Totally new to bike maintenance, so go easy.
Just threaded a crank puller into my (25ish year old) bike. Started off turning quite easily with fingers, pretty sure I didn't cross thread it. Then got harder so used a spanner to it seemed like I'd hit the end.
Quite a lot of force required to start turning the next thingy, but got much easier. But when it popped out, I'd just driven the whole crank puller backwards, ripping out the threads, instead of pulling the crank arm off! Kinda cool to see the threads in detached form, but also a bit depressing.
Wondering if anyone has seen/done this before? Already taken then chain and rear derailleur off, so probably going to take to a shop to see if they can help in some way, really want to salvage this bike.
Nice one reddit
by Affectionate-Mood-51
15 Comments
you used the big tip instead of the small one most likely.
The tip must fit inside the hole at the center of the cranks to push only on the bottom bracket. tip to big just pushes the arm against it’s own threads.
ooooorrrrr you cross threaded it.
Unfortunately it is cross threaded. I absentmindedly took off a thread starting to do that before. You will need new cranks. The crank puller should thread in easy all the way by hand.
Sure enough this happened to me already. I got a simple 6inch 3prong puller and pulled it off that way.
2prong may also work, but is less stable. Most importantly the center bolt has to be large enough to not work itself into the M8 thread, which on the 4inch version is just slightly too small.
I still use the Crank which i got off that way.
get a near by lbs involved, they can pull that crank a few different ways. its done tho, so unluckily you need a new one
I’ve done this before too, resulting in a very similar pile of shame shavings, so you are not alone.
You can pick up a puller from like harbour freight, one with 3 arms to go around the chainring, I imagine they are pretty cheap to buy from HF.
But you’ll need a new crank, threads are cooked.
You might also need a new crank puller if those threads are also cooked.
Steel vs aluminum
Yeah his is super common have to be so careful using those crank puller
You can drive a wedge between frame and crank to force it off or one of those bearing pullers with the claws
Fairly common occurrence, so don’t feel bad.
Some percussion engineering, using a block of wood through the frame to the back of the spider, might work. Combined with penetrating oil.
Otherwise it’s a couple of wedges of wood to pop it off.
It gets more destructive if you can’t get it off.
I have done this not a month ago on a *brand new and unridden* Brompton!
I ditched my 35 year old crank puller after that. It had not screwed in all the way but got stuck on all the accumulated grime. Looked ok at a passing glance, but no.
I did this recently. It was a Brompton with very seized cranks. I cleaned the threads and greased them before using the extractor and it was not the big tip.
To fix it you have to break the corrosion, heat is your friend. I put a plumber’s heat proof mat around the crank. The one with a slit in it that goes around the pipe. I then put a blowtorch to it… it’s not as dramatic as it sounds. The matt fully protects the bike and it will only heat soak into the bottom bracket so consider that toast as well, it’s cheap though so who cares.
Then when it’s roasting hot spray it with your preferred penetrant, I used wd40 but you can use any kind at this point, the heat should have hopefully opened up a gap. Finally beat the devil out of it with a hammer, try and knock it off the bike obviously.
I used an air hammer on mine which worked a treat but a chisel and hammer will work just as well, the cranks toast so don’t be gentil.
Works every time (Disclaimer I have only done this once)
Anyone around for the big Shimano crank recall back in the day just got triggered by your image.
Yes that sucks.
What I did before was ride the bike slowly around the block and the cranks should loosen. Maybe hop a lil on them to help it along.
Can also put the bolt back in and back out off a lil so the crank won’t suddenly fall off and surprise you.
The classic boss fight is upon you. Time to get the dremel out
Happens to all of us
It helps to grease the threads on the tool, but it doesn’t matter if you used it wrong, cross threaded, or it’s majorly stuck
Always (!) clean and grease the threads of both (!) parts before use.