Red Rick said:
			
		
	
	
		
		
			How can mods know for sure when people are sock puppets, when do they get banned?
		
		
	 
There are some obvious ways but those obvious ways can also produce false positives, like cycling buddy roommates on the same connection or a family computer with several cycling fans or CN forum accounts. Those would be very low in number though, cycling isn't that popular a sport. Then there's the forum member logging on through a neighbors wifi, again hardly happens but could (produce a false positive). 
Then there's the other parameters from e-mail addresses and cookies, if you do it right you could fool anyone but most don't as a sockpuppet account is usually for minor annoyance and way too much effort to use the real tools as it takes time to setup. Proxies can be used but are also easy to detect to a knowledgeable person with the right tools, hence the cookie angle. 
As a web surfer you have a footprint so to speak and that is one thing the Do Not Track fiasco is about, most sites will track you based on where you have been before and what led you to their site and a few dozen other parameters, which in the end can uniquely identify you as you.
At the same time there are many tools to help anyone keep their anonymity but its does take effort. There's a few tools that can make you so unique you'd have trouble knowing you were you.
It seems obvious laziness is the number one way the mods get sockpuppet accounts, logging on from the same computer, same computer profile and same browser profile as the real account. I'm not sure what the full extent of forum software features this version of the CN forum have (or were paid for) but if they are anywhere near the modern age they have some of the features listed above, again it being CN I would guess they only have one (based on the time it takes to spot them).