Frankly, I don't know. "NY Triathlon" showed up in my search data and I registered it on an impulse.
I just looked into this: Newyorktriathlon nyctriathlon.com nyctri.com and nytri.com are all taken. Then there's also nytc.org and nytri.org. Judging by alex rank, none are famous.
The market for NY triathlon domains seems to be pretty saturated...