>>1194236This, and I'll explain why below.
>>1194257Depends on how much you ride, the conditions you ride in, how well you do at cleaning and lubing the chain regularly, how hard you ride your bike, etc.
>>1194273See above. You can't assign an arbitrary value to this.
>>1194286Unless the bike is never ridden your drivetrain is proabably worn out/ruined then.
>>1194301>But twice a year seems much.Again: see above. You can't use an arbitrary time measurement in this case.
Listen dude, and anyone else: as the chain stretches, it doens't mesh properly with the teeth on the chainrings and cogs. That causes more pressure and friction, which causes more wear of the chainrings and cogs. Eventually you get to the point where they're so badly worn that a new chain doesn't mesh with them worth shit and you have to replace the chainrings and the cassette, too, and possibly the rear derailleur because even the pulleys will get worn out. Now instead of spending $35 for a chain you're spending a couple hundred bucks for all those new parts.
This is easily avoided by checking chain stretch regularly, and cleaning and lubing the chain when it needs it (i.e. when it starts to make noise), and replacing the chain before it even gets to the 0.75mm stretch point.
Personally I only use a chain for 1500 to 2000 miles at most, and typically clean and lube it every week, but of course I ride 200 to 300 miles a week, some of it hard, some of it road racing, so at the end of a week it usually needs it. YMMV, literally speaking.
Most of you are poorfags and don't have hundreds of dollars to blow on parts you shouldn't have to replace. Take the above advice and you'll maximize drivetrain life and not throw money away needlessly.
