I'm looking at the Ampedbikes 26 product description on amazon.com and see a weird statement that doesn't quite compute
Brushed motors are very inefficient and wear down your batteries quick!
A battery contains N kilowatt-hours and I don't think it matters whether a motor is brushed or brushless. The controller & motor consumes electricity and the battery delivers electricity. If a given motor is less efficient than another given motor then the same work takes more KWH's to perform.
BLDC motors are often more efficient at converting electricity into mechanical power than brushed DC motors. This improvement is largely due to the absence of electrical and friction losses due to brushes. The enhanced efficiency is greatest in the no-load and low-load region of the motor's performance curve. Under high mechanical loads, BLDC motors and high-quality brushed motors are comparable in efficiency.
"are often" is not "always". The wikipedia page makes it clear there are several factors to motor efficiency, not just brushed or brushless.