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A new thread on threads

Old 06-12-19, 03:27 PM
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Cycle Tourist
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A new thread on threads

I've been working on bikes for quite a few years now and remember working on an old bike I thought was a Raliegh. I tried replacing the headset with an English (Japanese) headset and had trouble with the threads. It seemed to fit and the first couple of turns screwed on fine. As I continued though it got more and more reluctant to turn. I checked for cross threading and didn't see an issue but couldn't get the nut to go more than a few turns on the forks without resistance. I did a little research and found an article on different but similar threading that seemed to fit my situation. The article said that by continuing to force the nut I'd "adjust" the similar threading to fit the Japanese nut but once "adjusted" I couldn't go back to the original threads. I grabbed a bar to give me more leverage and some oil and went to work. Everything worked out and I now could easily screw and unscrew the nuts that held the bearings snug on the fork. I came upon the same situation on the bottom bracket and used the same method to change those threads. It seems to me both sides of the bottom bracket were right handed threads and I ended up using adjustable cups instead of fixed cups on the drive side. It was so long ago I can't remember what threads those were. Did old English bikes use Italian threads or was it something else particular to English bikes of the 70's? French threads seem quite a bit different so I don't think they were those. I came across an old french bike that had English threads recently and that started this whole thought process. I'm sure someone here knows exactly what the heck I did low those many years ago. As an addendum that old bike took me from Norwich Connecticut to Montreal and back without incident so whoever wrote that article knew what they were talking about.
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Old 06-12-19, 05:36 PM
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Old English bikes used British Whitworth threads which is a completely different system. Roger
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Old 06-12-19, 06:10 PM
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The Nottingham Raleigh standard was 26 TPI, not 24 TPI:

https://www.sheldonbrown.com/raleigh26.html
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Old 06-12-19, 06:26 PM
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Originally Posted by rhenning View Post
Old English bikes used British Whitworth threads which is a completely different system. Roger
Yeah, and the wrench sizes are different, too, 1/2" Whitworth wrenches won't fit standard 1/2" bolt heads.
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Old 06-12-19, 08:23 PM
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One person's thread adjustment is another's damage. Yes there are different headset and BB thread pitches which share very close diameters. England used both 24 tpi and 26 tpi pitches on both locations.

With a headset the number of engaged threads is few enough to not have much of the miss match catch up and cause major issues excepting the going back and forth between old and new thread pitches. But a BB will usually have more thread engagement so a pitch miss match will generally become an issue sooner. Given the tools used to work the cups are often lacking in their grip on said cups the binding up of a miss matched pitch combo is to be avoided.

Now the thread direction is a whole nother thing. It would be a rare English bike that had a French or Italian BB thread. But there have been more then a few English bikes with rather loose tolerances so starting a wrong threaded cup is not too hard, and the hardened cup will mash the softer shell threads. I have seen cups with a slight taper to the threaded OD too, further allowing backwards insertion. Andy
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Old 06-12-19, 10:58 PM
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We'll, thanks guys. Guess I got my answer. I thought it was something like an English bike not having english threads so this all seems vaguely familiar and I'm not entirely sure the BB was threaded the same on both sides. I may have been working with a Peugeot at nearly the same time and was learning some lessons the hard way, trying to unscrew the BB cup in the expected (reverse) direction. All this seems rather amusing now like the time I tried to put my 27" wheels on my newly purchased Cannondale frame.🙄
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Old 06-13-19, 07:00 AM
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Originally Posted by rhenning View Post
Old English bikes used British Whitworth threads which is a completely different system. Roger
+1 this. Many older British bikes, especially at the low-end and utility bikes, used Whitworth thread headsets (1" x 26tpi 55 thread angle). "English" thread headsets are 1" x 24tpi 60 thread angle.

What specific bike are we discussing?

But the pressed fittings shouldn't be a problem. If the threaded cup and top nut are in reasonable condition, you could replace the lower stack with new parts (that's the part of the headset that takes the load and wears the most, after all) and retain the Whitworth upper stack to hold everything in place and in alignment.

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Old 06-13-19, 07:05 AM
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Originally Posted by Bandera View Post
The Nottingham Raleigh standard was 26 TPI, not 24 TPI:

https://www.sheldonbrown.com/raleigh26.html
This ^^^^^^

I have a 1972 Raleigh Super Course with a 26 tpi steerer tube. Thankfully the original headset is still in good shape. When I need to replace it, I'll be replacing the fork.
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Old 06-16-19, 08:24 PM
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Originally Posted by JohnDThompson View Post
+1 this. Many older British bikes, especially at the low-end and utility bikes, used Whitworth thread headsets (1" x 26tpi 55 thread angle). "English" thread headsets are 1" x 24tpi 60 thread angle.

What specific bike are we discussing?

But the pressed fittings shouldn't be a problem. If the threaded cup and top nut are in reasonable condition, you could replace the lower stack with new parts (that's the part of the headset that takes the load and wears the most, after all) and retain the Whitworth upper stack to hold everything in place and in alignment.
I think it was a grand prix. It had beautiful chromed lugs and changing the threads on the fork and BB allowed me to use some of my spare parts I had on hand to extend the life of a pretty nice bike, (at the time).
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