Andiroo99

Hi All

Does anyone know a supplier / source of steel pins used on chainrings to help with shifting?



Many thanks

Arb

Wilfred Laurier

I have never seen them for sale separately. They are installed as part of the manufacture of the chainring.

Although they are likely some off-the-shelf fastener or part that can be purchased, but I don't know what you would call it outside of a bicycle drivetrain.

Andiroo99

I am sure there are off the shelf pin options - just need to find a source.

CliffordK

My guess is those pins are extremely proprietary. Is that a Campagnolo crank in your photo?

Drop stop pins for between the large ring and crank may be available, as for some reason they often were designed to be installed by the end user. However, I'm doubting those shift pins are widely available. If they are a wear item, the chainrings usually have significant wear before the pins would fail.

You could try contacting a small domestic chainring manufacturer such as Vuelta and ask if you can buy some.

https://www.vueltausa.com/components/chainrings.html

Or, perhaps try to track down a Chinese chainring manufacturer.

If I was making my own, I'd start with something extremely hard such as a tool steel, or high speed steel. Perhaps a drill bit shank. After machining, they may need hardened. Perhaps even tungsten carbide.

jadocs

Yeah, I wouldn't even know how to install something like that properly.

dsbrantjr

They will need to make an interference fit and to be pressed in; adhesive will not be strong enough.

WizardOfBoz

I suspect not. The mechanical design of those things is NOT trivial, nor is the incorporation of the pin into the chainring easy (especially under conditions of use). Also, the design must be made for both chainrings - one doesn't add pins to a ring without knowledge of the oother ring(s).

Even if you could get them, to install them you'd have to have some pretty sophisticated milling and drilling and press and measurement equipment. I don't think adding the pins is practical, compared to just buying the pre-made chainring set.

But perhaps the OP owns a machine shop....

jadocs

Yeah that's what I mean, not an easy task for the home mechanic.

ChrisAlbertson

The pins are not generic items and are specific to the make and model chainring. If you still have one you could take it to a machine shop and have them make more for you. But the cost would be high as they'd have to make them one at a time, my hand. Better to contact the manufacturer and see if they can supply them. Likely they are not user-installable and you have to buy a new chainring. But the chainring might cost less than having pins custom made.

Are they "pressed" in? Then you'd need a press and a fixture (jig) to install them.

AnkleWork

Lots of sources: pin manufacturers, rivet vendors, round head screws threaded in and peened...doesn't make it easy to do it right.

Andiroo99

Thanks for all the input on this. We have access to all of the processes and tooling necessary to manufacture we just want to determine if it is possible to purchase these from a supplier rather than make our own.
Thanks

ThermionicScott 

I've read of people using a small bolt and nut to act as a chainring pin, but don't have a link handy.

WizardOfBoz

Again, if you look at the picture you see that the pin in the larger chainring is meant to catch the chain. The chainring has a groove that will allow the chain to extend directly from the small chainring to the pin on the larger one. The groove in the pic is tapered, that is, its deeper the closer it gets to the small chainring. Clearances and geometry are chainring (large and small) specific. I believe that, because the chains are normally high-strength steel (that is heat-treated and hard). the pins must be too. To engineer pins for a new chainring pair, I'd suspect you'd have to get very accurate pins (more like disks) and carefully consider geometry, testing a few positions. I'd probably heat-shrink the pins in (pins in dry ice/propanol, chainrings on a bearing heater) and might even add geometric retention (kind of a dovetail end on the pin, larger at the end, with the chainring holds bored with a taper, larger diameter deeper in the hole).
To ensure that the things don't pop out, I suspect that you'd precision grind them as well, to ensure a tight fit.

Wilfred Laurier

I would think a flat head screw, maybe M3 or M4 thread, threaded into a hole tapped and then partially countersunk in the chainring , would make a reasonable facsimile of a chainring pin. Selecting the most advantageous location, and modifying adjacent teeth, will be a bigger challenge.

CliffordK

If you are planning on doing a one-off, then you can probably find a hack that will work. However, if you are planning on manufacturing for resale, then I'd encourage you to purchase a half a dozen different brands of rings (pairs of rings). Test, then disassemble to see how they work.

I am a little curious about pressed vs threaded. Also note, Aluminum has a bit higher thermal expansion than either steel or tungsten, which you might be able to use to your advantage.

dedhed

https://patents.google.com/patent/US8506436

Many appear to be SS. likely 400 series.
https://www.chainreactioncycles.com/...g/rp-prod35784

Jeff Wills

I've done this, using stainless M4x0.7mm hex socket flat head screw for pickup pins. I drilled the chainring on its webbing where it had the most material, tapped the hole, countersunk it slightly, then inserted the screw. This left the head of the screw slightly proud of the chainring's surface.

I then Dremeled off most of the excess screw and peened the end so there was no chance of it backing out.

It worked until I wore the chainring out.

Andiroo99

Thanks Jeff and All

So it seems like these are not something we can purchase off the shelf which is in itself good to know. The screw option is obviously an option albeit this is a very manual process and ok for one-offs but not really viable at a larger scale when you would want to be using a press to insert correct sized pins to ensure consistency.

Thanks