Years ago, I made the newbie mistake of forcing a rack screw into a steel braze-on. I had to replace that fork. And I've heard this advice many times: When putting a screw into a braze-on, put a little lube on the screw to keep rust from forming. So I take good care of rack screws and braze-ons now.

I was putting fenders and racks back on a bike today, and I had finished cleaning the screws and eyelets. When I reached into my tool bag for some lube, I realized I had regular bike lube as well as polylube. (That's the goopy stuff you use for seatposts.)

I tried polylube on a pair of 5mm screws and regular lube on a set of 4mm screws. Over time, I'll see which set of threads is cleaner, or if there's any difference at all.

I'm using Parktool Polylube 1000 and Prolink Chainlube (regular lube, not wax).

My question: Is there a difference between using regular bike lube and polylube to lubricate threads? Can polylube be harmful in this context? Or should I be using something else entirely?

  • Can you be more specific in what you mean by regular lube and poly lube? Brands would be helpful. (For most non-rotating threads, the lubricant does more to displace prevent water from penetrating the threads. Light oils will eventually get washed away, but denser grease and wax will stay put.)
    – WTHarper
    Feb 11 '13 at 22:48
  • @WTHarper - Sure, see my edit. Feb 11 '13 at 22:53
  • Odd, I never (well, hardly ever) lube rack/fender/water bottle screws, and have never had any trouble. Of course, I always use SS screws. But, to answer your question, any lube that forms a coating and won't easily wash off should be fine. Feb 11 '13 at 22:54
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    Looking at the specs, the Polylube is probably slightly better. The ProLink chain lube sounds to be a bit on the "dry" side. Feb 11 '13 at 22:56

Definitely the polylube -- for the same reasons you use it on your seat post.

  • I'm also thinking it'd be nice to have a use for the stuff. I use maybe a few squeezes a year, and that's on five bikes. Feb 12 '13 at 2:08
  • @NeilFein, I use it on my fence gates. Get a small kid with their bike and repack the coaster brake hubs, half a tube of use right there.
    – BPugh
    Mar 9 '16 at 18:16

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