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Stripped pedal thread on Tiagra crankarm

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Stripped pedal thread on Tiagra crankarm

Old 07-11-10, 09:22 PM
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Just so you know the inserts alone cost $5-$7 depending on were you get them so you take it from their
It may not be fancy but it gets me were I need to go.
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Old 07-12-10, 05:14 PM
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Okay, I went to one shop (sort of snooty LBS) that wanted to charge me $70 to do both sides and then didn't have the right part for the left side crank arm. Then I went to the guy that's right down the street from me, and he just wanted to change the crank arm (he either didn't understand my question about the helicoil or didn't agree--he speaks primarily Korean and I don't but we usually figure it out) but he only had a diamond crank arm not a square. He got the pedal in and said it would hold but not under a lot of pressure. I really want to keep the original crank arm, but I can't seem to find anyone to do the repair reasonably (they all make it sound like this extremely big deal). I'm willing to go to a new crank arm but...any suggestions on the helicoil anyone? Some one suggested I just go to an auto mechanic and have it done.
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Old 07-12-10, 07:45 PM
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Drilling, tapping and installing the coil is not a big deal but I would not trust anyone to do it that does not use a drill press. This is needed to assure alignment of the drilled hole with the square taper axis so the pedal doesn't wobble as it goes around. In fact a bare BB axle should be lightly installed and checked for plumb before the arm is firmly clamped in whatever they are using and the hole is drilled. Once drilled and without moving the arm the tap is gripped in the drill chuck and the threading started for a few turns to again ensure that everything is bang on axial and in line with the taper axis. This may sound techy if you're not a machine shop wiz but it's about as basic as ketchup on a burger. And it is an EXCELLENT repair despite what some shop guys may tell you.

What it sounds like to me is that few of the shops are set up to do this and fewer still have anyone on staff that actually knows enough to do the job right. The way things are going you may well end up with a new crank arm anyway.
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