BT014 is a different tread pattern and I think the compound is softer. Its usually not a problem mixing tires as long as they are the same manufacturer and the same type of tire. As for being the same type of tire I mean sport tires with sport tires , not sport tires with touring tires. The BT014 is a better sport tire but I think the best choice would be to either change both front and rear tires or put on another BT56 on the rear and by the time you wear that one out you will be ready for a front tire too. If you just put the BT014 on the rear you might have some handling problems. These would be if you were riding hard in the corners with a harder front compound than on the rear, for just comuting you should'nt have any problems