Pedal threads jammed with aluminum from cheap cranks

A friend ordered me a new Nimbus 29 road uni a couple of years ago. It shipped from somewhere in Ohio, and just now, after hundreds of miles of riding, I removed its Qu-ax lightweight cranks for the first (and probably last) time. They didn’t come off easily. They were either put on with Loc-tite or without grease, or maybe they just galvanized onto the pedal spindles on their own.

Anyway, the result is that I have two perfectly good Nimbus pedals whose threads are jammed with aluminum. Is there a way to fix them? I’ve tried digging out the aluminum with the tip of a nail, but that doesn’t seem to work.

This ancient Unicyclist discussion says that my problem can be solved by any friendly machinist, but as far as I know, there are none left in my area. Other suggestions?

Acid reacts with aluminium. Maybe some hydrochloric acid? Even vinegar might be worth a try.

They look like they didn’t have any grease on them. Blue loctite would have made them much easier to remove; although, grease is the go to for pedal threads.

I have had threads like this before, and it is a pain. you may get lucky with a wire brush (either hand powered, or on a drill). First you might want to soak it with penetrating oil to try to break the bond, then follow with the wire brush.

I have used a needle file to clean threads like this as well.

I haven’t ever seen pedal dies, but maybe a good bike shop will have dies of the correct threading to chase the threads on your pedals.

I’ve had this same problem with my qu-ax cranks.
I used a small flat screwdriver to remove all aluminium pieces. It was very easy to do.
Hope this will help.

Oh wait! The one who put those pedals on without grease was I! At that time, I had recently had a problem with pedals coming unscrewed, and thought I could perhaps prevent a recurrence by using no grease. I also thought the idea of the pedals galvanizing onto the cranks sounded kind of cool. Little did I know that on a 29, I would almost never ride backwards, and that one day I would have a spare set of shorter (110mm) cranks that I would want to put on.

Thanks for your help, guys! I used to work at a place that had plenty of hydrochloric acid on hand, but that was a while ago, and I used to have a can of WD-40, but it died. Acetic acid is not very strong, and I can’t tell if it helped, but I did soak my pedal spindles in vinegar before getting to work with the very small flat screwdriver, and I seem to be making progress. It’s definitely not easy, though.

Ali in thread

Dead easy mate, just use junior hacksaw blade, it will come out easily.

Not having a hacksaw that was junior enough, I continued with the tiny screwdriver (one meant for computer repair) and eventually got the job done. By digging firmly at those aluminum-filled threads from one end or the other, I was sometimes able to dislodge whole semicircular strips of aluminum. Filing the aluminum down bit-by-bit with a small saw or file would have actually been more laborious and, I think, could have also damaged the threads.

Now my 29 is ready to ride again, but this time with properly greased 110mm KH Moment cranks- shorter, much sturdier than before, and only a little bit heavier. My Qu-ax lightweight cranks are now toast, right?

I would expect that the cranks have lost too much material to be reliable, but you never know. The aluminum in those things is super-soft, and cranking some pedals onto them might just tap them enough to re-cut the threads.

At least worth a try, normally I would run a tap through something like this, but it’s likely you don’t have the required one either, I’d clean the threads up as best as I can, make sure there are no shavings inside anymore with something like a needle, and carefully thread my pedal on, making sure to not cross thread it.

Acid + Aluminum

Woah, Acid would effect your steel pedals adversely, use a caustic solution to remove aluminum, acid would have no effect at all !

So NaOH (sodium hyroxide) then? Or baking soda, since I no longer work in a lab and don’t straighten my hair? I guess adding NaOH in this situation would make aluminum hydroxide, if I remember my chemistry correctly.

Oh well, I already got my threads cleared out, and for what it’s worth, I did rinse the vinegar off and then grease them, but I am curious about this.

Dental picks might not work for this, but are handy to have around.

Acid vs. Base

Yes, mild but correct !

Acid most certainly reacts with aluminium unless it has a well developed oxide coating.

But yes, Sodium Hydroxide is a better choice.

This thread (pun intended) reminded me I had some pedals clogged with aluminum from a crank. I’d already tried to pick it out with a wood screw and a needle file with zero success so gave up and put them in a drawer. This afternoon I stood it in shallow dish of caustic soda solution (sodium hydroxide) . After about an hour I took it out and the aluminium slivers pretty much fell out. Now rinsed off and greased they are ready for use again.