Bicycle pedal threads

Just buy a new pedal arm.

Who's the idiot that made these things 9/16-20? Now I had to order a special tap to fix my sons bike. MSC does not even carry the LH version. McMaster does. Luckily I only needed the RH one. LH is almost $70.00 OUCH.

for special bike tools, I might have to order the set off ebay, local bike is listed as a park tool dealer, they never heard of a tap or park tool. WOW.

Thank You, Randy

Remove 333 from email address to reply.

I remember cross threading one of my pedals when I was a kid. I am guessing that is what happened to your son's bike. I was able to start the pedal from the backside and reform the threads. How I thought of this at 11 or 12 I don't know, but it straightened out the threads enough that I was able to reinstall the pedal. I also remember taking apart the Bendix brake and never having work properly again though too. Ahhh those were the days riding my bike with a playing card flapping on the spokes held in place with a clothes pin. Steve

Ouch! that one is a toughy. I checked three of my favorite bike part sites, nada... FWIW I have dealt with these two companies years ago with decent results:

This one has some odd things, but I've never ordered from them:

You could always try sending them (Nashbar/Performance) an email, ask if they can get the Park TAP-6 and what it would cost. It used to be a lot cheaper getting my stuff through them.

You maybe able to by a whole crank arm cheaper. Be sure and get the right length and Crank/BB mount style.

I have a set of 9/16-20 RH and LH taps you could borrow if you're doing a one-off. They are really not in the best of shape, I salvaged them 30+ years ago from a shop that burned down. If carefully cleaned up and you were careful, I think you could get a decent thread out of them.

Ping my email direct if you're interested.

Jon

I don't know what brand you have there, but I seem to remember that, when I was a kid,(1940's and 1950) the Schwinn was the one that was totally non-standard.

Pete Stanaitis

Randy wrote:

We went for corrugated cardboard with three or more clothes pegs along with the extended front "chopper" forks then again we were rebels.........

Almost all pedals made today are threaded 9/16 x 20.

The reason that the left-hand ones are threaded that way to to prevent them unscrewing due to precession.

A small number of (usually) cheaper pedals are still made with 1/2 x 20.

Previously there were metric-threaded pedals made (14mm x 1.25); and I believe that there may have been two varieties of these depending on thread form angles.

Pedals are usually marked R and L (or D or G, or D or S; for French and Italian, respectively).

Shimano, the goliath of bicycle equipment manufacturer, as part of their unending practice of introducing "new, therefore better, therefore you must buy it") bits of kit that just happen to not be compatible with the old kit, did try to sell a set of unusual pedals with 1 x 24 thread; not a commercial success.

Any decent bicycle shop will have the thread taps and ought to run it through your mangled crank arm for a modest fee; if they happen to be metric a 9/16 x 20 tap will change them without too much difference in the thread (it's 14.28 x 1.27, and the arm will only be about 5/8 of an inch thick).

Thanks for the offer, I did order one from MSC yesterday, shhould be here about 2PM.

Thank You, Randy

Remove 333 from email address to reply.

Running a tap through would not fix this arm, end was completely stripped out smooth, and egg shaped. Milled the end off and made a new end from 7/8 crs. welded it on and drilled and tapped it. Old end was 3/4 dia and I went a little bigger for more wall thickness.

I wonder if I could have used a 1/2-20 STI tap, (helicoil) it measures 0.569" major diameter.

Thank You, Randy

Remove 333 from email address to reply.

Back to the original question, If old pedals were 1/2" NF why did they not just go to 9/16 NF if they wanted bigger/stronger threads. Who decided that 20 TPI was somehow magical? Special is better, idiots.

Thank You, Randy

Remove 333 from email address to reply.

9/16 x 20tpi would be the British "cycle thread", which probably predates NF. Not to say that it's better, but given that they invented the current bicycle system, I guess it's reasonable that they specified the threads too. Nice that most makers followed suit.

Jordan