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Big Chainring Pin?

Old 10-16-23, 06:18 PM
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Big Chainring Pin?

I just picked up some Stronglight chainrings. The big ring is drilled (and apparently tapped) for the pin that prevents the chain from jamming between the crank arm if it falls off in an over shift.

Are these pins available? Im not even sure what search term to use.

Thanks.
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Old 10-16-23, 06:28 PM
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Originally Posted by smd4
I just picked up some Stronglight chainrings. The big ring is drilled (and apparently tapped) for the pin that prevents the chain from jamming between the crank arm if it falls off in an over shift.

Are these pins available? Im not even sure what search term to use.

Thanks.
The Cyclo-Pedia catalog called them "chain guide screw/spacer".
Not sure that's gonna help a lot, though!



Maybe just buy some small metric screws, see what matches the threads, and make your own?

Steve in Peoria
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Old 10-16-23, 06:32 PM
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Originally Posted by steelbikeguy
The Cyclo-Pedia catalog called them "chain guide screw/spacer".
Not sure that's gonna help a lot, though!

Maybe just buy some small metric screws, see what matches the threads, and make your own?

Steve in Peoria
Thanks Steve. Assuming I might not be able to find them, rolling my own was option 2.
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Old 10-16-23, 07:07 PM
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Originally Posted by smd4
Thanks Steve. Assuming I might not be able to find them, rolling my own was option 2.
BITD, rolling your own was always an option, maybe even the preferred one.

Oh, wait, you mean something different. Never mind.
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Old 10-16-23, 07:09 PM
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HA!

Anyway, a metric pan head screw and a 1/4 length of aluminum tubing should do the trick.
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Old 10-16-23, 07:51 PM
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Old 10-16-23, 08:14 PM
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Originally Posted by smd4
HA!

Anyway, a metric pan head screw and a 1/4 length of aluminum tubing should do the trick.
if only the French made it so easy. Often they use a different thread pitch than you assume they might.
1/4 it is a French bike, metric dimensions only.
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Old 10-17-23, 05:12 AM
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Originally Posted by repechage
1/4 it is a French bike, metric dimensions only.
1/4 in length.
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Old 10-17-23, 10:13 AM
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Originally Posted by smd4
1/4 in length.
Imperial units for across the Channel.
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Old 10-17-23, 11:36 AM
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Originally Posted by smd4
1/4 in length.
6mm in length
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Old 10-17-23, 11:44 AM
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Originally Posted by John E
6mm in length
I'll just match it to the DA one I already have.
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Old 10-17-23, 12:58 PM
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This is one of the few things I hate about the 2000s era Campagnolo. The hidden bolt chainrings have that pin in a different place than all-five-visible cranks. If I wear out the 53 on my Records, and can't simply slap on one of the Chorus rings. One the other hand, the 39s are the same.
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Old 10-17-23, 01:12 PM
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speaking of rolling your own....

I was having some issues with dropping the chain on my SunXCD cranks with 50-34 rings. I think I've gotten the front derailleur adjusted better now, mitigating the need for an anti-drop pin (a.k.a. "chain guide"). However, I did a little experimenting on an old, worn chainring.

I did play around with a M3 screw, using one as a tap. I had the tip tapered a bit, and dremel'ed a slot to create cutting edges. It's definitely a bit of a hack, but maybe sufficient??
Haven't actually tried this on anything that will be ridden, but thought it might be of interest.



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Old 10-17-23, 02:04 PM
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Originally Posted by steelbikeguy
It's definitely a bit of a hack, but maybe sufficient??
Sort of what I had in mind, though I'd replace the three nuts with my 6mm or 1/4" or 1/70th of a cubit or whatever, aluminum tubing, only for a cleaner look.
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Old 10-17-23, 02:45 PM
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Here's my TA pin hack. I needed to relocate the hole for a Campy Record crank. Original hole (3mm) in the first photo. I forgot what size I used for the hole I drilled, but is was definitely non-metric. But I used a tap for the threads. And I used a piece of auto brake line as a spacer. 2nd photo.

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Old 10-17-23, 05:01 PM
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Originally Posted by gearbasher
Here's my TA pin hack.
Cute!
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Old 10-17-23, 06:59 PM
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Originally Posted by gearbasher
Here's my TA pin hack.
Pretty much what Im imagining my solution will look like.
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Old 12-08-23, 07:39 PM
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My fix worked perfectly.

For the record its an M4 thread. Picked up a couple pan head screws from Ace for about a buck. Got aluminum tubing from Hobby Lobby for a few bucks more (came in a package of three different sizes. Im sure Ill have uses for the remaining tubing down the road).

Chucked a screw in the drill and turned the head down using a file until no wider than the Phillips slots. Its only slightly wider than the tubing.

Cut a piece of tubing slightly longer than 1/4 and filed to final length. Measured the screw, and cut off the part buggered by the drill chuck. Filed to final length.

Put blue Loctite in the hole and put it all together. After I had all the materials, everything was finished in about a 1/2 hour. Looks about as factory installed as I could have hoped, and will function as intended (still wonder why Stronglight didnt just include one. ).

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Old 01-27-24, 11:11 AM
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So here are the results. 4.8 mm OD aluminum tubing and a metric pan head screw with the head turned down in a hand drill to the slots.


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Old 01-27-24, 12:26 PM
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Looks great. Maybe think about adding a drop of Loctite. Now owned by the German company Henkel, so compatible with metric threads. Since you'll probably never want to remove it, maybe go for the strong stuff.
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Old 01-27-24, 12:34 PM
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Originally Posted by Trakhak
Looks great. Maybe think about adding a drop of Loctite. Now owned by the German company Henkel, so compatible with metric threads. Since you'll probably never want to remove it, maybe go for the strong stuff.
I did use the blue stuff but youre right, the strong stuff would be better.
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Old 01-27-24, 02:10 PM
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Originally Posted by smd4
I just picked up some Stronglight chainrings. The big ring is drilled (and apparently tapped) for the pin that prevents the chain from jamming between the crank arm if it falls off in an over shift.

Are these pins available? I’m not even sure what search term to use.

Thanks.
I seem to remember using electronic circuit board stand-offs for that in the past, probably with a little modification.
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