EDIT (March 2010): It's still holding tight after 1.5 years!----
Brief summary: It's been working great for over 3 months on my bike.
Longer version:
The left crankarm on my 20+ year old bicycle was coming loose every month or so. The local bike shop said that there was nothing I could do short of tightening it and that the problem would get worse until I replaced the crankarm (a >$100 fix and lots of fun trying to locate an overpriced unused vintage part on auction sites).
I researched the problem online and came across a few mentions of people using Loctite threadlocker to fix the problem. I decided to get the Loctite 243 since it is resistant to grease. Unfortunately, the local shops only carried Loctite 242 (not oil resistant). Amazon carries Loctite 243, but it is through a third party vendor which charges as much as the item costs for shipping. Fortunately, I came across this Permatex threadlocker, which is also grease resistant (#24300) and is offered with free shipping. My impression is that this is the same exact product as the Loctite 243, but rebranded.
Over 3 months ago, I removed my crankarm and wiped the gunk off both the male and female threads. I applied Permatex to the male threads and screwed the crankarm back in. I let it sit undisturbed for 2 days to allow the stuff to fully cure. I have been riding my bike almost everyday since then (about 1000 total miles), but the crankarm has not come loose.
I'm so impressed by this product that I decided to use it on other screws that would periodically come loose (like on my rear rack). Everything has stayed in place.
If you're unfamiliar with these thread locking compounds, be aware that there are several versions of the Permatex and Loctite. The blue stuff is of medium strength; one should be able to break the seal using the force from hand tools. There's a regular and an oil-resistant version of the blue stuff (best to go with the oil-resistant if you have a choice). If you need something stronger, there's a red version. You'll need to heat that stuff with a blow torch to break the seal. A low strength purple version is also available.
Click Here to see more reviews about: Permatex 24300 Surface Insensitive Threadlocker Blue, 10 ml Bottle
Product Description:
Medium/high strength threadlocker for general-purpose applications. Especially well-suited for 1/4" to 3/4" fasteners that have a slight oil film.
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