In my experience a very bad idea. BBS02 motors, really hate being lugged. They are easy to overheat if not actively shifting and using appropriate gears. The speed gain is negligible and the damage is easily done. I have 2014 BBS01A 250W and 350W still running BUT I never use a throttle to take off unless I'm on the largest rear sprocket. As usual, you can find lots of other "one off" opinions. I added a shunt and accurate watt meter(CA3) to test my BBS01 and 02s for watts drawn under stress. And sure enough, the 52T really pushed the limits and it was easy to raise motor temps. I backed off and have 48T and 52T OEM gathering dust on a shelf, where they belong, for 5 years. Larger chainwheels often won't fit on fat bikes due to the wide chainstays.