I just purchased a new road bike and had a friend assist me in the assembly. There must have been a problem because it fell off after only 2 miles of riding for the very first time. I used a pedal wrench and tightened it. The pedal was indicated as being the "left" pedal and has reverse threads.

Now the threads on the left crank are about half stripped. I have successfully screwed the pedal on but am worried about it failing now. The crankset is a Shimano FC-RS500. I would post a picture but I don't want to do anymore damage to the threads by taking it off again.

Do I replace the left crank now or just wait and see?

  • Are you 100% sure that you put the left pedal in the left side and the right pedal in the right side? And is it possible you were sent two right-side pedals? Remember, the left side should screw in "backwards". (And consider that crank to be toast.) Jun 23, 2016 at 11:56
  • Also, I'd recommend checking your right pedal as well.... make sure that one is not coming loose as well. In fact - go over the whole bike from scratch making sure the assembly instructions were followed correctly. Did you do the pedals or was it your assistant? How hard was it to thread the pedals in, initially? Should be no-to-minimal force required until its snugged up, then a last tighten with the pedal spanner.
    – Criggie
    Jun 23, 2016 at 23:16

3 Answers 3


I'd be contacting whereever you got the bike from and raise the question of warranty - given its a brand new bike.

Warranty may be void if you attempt to repair it yourself.

Also, check whether self-assembly voids the warranty... some have a rider that "bike must be assembled by an authorised dealer" I think Giant has this requirement.

  • 1
    I contacted them a few hours ago. They responded immediately and seem helpful. They've requested pictures so yes, hopefully they will help solve the issue! Jun 23, 2016 at 23:23
  • 1
    Update: They have shipped me a replacement part. Thanks! Jun 27, 2016 at 19:46

First thing to check: the left pedal uses a left-handed thread. Was it screwed in correctly? Depending on the amount of damage to the threads, it may be possible to sort-of screw it back in the wrong direction, which will damage it even more.

  • It was the correct pedal and I referred to various instructions online on how to install them properly. I've contacted the company so hopefully they assist me! Jun 23, 2016 at 23:23

You can chase the threads back around with a thread cutting kit and you can also repair the thread with a helicoil kit.

If the pedal is in and secure - you might get away with using a threadlock to keep it in place.

And of course there is also the option to buy a secondhand replacement from ebay.

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