I have a crank and chainring setup pictured below, running as a 1x with a chain guard where the outer ring would be.

I am trying to remove the chainring from the crank and am having trouble.

The bolts take a standard allen key but on the other side there is an irregular screw that needs to be held in place in order for the bolt to loosen. It seems one would need a special tool to hold it in place while he bolt is loosened.

I managed to loosen one of the bolts without holding this screw in place, but the others won't budge, i.e. they turn with the bolt and thus do not loosen. One can see in the pictures below that there isn't enough clearance to fit a standard flat head screw driver to hold it in place.

Is there a common tool(s) I can use to remove these bolts? If not, what is the tool called that I need in order to loosen these bolts?

enter image description here

(below) Not enough clearance to use a standard flat head

enter image description here

(below) A bolt that did loosen, without any holding in place

enter image description here

  • 1
    There is indeed a special tool for that. Or you can find an extra-wide screwdriver and grind notches in it. Feb 15, 2017 at 3:21
  • 1
    Other workarounds include using the tips of a small pair of needle-nose pliers, holding a flat-head screwdriver at an angle so one corner digs in... Feb 15, 2017 at 4:27

1 Answer 1


What you need is known as a "Chain ring spanner" or a "Chain ring peg spanner". Very cheap to purchase.

enter image description here


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.