A little bit of advise on cranks/ chainrings please 🙂
 

Hello,


My name is Dieter, I'm new to the forum. I'm rebuilding a vintage 1970's racebike for my father in law as a surprise gift.


I've been able to get a lot of things done so far, but now I grinded to a hold due to chain rings.


The current situation is the following, the bike was originally equipped with campagnolo, but over time a lot of the parts were replaced with non campagnolo parts. The current crank mounted is a Coronado one but the chain rings need replacement. Now I'm not sure what to do. Finding chainrings referring to a Coronado seems impossible. I find chainrings from other brands like stronglight, shimano with the right bcd etc. but most of the time for 9/10 speeds where my intage bike only has a 7 speed. I have read (and figured out) that this should be able to work although this coul result in some noise. I am however more afraid to have a wrong 'offset' sideways which would make shifting bad or impossible.


I have been considering buying a second hand campagnolo crankset, but these aren't cheap and would mean I'd most likely would need to buy a new set of pedals (the one's I now have are French thread).


The brand of the parts will not mather to my father in law (read: me making excessive costs to mount campagnolo will make no difference to him :))


So due to lack of experience my question now is: what would you experts try? Try buying other chain rings and hope for the best or is this doomed to fail,....


I'm looking for the cheapest solution which is acceptable and doesn't cause major problems.


Thanks in afvance for your input!

The brand of crank doesn't limit the choice of chainrings.

The Bolt Circle Diameter( distance between two mounting holes, skipping one in between) is your number
144,151 are common old sizes.

Find a Sutherlands Manual for Mechanics and the information on this ( and lots of other stuff) will be at your fingertips.

Pedals are another story.
French threaded pedals are not real common.
Almost any modern replacement crank( or vintage stuff in the US) will be BSC(British Standard thread).

Depending on your location, most larger cities have a bicycle co op or used bicycle shop. That would be a place to start.
Also, look for the oldest bicycle store in your area. They likely have the knowledge or can direct you.

rusty

Give us a picture of the Coronado crank please. We can be of more service that way.

Sorry for this spam but I need 10 posts to be able to upload pictures.

And again.... Sorry

This should be my 4th

:( Sry

Pic assist
 

Here you go:
https://cimg5.ibsrv.net/gimg/bikefor...9b53c47b00.jpg
https://cimg7.ibsrv.net/gimg/bikefor...89b641f926.jpg
https://cimg0.ibsrv.net/gimg/bikefor...53713d5fde.jpg

That is a gorgeous crank. My first choice would be to buy a replacement ring and compare with the original one. The front derailleur would likely have enough adjustment to compensate for any chainline difference.
Since it sounds like your father would be happy with whatever you installed, a second option is to sell the Coronado and buy a vintage Stronglight, TA or Nervar crank. You may even find one with French pedal threads.

Welcome to the forums, @Dieter p. Have you tried flipping the chainrings around, so that the chain bears on the other side of the teeth?

Thanks for the pics. That BCD doesn't look too uncommon. If someone can figure out what it is, we can probably find some rings that will fit. The small ring is a 42. Might be a 130BCD.

Here's part of the BCD crib sheet from Sheldon Brown. It should be straight-forward enough to sort out with a ruler.

https://cimg9.ibsrv.net/gimg/bikefor...52ae44dad0.jpg

Ok, so you have about 42T on the small ring.

Thus, your crank definitely IS NOT 144 BCD (or larger).

I'd guess that it is probably 130 BCD, unless it is some oddball.

Fortunately 130 BCD is one of the most widely supported sizes. Depending on your Father in Law, I'd probably find something like a 39/50 or 39/52 ring set.

There should be a great variety of rings available. Some with drilling.

Good evening to all of you,

First of all thanks for all the replies you posted, I wasn't able to answer them because I reached my 24h limit of 5 post.

BCD is indeed 130mm, small is 42, big is 52. New rings can be a little less I think.

I'll try to answer everyone's questions/remarks.

First of all I also very much like these cranks so if possible I would in fact like to keep them 🙂.

I have looked around and read into different topics on this and concerning turning the chain rings around, I thought of that as well, but the offset sideways would change ( two chainrings would lie 2 mm further away from each other and I don't know if this would cause problems shifting (shifters are on the frame, I don't know if these have 'fixed' positions per gear or if they can be freely moved to fit the gear,...)

I have found fairly cheap new chainrings (online so comparisons are difficult to make) I think should work (stronglight) but I'm worried on three things.
1) the new chain rings are for a 9/10 speed so I assume more narrow.
2) the offset sideways, so for possible shifting issues.
3) the inner diameter of these chain rings, if the would fit the cranks (so not bcd but the smallest diameter of the chainrings). I do however not see this point as the biggest issue 🙂. Grinders etc.

For the table you shared, for bcd 130 the teeth don't match so I'm not sure what to make of this.

Would you take the chance with the 9/10 speed stronglight? Maybe choose an 8 speed chain and hoping for the best on my 7 speed casette?

Please feel free to share your thought, I find this all very fascinating.

Thanks and with kind regards Dieter

Thinner chainrings shouldn't be a problem. Slight offset shouldn't be a problem. Wrong BCD would certainly be a problem.
What distance do you measure between adjacent or alternate bolt holes?

There are plenty of 130 bcd chainrings sitting on the dock of Ebay. Some old school SR Sakaes, but they can be pricey. Suginos also.

Here’s the Coronado crankset I acquired for a black bike I own.

Not to steal a thread, but anyone got info on this German component?

https://cimg8.ibsrv.net/gimg/bikefor...7a212c6d4.jpeg

Interesting there are at least two variations for these, plus color. Your crank appears to be swaged, whereas Dieter's is forged.

Never studied the differences, but I thought of swaging as a form of forging. Not sure about the equipment used nor hot/cold processes. Guess that's another thing to check-out. The 2 cranks do have a different appearance (beyond the color).

Coronado cranksets were/are made by Thun. They turn up regularly here in Europe, mostly in swaged form on lower level bikes. They were probably cheap.

Having said that, the OP's set looks nicer than any I have seen (one piece, is it?) and the sets I have feel very, very light, so I'm holding on to them for a weight weenie build. :)

As for the chainring replacement, I would just take any pair of decent 130 BCD rings with the required tooth count, and not expect any problem other than *maybe* having to adjust the limit screws on the derailleurs. The only time I ever ran into trouble was with chainrings that were made for 1/8th chain, and I don't think those ever came in 130 BCD.

Thanks for al the replies.

I have indeed heard from someone these Coronado's were cheaper replacement parts. That being said, I think they look very nice and there in a good general state. Replacing them for a similar type campagnolo would set me back for €80 and probably a set of pedals which isn't worth it for me.

I'm going to take my chances with a 'random' set of chainrings. I'm thinking of switching to 38or39 and 49 or 50, think this might make riding the bike a little easier.

I'll let you all know how it turned out and I'll post a picture of the finished product (in a while of course :))

happy to help you with your sprockets, Dieter. :)

I see what you did there. "We dance now!"

You know the Germans always make good stuff.

Yours do look nice, and I wouldn't replace it unless I wanted a smaller BCD. TA makes a 38T 130 BCD ring, but be aware there is a reason Shimano offered no lower than 39T: the chain might (read: will) not clear the spider arms. However, the solution is simple: file off a couple of millimeters from the tops of the spider arms. I did it to a 600 EX spider and the result was quite satisfactory:

https://cimg4.ibsrv.net/gimg/bikefor...5fed870117.jpg