Front brakes bigger than rear brakes.

[Trail Cruiser]

At first glance, it appears non-intuitive to have bigger brakes to the front, But as you look around, this principle applies basically to all transportation with wheels. We cannot escape from the laws of physics, that as we slow down to a stop, the weight goes to the front while the rear lifts up (sometimes off the ground). The rear needs lesser braking force or it will lock up early and skid sideways. You see it (bigger front brakes) even on many electric bikes with 180 front and 160 rear discs.

(Link Removed - No Longer Exists)

So if you want improve your ebike's stopping power, upgrading only the front brakes may be enough to get the job done. I upgraded my front brake with 4-piston caliper (assembly consisting of left lever, hose, caliper that is already pre-bled) and it made a night and day difference on the stopping power of my ebike.

https://www.ebay.com/itm/TRP-Slate-4-Piston-Hydraulic-Disc-Brake-System-Left-Lever-Front-Caliper-Black/182792714551?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649&afsrc=1&rmvSB=true

 

[JRA]

TRP's Hy-Rd is a good way to upgrade any cable activated system easily and maintains the stock levers/cutouts. https://www.trpcycling.com/product/hyrd/

 

[Camac]

I have serious reservations about my greater deceleration load going through the front wheel. On a motorcycle you have the greatest mass in the motor and associated equipment. On a cycle the greatest mass is you. Up a lot higher. If you take a line from the mass of the motorcycle through the front brakes that line intersects with the ground some distance in front of the motorcycle wheel. Draw that same line on a cycle and it intersects with the ground very close to the front wheel. There is a far greater chance of you going base over apex if too much braking force is applied to the front brakes in a hurried stop.
One of our group, stopping in a hurry on the front brakes, went over the handlebars and broke C1 and C2 in the neck. He wore a steel halo for a long time, now wears a support collar and hasn't been riding since.
I commuted thousands and thousands of miles on a motorcycle and always used the front brakes as my main means of stopping. On my cycle it's the rear brakes every time.

 

[Trail Cruiser]

I have serious reservations about my greater deceleration load going through the front wheel. On a motorcycle you have the greatest mass in the motor and associated equipment. On a cycle the greatest mass is you. Up a lot higher. If you take a line from the mass of the motorcycle through the front brakes that line intersects with the ground some distance in front of the motorcycle wheel. Draw that same line on a cycle and it intersects with the ground very close to the front wheel. There is a far greater chance of you going base over apex if too much braking force is applied to the front brakes in a hurried stop.
One of our group, stopping in a hurry on the front brakes, went over the handlebars and broke C1 and C2 in the neck. He wore a steel halo for a long time, now wears a support collar and hasn't been riding since.
I commuted thousands and thousands of miles on a motorcycle and always used the front brakes as my main means of stopping. On my cycle it's the rear brakes every time.

If ever you are concerned of toppling over, the road bikes with aggressive forward positions are the most likely subjects.

The more relaxed and upright riding position has more weight to the rear, less toppling tendency. Gone are the days of rear only coaster brakes where you slide side ways (often leading to accidents) once the rear wheel locks up. On emergency panic stops, the goal is to lock the front earlier than the rear since it is less likely to lose control and can easily be modulated to prevent wheel skid. This is the topple happy bicycle (below).

And they called this as the safety bicycle (below) since there is less tendency of toppling and has lower height for safer falls.

 

[Nutella]

I have serious reservations about my greater deceleration load going through the front wheel. On a motorcycle you have the greatest mass in the motor and associated equipment. On a cycle the greatest mass is you. Up a lot higher. If you take a line from the mass of the motorcycle through the front brakes that line intersects with the ground some distance in front of the motorcycle wheel. Draw that same line on a cycle and it intersects with the ground very close to the front wheel. There is a far greater chance of you going base over apex if too much braking force is applied to the front brakes in a hurried stop.
One of our group, stopping in a hurry on the front brakes, went over the handlebars and broke C1 and C2 in the neck. He wore a steel halo for a long time, now wears a support collar and hasn't been riding since.
I commuted thousands and thousands of miles on a motorcycle and always used the front brakes as my main means of stopping. On my cycle it's the rear brakes every time.

Grabbing too much front brake will make you endo regardless of your rotor size. Not moving your mass back under hard braking will also make you endo. Your momentum gives your front wheel better traction under braking, which gives you a greater braking ability, just like a motorcycle. Besides giving you a larger lever, the greater surface area of a bigger rotor cools it faster. The most efficient way to brake on a bike is loading the front brake to the limit of it's traction.

 

[Trail Cruiser]

This one has enormously biigger front brake than the rear plus it has 4 pistons in the front compared to 2 pistons at the rear.

BRAKE DETAILS:
Magura MT Trail Sport Hydraulic Disc with 203 mm Front Rotor and 180 mm Rear Rotor, Quad-Piston Front Caliper and Dual-Piston Rear Caliper, Magura MT Trail Sport One-Finger Levers with Adjustable Reach
https://electricbikereview.com/moustache/samedi-27-trail-8/

 

[MLB]

If ever you are concerned of toppling over, the road bikes with aggressive forward positions are the most likely subjects.
View attachment 19181
The more relaxed and upright riding position has more weight to the rear, less toppling tendency. Gone are the days of rear only coaster brakes where you slide side ways (often leading to accidents) once the rear wheel locks up. On emergency panic stops, the goal is to lock the front earlier than the rear since it is less likely to lose control and can easily be modulated to prevent wheel skid. This is the topple happy bicycle (below).
View attachment 19182
And they called this as the safety bicycle (below) since there is less tendency of toppling and has lower height for safer falls.

All makes perfect sense. IF you were stopped..... but since you are moving forward, your sitting position has very little to do with where you end up. Momentum will see to that. And you NEVER want the wheel (any wheel) to lock up from too much brake. There is no steering control on a locked wheel. Just short of locking up is the strongest braking with shortest stops any vehicle can do.