Originally Posted by
Fox Farm
Your local bike shop can get the non drive side. Assuming that Ultegra and 105 have the same Q factor offset, go with that. If you were to put the helicoil in, I would have a machine shop do that where they can insert it with precision.
The one issue with having a machine shop do the helicoil is that they may not have a left-hand helicoil for the non-drive side arm.