Having a fixed gear drive counts as one, you also then need to have a brake, doesn't matter what wheel it's on etc.
INAL, but I'm pretty sure it has to be independent methods of stopping each wheel. Not sure a rear brake and FG count?
It's independent so if one fails you have the other, both can be too the same wheel because if your wheel fails you'll be stopping pretty sharpish anyway.
Same for all road vehicles and plenty of cars and trikes have both brakes on the same axle.
@Khornight2 started
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INAL, but I'm pretty sure it has to be independent methods of stopping each wheel. Not sure a rear brake and FG count?