French pedal threads, I'm struggling here

[agentorange]

OK, I don't know a great deal about this but since moving to France I've become aware that there are differences in pedal thread sizes. However, I have a French Campagnolo Gran Sport crank (from a bike I bought in France) which 'should' by rights have a French thread but it doesn't, or at least I don't think so.

I have some French pedals which don't fit in some cranks which I know are non-French, however I also have some non-French pedals which struggle (but might with some light force) to fit in some French cranks. But the thing is I have no cranks which I'm sure have French threads so i'm reluctant to use any force at all.

I need a guide, do French threads not fit non-french cranks i.e. not even begin to bite? or are the two only slightly out? My Gran Sport cranks say '9/16 x 20F' what does this mean? does 'F' mean French, if so, then why do my UK pedals fit it?

Any help would be great.

 

[jCymbal]

My Gran Sport cranks say '9/16 x 20F' what does this mean?

That's not french. That's the standard thread.

Here's Sheldon for the help.
http://www.sheldonbrown.com/gloss_p.html#pedal

 

[one-eyed_jim]

I need a guide, do French threads not fit non-french cranks i.e. not even begin to bite? or are the two only slightly out?

They're actually pretty close, the French thread being very slightly smaller in both diameter and pitch. A BSC thread won't get started in a French crank unless forced. A French pedal in a BSC crank will often thread in loosely at first before binding. You can tap a French crank out to BSC quite easily.

My Gran Sport cranks say '9/16 x 20F' what does this mean? does 'F' mean French, if so, then why do my UK pedals fit it?

All French threads are metric, so you'll never see them expressed as a fraction like 9/16. That's a BSC (British) pedal thread.

The F often appears on Italian and French-made Imperial threads, and I've always taken it to be short for "filetti per pollice" or "fils par pouce" i.e. threads per inch.

You'll sometimes see parts advertised as "pas français" which I initially misunderstood to mean "not French". In fact "pas" in this context means "pitch".

It can be a bit of a minefield. I've bought explicitly French-threaded parts at brocantes de vélos in France that the vendors swore blind were interchangeable with modern (BSC) components.

 

[agentorange]

My Gran Sport cranks say '9/16 x 20F' what does this mean?

That's not french. That's the standard thread.

Here's Sheldon for the help.
http://www.sheldonbrown.com/gloss_p.html#pedal

Ahh, if I were honest the 'F' on the Gran Sport sewed the initial seed of doubt in that I had this down as my French reference point so any pedal that fitted was French. Then, what I have here is just a bunch of standard non-Frencg pedals and threads, some needing a good clean.

What can I say, thanks a bunch.

 

[Lazarus]

Hi Agent In answer to your question buddy, French pedals "fall into Italian/English threaded cranks, .... unmistakeably fall into. French threads are considerably smaller than Italian / English.

Your dilemma comes from "tapered threading" more prevelant on older Campagnolo cranks. Its is not hugely tapered, perhaps only 2-3 threads long, but tightens noticeably as you get about 3/4 down the thread. It does ease as it bottoms out. Oil/WD40/Butter helps the pedals ease in. They also get warm if you just try to whizz them home without some lube.

Classic scenario " 1971 cranks taking 1987 pedals" Slightly tapered cranks from the 70's fighting with newer square late 1980's pedals, both the correct thread.

Recently bought a set of 1971 3arm chrome Campagnolo cranks from a chap who thought he had wrongly fitted English pedals to Italian threaded Cranks. I got them and my 1972 Super Record pedals went in smooth as silk, just got a wee bit tighter as they bottomed out.

Bottom line Agent, for future reference, French threads are metric, English are Imperial. Nothing metric will ever give a good fit in an imperial thread, and nothing imperial will ever fit a metric thread, you'll just strip 1 or both threads trying imperial into metric.

Both the diameters AND thread pitch ... distance between each individual thread are different, trust me 99.9% of people would know instincively when they are forcing an imperial into/onto a metric.

Happy that you've sorted your problem buddy, but have posted lest others come across this issue. My best to you, yours Laz.

........................................

Hi Jim

Quote "The F often appears on Italian and French-made Imperial threads, and I've always taken it to be short for "filetti per pollice" or "fils par pouce" i.e. threads per inch. "

You seem to know your stuff my friend, and who am I to doubt, but for my own peace of mind, I always understood the "F" to mean "Fine"

9/16 is the thread diameter outer on the pedal / inner on the crank. BSC stands for British Standard Coarse, the pitch. 20F means 9/16th inch dia with a Fine 20 TPI thread. If I am wrong please let me know

Worked for many years as a Fitter/Turner and used to know my BSF's from my BSC's to my BSP's. Not doubting you buddy, but am confused.

yours Laz.

 

[one-eyed_jim]

You seem to know your stuff my friend, and who am I to doubt, but for my own peace of mind, I always understood the "F" to mean "Fine"

9/16 is the thread diameter outer on the pedal / inner on the crank. BSC stands for British Standard Coarse, the pitch. 20F means 9/16th inch dia with a Fine 20 TPI thread.

There are coarse and fine thread standards, but that's not the issue here. You don't need to specify one or the other if the pitch is given. BSC is British Standard Cycle, and within the BSC standard there are no coarse and fine variants.

The "F" only appears on Italian and French components that have an Imperial thread pitch, where British parts would use "tpi". For example, an Italian-threaded Campagnolo track sprocket is marked "35 x 24F", but a French-threaded Campagnolo bottom bracket cup is marked simply "35 x 1". You'll never see "F" used like this on British parts.

I'm reading between the lines a little, but it seems to me that the logical conclusion is that "F" is "fils (par pouce)" or "filetti (par pollice)" rather than "fin" or "fino". I'd love to hear a definitive answer though.

 

[Lazarus]

Cheers Jim Appreciate that clear up buddy. It was the meaning of the "F" that caught my attention. The rest of my post was about old cranks, newer pedals, and tapered threads.

My best to you, Laz.

 

[agentorange]

threads

All very useful and interesting stuff gents, for which i thank you again.

 

[masterfox]

Nobody mentioned the french threading yet: it's M14 x 1. Diameter is 14mm, pitch is one thread per millimeter.
That's 0.28mm smaller compared to the standard 9/16 x 24 thread.

French threading on bottom brackets (M35x1), headsets (M25x1) and pedals (M14x1) disappeared in the mid to late seventies on french bikes, they at last switched to British Standard Cycle.
So any french part dating from before c.1980 must be checked carefully!

 

[one-eyed_jim]

Nobody mentioned the french threading yet: it's M14 x 1. Diameter is 14mm, pitch is one thread per millimeter.

You might at least have checked: the pitch is 1.25mm

French threading on bottom brackets (M35x1), headsets (M25x1) and pedals (M14x1) disappeared in the mid to late seventies on french bikes, they at last switched to British Standard Cycle.

You're about a decade early. French threads were still fairly common in France through the eighties, with one or two late hangers-on into the nineties.