I'm looking for a bike to use to ride to work and exercise. Will mostly be ridden on pavement but I'd like to still be about to take shortcuts and not struggle to get over curbs. Certainly won't be doing any technical terrains. I've found many used options in my area for around $100 but I'm not really sure what I'm looking for. I found a trek earl bike that I'm thinking of purchasing but reviews say it's too heavy and taking hills will be difficult without gear options... How true is this? Any advice or suggestions would be greatly helpful. Thanks

The trek is a single speed (44-17 gear ratio). Fine for flat riding, but if you hit any kind of hill it is difficult to spin the wheels with a 44-17 gear. OTOH, if you ride on pretty flat terrain, it's fine.