An e-bike for seven kilometers is basically the perfect scenario, because the distance doesn't require a super-powerful battery, but the discomfort in heat and winter on a regular bike will really wear you out after a month or two. The main thing is to buy a model with battery range to spare (at least 50-60 km per charge) and pedal assist up to 250W, so you don't run into registration costs. The cost pays for itself through savings on fuel and public transport plus the convenience, especially if it's rainy or hot: you won't show up to work all sweaty like you would on a regular bike. Sure, it's not cheap, but if you've ridden a bike before, then you're ready for this kind of transportation - the electric version just eliminates the downsides.