nrsmd

My road bike pedal is labeled as 9/16, but I believe that is the size of the wrench needed to put in or take out the pedal.

The bike is a Fuji.

What is the actual thread size?

Thank you.

jimc101

9/16th x 20 tpi is almost the standard size, there are some (very) older which are different, but you would need to be looking at C&V for them https://www.sheldonbrown.com/gloss_p.html

For removal / installation, this depends on the pedal, you may need a hex wrench (normally 8mm) or 15mm pedal wrench, see here https://www.parktool.com/blog/repair-...-4-pw-5-hcw-16

Doohickie

Note also that the left pedal has a left-hand thread.

jimc101

Good point, can catch many people out first time

FBinNY 

Poeple get confused about right and left pedla threads, especially if using an allen key in the end of the axle. So I prefer to tell people, turn top to the front of the bike to install, and to the back to remove.

Or they can apply a variant of Murphy's Law. When you install the pedals and all is good, the chain keeps the crank from turning making it very easy. But when you go to remove pedals and need lots of torque the crank provides no help, and you'll face the joys of having the crank spin back making a tough job that much harder. So all you need to remember about which way to turn a pedal to remove is that it's the harder way.

nrsmd

I am certain you are 100% correct. My first question was the easy part. On the right pedal, the entry thread is a bit damaged on the pedal (female), so I am afraid to attach the pedal for fear of doing more damage. But, when I screw the pedal in the opposite direction, it goes in completely and smoothly but does not quite reach the first few threads. So I was thinking of buying a longer bolt (Lowes) of the same size, threading it in in the opposite direction all the way through to re-seat the first few threads before taking it in for repair or purchasing a repair tap I found on the internet made by Park Tools. Hoping to do it myself.

Thanks for the help.

FBinNY 

9/16x20 is a pretty rare thread, so you're not likely to find a bolt at the hardware store, and definitely won't find a left thread one.

You have two reasonable options. The first and easiest is to bring it to the local bike shop or co-op, and have them run a tap in from the back to clean up the first thread. This should be a very inexpensive 5 minute (or less) job, which most shops would do free for a regular customer, but may charge a walk-in unless you were buying something else at the same time.

The other is a DIY option. If you own a rat-tail file, you can carefully file out the damaged 1st thread at 45° just enough so that the pedal can pick it up and go in straight. If you own a large enough countersink bit and drill you can use that. There's no issue because the 1st thread or two don't matter. If you look at the pedal, odds are you'll find thread relief of about 2mm where the thread meets the shoulder of the pedal. Thread relief is standard because it's impossible to produce a thread up to a shoulder, so either the crank or pedal (or both) have to be made to allow for no thread engagement at the shoulder.

nrsmd

Thank you so very much. Would gentle use of a Dremel tool serve the same purpose as a rat-tail file if I limit its use to the first 2 mm only? After that, I would take it in or buy the Park tool.

fietsbob

nope, pedal wrenches are 15mm, and thinner, 1/8" thick typically.

first few threads buggered up? try screwing the pedal in from the inside..

if that does not work, there are pedal taps , bike shops have them.

FBinNY 

Yes, the method doesn't matter, only the results. Work by degrees, testing the pedal at intervals. Just be sure you don't let a bad first thread cause you to cross thread it. It needs to go in easily, or at worst with steady resistance. Resistance that gets worse as you go deeper means that it's cross threaded and you need to back out and try again. Do not extend the mis-aligned thread deeper hoping for the best, it only gets worse that way.