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Discussion Starter · #1 ·
Unfortunately I stripped the first one or two threads of my 68mm bottom bracket. There is only damage to the first two or so fortunately, but I'm afraid if i try to self tap the BB it will ruin it all. My bike manual says to bring it to a LBS to have it rethreated. Can I do this? Can someone share their experience with this? Thanks.
 

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noMAD man
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Most decent shops have BB thread chasers.

matt719 said:
Unfortunately I stripped the first one or two threads of my 68mm bottom bracket. There is only damage to the first two or so fortunately, but I'm afraid if i try to self tap the BB it will ruin it all. My bike manual says to bring it to a LBS to have it rethreated. Can I do this? Can someone share their experience with this? Thanks.
Park and some others make a nice set of self-aligning tools that hold different thread chaser of different standards. Yours are probably English threads like most bikes. If indeed your first couple of threads are no longer functional after being cleaned up with one of these tools, sometimes you can find a deeper BB cup design to insure enough cup and thread interface. Are you sure that it's not just cup thread material imbedded in the actual BB? If so the thread chaser will remove that and restore your original threads.
 

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Discussion Starter · #6 ·
I'm not sure what you mean by cup. My situation is the actual BB (not the other side that screws on), the drivetrain side, is stripped. It looks like the first two threads were bent over. I can screw on for a little bit, which i'm sure is what i self tapped when a stripped it, but then it stops screwing in and just turns in the same place. it's a Cannondale CAAD4 frame. I'm going to call my LBS tomorrow and see what's up. There is bound to be a least one shop around that can do it, but I'm sure most all must.
 

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noMAD man
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Cup

matt719 said:
I'm not sure what you mean by cup. My situation is the actual BB (not the other side that screws on), the drivetrain side, is stripped. It looks like the first two threads were bent over. I can screw on for a little bit, which i'm sure is what i self tapped when a stripped it, but then it stops screwing in and just turns in the same place. it's a Cannondale CAAD4 frame. I'm going to call my LBS tomorrow and see what's up. There is bound to be a least one shop around that can do it, but I'm sure most all must.
The cup(s) are the two threaded fixtures on either end of the BB spindle that actually thread into your frame. Your frame (BB shell), I take it from your description, is the part that's stripped? Some BB brackets have removable cups on both the drive and non-drive sides and most all have at least a removable non-drive side cup.
 

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Born of Fire
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I talked with me lbs about that today. My buddy bought a new frame with the same problem and the shop said he had two different tools to handle the job. Ten bucks if it was the small tool. Thirty bucks if he had to use the big tool.
 

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you're really lucky they can chase and retap the threads.

if they were REALLY mangled, you would have to kiss the frame good-bye unless you wanted to convert it to an EBB singlespeed... which is possible because the entire BB shell gets cut out of the frame to install the EBB shell, which is much larger in diameter.
 

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Discussion Starter · #10 ·
if the threads are that mangled, since i have a 68mm shell, couldn't i drill it for 73mm and tap it for a 73mm BB?
 

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matt719 said:
if the threads are that mangled, since i have a 68mm shell, couldn't i drill it for 73mm and tap it for a 73mm BB?
Nope. The size refers to the width of the shell, not the diameter. If its just a couple of threads you should be fine. I screwed up a good 1/4" of thread on my old bike and my LBS was able to rethread both my BB shell and the BB cup.

Duc
 
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