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French threaded headsets

Old 02-25-21, 07:07 AM
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bbader
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French threaded headsets

I am attempting to mount a headlamp on a vintage Motobecane but the top race is too big to allow the bracket to sit flush. Would like to replace the headset but the french headsets I have found (velo orange) have stack heights that are too high for my steerer tube. The stack height of the original headset is around 32mm. Options I have considered are: extend the steerer tube, replace top race with smaller top surface area, convert to ISO headset. file bracket seat to make flat). Some of these may not be feasible. I am hoping that I can replace just the top race but not sure if I would also need to replace the bearings and bottom race as well. For some reason I cannot uplaad pics (only gets to 50% and then get an alert with no explanation).


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Old 02-25-21, 07:17 AM
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@bbader - have you tried to replace the washer with the mount?
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Old 02-25-21, 08:06 AM
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Having dealt with short stack headsets I can say that you're on the road to frustration. It appears that your current problem is that your lamp bracket is flanged so that it interferes with the top race. Can you bend or grind the bracket so that it fits? That would certainly be easier than trying to adapt a higher stack headset, which could require a different fork or perhaps just cutting down the head tube a bit.

Personally I'd give an hour or so to modifying the bracket and if that didn't work I'd opt for a bracket that mounts at the fork crown.

Good luck to you.
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Old 02-25-21, 08:21 AM
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Thanks for the input. I agree that grinding down the flange would be the easiest solution although it would end up looking less elegant. I was wondering if rather than replacing the entire headset, I could just find a different top race that would not increase the stack height and allow the flange to seat properly. ie, are these interchangeable or perhaps replace the top of the headset (bearings and race).
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Old 02-25-21, 08:27 AM
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not sure what washer you are referring to. THe large flat coin looking object is actually the top race. I was hoping to replace this with a more standard looking race but didnt know if there were different size races that were interchangable with this one
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Old 02-25-21, 08:56 AM
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Originally Posted by bbader View Post
not sure what washer you are referring to. THe large flat coin looking object is actually the top race. I was hoping to replace this with a more standard looking race but didnt know if there were different size races that were interchangable with this one
I think what he's referring to is shown in the first picture, where the sequence (going downward) is locknut-washer-toprace-steerer. He was suggesting you don't use the washer and put the hanger there instead. I think that may not work - if the bottom of the hanger needs the washer so the side-reinforcing web clears the toprace, well, it needs it.

In which case, yes, file the web of the hanger for clearance, dab the cut with cold galvanizing paint, and it should do just fine as a combined washer/mount. It's only a lamp, the loss of strength is unlikely to matter.

Last edited by oneclick; 02-25-21 at 10:09 AM.
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Old 02-25-21, 11:10 AM
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Originally Posted by oneclick View Post
I think what he's referring to is shown in the first picture, where the sequence (going downward) is locknut-washer-toprace-steerer. He was suggesting you don't use the washer and put the hanger there instead. I think that may not work - if the bottom of the hanger needs the washer so the side-reinforcing web clears the toprace, well, it needs it.

In which case, yes, file the web of the hanger for clearance, dab the cut with cold galvanizing paint, and it should do just fine as a combined washer/mount. It's only a lamp, the loss of strength is unlikely to matter.
Thanks
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Old 02-25-21, 11:11 AM
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Thanks
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Old 02-25-21, 11:19 AM
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+1 to grinding the flange of the mounting bracket. That seems by far the easiest solution. The headlamp will not need too much support, and that steel bracket should be plenty strong to hold a lamp with or without the flanges.

What vintage lamp are you using? I'd be curious to see it since I'm in the market for a head lamp for my own project.
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Old 02-25-21, 11:22 AM
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Originally Posted by bbader View Post
not sure what washer you are referring to. THe large flat coin looking object is actually the top race. I was hoping to replace this with a more standard looking race but didnt know if there were different size races that were interchangable with this one
Typically the HS assembly is the race (threaded) washer, and lock nut. The washer may have a tab on the ID to fit into a slot on the steerer or a flat section for the same on the steerer. The intent is that the lock washer would not cause the race to rotate while it is being tightened.
If you don't have a washer, then I suspect the steerer was cut too short at some point. If you do, then compare the thickness of the washer with the mount to determine if the lock ring will engage enough threads.
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Old 02-25-21, 11:35 AM
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Can you mount the lamp to the fork crown instead?
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Old 02-25-21, 11:48 AM
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I think the bracket does replace the lock nut washer. And I think there is a possibility that you have it mounted upside down.

When you look at this vintage Raleigh manual from the 1950's. Their bracket is oriented the other way.




Before I start grinding everything down. If you want your light lower I would look into the possibility of using a brake mount bracket.

Last edited by cbrstar; 02-25-21 at 11:53 AM.
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Old 02-25-21, 12:29 PM
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Originally Posted by SJX426 View Post
Typically the HS assembly is the race (threaded) washer, and lock nut. The washer may have a tab on the ID to fit into a slot on the steerer or a flat section for the same on the steerer. The intent is that the lock washer would not cause the race to rotate while it is being tightened.
If you don't have a washer, then I suspect the steerer was cut too short at some point. If you do, then compare the thickness of the washer with the mount to determine if the lock ring will engage enough threads.
Thanks. It is a french steerer so the washer has a flat area to keep the race from loosening. I believe there are enough threads to add a mount but not this one because the upper race is too wide for the mount flange to cover. I will see if I can find another french upper race that is not as wide.
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Old 02-25-21, 12:32 PM
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I dont believe I can since I adapted dual pivot brakes to this 70s bike there is no room on the bolt and still be able to add the nut
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Old 02-25-21, 12:38 PM
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Thanks. I did consider both the brake mount and the raleigh mount which uses a second bracket to attach the light to the mount. I believe the flange is intended to point down otherwise water and dirt would collect on it. I also did not want the lamp to be above the hadlebars.
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Old 02-25-21, 01:35 PM
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Originally Posted by gaucho777 View Post
+1 to grinding the flange of the mounting bracket. That seems by far the easiest solution. The headlamp will not need too much support, and that steel bracket should be plenty strong to hold a lamp with or without the flanges.

What vintage lamp are you using? I'd be curious to see it since I'm in the market for a head lamp for my own project.
Its a Miller from the 50s. I had it blasted and powder coated matte black. It was a labor of love to keep the original components but convert to LED and battery. Someone sent me a link to a German site that had tons of vintage headlamps that looked cool. I would advise to find one in good condition to avoid many hours of restoration.
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Old 02-25-21, 01:45 PM
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...I, too, think maybe you are trying to mount that bracket upside down. And water and dirt will accumulate in the recesses regardless of which way you mount it.
If I were trying to accomplish what you seem to want, I'd just bite the bullet, buy and mount some fenders, and mount the headlamp on the front fender. Which is where you see many of the French originals anyway.
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Old 02-25-21, 02:18 PM
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Originally Posted by 3alarmer View Post
.
...I, too, think maybe you are trying to mount that bracket upside down. And water and dirt will accumulate in the recesses regardless of which way you mount it.
If I were trying to accomplish what you seem to want, I'd just bite the bullet, buy and mount some fenders, and mount the headlamp on the front fender. Which is where you see many of the French originals anyway.
it was originally a racing bike and has dual pivot brakes so no room for fenders
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Old 03-09-21, 04:38 PM
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Originally Posted by SJX426 View Post
Typically the HS assembly is the race (threaded) washer, and lock nut. The washer may have a tab on the ID to fit into a slot on the steerer or a flat section for the same on the steerer. The intent is that the lock washer would not cause the race to rotate while it is being tightened.
If you don't have a washer, then I suspect the steerer was cut too short at some point. If you do, then compare the thickness of the washer with the mount to determine if the lock ring will engage enough threads.
I finally located the correct headlight mount. It looks very similar but the part that goes over the steerer tube is recessed so that it sits flat. Also completed wiring on the 50s Miller headlamp. Whenever I fix something I always brake something, so true to form I broke the lens (will keep an eye out for a new one.)


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Old 03-09-21, 04:51 PM
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You might be able to hide that split a lot by using cyanoacrylate cement. Fit the pieces, tape the inside (and make sure you have it well stuck on the seam edges), turn it and dribble a little into the top of the crack, if the match is good you can scrape off the excess with a blade.
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Old 03-09-21, 05:27 PM
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The glue idea is worth a try, but my experience is even tho CA glue wicks well into tight non-gapped gaps, the glue tends to craze and fog clear plastics. If this is an acrylic lens I'd try the same but with acetone and use a syringe with a blunt needle applicator, be very sparing as you "inject the patient". Use a tape that won't be melted by the acetone....best of luck!
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Old 03-10-21, 03:55 AM
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Originally Posted by oneclick View Post
You might be able to hide that split a lot by using cyanoacrylate cement. Fit the pieces, tape the inside (and make sure you have it well stuck on the seam edges), turn it and dribble a little into the top of the crack, if the match is good you can scrape off the excess with a blade.
Thanks I have seen commercials for a product they use on car windshields and the crack disapears. I may try this if I cant locate a new lens (it is #6 3 1/4" in diameter). I have seen a few old Miller lens on ebay from time to time.
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Old 03-10-21, 03:57 AM
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Thanks. The lens is made of glass.
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Old 03-10-21, 09:18 AM
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Originally Posted by unworthy1 View Post
The glue idea is worth a try, but my experience is even tho CA glue wicks well into tight non-gapped gaps, the glue tends to craze and fog clear plastics. If this is an acrylic lens I'd try the same but with acetone and use a syringe with a blunt needle applicator, be very sparing as you "inject the patient". Use a tape that won't be melted by the acetone....best of luck!
Haze can both be avoided while welding acrylics, and easily dealt with if properly handled. The trick is using the correct solvent, with the right process and right prep.

Weld-on #4 is what I use on acrylic turntable lids, works like a champ, and many aquarium builders use - use in a vented area, put a few drops in the plastic bottle, follow these instructions (3m 04s mark) to prevent spilling issues. The video also shows how you just need to tap a drop at a side seam and it'll pull through your piece, so you really don't need to worry much about hazing, as you see a great example of at the 3m 35s mark.

Hazing can happen, but it's nothing a decent wet/dry sandpaper kit won't fix, starting at 400 grit wet, then doubling the grit count through a couple of stages, finishing with Novus scratch polishing kit.

All three linked products are what I use for turntable restorations. It takes a little practice, but it's super easy to both repair acrylic, haze-free, or repair, and de-haze it.

But ... @ OP I see you said it was glass. Sorry I've got no experience with that.
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