guygadois 

Hello everyone. I am putting the finishing touches on my Flying Scot bike for the Eroica CA next month. My Camoy NR cranks have circle with a 1 in them (1981?). Does anyone know the BCD of these and what is the smallest inside chain ring I can put on it? I am going to get all the gears I can for the hills.

Cheers,

GG

BFisher

Sheldon's Chainring BCD Cribsheet

Thought I typed this; the BCD is 144mm.

Bianchigirll 

I’m pretty sure they are 144 and 42t is the smallest ring you’ll find. I believe there was supposed to be a 41 (non Campi) but I’ve never had the chance to see one.

they are hard to find and spendy but you could get a triplizer but then you need the NR triple spindle too

this MERZ is $155. https://www.ebay.com/itm/31365456222...hoCXuEQAvD_BwE


just random internet pics

jiangshi

I think I still have a 41t Ofmega laying around.

merziac

That auction is only the adapter ring, spendy to say the least, no bolts or small ring, you would still need an inner ring.

The 36t Campy's are easiest to find but still usually not cheap and not really low enough to justify the trouble and expense.

Here's a complete setup I was lucky enough to get, came with a 31t and also shown is a 30t that I also got my hands on from another source along the way.

Drillium Dude 

41T was indeed the smallest ring one could use with Campy's 144BCD crankarms without some sort of adapter setup. And yes, they made them:







DD

gugie 

If'n you're not a natural climber, and you want to modify your N.R. cranks, triplizer is what you want. 52-42-24 on this rig, 13-32 in the rear. I really want to get to the top of Cypress this year without walking.

My Eroica ride this year

Not cheap, but a good investment if you want to use a vintage 144 BCD crankset

https://www.redclovercomponents.com/..._42_Teeth.html $106
Triplizer bolt kit $12
74mm BCD 24 tooth chainring can be found for $10 in steel.
You'll need a longer bottom bracket, $25-40

oldschoolbike

It looks like Specialities TA in France still make "Competition" model (144 BCD) in 41T, but currently out of stock direct from the factory. Peter White Cycles in the US and Spa Cycles in the UK both list them currently. TA rings are beautifully made, and a "Competition" ring would be 100% authentic since TA made rings of that spec in the seventies.

oldschoolbike

bulgie 

I dunno about that, I have this here 39t that definitely fits on a 144 crank:


OK jokes are dangerous, someone might think I'm serious. Yes 41t was the smallest that Campy made, and probably the smallest possible without using String Theory or higher dimensions. OK maybe a 40t could be made with some "compromises", like say if you didn't need it to be strong or durable, or run smoothly without the chain clunking over each of the chainring bolts.

Have you seen this website that lets you CAD your own chainring? Fun stuff. Here's what a 40t ring would look like on a 144 BCD.




Note that it helps that 40t is divisible by 5, so each of the holes is "clocked" the same relative to the chain bushings.

Remember everything inside the red circles is gone, drilled out, "air". How much chainring remains for transferring force? And the spider arms of the crank usually come up even higher (radially) than the red circles. Though maybe you could get away with severely trimmimg the spider arms to where the chainring holes are completely "daylighted", for chain crlearance above.. Still strong enough? Do you feel lucky? Actually I might just try it for yuks. Please stop me if it's been done already.

Similar deal with the 30t minimum for Campy triples with a 100 mm BCD — you can limbo under that a little, to 29t, if you compromise, in this case using 6 mm chainring bolt holes instead of the normal 10 mm holes. Here's mine, it works great:



Chainring originally by Willow, modded by me. Bolts are 6/4 Ti (of course).
In case you're wondering, the chain doesn't clunk against the bolt heads, they just miss, and it runs smooth & quiet. No downsides other than a PITA to make, all for one measly tooth smaller.

And some bragging rights? No, not even, when you can go buy much smaller granny rings any day, if you just give up on those hopelessly obsolete Record triple 100 mm BCD cranks. You can even even stick with Record but have a regular Strada drilled at 74 mm BCD, like any sensible person.

I hope no one will double-drill a "factory" triple, that already has holes at 100 mm. You could do that, and the crank wouldn't break, but (to quote Richard Nixon) it would be wrong. Or at least look dumb.

Mark B

JohnDThompson 

Campagnolo made a 41T, 144mm BCD ring, as did Ofmega and TA. None are very common, and the trivially lower gear is seldom worth the odd-ball premium above what a common 42T,144mm BCD ring costs.

Bianchigirll 

I wasn’t 100% sure if Bianchi made them, surely some pro team must have requested them so made a run of the perhaps? Anyway I was sure and sort of added the disclaimer. The one catalog 18 I checked indicated that 42 was the smallest.

repechage

41 gets a bit lower gearing but % wise... not much.

don't use an old Regina Extra chain- side plates are too tall. They hit the crank spyder arms.

consider a triple or maybe an IRD 50/34 compact crank. All depends on your leg strength.

52telecaster

Beautiful. What size tires?

gugie 

700c x 35 Rene Herse. Low gearing, fat tires, good brakes. If I don't make it up Cypress this year witthout walking I'll start doing the Piedras Blancas flat ride from now on!

52telecaster

When touring I used to be so proud of not walking. Now I consider it CrossFit. I have two of those cranks and finally got my father's vertical mill and indexing head. If I ever get the garage sorted I may try to drill and tap them for 74mm bcd.

norskagent

Quick way to measure bcd is distance between 2 adjacent bolt holes times 1.7.
Not exact but close enough to figure out what it must be.

JohnDThompson 

Ofmega made Bianchi-branded cranks, so perhaps they were Ofmega rings?

One problem with running a 41T, 144mm BCD ring is that the chain side plates can hit the spider arms as you're pedaling, making an annoying jump in the chain each time it lands at the end of one of the spider arms. Ofmega dealt with this by milling away a little bit on the inside of the spider arm to provide clearance; Campagnolo expected you to do that yourself if you wanted to run a 4T ring.

Bad Lag

Peter White sells new 41T chain rings,... and 42T and...

Link to Peter White cycles

So does Spa Cycles

Link to Spa Cycles

Bad Lag

IMO, what you really want is a wide range freewheel and a wide range rear derailleur to go with it. You'll probably also need a new shift cable and a longer chain to go with those things. It takes about half an hour to swap them out.

Consider also going to half-step gearing. That would mean using 42/45T chain rings up front, along with the wide range freewheel.

Mine is an Ultra-6 13-43T freewheel with a Shimano Deore XT derailleur. I use an Ultra-6 chain. I do use the half-step gearing.

This set up will get you up just about any mountain road with relative ease, yet the half-step gears it provides are really nice on the regular roads.

USAZorro

I get the Campagnolo love, but mine has limits. TA, Stronglight and Williams all could provide lower gearing, maintain historical correctness, and might even cost substantially less.

steelbikeguy

nothing wrong with going to lengths to keep the Campy cranks on the bike, but I agree that other options should at least be considered.
When I decided that I needed low gearing on one of my shiny old bikes, I chose to use the Sun XCD clone of the T.A. Cyclo-touriste. This gave me 50-34 chainrings with a 13-26 six speed freewheel. Not quite the close gear spacing of the original 13-24 freewheel, but pretty close. In exchange for that, I was able to grunt my way up the local 14% grades.

Before:



After:


I'm not sure how available the various T.A. clones are. Sun XCD seems to be getting a bit rare, but I think the Velo-Orange clone is still around??

Steve in Peoria

52telecaster

V.o. is still there and excellent. Plus the v.o. fasteners are vastly superior to old t.a. ones. I prefer t.a. cranks and rings to v.o. but I prefer v.o. fasteners.

steelbikeguy

Good to hear that V.O. still sells their version!
I never owned the original T.A. crank, but have heard that the bolts were not as strong as most folks would expect. They may have been made from pot metal, or maybe just a hard cheese??

I was poking around the web and found that Velo Duo (in the UK) still sells the Sun XCD clone with a variety of T.A. rings. This is where I got mine, and I'm quite happy with it. Shipping costs have gone up since I got mine, so that will have to be considered.
https://www.veloduo.co.uk/collection...tronglight-49d

Steve in Peoria

52telecaster

The fasteners we're steel but a bit soft which is weird because the t.a. rings are really hard for aluminum.

USAZorro

I've broken a couple doing things that should not have resulted in anything approaching catastrophic failure. One was on a TA and another on a Nervar (I suspect they had some association). I replaced them with Home Depot 7mm hex bolts which I dremel'd the heads of down to a passable profile, and leaving about 1mm more of purchase for my double-ended hand wrench to apply leverage without damage.