It is ideal to use a cadence of more than 100 rpm and a relatively low gear. For example, on an 18-speed bike, place it in low and sixth, low being the smallest gear by the pedals and sixth being the sixth gear outward from the rear wheel.
Thus the time period for becoming a lawyer after high school graduation is as follows: 4 years for undergrad + 3 years of law school + 6 months for bar study, passing, swearing in.
There is really no shortcut on how to become a lawyer. You should have participated in relevant activities at the undergraduate level or interned at law firms over summer to make a compelling case of wanting to become a lawyer. After law school, you can take the bar exam to practice in particular states.