Even if you do 75% of braking with your front brake, a rear brake is also very useful. Such as when hitting a corner too quick, using the back brake will allow you to scrub speed whilst taking the corner tighter, using the front will cause the bike to become unstable. Also riskier in the wet.... Then there's the argument for what if the cable snaps? I've had this happen and it was scary... luckily it was on a fixed bike so I managed not to end up in a bus. I have been riding fixed brakeless since this incident so don't want to come across as a hippocrit, I also have a mtb running just a back... But I would never run a bike like yours with just the one brake, what's the point? Aesthetics? Weight saving? neither make sense.
Even if you do 75% of braking with your front brake, a rear brake is also very useful. Such as when hitting a corner too quick, using the back brake will allow you to scrub speed whilst taking the corner tighter, using the front will cause the bike to become unstable. Also riskier in the wet.... Then there's the argument for what if the cable snaps? I've had this happen and it was scary... luckily it was on a fixed bike so I managed not to end up in a bus. I have been riding fixed brakeless since this incident so don't want to come across as a hippocrit, I also have a mtb running just a back... But I would never run a bike like yours with just the one brake, what's the point? Aesthetics? Weight saving? neither make sense.