Any bike that properly fits the rider can be comfortable. My fixed gear track bike is completely dialed in for me. I will ride that every day over an ill fitting hybrid or mountain bike or a dutch bike for that matter. I have no knee, back, neck, or any type of pain on my 8 mile daily commute on that track bike. The bike fits the rider, and taking it on a commute is like a warm up. I have taken it on 50+ mile rides with no issues.