chainring installation

[Jim S.]

Hi, I'm installing a T.A. chainring, and it comes with a small screw, nut, and spacer. I'm perplexed. Does anyone know what these are for?

[Peter Adler]

Not entirely certain (my TA chainring experience is firmly rooted in 50s-60s stuff), but let me hazard a guess:

See that teeny hole below the teeth? My hunch is that if you stuck the machine screw through the spacer, through the hole, and attached the nut on the other side (long side away from the frame), it will act as an overshift pin, to prevent you from shifting so far outboard that the chain comes off the ring and jams between the big ring and the crankarms.

What say ye, peanut gallery?

Peter "more TA stuff than he knows what to do with, but nothing that new" Adler

Berkeley, CA/USA

[Joe Bernard]

This was my guess, too, but it's a really long contraption for that job. I'm curious the origin of the chainring, I wonder if the screw/bolt/washer got in the box accidentally. 

Joe Bernard

[Garth]

Peter is correct, it's a chain drop pin for the hole in the photo. TA is known for details you may not otherwise consider, they surely dance to their own beat. I like that about the European parts manufacturers, their creative ways are a stark contrast to the ways of the East. 

[David Hallerman]

Yes, I’ve installed many TA chainrings, and that screw/nut/spacer is to be used when the crank is a 5-arm spider. The s/n/s goes on the out-facing side of the big ring to prevent chain drop jamming.

With a 4-arm crank, no need for s/n/s.

On Fri, Dec 17, 2021 at 12:05 AM Jim S. <jjsi...@gmail.com> wrote:

Hi, I'm installing a T.A. chainring, and it comes with a small screw, nut, and spacer. I'm perplexed. Does anyone know what these are for?

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[iamkeith]

Here's an image.  One thing to be aware of, assuming your screw head is as thick as this:  In some gear combinations, when my chain is on the ring adjacent to the big/outer ring with the pin, I get a "ticking" as the screw head rotates around and hits the chain.  Took me forever to figure it out, after which I just didn't worry about it.

[Joe Bernard]

I just don't understand that solution. All the chain-drop-stoppers I've seen are a small grub screw that threads into the chainring, there's no screw/spacer on the backside of the ring. 

[Kevin D norcal - santa rosa]

here's another thread discussing the T.A. drop pin and a couple good pics.  I'd guess the spacer is used to lengthen the set-up if there's a larger gap involved, between chainring and crankarm.

Having the screw head on the inside is apparently correct but seems undesirable - why didn't they tap the hole so all the working parts could be outboard of the chainring (I guess you'd have to install the drop-pin before installing the chainring that way, so less convenient perhaps).  The pics at this link show a 5arm spider but the 5th arm isn't in line with the crank (not hidden).  Dave H pointed out the pin is intended for the 5th arm, when hidden I presume.  So maybe not needed on this version . . . or do other set-ups still jam to some degree and this could help anyway? 
https://www.cyclechat.net/threads/ta-chainrings-what%E2%80%99s-this-spacer-for.277396/

[Huston]

For those who have installed TA rings on a 5 bolt spider, where do you orient the pin relative to the crank arm?  In this case (TA crank with TA rings), one chainring bolt is "hidden" behind the arm.  I figured the pin would go behind the arm as well, but that's not an option.  So, if the arm is at 6:00, the pin can be at 4:48 or 7:12 but not 6:00.  Of course, there are 3 other options (including high noon).  Any guidance would be appreciated.

Thanks,

Huston