positioned to far to the rear and if you do put a decent amount of weight behind you (say 50+ lbs) you start to loose traction on the front tire.

In all honesty your best bet is to go down to a bike shop and order yourself a decent Hybrid Automatic 21 Speed bike fr a decent price (say about 500ish dollars) and then go buy one of the very nice electric motors that power the chain and not your tire or your peddle. the reason for this is you can then have a standard bike rate up to about 45 MPH if you really wanted to but could also tone it down to the standard 25MPH all by the adjustment of a derailer.