Not a good test. The grit on the dirty chain will have a sand paper effect on the cogs, and wear them out, both chains are going to stretch to the size of the grove between the teeth of the cog. No one seems to understand the cause and effect between chain and cog. Chain stretch = bigger space between the teeth on the cog. Both chains are going to stretch too that same space.

Do clean your bicycle, and your chian, and your cogs. A clean chain and cogs will last a little longer, not a lot longer, a little longer.


If you find it to embarrassing to use an old tooth brush and discarded shop rag to clean your drivetrain, buy a $5 park tool.

Park Tool’s GSC-1 GearClean™ Brush has a unique design
A large comfortable handle with a curved, toothed-end reaches dirt deep between the gears, and tough nylon bristles clean the derailleur and chain
Saves wear and tear on your chain and freewheel
Works great on brakes or other places where dirt collects
10-speed compatible
Handy size for quick cleaning anywhere
Made of sturdy nylon

The last time I needed a chain on tour, the guy in Sisters wanted $70 for a piece of sram. I was able to make it to the rei in Bend and pay $26 for a shimano chain.

[Workers exposed to solvents may continue to experience cognitive difficulties decades later, according to new findings by Harvard School of Public Health ]
https://www.hsph.harvard.edu/news/hs...-brain-damage/

No solvents on my bicycle.
One more reason for biodiesel