Originally Posted by CompleteStreets

So, by "those can be had," you mean "those cannot be had." Big, big difference between a chain guard and a fully enclosed chain case. The derailleur bike needs to be revolutionized, or perhaps scrapped in favor of a brand new design. IGH bikes are great but they are heavy and don't operate as well on uphill stretches as derailleur bikes. Maybe one day there will be a bike that has the best of both worlds (great on hills and zero maintenance with no need to roll up pant leg).