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Stripped Disc Brake mounting threads in fork

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Stripped Disc Brake mounting threads in fork

Old 01-25-23, 09:15 AM
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Jughed
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Stripped Disc Brake mounting threads in fork

Any way to fix stripped threads in a fork? I don't want to replace the entire fork... I don't think there is enough material for a tap/helicoil type fix.

2019 Giant TXC, carbon fiber, for reference.

PS - I plan to have a pro do this work, just didn't even know if its possible.

Thanks!!

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Old 01-25-23, 11:06 AM
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Can't see without pics.
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Old 01-25-23, 01:21 PM
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In most cases it should be possible to drill out the thread and mount the brake with a bolt and nut.

It's not a difficult job, and done right, as good as new for practical purposes.

BTW don't let assumptions prevent consideration of a coil insert. These don't involve removing much and in soft materials produce a stronger thread than original.

Last edited by FBinNY; 01-25-23 at 01:29 PM.
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Old 01-25-23, 01:28 PM
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What type of mount for the calliper? If it is a flat mount a helical might be the only solution. Either that or tapping the mount out to a larger size and using a larger mounting bolt
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Old 01-25-23, 01:49 PM
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How did you do this? was it user error, or a defect that would/maybe be covered under warranty (you get lifetime as the original owner if a defect)

Would look at the cost of a replacement fork vs Helicoil, there isn't much material on a tab to fit one (the 2019 Giant TXC has flat mount), and unless doing it yourself, a LBS may refuse as there is the liability issue for a safety critical part
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Old 01-25-23, 02:33 PM
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Originally Posted by GamblerGORD53
Can't see without pics.
will try to get a pic...
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Old 01-25-23, 02:41 PM
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To answer some of the above questions:

Flat mount
There is very little material.

I am the second owner. See my post on the Chinese frame thread - when the aftermarket Chinese bars exploded and I crashed, that side of the bike.

I took everything apart to check inspect everything for cracks, went to put the nut back in and it just spun in there, probably got torn up in the crash. Took it to Giant for a frame inspection - it passed... asked them to fix that along with other issues and they made a mess of the bike. I had the new bars and hoods loosely put on - I asked them to level the bars, correctly mount the hoods, torque everything and put on bar tape, fix the fork... they only put on bar tape, everything else was loose and in the same position I left it in. So I wont go back to that shop...

I guess I need to find a better LBS that can actually do real work. I asked here first to see if its even possible to fix.

Thanks
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Old 01-25-23, 07:10 PM
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Originally Posted by Jughed
To answer some of the above questions:

Flat mount
There is very little material.

I am the second owner. See my post on the Chinese frame thread - when the aftermarket Chinese bars exploded and I crashed, that side of the bike.

I took everything apart to check inspect everything for cracks, went to put the nut back in and it just spun in there, probably got torn up in the crash. Took it to Giant for a frame inspection - it passed... asked them to fix that along with other issues and they made a mess of the bike. I had the new bars and hoods loosely put on - I asked them to level the bars, correctly mount the hoods, torque everything and put on bar tape, fix the fork... they only put on bar tape, everything else was loose and in the same position I left it in. So I wont go back to that shop...

I guess I need to find a better LBS that can actually do real work. I asked here first to see if its even possible to fix.

Thanks
So …

They used to be a giant dealer but aren’t any longer. Bike Doctor in Arnold MD talk to Steve if he is in. They are a great shop.

cheers
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Old 01-25-23, 09:07 PM
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In that case, JUNK the bike.
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Old 01-26-23, 05:38 AM
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Originally Posted by Shadco
So …

They used to be a giant dealer but aren’t any longer. Bike Doctor in Arnold MD talk to Steve if he is in. They are a great shop.

cheers
Thanks Shad.

I just found an old school LBS (Wooden Wheels) near my office... I didn't know they were still in business. I've tried both of the big box bike stores around here and the mechanic service has been hit or miss.

If that shop can't help, I will call Bike Doctor.
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Old 01-26-23, 05:43 AM
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Originally Posted by GamblerGORD53
In that case, JUNK the bike.
The nearest LBS said the same thing. They wouldn't even look at the bike - they said "carbon fiber in a crash, throw it in the trash".

Easier said than done... these items are quite expensive as we all know.

And I just can't fathom that a purpose built Cyclocross frame would be trash after a crash.

People would be throwing bikes away multiple times per season... maybe they do?
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Old 01-26-23, 08:29 AM
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Originally Posted by Jughed
The nearest LBS said the same thing. They wouldn't even look at the bike - they said "carbon fiber in a crash, throw it in the trash".
The best thing about CF is that most damage can be repaired, sometimes even by the home mechanic doing it the first time. It just depends on what the damage is. If no luck with bike shops look for CF repair specialists if you don't feel comfortable doing this yourself and as mentioned above you may be able to buy one of the thread restorer options you could do yourself. Posting photos of the mount would be helpful as well.

Last edited by Crankycrank; 01-26-23 at 08:33 AM.
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Old 01-26-23, 08:46 AM
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Originally Posted by Crankycrank
The best thing about CF is that most damage can be repaired, sometimes even by the home mechanic doing it the first time. It just depends on what the damage is. If no luck with bike shops look for CF repair specialists if you don't feel comfortable doing this yourself and as mentioned above you may be able to buy one of the thread restorer options you could do yourself. Posting photos of the mount would be helpful as well.
Thanks - there is no damage to the CF, just a stripped thread that may or may not have happened during the crash.

And, I've got about 1000 miles on the bike since the crash - mostly dead flat gravel roads. The structure is of the bike fine. I just don't use the front brake. I want to get the bike ready for some real gravel races in the mountains this summer... a front brake would be nice for that.

I will try to get a picture at some point.
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Old 01-26-23, 09:15 AM
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I was curious just how easy it would be to find a pro to fix it, so I typed "carbon fiber bike repair maryland" and the helpful search engine appended "lottery."

I don't know that the odds are stacked against you that badly. But I personally wouldn't think about riding that bike in mountainous terrain where I needed a front brake before I had a specialist look at the fork (at a minimum) or the entire frame (better) and give me the OK to ride it.

If you've got a good ear and a quiet place to work, you could try the coin tap inspection. Tap the frame and fork with a dime, spacing the taps by the diameter of that time. Cover the entire frame. Any place where the normal click comes back as a thud is suspect.

If you can't afford to replace the frame (or the bike), how do you expect to pay the medical bills when the frame fails and you crash?
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Old 01-26-23, 09:41 AM
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Originally Posted by pdlamb
I was curious just how easy it would be to find a pro to fix it, so I typed "carbon fiber bike repair maryland" and the helpful search engine appended "lottery."

I don't know that the odds are stacked against you that badly. But I personally wouldn't think about riding that bike in mountainous terrain where I needed a front brake before I had a specialist look at the fork (at a minimum) or the entire frame (better) and give me the OK to ride it.

If you've got a good ear and a quiet place to work, you could try the coin tap inspection. Tap the frame and fork with a dime, spacing the taps by the diameter of that time. Cover the entire frame. Any place where the normal click comes back as a thud is suspect.

If you can't afford to replace the frame (or the bike), how do you expect to pay the medical bills when the frame fails and you crash?
The frame is OK. It's been coin tapped. It was inspected by Giant. It was inspected at my local Trek shop - but they will not sign off on any CF bike that was in a crash, but they said the frame was not damaged.

It's just a thread issue. An issue with the metal insert in the CF fork.
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Old 01-26-23, 09:53 AM
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posting a picture will help.

calfee is well known for carbon repair https://calfeedesign.com/carbon-repair/

call them, if they won't take it on, time for a new fork
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Old 01-26-23, 10:46 AM
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I read his "story" as consistent. A previous shop mechanic or owner overtightened the caliper bolt & it held until the OP messed with it & the insert threads came out with the bolt.

This is why thread compound, torque tools are used & anything other than IS mount sucks. (Don't get me started on thru-axle.)

OP: This would be a good excuse for a fork upgrade. Ritchey WCS or Whiskey make suitable forks that probably weigh less than your current OEM fork.

Last edited by base2; 01-26-23 at 11:31 AM.
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