Slide you don't say but if the difference between commuting with cage and bike is 15 min, I take it you leave way before 6 in the mornings, becuase the only way that could be true is if the traffic is still very light. My experience has been that if I leave for work before 6 in the morning and after 7 in the afternoon with a cage I spend about 30 min commuting anything later or earlier I spend 2 hours barring any accidents.
I tend to LDā??s point of view. I started commuting because it got to the stage where I was spending more time commuting to and from work and at work than at home (leave 05:45, get back 20:00). Now I leave 07:00 for a 40 min commute in the morning and 16:30 for another 40 min commute and Iā??m back at home just after 5 in the afternoons. My opinion is that Iā??m saving at least 2 and half hours commuting time every day and that makes it worthwhile.
IMHO you donā??t save any costs if you commute by bike if you retain the cage as well, at best you break even. My reasoning is that you end up still having to pay the carā??s instalments, insurance, license, maintenance etc over and above that for the bike. If you add all of these costs together you may in fact find that it is more expensive than having only the cage and commuting with it.
For me itā??s a life style choice, using the bike I spend less time commuting and arrive at my destination relaxed instead of stressed out. And yes, I agree the risks associated with it are higher but I accept them as part of the trade-off inherent in my choice.