I've this bike MTB hardtail Marin Bolinas Ridge 2012.

And it has generic composite pedals which I want to change.

So while choosing pedals I saw two different choices, 1/2 and 9/16 inch pedals.

I didn't understand what does this sizes mean and apply to what.

Please if someone can explain it to me.

For example: Diamondback Sound Pedal 9/16 and 1/2 model

  • which is the bigger ? just got pedals for my son,s bike thinking all pedals the game size but these are too big so would they be 9/16 ? it,s the smaller size he would want , so what would the smaller size be so i can get them ? thanks gary
    – user7752
    Commented Aug 9, 2013 at 15:37
  • 9
    The difference is 1/16 of an inch.
    – RoboKaren
    Commented Nov 20, 2017 at 15:48
  • Exactly 1/16". 9/16" - 1/2" (8/16") = 1/16".
    – Mathguy
    Commented Oct 7, 2023 at 18:03

3 Answers 3


The measurement is for the diameter of the pedal spindles, where they thread into the cranks. You need to find out whether your existing pedals' axle is 9/16" or 1/2". If there is no measurement indication on your existing pedals or the paperwork which came with your bike, ask your LBS if they could test out with some existing pedals to find out what size you need.

  • 15
    If your LBS is good enough to help you out return the favor and buy your pedals from them.
    – mikes
    Commented Jul 3, 2012 at 10:33
  • 3
    And if you're dead set on the model but they don't carry it, let them know that you'd much rather buy from them if they'd start carrying that brand. And make sure your next purchase comes from them.
    – jimchristie
    Commented Jul 3, 2012 at 15:49

1/2" pedals are for cheapo one-piece cranks, while 9/16" pedals are for 2 or 3 piece cranks. You probably need 9/16th...


I had the same question. I know the basics of a bike (experience earned repairing my bike along the years)Today I need to replace pedals and when asking for the measure of 9/16 and 1/2 question, the answers are not clear: number of cranks (?) or sending you to ask to the bike shop (?). A seller gave this information on the web: Standards 9/16 inches (14 mm) and 1/2 inches (12.7 mm) Diameter spindles threat So I took my bike pedal and measured: 12.7 !! so it must be 1/2 inch. Solved.

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