Cut the advertised discharge rate in half is my rule of thumb.
Not because they lied, but because you get less sag, and later on when the battery has lost capacity, you still have that extra to dip into then. As you near 20% gone, you are hitting harder on the remainder.
There is no china priced deals on batteries that come from a Vendor in the USA. To ship legal, provide a real warrantee, etc costs them. So that price is not unusually high.
Is it a deal? Is any battery a deal? You pay a lot for any good one, and shoddy ones are the most expensive purchase of all. The worst decision is to buy a good battery in too small a size that cannot possibly last running a huge motor and controller. Then you throw even more money away on a battery unsuitable for your bike.
That battery in the link is a poor match for a 30 or 40 amps controller is what I mean. Good for a 20 or 25 amps though. I'm not saying it cannot discharge the 60 amps. I'm saying it will like less amps a lot more. It should perform very well with a 25 amps or less controller.