campagnolo BCD cranks question..

General Help
1

ive recently aquired a campagnolo crankset…
and i dont know too much about campy stuff, to be honest with you…
its a 5 bolt crank.
its got a 52t chainring on it… and i think ill find it quite a strain on my morning rides to work…
im trying to work out the BCD on it, so i can maybe get a smaller chainring…

im not too sure where im looking to be honest…
on the crank arm, it says “170 [41] 9/16"X 20F”
ive done some googling, and the closest thing, i can work out is -

144 41 84.6 Old Campagnolo standard, still used for track applications.

ive deducted that the 41 has something to do with it…
any help would be GREATLY appreciated, as i really want to get this bad boy on the road.
pics available, if you need them…

2

There is formula you can use where you measure the distance between chainring bolts (C-C) to work out the BCD. I’ll either be 144 or 135mm.

Thanks Sheldon, what a legend:
Sheldon Brown’s Bicycle Glossary Bo–Bz

EDIT: you can get cycle underground in Sydney to make you a chainring with either BCD with any number of teeeth that the size allows.

3

For a 144bcd crank the smallest chainring you can use is a 41t. This might not work though as it might be cutting into the chainring bolts. So 42t is the smallest you can use (to be sure).

For other common bcd sizes …

151bcd - 44t

135bcd - 39t

130bcd - 39t (maybe 38t)

110bcd - 34t (maybe 33t)

4

my dearest Dice, and Spirito, many, many thanks!

5

If its the newer record pista crank it will be 144bcd

6

I have a 38T 130BCD, it can be done.

I’ve only seen a photo of a 41T 144BCD. Your cranks, if track, will be 151 or 144. As mentioned, measure the distance between two bolt centres, if it’s 84.6 then it’s 144BCD, if it’s 88.8 then it’s 151BCD.

7

here they are…
and, you know, i dont even own a tape measure…
may need to invest now…


IMG_2616 by wolfgland, on Flickr

8

They’re road cranks and are a 135bcd. There wasn’t any track rings (1/8") made by Campagnolo for them but Miche did madke them for that BCD. You could also get in touch with Fyxo and have a 135bcd track chainring made for you to suit these cranks. Of course if you can run 3/32" (road) chainrings then there’s plenty of options from 39t to about 54 or 55t.

A Miche 107mm BB will give you a good chainline with these cranks if you use the chainring on the outside of the tabs.

Nice cranks, not track but well made.

9

thanks again spirito, nice to know about these cranks…
i really need track cranks at the moment…
may just have to whack these up in the for sale section, i guess…
you saved me alot of headaches! i owe you a beer!

x

10

double post.

11

If you’re happy to use 3/32", go for these:
Stronglight Dural 135mm Campagnolo 8/9/10 Chainring
Stronglight Zicral 135mm Camp 9/10 Chainring

The Dural are a little softer and less finished than the Zircal, but they are mighty fine rings.

12

What blakey said +

I’d run them on the track no probs but if you are going to want a suite of chainrings to suit all events and venues then opting for a more standard 144bcd crank style will make it easier on the long run. But again, there’s nothing wrong with them and they can be made to work for you.