I am also wondering if perhaps there was a way to identify a triad on the street at the end of the 19th century. Did they have specific clothes or colors like todays gangs in the United States?
I can't speak to the presence of overseas gangs in the US, but I can share some details about the Chinese diaspora in Singapore and why they were less likely to be preoccupied by politics in the mainland. It's important to keep in mind that Chinese immigrants to Singapore didn't necessarily consider themselves to be "Chinese," but rather identified much more strongly with their own province, ethnic group, and/or language. These groups came to Singapore at different times and for different reasons.
The Hokkien Chinese from southern Fujian arrived in the mid-19th century, fleeing the violence of the 1854 Taiping Rebellion. These refugees came from impoverished backgrounds and were largely illiterate, and for the most part worked on pepper plantations. The Teochew Chinese, originating in Guangdong, arrived later in the 19th century. They worked primarily as fishermen and came to control the fishing industry on the island. The British considered the Teochew to be more trustworthy and business-savvy than earlier immigrants, and for several decades they held an elite status among the Chinese population. Later immigrant populations include the Cantonese, who competed with the Teochew over the island's commercial center, the Hakka, who found a niche in the construction industry, the Hainanese, the Fuzhounese, and still others.
Instead of working to build an oversees Chinese identity that could challenge Qing hegemony, these groups worked to protect their own kind. Different groups set up different kongsi, which is usually translated as "clan association". These organizations played many purposes, such as providing social spaces and activities, supporting new immigrants to the island (their immigrants of course), handing out loans to aspiring businessmen, and occasionally engaging in gang warfare with other clans.
All of this is to say that: yes, there were gangs in 19th century Singapore, but they were much more concerned with their influence on their own island than they were with mainland politics. Political refugees started to show up after the collapse of the Qing dynasty, fleeing the Republic of China and/or the People's Republic of China, but that's a different story for a different day.