Crank threading
 

I have a set of Stronglight 93's (I think) that are M14x1.25 threading. I also have 2 sets of TA cranks that I believe (normal pedals don't thread in more than 2 turns) are French threaded as well. I installed the Stronglights on my Astra w/out issue. I then went to install my French threaded pedals (2 different sets) and got about 2 turns into the Stronglights then got really tight. The threads look unbutchered and clean so that shouldn't be an issue. I tried the same pedal in both sets of TA cranks w/out issue. What gives?!?:twitchy: I really want to get this bike together and ride it. I could use another set of Stronglight 93s that I have but they are not polished like the ones on the bike and I don't feel like polishing anything....

9/16x20 crank with French pedals = too loose
French crank with 9/16x20 pedals = too tight

What makes you think your pedals are French? - or for that matter that your TA cranks aren't 9/16"?
French Pedals are usually marked "G" and "D".

Now you know why I sold you those French parts so cheap.......:D

Your TAs may have been retapped to ISO.

The only reason I thought the pedals are French is because 9/16" pedals do not thread into my TA cranks (either set) and the "French" pedals do. I'm going to take a crank arm to a place that sells taps and dies along w/ a "French" pedal and see what threading they are. If it comes down to it, I'll just retap them to 9/16" threads

Keep in mind that you will need two taps, one left and one right. Might be better off taking the crank set to an old bike shop in your area, if there is one.

Good point, forgot about that. I know a guy who has a set of taps;)

If you haven't been able to thread any pedals into the Stronglights perhaps the threads are gunked up. You can chase em with the right tap, or just hose em out with WD-40 and a paper towel real good and lube em and try again.

They look pretty clean, plus I don't have a M14x1.25 tap. I have 30-40 taps, just not that one!

Just to clarify, if I thread French pedals into ISO (9/16x20) threads, they will be loose? I threaded the Lyotards (the pedals I want to use) into a set of cheap Shimano mtb cranks and they were loose but, did snug down.

yes. But as you experienced you can get them to snug down.

There's enough thread biting to get em to snug down but if you put pedaling force to it they will come loose. Its only like a .2mm difference in diameter between the 2 sizes. That's why its so easy to tap French to ISO.

Silly question...did you grease the threads?

What brand pedals? Lyotard in particular are notorious for sloppy tolerances on the threads.

One set is Lyotards and the other ATOMs. I think I might just tap the threads and run carbon fiber spds:p