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I need to replace my handlebar on my Trek 830. I have a spare one, but it has shifters still attached to it.

I tried to remove them. However, the hex bolt on the front shifter is severely stripped! It's almost completely round not hex shaped.

I tried to wrap tape around the tip of the Allen wrench that is supposed to get the bolt out to make it have a tighter fit. That didn't work. I tried the next size bigger Allen wrench. That didn't work. Are there some other tricks? Like I mentioned, this is an unwanted shifter, so it can be broken off.

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    try an imperial hex key in the metric socket. (or vice versa) Depending on the size this might just be enough.
    – D Duck
    Commented Oct 21, 2023 at 18:40
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    One other trick is to use a rubber band in between the bit and the worn out bolt, sometimes it is enough friction and grip to get it moving. If the bit doesn't fit go down a size. I usually try this first as it wont hurt anything.
    – Nate W
    Commented Oct 23, 2023 at 23:28

3 Answers 3

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I can suggest three methods.

  1. The mounting clamp has a gap. You can use a thin saw to split the bolt there. It might scratch the clamp, but with careful action, the saw blade will not touch the handlebar. After that, you will be able to slide the shifter off the handlebar.

    Gap

    Come to think of it, you could even saw the clamp off at any position, if you don't need to preserve the shifter.

  2. Use a special bolt extractor bit. There exist several types, I successfully used ones similar to these, which are essentially "wrong"-threaded conical drills:

    extractor bit

    Note that the key to success using it is enough insertion depth for the bit to bite. This means that you will need to drill a hole using a regular smaller drill bit inside the bolt head. Without doing it, the extractor bit would just glide helplessly.

  3. Use a regular wider drill bit to shave the whole bolt head off. You goal is to weaken it enough to be able to break off the threaded part from the head part.

Good luck!

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    Another option is drill out the bolt head.
    – mattnz
    Commented Oct 19, 2023 at 7:20
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    A dremel style rotary cutoff tool can be incredibly helpful to either cut through the bolt via the slot (potentially saving the whole shifter) or to slot the head of the bolt to accept a flathead screwdriver, or finally to slot 3/4 of the way through the strap to weaken it, then tear it apart with a cold-chisel and hammer.
    – Criggie
    Commented Oct 20, 2023 at 0:11
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    @Criggie I agree, particularly if used with a diamond wheel or a cutoff disk. One thing that occurs to me here is that the bolt probably isn't hardened if it rounded relatively easily. Commented Oct 20, 2023 at 10:30
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    I didn't even think about a dremel! I recently got one too!
    – Alison
    Commented Oct 20, 2023 at 13:28
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    @Alison Further to Grigory's comments, wear safety glasses when Dremeling. I haven't used one in many years so maybe things have improved, but when I got my first one like 20 years ago, it came with these sort of ceramic discs for cutting metal but they were quite brittle and if they jammed while cutting through metal they'd sometimes shatter and fling little shards of ceramic outward. As I'm writing this, I really hope those aren't still the standard metal cutting discs.
    – SSilk
    Commented Oct 23, 2023 at 17:56
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Drilling out the bolt is probably difficult, because handlebars are not easily fixed to something rigid, and you have to drill freehand, in an unusual direction. At least, use some lubrication and a sharp drill bit.

If you know someone with a TIG welder, have them tack weld something to the hex bolt head, with the smallest torch (handset?) at hand. Something like a hex nut standing on one of the six edges, as the new handle to turn the bolt. Cover the shifters with tape before, cut the hex bolt free, then you might be lucky.

That said, these bolts are normally fastened with a torque wrench to 4-6 Nm, in order to not kill the delicate thread in the aluminium or fibre reinforced plastic part. If the hex bolt is completely done, I'd be suspicious of the receiving thread.

Other reasons that the bolt can not come lose:

  • someone used the wrong type of Loctite or similar product.
  • electrochemical corrosion where aluminium oxide from the thread grips the bolt firmly. I tore bolt heads off because of that.
  • metric bolt in imperial thread or vice versa.
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    You remind me - these pinch bolts are often open on the bottom. So it may be feasible to drill the leading face of the bolt from below, and then unscrew it from below.
    – Criggie
    Commented Oct 20, 2023 at 0:13
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    @Criggie to possibly state the obvious, you must remember if you unscrew from below that you have to turn it in the direction which you'd usually associate with tightening (speaking as someone who's gotten really frustrated the first time they had to replace their left pedal)
    – llama
    Commented Oct 20, 2023 at 14:35
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I've never done this myself, but I've seen videos of people using torx bits to remove the bolt. Use a hammer until it grips enough top turn the bolt. This could damage the torq nur could be just enough to remove the bolt

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    This will most certainly damage the torx driver bit - but its common to own a lot of them so sacrificing one is occasionally required,
    – Criggie
    Commented Oct 19, 2023 at 18:16
  • I have done this with success! The hammering was not needed in my case. I just jammed it into a pretty tight fit. The torx suffered some damage, but it was well worth it to remove a rounded and stuck brake-pad retaining bolt.
    – WornChain
    Commented Oct 19, 2023 at 20:28
  • Expanding on @WornChain's comment, sometimes a metric Allen key will fit a rounded Imperial/English head or vice-versa. Commented Oct 20, 2023 at 10:28
  • In my particular case nothing fit. I tried both metric and imperial hexes. The partial sacrifice of a torx did please the bolt-gods anyway.
    – WornChain
    Commented Oct 21, 2023 at 0:17
  • The other thing about torx bits in stripped hex heads is they're not only harder, they're tapered. So if you can get one to bed in enough something like an impact driver (handheld or power with lots of care) will bed the bit in further as it turns the bolts. Has often worked for me, but yes, the bit gets damaged.
    – 2e0byo
    Commented Oct 21, 2023 at 10:13

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