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I just ordered Park Tool PPL-2 Polylube 1000 Grease Tub (1 Lb) from my LBS. I was surprised when they didn't call it waterproof and tried to steer me to a Phil Wood product as the waterproof one, because I thought I'd seen Polylube described here as waterproof, i.e., suitable for unsealed bearings. Nothing against Phil Wood, I just thought people said PolyLube was waterproof too. Is it?

The Park Tool site says "repels moisture". I assume that's the same as "waterproof" and the LBS person was just misinformed?

compton
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    "waterproof" is such a strong phrase - no grease is water PROOF. Repels Moisture means that it sheds water off the outside. If grease could be waterproof, we'd be able to simply grease things and not worry about seals etc. – Criggie Oct 12 '16 at 22:01
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    @Criggie - Untrue. You'd still have to worry about dirt. – Daniel R Hicks Oct 12 '16 at 22:03

2 Answers2

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Different greases hold up varyingly well in different applications, depending on levels of dust, water, temperature, etc.

Park Tool Polylube PPL-1/2 are your basic bicycle greases -- they hold up well under most people's riding conditions (including repelling water enough; others like Phil Wood or Park Tool HPG-1 might be more water repelling). Depending on the conditions, you may end up repacking a bit more often than others, but its not really all that big of a deal, so long as the grease is doing its job (which for most people, it will just fine; if you're riding in -50 C, you might want to pick something else).

At the end of the day, note that many people are using just regular old multipurpose grease from the auto shop (that red stuff Valvoline sells for less than 5 bucks a pound) or marine grease and are doing alright (it's significantly more viscous than bicycle greases so not ideal; however, note that even a tube of Park Tool PPL-1 will last you quite a while, so the cost savings aren't immense for the home mechanic ). So, don't lose sleep over this.

Batman
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  • Thanks. PPL-2 on hand and deployed. I cleaned and repacked the front hub, which It turned out it was binding just a bit. (Not that I noticed it when riding, but still.) After cleaning and regreasing, spinning the wheel on an upside-down bike, it goes for-ev-er. – compton Nov 11 '16 at 13:46
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Grease itself does has various characteristic depends on application. Unless you are going to submerge your bicycle and keep cycling, otherwise general purpose grease will do the job.

Just a plain copy and paste :

Water Resistance Applications where the process employs water-based coolants or process chemicals have multiple problems to address. Water resistance is characterized by the grease’s ability to withstand one of four water-related problems, including:

  1. Washout Resistance - the ability of the lubricant to stay in the bearing while operating partially or fully submerged (ASTM D1264).

  2. Water Absorption - the ability of the grease to deal with the presence of water by either absorbing or resisting the washing and diluting action of the water. The grease may either absorb a large percentage of ingressed water and then de-gel (lose consistency but retain the water), absorb a lesser amount of water and retain consistency, or resist absorption of water altogether (which leaves water in a separate phase in the component or system).

  3. Corrosion Resistance - the ability of the grease to prevent corrosion of surfaces when water is present (ASTM D1743).

  4. Spray Resistance - the ability of the grease to resist displacement from a direct impingement of the water on the greased surface (ASTM D4049).

The thickener, in large part, determines the grease’s response to moisture. If the thickener is particularly good at absorbing moisture, such as with sodium soap greases, it may form an emulsion that traps and draws water away from metal surfaces. The downside to greases which emulsify is that they can be easily washed out.

mootmoot
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