Introduction: Unicycle Bicycle Cross Threaded Crank Thread Chaser
A simple and possibly free tool for the repair of cross threaded bike or unicycle cranks
Small grinder with a thin cutting disc
Step 1: Annoying Occurrence
From time to time I have needed to remove my pedals on bikes and my unicycles - they come off smooth and with no probs but when putting them back sometimes they try to cross thread and it does my brain in.
Working in industry for over 25 years I have never known such nonsense, why these little bleeders can be so uppity is a mystery - anyhoo it is not a problem now.
Step 2: To the Task at Hand
Cross threading on a crank will always happen from the outer face - this is the last place the pedal exits from when removing it or the entry point when fitting new or re fitting pedals after maintenance . the pedal shafts are handed so I guess it might be possible to damage them some how if a person was not aware of the threads direction - quite often cranks are an alloy and threads are pretty fine, still it seems odd that a happy thread one minute should try to strip the next.
We are lucky that no matter what you ride, the back of the crank is accessible - after making the tool carefully feed it in by hand from the back of the crank till it exits the other side by a good few threads.
Step 3: Get Some Guts
Take and old pedal or a cheap pedal set that has a hardened pedal shaft of the same size thread and!! same hand as the one you need to restore and strip out the guts to get out the pedal shaft .
With the grinder remove material from behind the threaded area - make sure you go below the thread depth so the tool can go all of the way through the crank without fouling - only remove enough material so that there is half of the spanner flat remaining ( you will use your thin bike spanner to rotate the tool when in place ).
Now using the thin grinding tool cut slits into the thread of the pedal shaft 3 or 4 should work - helps to stop clogging and helps the re forming of the thread being repaired - - see piks .
Going in from the back of the crank starting by hand, gently rotate the tool till it is in a couple of turns then using the pedal spanner rotate the tool through the crank, go in about a turn, then back off about half a turn , keep doing this until you are all the way through - clear off any crap before removing the tool - unwind the tool with care and clean out any shavings left behind.
Step 4: Good As New
Your newly re dressed crank should now be as good as new - re fit the pedal with care - any problems remove it, do not try to force it, if need be inspect the thread, remove crap or burrs that may be stopping the pedal seating properly then send the tool back through again from the back.
Once your job is all done you are in a happy position - the pedals are back in place and all is well, also! you now have a new tool that should this happen again for you or a friend the tool is ready to go.
NOTE!! - do mark your new tool in some way to designate left or right hand, you do not want to be trying to drive the wrong item down the wrong thread - very bad.