Originally Posted by
Sci-Fi
Seems like there are more than a few posts/opinions that polyurea is the only grease that is formulated/recommended for bicycle use...to a point where they should become sales reps for Park Tools grease....lol.
While some greases last longer than others and or excel in one area or another, I have yet to read or hear about unusually high wear or catastrophic bearing failure directly attributed to using automotive greases.
My guess is that ball bearings are harder on grease than roller bearings because they don't disperse the weight as much and the polyurea is a more durable thickener. Once the thickener is pulverized by ball bearings the oil leaks out and leaves nothing but the thickener leading to a dry ball track. Just a guess though. I know that everyone says that bikes are a light load application compared to cars when it comes to grease but I'm not so sure. I light car weighs about 2,000lbs. That 2,000lbs is distributed over 4 wheels so there is 500lbs per wheel. Cars have two sets of roller bearings per wheel so there would be about 250lbs per roller bearing. The roller bearings probably distribute that weight 50-100 times more than a bicycle ball bearing. So the actual pounds per square inch that a car's roller bearing applies to the grease might be less than what a bicycle ball bearing applies per square inch. Again just a theory.
I do have to say when the temps are in the single digits my bike feels slower. I'm not sure if it's the grease but it might be worth experimenting with other lubricants.