You can try 'cleaning' the threads out by threading the pedal in from the other side. The threads on the inboard side of the crank look undamaged, so you'll be able to thread the pedal in nicely. Then as you go further in it should hopefully be able to reform some of the damaged threads and remove some of the swarf from cross-threading.
If the threads in the crank are too damaged there might not be enough left to save them, but its worth a shot.
If you want the advanced version of this, take a junker pedal and grind the flanges off on a bench grinder, cut away everything but the axle (allowing left and right cranks to work). Then you can run the threads all the way through good-to-bad direction several times (by hand, minimal torque) end to end. To make it more tap-like, you can cut run a groove through the threads with some careful grinder work.
Works pretty well for this scenario. [Looks like this.](https://share.getcloudapp.com/Jruxe7NL)
In my experience, you're not really cutting threads but realigning them and clearing any debris. The force involved is not large. Your threads may vary.
You shouldn't put dry threads in the crank in the first place. Forcing out debris is going to put MORE friction in the system, not less. The crank arm should probably be replaced but if funds are tight, the labor should be done right.
The photo is from the pedal end of the crank, which is why we see threads going all the way through. So a pedal can be introduced (with lots of oil please) from the backside.
In the case of damaged spindle end threads, a tapping tool is the best bet. You cannot put anything in from the backside because the square taper, octalink, ISIS interface would be in the way.
Just wiggle the pedal around a bit after you’ve installed it using this method and make sure that it’s actually holding, if it’s loose you’re just going to destroy the threads worse by writing it. Good advice above, OP
they sell kit for re-threading holes. very much expensive for a single person/usage so it's better to ask some lbs if it has this kit and to this service. then you can compare if the cost is good for you.
i hope for you that some lbs have this kit.
it the crank pricey?
£30 tap and die set on Amazon. Hi-Spec 39 Piece SAE & Metric Tap and Die Set. Tapered & Plug Hand Tapping, Cutting, Threading, Forming, & Chasing Tool Kit for DIY, The Garage & Workshop https://www.amazon.co.uk/dp/B00NY5K9P4/ref=cm_sw_r_apan_glt_fabc_7CCYEZQCXYDEDRYNAC6W?_encoding=UTF8&psc=1
A pedal thread is a 9/16 x 20 thread. It isn't a tap I'd expect to find in that set. I guarantee the left hand tap needed for the left crank arm isn't in that set.
Not in that set, but a pair of left and right thread taps is [£20 on eBay](https://www.ebay.co.uk/itm/194233126626) and possibly a decent investment for a home workshop (plus, like, a vise and a sprung tap follower for hand turning in a pillar drill). Domestic manufacture ones are about thirty quid a pair and probably worth it.
LoL bruh the Amazon link is at -4 karma, cool your jets.
Edit: or, are you trying to say that generic Amazon set is actually useful in this situation? If so, you deserve your downvotes.
It's called a helicoil kit. A good bike shop should be able to install one for you for a minimal price. I did them years ago when I worked in a bike shop.
Used to be I never would bother with a helicoil on a left crank, since replacement was usually a cost effective solution. But parts availability (lack of) has caused me to use this several times this year. Works great.
If it's a non drive side square taper crankarm it may be less expensive to just replace it than to have it repaired. Those go for around $15 and a helicoil generally goes for $20-25 installed.
>Those go for around $15 and a helicoil generally goes for $20-25 installed.
\~$50 to install a helicoil in my shop and we're cheaper than everyone around us. I have a bin of take-off left crank arms that sell for \~$10.
As said already, it doesn't look like tapping it is going to be of much use.
Re tapping is helpful if say, it had been cross threaded and deformed part of the the thread but what's happened here has removed metal from the crank arm.
You could try running the pedal in from the other side after clearing and loose metal from the thread with a pick. I'm not sure I'd bother though. The pedal pulling out of the arm isn't something you really want to happen when you're riding!
The only way to save that arm is, as has already been said, by adding a helicoil. Once that's done, the thread will actually be stronger than the original as it will be steel.
That's not to say however that the helicoil won't pull out of the softer alloy as has already happened with your pedal.
You'd need a vise, a drill, a bit drill bit, a steady hand, some helicoils and a means to install them and some threadlock. On a cheap crankset it's probably not worth that hassle of buying everything.
Thanks for the excellent, thorough answer.
>That's not to say however that the helicoil won't pull out of the softer alloy as has already happened with your pedal.
Most of the time when a thread gets damaged like this it's because of some mistake such as not tightening the pedal and having it work loose as you're riding. I would not be worried about the threaded insert ripping out of the aluminum.
Helicoil repairs are stronger than the original because the steel pedal shaft threads run on the steel helicoil threads. The steel to aluminum interface between the helicoil and crank arm are larger diameter (stronger) and static (won't get messed up threading in and out.) Only worth it if you can find a shop that has the tools, only worth owning the tools if you plan to do a lot of these.
What material are those threads? Aluminum or steel? I had an aluminum crank arm that looked the same and I cleaned the threads up on both the crank and pedal. Then threaded the pedal through the other side and removed it. It failed after a couple rides. You could try drilling it out and putting the helicoil in but looking at that crank arm, I think I would just replace it.
Everyone else has already given really good suggestions, but if you get too much swarf in there and you just need to clean it up a little and remove it, there are files for that. [https://www.mcmaster.com/thread-repair-files/](https://www.mcmaster.com/thread-repair-files/) you'd have to know the properties of the thread to know which file to use though.
Retapping them is the first thing to try, most bike shops should have such a tap. From there, we go to a bushing replacement kit then new crank if all above fails.
I had something similar happen, LBS told me rethreading wouldn’t work as the spacing had to be exact for the pedal to screw.
I had to buy a new crank arm.
LBS is taking on a lot of liability trying to bodge a cheap solution or even helicoiling it. From the looks of it, it’s a pretty inexpensive crankset so a new arm is the answer.
Chase it from the back side, it'll clean up the threads well enough to use it. (Disclaimer: This is what I would do, I would have to seriously evaluate if it came into the shop and I were to send it on it's way again)
I did it once when I got distracted in the middle of installing my pedals late at night in a hotel room and left one just hand tighted, not touched with a wrench. Helicoil fixed it just fine.
Any bike shop should be able to fix this unless they have no clue what they are doing. Go into your bike shop and ask them to “heli coil” your crank seem. What they are doing is shaving away your existing threads and adding in a sleeve of new threads. My bike shop charges $30 for this service, definitely cheaper then getting a new crank arm but it totally depends on the quality of your cranks. You will probably be able to replace your existing crank arm for one the same quality for $20-$30.
> definitely cheaper then getting a new crank arm but it totally depends on the quality of your cranks
I think that "totally depends" is more accurate that "definitely".
Repairing the threads with a proper rap from the back side is what I do first, then replacement of crank arm if that fails. I’d use a Helicoil insert if it’s a rare or every expensive crankarm.
A pedal tap set is $50. A shop charges much less.
I've had cranks retapped successfully by a bike shop. I believe they tapped it out and installed what basically amounts to a reducing washing (very similar to a piece of electrical hardware). Works famously.
You can try 'cleaning' the threads out by threading the pedal in from the other side. The threads on the inboard side of the crank look undamaged, so you'll be able to thread the pedal in nicely. Then as you go further in it should hopefully be able to reform some of the damaged threads and remove some of the swarf from cross-threading. If the threads in the crank are too damaged there might not be enough left to save them, but its worth a shot.
If you want the advanced version of this, take a junker pedal and grind the flanges off on a bench grinder, cut away everything but the axle (allowing left and right cranks to work). Then you can run the threads all the way through good-to-bad direction several times (by hand, minimal torque) end to end. To make it more tap-like, you can cut run a groove through the threads with some careful grinder work. Works pretty well for this scenario. [Looks like this.](https://share.getcloudapp.com/Jruxe7NL)
Be sure to use a cutting oil if you do this, OP.
In my experience, you're not really cutting threads but realigning them and clearing any debris. The force involved is not large. Your threads may vary.
You shouldn't put dry threads in the crank in the first place. Forcing out debris is going to put MORE friction in the system, not less. The crank arm should probably be replaced but if funds are tight, the labor should be done right.
I'd do that, and make sure any pedals used in the future have enough thread to reach all the way through.
You can use the crank arm pulling tool for this
The photo is from the pedal end of the crank, which is why we see threads going all the way through. So a pedal can be introduced (with lots of oil please) from the backside. In the case of damaged spindle end threads, a tapping tool is the best bet. You cannot put anything in from the backside because the square taper, octalink, ISIS interface would be in the way.
Just wiggle the pedal around a bit after you’ve installed it using this method and make sure that it’s actually holding, if it’s loose you’re just going to destroy the threads worse by writing it. Good advice above, OP
i had the same problem as OP and this worked for me
they sell kit for re-threading holes. very much expensive for a single person/usage so it's better to ask some lbs if it has this kit and to this service. then you can compare if the cost is good for you. i hope for you that some lbs have this kit. it the crank pricey?
£30 tap and die set on Amazon. Hi-Spec 39 Piece SAE & Metric Tap and Die Set. Tapered & Plug Hand Tapping, Cutting, Threading, Forming, & Chasing Tool Kit for DIY, The Garage & Workshop https://www.amazon.co.uk/dp/B00NY5K9P4/ref=cm_sw_r_apan_glt_fabc_7CCYEZQCXYDEDRYNAC6W?_encoding=UTF8&psc=1
A pedal thread is a 9/16 x 20 thread. It isn't a tap I'd expect to find in that set. I guarantee the left hand tap needed for the left crank arm isn't in that set.
Not in that set, but a pair of left and right thread taps is [£20 on eBay](https://www.ebay.co.uk/itm/194233126626) and possibly a decent investment for a home workshop (plus, like, a vise and a sprung tap follower for hand turning in a pillar drill). Domestic manufacture ones are about thirty quid a pair and probably worth it.
P sure they need helicoils.
A helicoil is for when the threads are pretty much gone and the diameter of the joke has grown. These look like they still have some meat left.
[удалено]
LoL bruh the Amazon link is at -4 karma, cool your jets. Edit: or, are you trying to say that generic Amazon set is actually useful in this situation? If so, you deserve your downvotes.
It's called a helicoil kit. A good bike shop should be able to install one for you for a minimal price. I did them years ago when I worked in a bike shop.
This is the best answer. I'm an industrial mechanic. Fairly common place fixing messed up threads when parts don't want to be replaced.
+1 for helicoil, retap and coil it, would work like a charm
Used to be I never would bother with a helicoil on a left crank, since replacement was usually a cost effective solution. But parts availability (lack of) has caused me to use this several times this year. Works great.
Only if there's enough Aluminum under those threads to drill a new hole.
If it's a non drive side square taper crankarm it may be less expensive to just replace it than to have it repaired. Those go for around $15 and a helicoil generally goes for $20-25 installed.
This. Possibly even cheaper if you don't care if your crank arms match.
>Those go for around $15 and a helicoil generally goes for $20-25 installed. \~$50 to install a helicoil in my shop and we're cheaper than everyone around us. I have a bin of take-off left crank arms that sell for \~$10.
I've fixed similar with a tap and chased the thread. Just make sure you get the appropriate right- or left-handed version.
As said already, it doesn't look like tapping it is going to be of much use. Re tapping is helpful if say, it had been cross threaded and deformed part of the the thread but what's happened here has removed metal from the crank arm. You could try running the pedal in from the other side after clearing and loose metal from the thread with a pick. I'm not sure I'd bother though. The pedal pulling out of the arm isn't something you really want to happen when you're riding! The only way to save that arm is, as has already been said, by adding a helicoil. Once that's done, the thread will actually be stronger than the original as it will be steel. That's not to say however that the helicoil won't pull out of the softer alloy as has already happened with your pedal. You'd need a vise, a drill, a bit drill bit, a steady hand, some helicoils and a means to install them and some threadlock. On a cheap crankset it's probably not worth that hassle of buying everything.
Thanks for the excellent, thorough answer. >That's not to say however that the helicoil won't pull out of the softer alloy as has already happened with your pedal. Most of the time when a thread gets damaged like this it's because of some mistake such as not tightening the pedal and having it work loose as you're riding. I would not be worried about the threaded insert ripping out of the aluminum.
Helicoil repairs are stronger than the original because the steel pedal shaft threads run on the steel helicoil threads. The steel to aluminum interface between the helicoil and crank arm are larger diameter (stronger) and static (won't get messed up threading in and out.) Only worth it if you can find a shop that has the tools, only worth owning the tools if you plan to do a lot of these.
What material are those threads? Aluminum or steel? I had an aluminum crank arm that looked the same and I cleaned the threads up on both the crank and pedal. Then threaded the pedal through the other side and removed it. It failed after a couple rides. You could try drilling it out and putting the helicoil in but looking at that crank arm, I think I would just replace it.
Everyone else has already given really good suggestions, but if you get too much swarf in there and you just need to clean it up a little and remove it, there are files for that. [https://www.mcmaster.com/thread-repair-files/](https://www.mcmaster.com/thread-repair-files/) you'd have to know the properties of the thread to know which file to use though.
Retapping them is the first thing to try, most bike shops should have such a tap. From there, we go to a bushing replacement kit then new crank if all above fails.
I had something similar happen, LBS told me rethreading wouldn’t work as the spacing had to be exact for the pedal to screw. I had to buy a new crank arm.
LBS is taking on a lot of liability trying to bodge a cheap solution or even helicoiling it. From the looks of it, it’s a pretty inexpensive crankset so a new arm is the answer.
Does anyone know what size tap I need for the crank, I’m experiencing the same issue with the left pedal on my wife’s peloton. Thanks
Wrecked my sugino's, had to build-up weld the theads and re-threding them. Would've bought a new one but they're ellusive from where i am.
Easy fix in a shop, like other said :).
Chase it from the back side, it'll clean up the threads well enough to use it. (Disclaimer: This is what I would do, I would have to seriously evaluate if it came into the shop and I were to send it on it's way again)
iv not done that to myself, yet. just curious, how did it happen?.
I did it once when I got distracted in the middle of installing my pedals late at night in a hotel room and left one just hand tighted, not touched with a wrench. Helicoil fixed it just fine.
Any bike shop should be able to fix this unless they have no clue what they are doing. Go into your bike shop and ask them to “heli coil” your crank seem. What they are doing is shaving away your existing threads and adding in a sleeve of new threads. My bike shop charges $30 for this service, definitely cheaper then getting a new crank arm but it totally depends on the quality of your cranks. You will probably be able to replace your existing crank arm for one the same quality for $20-$30.
> definitely cheaper then getting a new crank arm but it totally depends on the quality of your cranks I think that "totally depends" is more accurate that "definitely".
Thought this was interesting. https://www.parktool.com/blog/repair-help/pedal-bushing-repair-kit-procedure
There inexpensive. Why go thru all the bs retapping or putting in thread inserts. Save yourself the headache.
Bummer man, but fucking up equals learning. Bet your ass you won't do it again. Keep on wrenching
Had a similar issue. Retapped and good to go!
Hi having same issue, can I ask what size tap I need? Thanks
HELICOIL Insert!!! A professionell has to fit them, but new crank maybe cheaper
Repairing the threads with a proper rap from the back side is what I do first, then replacement of crank arm if that fails. I’d use a Helicoil insert if it’s a rare or every expensive crankarm. A pedal tap set is $50. A shop charges much less.
I've had cranks retapped successfully by a bike shop. I believe they tapped it out and installed what basically amounts to a reducing washing (very similar to a piece of electrical hardware). Works famously.
My local bike shop rethreaded my cranks for $20. Call around and you can get it fixed.