PTFE is one of the best-known and widely applied PFAS commonly described as persistent organic pollutants or "forever chemicals". Only since the start of the 21st century has the environmental impact and toxicity to human and mammalian life been studied in depth. For decades, DuPont used perfluorooctanoic acid (PFOA, or C8) during production of PTFE, later discontinuing its use due to ecotoxicological and health issues that led to legal actions. Dupont's spin-off Chemours today manufactures PTFE using an alternative chemical it calls GenX, another PFAS. General recommendation would be an ordinary lithium (soap based) grease. Available, cheap, with characteristics that satisfy all the criteria for this use. It hardly makes sense using anything else. Even those satisfying ISO water resistance standard with H level are not too expensive. Soap greases. Soaps are usually made by saponification of fatty acids with hydroxides of various metals – aluminium, calcium,sodium, barium. Reason seems to be advocating for research and evidence that substantiate Relja’s views/opinions. I say the value of the post is in the explanation of grease technical specifications that allow others (like me) to make our own evaluation based on local conditions and habits. I thought Relja clearly made the point that there is no ‘optimal grease’ for every situation. Personally, Relja’s recommendations were a most welcome addition to the post. Yes, the working range of the grease is written on the label of said grease. Duh. However, the working range ISN’T determined by grease type! All lithium grease are NOT ONE RANGE!

That is correct. I leave that to the reader – to compare data that are critical to them and choose for themselves. General recommendations for certain purpouses are given in chapter 7 and they’ve been proven good enough through decades of experience, including my personal. The main “problem” with NLGI 1 hardness in my experience is not being able to keep the bearing balls in place well enough, during the re/assembly (regular bearing overhaul). Basically we can conclude that you have literally zero data comparing the greases to substantiate your opinion. This is what you’ve shown thus far.Silicone oils suspended in a soap of lithium, calcium, PTFE, fumed silica etc. Lithium soap based silicone greases have excellent properties for lubricating bicycle bearings, but are outrageously expensive. Because there are greases that cost a lot less, while being good enough, and because it makes no sense for lubrication after a few seasons to cost more than a new bearing, silicone greases are not an optimal choice.

Consistency (hardness) is measured with a cone, by methods standardized underASTM 217 IP 50, or DIN 51804, part 1. Measuring unit represents depth the measuring cone enters the tested grease. Testing procedure is shown in the picture 1. Picture 2 The working temperatures of literally all the greases you listed is perfectly fine for 95% of riders out there. Trying to make recommendations by a maybe 30*F change in ambient is not based on science. Now that grease types and solid lubricant (additives) types have been explained, it is clear that there are numerous possible combinations. For the purpose of re-lubing an already lubed bearing, if completely washing out old grease is not possible/practical, it is important to know which greases (with which additives) are compatible (i.e. can be mixed) with which greases.Criterion 5 – Keeping stable structure and hardness for a longer period of exploitation. Re-lubing bicycle bearings more often than once a year is highly impractical. By 1948, DuPont, which founded Kinetic Chemicals in partnership with General Motors, was producing over 2,000,000 pounds (910,000kg) of Teflon-brand polytetrafluoroethylene per year in Parkersburg, West Virginia. [8] An early use was in the Manhattan Project as a material to coat valves and seals in the pipes holding highly reactive uranium hexafluoride at the vast K-25 uranium enrichment plant in Oak Ridge, Tennessee. [9]

Same deal with most aluminum based. And again, a 1lb tub of grease will last you 50 years so there’s literally no reason NOT to use it.” Some (many?), even well renowned, manufacturers don’t state ISO, (n)or DIN standards, but make claims about superiority of their products. Even such greases (of renowned manufacturers) are usually of relatively high quality and do the job they are meant for very well. I prefer to pay less for the same/similar quality AND know exactly what I’m getting for that money. However, it would be unfair to say that the companies you noted don’t make good greases: one wouldn’t do wrong with Phil Wood, Bel-Ray, or Shimano, just to name a few. Minimal 4 ball weld test of 1000 N or better was a safe margin recommended by the post’s co-author, an expert on the subject, Stevan Dimitrijević. If you have relevant data that proves otherwise, please share it, I’d be more than happy to link it and correct the data in the post. For pressing in the bearings (not for lubrication of moving parts), I prefer (and recommend) using some kind of anti-seize, not grease. Because it provides long(er) term protection from seizing (corrosion), helping both with mounting and dismounting. Grease can be relied upon for only up to one year, if not even shorter period, for anti-seize protection. Products sold as “copper grease” are quite good for that task.

Greases

Of important criteria listed in paragraph 3.1. these greases only have problems with fulfilling Crit. 1. (for extreme conditions of bicycle use), while Crit. 3. is probably best satisfied of all the other grease types, except some enormously expensive ones. Yes, the working range of the grease is written on the label of said grease. Duh. However, the working range ISN’T determined by grease type! All lithium grease are NOT ONE RANGE!”