Making the most money from your MC Business is all about balancing supply and delivery.
While the MC businesses introduced in GTA Online's Bikers DLC aren't the most profitable ventures in the game and come with the unfortunate side effect of receiving constant phone calls from LJT whinging about your work ethic, they're a great way to get some low-effort cash while working on more efficient jobs. Check out our full GTA Online making money guide or our Most Profitable Activities guide for where Bikers MC Businesses fit in the scheme of things.
However maximizing profit from the businesses is key to making them a worthwhile pursuit, and there's a lot of data the game doesn't tell you upfront. It's possible that your way of managing your businesses needs a whole lot of streamlining and optimization but you don't even know it and profits might improve significantly as a result.
A useful chart put together by Reddit user Echobox419 (reproduced below) has reiterated that the Cocaine Lockup is the most profitable business, however some further intricacies of the business mechanic has been revealed as well. Much like in the case of our Vehicle Durability Guide, some of the underlying systems here aren't apparent to the player.
Before we jump into the hard data, an interesting observation to remember is that the three Biker businesses centered around drugs produce at a misaligned ratio, meaning that a full bar of production doesn't equal a round number of sellable units. This is why having one completed bar won't allow you to sell any product with the Cocaine Lockup, for example.
The fractions add up to a whole number at 5 bars in each case, however in between there is always some excess product created, and that excess is wasted whenever you shut down a business. Keep in mind that these numbers come from MC businesses with fully upgraded Equipment and Staff attributes, so un-upgraded businesses may yield varied results.
Cocaine Lockup
Another thing to consider before immediately picking the Cocaine Lockup is your playstyle. Unlike in the case of CEO work, delivering more crates — or product, in this case — won't give you a bonus on profit. You'll get the same percentage payout regardless of how many units of product you deliver. If you're playing solo, dealing with more delivery vehicles can be a pain and you might end up losing a whole lot more than you gain.
Since Cocaine doesn't produce any sellable units with the first bar, and the second bar sells for less than Meth, Weed and Counterfeit Cash while selling for the equivalent of Documents, it might not be the best choice. It becomes the best paying business from three bars and up, which is also when delivering solo becomes tricky.

A different spreadsheet also exists which has somewhat different numbers, but reaches the same conclusions in terms of which business is the most profitable, leaving Cocaine at the top of the food chain. This other chart comes from Reddit user jc9289 and can be found by clicking here. The main advantage jc9289's chart has over the one above is that it includes the exact time required to break even with your businesses, and the statistics can be important for solo players.
Counterfeit Cash
After Cocaine, Counterfeit Cash is the second most lucrative business, selling at pretty decent rates even with few bars. As a solo player, a good technique is to deliver fewer units more frequently to keep a high success rate. Delivering a larger haul alone is possible, but it requires skill and above all else, time. In the long run, multiple short deliveries will be quicker than fewer big hauls.
Supplying Your Businesses
You should also balance how you'll supply your businesses. You might initially think that in the pursuit of more money, stealing the supplies is the best course of action as opposed to buying them, as this will lead to greater profit, however the best hybrid money making method relies on using businesses as a semi-passive source of income alongside Import/Export work.
The key here is that export missions yield greater profits than a business powered by stolen supplies. This means if you save time by buying supplies, and spend the extra time on export missions, you'll end up with more profit than if you spend extra time on stealing supplies for your business. Of course, this mainly applies to solo players.