Sorry to start yet another thread relating to my Motobecane build woes- but it's almost done! These pedals were given to me off of what I was told was an early 70s Pugeot. However, the spindle ends say L and R not D and G. They need to go on stronglight 93 cranks. Is there an easy way to test without risking damage?

The axles should be standard thread and the cones should be french.

Ah, meaning they wont work, correct?

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pedals are model 36

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What does this indicate? Some research shows that before 1977 this model had screw on caps, which these do. Would these french pedals not be french threaded pre 1977? Is L and R a dead giveaway that they wont work?

If you screw a French (one of the two standards: M14 x 1.25) into an Imperial (the other standard: 9/16-20) crank, it will be a bit wobbly, because while the thread pitch is close, the Imperial has about a 2% larger diameter. Threads (both internal and external) should be clean when you try this. You shouldn't be able to screw an Imperial-threaded pedal into a French-threaded crank without brute force. A French-threaded crank can be retapped easily for an Imperial-threaded pedal, but not vice-versa (obviously).
"The great thing about standards is that there are so many to choose from".

Are you sure your crankset is French threaded? Not all 93’s were.

I just took a measurement from some French threaded Lyotard pedals and they are .639". For contrast a pair of Look pedals measured .654" The French threaded pedals will tread into a bsc crank loose then appear to tighten up at the end of the thread, but I wouldn't ride on them that way. The Look pedals won't go into the french (stronglight 93) crank at all.

Hm, I didn’t know this. Im not sure how to measure the threads to find out.

How about - gently - taking a known set of English pedals and seeing if they'll fit the Stronglights? If they don't go on at all, fine, the cranks are French threaded. As far as these Lyotard pedals go, I would suspect the L and R indicate 9/16/BSC/ISO threads, because the comparable Lyotards on my outrageously French Liberia are marked D and G. You can gently thread these Lyotards into a known BSC crank and see if they feel loose nor not.

FWIW, the only Stronglight 93s I've owned that were French-threaded were on Peugeot PX-10s; all the others had English threads either because (a) someone decided bikes sold in the Anglosphere markets should have 9/16 threads or (b) someone ran some 9/16 taps through to convert them.

This is all good info, thank you. I tried threading these on gently and couldn’t even get one rotation in, though I’ll try with some other pedals. If they happen to be English threaded I’ll be very happy.

If not, this A08 is near me and I can pick it up for $20 and use the pedals if they look like they’ll clean up alright.Anybody have an idea if they’d be French threaded? Looks like a 75-76ish model.

QUOTE=polymorphself;21704262]Ah, meaning they wont work, correct?[/QUOTE]

Stronglight crank arms were marked with thread spec on the back side. "14 x 125" is metric (aka "French") thread; 9/16 x 20F is English. Unless you are the original owner, it is possible that a metric-marked arm has been re-tapped to English thread.

Stronglight crank arms were marked with thread spec on the back side. "14 x 125" is metric (aka "French") thread; 9/16 x 20F is English. Unless you are the original owner, it is possible that a metric-marked arm has been re-tapped to English thread.[/QUOTE]

Ah! Well that solves it then. These are metric. 14x125 stamped on them. The Japanese pedals I have just barely begin to go in and then stop, as expected.

Thank you! Hopefully the pedals on the above A08 are French and work out for me...

I'm pretty sure those pedals with have English threads. I have a similar mixte (from '70), and I replaced the cottered crank and spindle with a square taper spindle and a Sugino crankset, and I'm using the original pedals. The threads don't have a loose fit, and they've been in there for over a year now (I think they'd have backed out by now).

Dangit!

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...I have asked this question before of someone, but ever adventurous, I will ask again. Is there some specific reason you don't want to rethread these cranks a little larger, to the now standard 9/16 ? As already stated above, it's easily done, and the only person who will be able to tell looking at the bicycle is you.

I have some French threaded pedals I will never use, if you want them. But they are not those flat platform Lyotards. I'm of the opinion that retapping to 9/16" makes a lot of practical sense in 2020, unless you enjoy the adventure of shopping on the French ebay site.

Definitely nothing against it! I just don't know how to do it, or quickly I could find a shop to do it. I'm very pressed for time on finishing this. and basically need to figure out the pedal solution by today or have some on the way to me that will arrive before end of week. Will any good shop be able to do this?

Hi! First post, and I saw a lot of discussion about that topic, but I haven’t found anything about this:

On the internet, Amazon, etc, I can see extender adapter for pedals. Are there US to FRENCH threaded pedal adapters? Not too long and weak.....

if not, It would be easy to do ( for someone who knows how!!!!!) It already exists for 1/2 to 9/16.

I love my “new” 1987 Px10 Peugeot, but it’s reAly awkward to pedal without SPD pedals....

thank you!

Worse comes to worse, you can get a Stronglight 106 or 107 crankset with BSC threading, then you will open up the option for all sorts of modern pedals for your bike. Stronglight did make those two cranksets with BSC pedal threading, but the problem is, everyone wants them, so they will be harder to find and more expensive to buy, if you do find them.....

1. Are you sure the cranks on your Peugeot are French threaded?
As a check you could try threading your SPDs into the cranks. If the cranks are French thread you won't get very far.

2. As mentioned above, you can tap out French threaded cranks to 9/16". To find someone who can do this for you look for the oldest bike shop in your area, or let us know your location and one of us might be able to help out.
Brent

Yes, any good shop will be able to do this. Pedal taps are something every shop should have.