chuckybb

I have a lovely old Campagnolo Victory rear hub with England (1.370"x 24tpi) threading. I'm thinking of changing the 13-21 freewheel to one with a bit larger cog. I have a Shimano MF-TZ500-6 Bicycle Freewheel 14-28T, but I'm concerned that this freewheel might have the slightly larger ISO threading and might damage the hub. I do have some older hubs and I wonder if there is any chart that indicates freewheels thread standard? Any advice will be appreciated.

SurferRosa

I've never heard of any significant difference between English and ISO threading for vintage bicycles.

chuckybb

From the great Mr. Brown: https://www.sheldonbrown.com/freewheels.html

dddd

To help put these concerns into perspective, at least for those who are familiar with the dimensional differences among the various standards, I've owned a few bikes that had English-threaded freewheels on French hub threads.
Those bikes got ridden hard, too, mostly foothills riding.
I didn't use super-low gearing though, and I only weigh in the 140-150lb range over these years.

My Bianchi Nuovo Racing has a wheelset that has French-threaded Tipo hubs, with a Shimano 13-28t freewheel, and I've ridden this bike up 20% grades a few times over the last three years.

Kai Winters

In general it should fit as the thread area is standard...in general
What's fun is the helical freewheel hub...

Trakhak

Are you sure the Tipo hub has a French thread? The first thing I did with my brand new Helyett track bike when I got it in 1964 was change the rear sprocket, going from 51/15 to 51/19. The second thing I did was strip the threads on the rear hub on the first ride.

The original sprocket was, of course, French threaded; the replacement was English threaded. Thus, I find it a bit hard to believe that you've ridden on that combination with no consequences.

A tip for anyone reading this who stripped a French hub the way I did - after the threads stripped, the mechanic in the bike shop wrapped the hub in aluminum foil, which worked fine to secure the BSA sprocket in place.

mpetry912 

if it's English to ISO, no problem, very minor differences in the thread profile

French will only work with French.

Italian to english / ISO is a class B fit.

/markp

dddd

Wow, I feel better about riding my French-thread mis-match now. I wouldn't think of going out riding on it after it had stripped!

Actually, the first time I realized I had been riding on such a mis-match was an early-70's Peugeot, when I removed the English-threaded Shimano freewheel.
The threads were visibly severely slumped over on some portion of the threading, but not all of it (due to the pitch being off).
But the metal threads yielded instead of cracking.
Perhaps your hub was made of a different alloy that had far less ductility, since your gearing didn't apply much torque while riding.
Perhaps also, your threaded cog had tolerances that somehow were more effective in stripping off most the threads during installation(?), or (most likely of all) was able to ride over the OD of the French threads without much having to distort more than the tips of the threads. Your shim fixed that!

On the Tipo rear hub, after actually measuring the thread pitch using a gauge, I mis-matched it deliberately, since I really wanted to use a 6s Uniglide freewheel. The freewheel went on a few turns and predictably binded up as I forced it on all the way. Again the threads yielded and the freewheel attachment seems able to sustain high loading.

I also once purchased a pair of tipo hubs from someone who claimed they were English-threaded.
Knowing that perhaps most of these hubs have French threading (being sourced from French bikes with tubular rims), I held the rear hub in front of my monitor, where I could clearly see the severe thread distortion pattern exactly as I had seen on the Peugeot's rear hub many years prior. I have yet to build these hubs up, but I can clearly see that the rear hub has seen use with an English or possibly Italian freewheel, without stripping.

EDIT: Adding that, in addition to my own experience, I had heard anecdotal evidence testifying to use of an English-threaded freewheel on a touring tandem, for some time with no failure. I recall that it may have been Jan Heine reporting that.

Oh, and lastly, changing different-threaded freewheels back and forth even once on a French-threaded hub after thread-re-forming had occurred, likely WOULD strip off the threads in my estimation (aluminum not having such great repeat-ductility). So switching to an English-threaded freewheel is perhaps more of a commitment than a risk (again, in my estimation).

Bianchigirll 

I'd be more concerned about the deraileur capacity and chain wrap.

bulgie 

Being large myself, and kinda fast-twitch/sprint oriented by biology (not by choice), I have stripped French hubs with Eng FWs, probably 2-3 times, mostly in the '70s. I recall that it wasn't easy to do — it would work fine until the steepest hill, or the hardest take-off from a stoplight (which I treated like a Kilo TT start on the track, in my younger more exuberant days), or some other event that was over the usual amount of torque.

Seeing if an Eng. FW will thread on is not a good test; as others have pointed out. It can give you a false reading in either direction. It can thread on relatively easily on a Fr. FW, without the binding up in the last few threads, leading you to believe the hub is Eng. Or it can bind up in the last few threads for some reason other than pitch mis-match, leading you to think it's a Fr. hub when it's Eng. with threads a little mucked up or out of tolerance. So I always keep a known-French FW around to do the testing with, it's a proper Go/NoGo gauge. If it goes on, the hub has to be Fr.

dddd

Does your observation have to do with 1-3/8" being slightly smaller than 35mm, or is it a different factor such as the thread angle?

I've been using a proper SAE/Metric thread gauge over the last few years, but previously tested freewheels and hubs by test-fitting every possible combination before condemning parts as French-threaded.

Having got used to Japanese freewheel cog tooth profiles, I rarely (and prefer not to) deviate from them on my own bikes. Not that the French ones are bad, it's just that by habit, I typically sustain at least some power while shifting.