Reynolds 531 

Hello again. I never left your side. I got so busy during covid etc. , that all vintage bike stuff was on the back burner.
Now a tiny bit back on with the old bikes, and I would like to revisit a project of mine. I need a bit of help.

I have a Campagnolo NR Triple crankset, missing the little studs. You probably do too. I would like to go to Eroica this year. You probably do too. I know there are many cranksets on ebay, missing the little stud / bolts. You probably do too.

I just need some dimensions, to get a quote on making these bits. All I need to know is how many mm the height is without the step. Pics attached. If I make some, I can make extra, if desired.

repechage

I would go to Jim Merz.
He haunts the CR group.
Probably has them made up in stainless or ti.

merziac

Its possible but I've never seen them from him, any version of this is still going to be cost prohibitive.

SwimmerMike 

I'm planning on taking my NR triple off this weekend to put a 32 on it (modified TA Chain Ring). If no one gets the measurements before then, I can post the dimensions of the posts.

Mike

merziac

This is an age old pursuit as we know, @bulgie has addressed it, he and I had a good discussion about it awhile back.

These are a huge pita for a couple of reasons, not the least of all being they have the allen key recess for tightening them inside down at the bottom below the chainring bolt threads.

If you were prepared to have the wrench flats on the outside it could make this very doable but they need to be pretty hard and that may be an ask too far.

You can get a tripleizer setup far easier than finding or making these bolts, and then you are still limited to no less than 30 teeth with 36 being standard.

I'd be surprised if you can get anyone to make these, let alone at any kind of reasonable cost that would even remotely make sense.

Reynolds 531 

Thank you, much appreciated.

Let's just say I know a guy.

merziac

I'm sure you do, I do too, if @bulgie or Merz haven't gone there it's a very big ask but nobody is rooting for you more than I.

Let me/us know if we can add to the pot to get it done, standing by.

merziac

@Reynolds 531

Also keep these in mind.

Doug Fattic 

Well you got me off the coach watching History Detectives on PBS and down to my basement were I have 2 NOS Campy Record Triple cranks. In my frame shop I have a digital calipers. The distance not including the step is 11.00 mm. You're welcome.

SwimmerMike 

or this one: I know it's not original, but it shiny.....

merziac

So, you ever more than contemplated making some or a reasonable facsimile from scratch?

merziac

The 30's aren't original either but they are somewhat currently available, yours is a 34, right?

The 36's are the only original ones as far as I know and in my mind not worth the bolt hassle for them, but 30t, now we're talkin!

Doug Fattic 

No, I have a nice 9" tool room South Bend lathe but I'm not that versatile

merziac

My knowledge is rudimentary at best but isn't the allen in the bottom the really tough part?

SwimmerMike 

This one is a 32 that is a modified TA. I then stripped the anodization off, did some filing, and then polished.

I figured a 32 was an additional 11% drop from the 36 so it made sense to me.

Doug Fattic 

Yes and I have no idea how it can be done. it takes a 4mm allen key to install and remove.

bulgie 

I recently got some Merz ones in Ti, super nice, as you can imagine. I don't see them on his ebay store at the moment though, so that probably means he's sold out.

BITD Jim made them in 7075 T6 aluminum alloy, and they held up for very long miles. I think he said his friend toured 15,000+ miles on them, fully loaded. His friend was a big Cat.2 racer too, so probably not soft-pedaling.

I suggested to Jim that he make them from hexagonal stock, so no internal allen socket needed for mounting them to the spider, but he thought (and I agree) that would be ugly. So he broached the little socket down in there, the way God intended (or Tullio... same difference).

I also not too long ago bought a set of Stronglight Mygal bolts. I think I found them in England or Europe, Spa Cycles maybe? Not "NOS", they were still a currently-made product I believe, at least a couple years ago anyway. Let me know if interested and I'll try to find out where I got them. Unfortunately they won't work with Campy chainrings that have a 10 mm hole for the chainring bolts, because the Mygal bolt heads are 10 mm diameter, and fall right through the 10 mm holes. But just about everyone else's granny rings have 8 mm holes, so Mygal bolts are a good economical choice if you don't mind using those rings.

In fact if you use Campy bolts with those rings with the 8 mm holes, you either have to drill out the chainring holes to 10 mm, or remove the raised lip doodad on the Campy bolts that fits inside the 10 mm hole. Here's my pic of one of my Campy bolts where I removed the lip, next to an original bolt with lip intact:


Jim's Ti bolts are faithful reproductions of the Campy #818 bolts, including the 10 mm lip. I had him make mine in the no-lip style, because I like granny rings with 8 mm holes. For one thing, smaller holes lets you get away with using a smaller ring on a given bolt circle diameter. For example on the Campy Record "factory" triple with the 100 mm BCD, Jim Merz felt you couldn't go smaller than a 31t granny. But I made mine in 30t, and there's still enough "meat" between the teeth and the bolt hole, because of the hole being smaller. Then I made one in 29t, using 6 mm bolts, and of course 6 mm holes in the granny, just to get that one silly tooth smaller. 30t really is the most beautiful though IMHO, since 30 divides by 5, so it's symmetrical on a 5-bolt spider. Not that anyone will notice.

Other choices include Ofmega/Avocet granny ring bolts, maybe just as unobtainable as original Campy bolts, but if you can find some, they work perfectly. Bob Freeman also made some from generic Shoulder bolts and generic aluminum spacers he got from McMaster-Carr. There was a single lathe-turning operation needed on the bolt heads, but no allen-socket broaching or tiny inside threads like on the Campy parts, and the aluminum spacers were plug'n'play. Let me know if you need more details, like part numbers, I might be able to dig that up.

I can confirm the Campy spacer is 11.0 mm, and it was intended for ancient 5-speed (wide) chains, so you can go narrower if you use narrow chains. The Mygal spacers are 10.5 mm. 7/16" spacers from McMaster are 11.1 mm, close enough.

Mark B

bulgie 

@merziac asked "isn't the allen in the bottom the really tough part?
"The allen socket is made with a broach. Rotary broaches are the coolest (and fastest). I'm not enough of a machinist to know which would be best to use for making these little chainring bolts, but here's a cool video on how rotary broaches work: I bet you won't guess how they work, it really is rather astounding. Regular non-rotary broaches can be simply pushed in with a press.

Mark B

merziac

I stand corrected, as @bulgie points out, he recently got some Ti ones from Jim..

In my defense, I have never seen them on his efbay or FB page and most of his stuff shows up on one or the other or both.

Reynolds 531 

Thank you. I made a jig to space the chainrings, and came up with 10.5mm, but the chainrings are worn and dubious.

davester

Where can those 30T rings be obtained? I have a friend with a Paramount equipped with the NR triple and I know that he would be very eager to replace that ridiculous 36T ring with something substantially smaller. Does anybody here have one that they'd be willing to part with for a small fee?

SwimmerMike 

@davester Can't help you on the 30, but Cupertino Bike shop can get the 32's. They don't usually carry them in stock, but they "know a guy". If you're interested in that route, you'll want to talk to Greg, who is their C&V guy. Greg works on Wednesday's through Friday.

bikingshearer 

As a not-period-correct-but-works-great-and-still-looks-good alternative, there's always a Red Clover triplizer for a 144mm BCD Campy crank. Since it gives a 74mm BCD inner, you can easily go 30 tooth or smaller chainwheels. It also supports a fellow BF C&Ver. I've done business with Red Clover - top-drawer guy and a good product.

Oh, and he also has the right bolts to attach the inner to the tripilizer. Easy peasy lemon squeazy.

This has to be easier than a quest to buy or make a Holy Grail. Just sayin' . . . .

Reynolds 531 

Even a trip through the mind of Sheldon Brown, did not reveal a 5x100 BCD 30t chainring. Only a vague mention of a 31t.

Can you share what those chainrings are?

I have sketched up a 94BCD to 100BCD offset stud, but it won't be terribly simple.

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My current thought, is that the true triple Campagnolo (never "Campy") cranks are owned by the more originalist of us, and recreating the most difficult to find (at a good price) part would be for them.

A 94 BCD 30t, would be a candidate for drilling and tapping an existing crank, since the originality would be long gone in any case. Just like in the olden daze.

bulgie 

The 30t ring pictured by @merziac earlier is the brainchild of Bob Freeman. He used to have a bike shop (since closed), called Elliott Bay, in Seattle, partnered with Bill Davidson the framebuilder. Bob is retired now but he still does little projects for fun and sells a bit. These rings were made for him by a friend of his with a small CNC milling machine. Last I heard, he couldn't get more rings made because that friend passed away. Because so few were made and they were all sold, your chances of finding one are very small.

There have been a couple other small custom-chainring manufacturers that offered 100 mm BCD rings in the past, sorry I don't remember their names, but I'm pretty sure they're no longer offered. I don't know of any currently for sale, but I'd be glad to be proven wrong — if any BF people know a place, do tell.

The 31t was made by Jim Merz in the late '70s or early '80s in decent numbers, were offered in the mail-order catalogs at the time, but are very rare now. He made a 32t also. which is about equally hard to find.

I and a few other DIY-ers have made 100 mm BCD rings by taking a 74 mm ring, drilling and counterboring 5 new holes, then cutting the old holes off. Since it's a fair bit of work, I start with the best quality and nicest-finish rings I can find. In my case that was Mavic MTB rings from the '90s, sadly no longer available. TA rings in 74 mm are probably more available and have a nice finish. Tons of other boutique brands made 74 mm rings out of the good alloy, 7075 T6, but some of them (FSA and Vuelta for example) have goofy shapes and/or ugly anodizing that won't look right on a vintage bike. The one 29t I made used a no-longer-available Willow brand 74 mm ring. It had a weird pale gold (champagne?) anodizing that I removed and polished. Looked nice when done, but too much work.

Here's my Flickr on how to make a 100 mm ring from a 74 mm. I didn't even have a drillpress at the time, so this was all done with a hand drill and other hand tools.

Here's a 30t made by Dennis Stover, a machinist who only makes stuff for himself, not for sale, just further indication of what you can do with access to a milling machine.
Before trimming the 74 mm holes off:


After trimming to final shape on the mill:


Dennis used a Sugino ring as his "organ donor".

Mark B