Pedal washers are something most folks forget about when they jam pedals on a bike. But you know they’re important, cause lots of crank manufacturers send ‘em out with new cranks. Basically, the pedal washer isolates the crank from the twisting tightening motion of the pedal as you screw it in. If you don’t have a washer, once the pedal gets tight, the harder steel axle bites into the softer aluminum crank arm. This is even true for steel cranks. The pedal spindle is made from much harder steel than a crank arm.
If you install enough pedals on a crank arm, eventually the arm gets wallowed out, and aluminum shavings flake off and get stuck under your fingernail, forcing you to swear prodigiously in front of your 9 year old niece. Obviously not good for your fingernail or your crank, your niece will probably be okay.
We sell nice US made pedal washers. They are not fancy. They’re just pedal washers. But you need them. Don’t think you don’t. Buy them now, and a water bottle too, because we just saved your cranks from long term destruction, and that’s worth the cost of a water bottle, right?