fender1

Does anyone know what size is the smallest inside ring for a vintage campy triple? Also what is the bcd of the small ring?

dbakl

As far as I know, there was only 1 inner ring for the Campagnolo triple; 36 I believe. Maybe there was something else that fit, don't know the bcd.

melville

Campy made just the one. 36t. The shop I worked at in Seattle modified many Campy doubles to take a 74mm (24t minimum) inside ring, using Avocet bolts. It may have been just a situation of working there, but I saw more modded cranks than genuine Campy triples by a factor of 10 to 1. The fixture we used looked to be a commercial product, so I presume there were other shops equipped to do this mod. I think we ran out of Avocet bolts before we ran out of people who wanted the mod.

So anyway, there are more Campy triples now than there ever were, and a lot of them will take 24t minimum.

Sierra

The bcd of the 36t Campag. granny is 100mm.

I recently saw a set from a tandem on ebay and the granny was 32t. I thought it was a mistake but I counted the teeth in the photo and sure enough, it was 32. That's the only one I have ever seen. The crank looked like it was original, not redrilled. I don't know if this was a custom made ring or something that was only available on the crank sets made for tandems. Sure would like to get my hands on a couple of those rings though!

John E

36T was also the default granny size on cottered 3-bolt steel triples of the day, typically in either a 52-47-36 / (13-26 or 14-28) half-step-plus-granny combination or its French variant, 52-45-36.

vjp

I am not sure if you mean Elliott Bay Bikes, but I just had a cranks arm modified by them and chose a 26t TA ring. They do good work.

dbakl

Good to know. What'd it cost?

melville

Yes that was EBB. We ran out of Avocet bolts in 1994, but clearly demand has forced the development of an alternative, or the discovery of a stash. Good to know the mod is still in order.

pastorbobnlnh 

And there is always the option of installing the snazzy TA triplizer, which handles a 74 BCD granny chainring. The question then becomes "How low can you go?"

vjp

It was $109 including taxes for: drilling, tapping, avocet bolts & spacers, 26 tooth TA ring and shipping.

fender1

Thanks all for the info. Where does one find a triplizer? Does it just bolt in the exisitng holes w/ a different bcd?

byrdwyngs

Back in the late '70s, Jim Merz (before he went to work for Specialized, and when he wasn't busy building some of the nicest custom touring racks and bikes around) made 31 and 32 tooth chainrings for the Nuovo Record triple cranks. I've got one of his 32 tooth rings that I bought new around '78 or '79.

Charles Wahl

Here you go ($99 from Bicycle Classics)
https://00eda5d.netsolhost.com/chainrings.htm

It bolts on the small ring position, and has hangers (slotted to allow the lands on the backside enough clearance) for mounting a 74 BCD ring. Somewhere I swear I've seen another version with hangers between the crank arms. That's right, I did. In fact there are, or were, several:
https://www.vintage-trek.com/tripleizer.htm

fender1

Any desire to part with it?

fender1

Charles,

Thank you for the information. I am wondering if using a triplzer on an exisitng campy triple poses any problems?

Charles Wahl

Structurally, I don't see why. The NR/SR crank has its weakness (the tendency to crack at the arrises between drive-side crank arm and the spider), but having a smaller ring added won't change that. If you really want to honk like Mr. Merckx or Mr. Indurain, then you should be looking at a more robust, if less appealing, crank.

What you probably need to do is get a longer spindle if you convert to a triple. With 3 rings, you want the middle ring to be centered on the middle of the freewheel or cassette cluster, chainline-wise. That's, broadly speaking, a displacement of 2.5 mm from the standard 2-chainwheel setup (where the space between the two is centered on the cluster), meaning a spindle that's about 5 mm longer overall.

Also, just in terms of clearance, there might not be any at the chainstay if you're adding a 3rd ring on the inside.

PastorBob or someone else with first-hand experience will probably chime in with what their setup is.

pastorbobnlnh 

fender1 and Charles,

If fender already has a NR triple and just wants a smaller granny, his existing BB should be fine for the spacing (is this on one of your Paramounts?).

I've upgraded two of my bikes using triplizers, the '66 Paramount and Sporty (crank pictured above). In both cases I had to use a different BB. When trying to determine what I needed with the Paramount, nothing seemed to work or I was outbid on the appropriate Campy BB each time. Finally I took the plunge and invested in a Phil Wood BB. With Sporty I didn't even bother looking, and just went straight to a Phil BB.

On the Paramount I found the triplizer on ebay. The seller didn't know what they had and the 144 BCD was not listed, so I got it for a very reasonable price ($20 with shipping, I seem to remember which included the granny). I never knew what I had until Charles posted the link above. The Merz has a different granny BCD then 78 or Campy's 100, but at this moment I forget what it is. BTW, it has a 31 tooth granny. Thanks for solving a mystery!

Charles Wahl

I had forgotten that fender1 asked about smallest granny for a Campy triple -- sorry for my inattention!

FInding something with 74 BCD gives the most options, since rings for that spacing are readily available, and smallest ring is 24 or so.

If OP doesn't have the triple yet, a machine shop could drill/tap a standard double crank for 74 BCD, no (same way the triple NR/SR works, but at a different BCD)?