Originally Posted by
Andrew R Stewart
With a way to tension the chain and the large chain wrap around the cog one can very likely ride the chain way past 1% wear and not have a "problem". Chain wear is a gray shade, not a black/white line. Andy
This.
Depending on the cost of your front chainring/cranks (and the rear chainring), and other factors, your optimal choice may vary.
Some options:
A) Replacing in time
Replacing the chain at the 0.5% elongation will give you the longest possible chainring life.
B) Not in time, but not waiting for a problem
Grey area between the two extremes
C) Replacing when the drivetrain "gives up"
Replacing the chain when it starts skipping will give you the longest possible chain life (and replacement intervals). But this comes with some notes:
- Severely worn chain will shift poorly with standard derailleurs (not applicable in this case since it's a gear hub).
- Severely worn chain is a bit more likely to break (also less of a probability with a practically singlespeed setup - the gears are all in the hub in this case).
In my experience, for most "casual" cycling, and low to mid-priced drivetrains, the option C is the cheapest.
Yes, chainrings may not last as long, but you swap a lot fewer chains and save there, so the overall cost is a lot cheaper than replacing the chain "on time" - especially if the cranks/chainrings aren't some super-expensive.
In addition to saving costs on chains, it also saves time (a lot longer replacement intervals).
The option A is the safest in terms of preventing problems and providing best possible drivetrain performance (more important with classic derailleurs, i.e. not geared hubs).
This is all without going into any "legal" and "liability" stuff (i.e. whose responsibility is to make sure it all works, what happens if/when a chain breaks etc.).
My long-winded drivel on
how to measure wear and when to replace a chain