Another NR RD capacity comment
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Another NR RD capacity comment
Last night I was putting together a '73 Bianchi that I'm planning on riding this Saturday for a local charity ride.
Last year I had built a '72 Cinelli with similar gearing, and everything worked just fine.
On the Cinelli, I was able to run a 14-28 5 speed freewheel, provided I removed the dropout adjusting screws.
I was building the Bianchi exactly the same. I even removed the chain from the Cinelli and made the Bianchi chain length identical.
Upon installing everything, I found the chain on the Bianchi way too loose, so I went back to the old "big-big + 1 link" chain sizing estimate. Reinstalled everything, and now I can't get on the big-big.
I haven't checked chainstay length, but my suspicion is they aren't the same.
Still a work in progress.
Last year I had built a '72 Cinelli with similar gearing, and everything worked just fine.
On the Cinelli, I was able to run a 14-28 5 speed freewheel, provided I removed the dropout adjusting screws.
I was building the Bianchi exactly the same. I even removed the chain from the Cinelli and made the Bianchi chain length identical.
Upon installing everything, I found the chain on the Bianchi way too loose, so I went back to the old "big-big + 1 link" chain sizing estimate. Reinstalled everything, and now I can't get on the big-big.
I haven't checked chainstay length, but my suspicion is they aren't the same.
Still a work in progress.
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Looking at your picture, suggest you slide the rear wheel forward in the dropouts to give (effectively) more chain.
In general, when the chain's on the small / small combination, the pulleys should be at the limit of their take up. See pic of the "positive net worth" Cinelli s/n 1183 below. Note the position of the pulleys and the location of the axle in the rear dropouts.
If your Bianchi - which looks very nicely turned out by the way - is missing the dropout adjuster screws, ebay seller Ti Cycles has some really nice ones in stainless steel that are better than the original.
https://www.ebay.com/itm/Dropout-adj...n/182263111133
Mark Petry
Bainbridge Island, WA USA
In general, when the chain's on the small / small combination, the pulleys should be at the limit of their take up. See pic of the "positive net worth" Cinelli s/n 1183 below. Note the position of the pulleys and the location of the axle in the rear dropouts.
If your Bianchi - which looks very nicely turned out by the way - is missing the dropout adjuster screws, ebay seller Ti Cycles has some really nice ones in stainless steel that are better than the original.
https://www.ebay.com/itm/Dropout-adj...n/182263111133
Mark Petry
Bainbridge Island, WA USA
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Thanks Mark. Beautiful Cinelli you have there!
I took the adjusters out in order to slide the rear wheel all the way back in the dropout. That was the only way I could get clearance between the jockey wheel and 28t sprocket. It was late, I was tired and I'll give it another look later today.
Kurt
I took the adjusters out in order to slide the rear wheel all the way back in the dropout. That was the only way I could get clearance between the jockey wheel and 28t sprocket. It was late, I was tired and I'll give it another look later today.
Kurt
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Hmmmm.
Might want to check the distance between the axle and the dropout hole on both bikes and see if they are different. Just a small difference at the mounting hole for the RD can make a big difference at the big cog.
In my experience, 28 with an NR RD is always a bit of a stretch, while the SR RD seems to do it more easily.
If your chain length is set at big-big plus a linkset, it should be correct for this application. What happens when you try to shift into big/big?
Too tight? Skates across the freewheel?
What kind of freewheel are you using? When trying to use larger freewheels, have always had the best luck with mid-late 80's Shimano UG series. Now that I think about it, also used 10 tooth Shimano pulley wheels on the RD.
Might want to check the distance between the axle and the dropout hole on both bikes and see if they are different. Just a small difference at the mounting hole for the RD can make a big difference at the big cog.
In my experience, 28 with an NR RD is always a bit of a stretch, while the SR RD seems to do it more easily.
If your chain length is set at big-big plus a linkset, it should be correct for this application. What happens when you try to shift into big/big?
Too tight? Skates across the freewheel?
What kind of freewheel are you using? When trying to use larger freewheels, have always had the best luck with mid-late 80's Shimano UG series. Now that I think about it, also used 10 tooth Shimano pulley wheels on the RD.
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Notice how the offset of the top pulley from the cage pivot allows the pulley to move through an arc as the chain moves from one chainring to the other.
So the secret to this working optimally (as best as can be achieved with existing gearing) will be for the top pulley to be the same distance from the freewheel in each of the two chainring positions with the largest cog selected.
Consideration should also be given to the chain gap between pulley and freewheel when the chain is on the small chainring, as interference might occur at that time.
This is achieved by fine-tuning the chain's length, and you might have to add chain length/slack if the reason that the chain won't climb to the largest cog while in the big ring is because the pulley is being pulled too far from the freewheel as the cage rotates counter-clockwise.
You didn't say whether there is a problem with physical contact between pulley and freewheel or if the problem is that the chain won't move to the largest cog because of an excessive chain gap, so that should be the first thing to determine here.
So the secret to this working optimally (as best as can be achieved with existing gearing) will be for the top pulley to be the same distance from the freewheel in each of the two chainring positions with the largest cog selected.
Consideration should also be given to the chain gap between pulley and freewheel when the chain is on the small chainring, as interference might occur at that time.
This is achieved by fine-tuning the chain's length, and you might have to add chain length/slack if the reason that the chain won't climb to the largest cog while in the big ring is because the pulley is being pulled too far from the freewheel as the cage rotates counter-clockwise.
You didn't say whether there is a problem with physical contact between pulley and freewheel or if the problem is that the chain won't move to the largest cog because of an excessive chain gap, so that should be the first thing to determine here.
Last edited by dddd; 04-26-19 at 10:55 AM.
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#9
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Consideration should also be given to the chain gap between pulley and freewheel when the chain is on the small chainring, as interference might occur at that time.
This is achieved by fine-tuning the chain's length, and you might have to add chain length/slack if the reason that the chain won't climb to the largest cog while in the big ring is because the pulley is being pulled too far from the freewheel as the cage rotates counter-clockwise.
This is achieved by fine-tuning the chain's length, and you might have to add chain length/slack if the reason that the chain won't climb to the largest cog while in the big ring is because the pulley is being pulled too far from the freewheel as the cage rotates counter-clockwise.
The BIG/big method often makes the chain length too short. Try adding a link.
Just to state the obvious, the BIG/big combination should not be used when actually riding. Same with SMALL/small. No doubt 99.9% of the people here know this, but I see people riding in them all the time...
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Exactly.
The BIG/big method often makes the chain length too short. Try adding a link.
Just to state the obvious, the BIG/big combination should not be used when actually riding. Same with SMALL/small. No doubt 99.9% of the people here know this, but I see people riding in them all the time...
The BIG/big method often makes the chain length too short. Try adding a link.
Just to state the obvious, the BIG/big combination should not be used when actually riding. Same with SMALL/small. No doubt 99.9% of the people here know this, but I see people riding in them all the time...
After a little further examination, the chainring on the Cinelli is a 51, it's a 52 on the Bianchi. Chainstays on the Bianchi are also shorter. When doing this late last night, I originally had the dropout adjusters in place. Like the Cinelli, I had to remove them in order to gain clearance between the jockey wheel and the freewheel.
After these headaches, I'm thinking I'm just going to switch freewheels and live with it. I have a 13-26 that will probably do the trick.
Kurt
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13-26 sounds like a plan.
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That is one beautiful Bianchi @satbuilder, you did a fantastic job on that one sir.
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Looking at your picture, suggest you slide the rear wheel forward in the dropouts to give (effectively) more chain.
In general, when the chain's on the small / small combination, the pulleys should be at the limit of their take up. See pic of the "positive net worth" Cinelli s/n 1183 below. Note the position of the pulleys and the location of the axle in the rear dropouts.
If your Bianchi - which looks very nicely turned out by the way - is missing the dropout adjuster screws, ebay seller Ti Cycles has some really nice ones in stainless steel that are better than the original.
https://www.ebay.com/itm/Dropout-adj...n/182263111133
Mark Petry
Bainbridge Island, WA USA
In general, when the chain's on the small / small combination, the pulleys should be at the limit of their take up. See pic of the "positive net worth" Cinelli s/n 1183 below. Note the position of the pulleys and the location of the axle in the rear dropouts.
If your Bianchi - which looks very nicely turned out by the way - is missing the dropout adjuster screws, ebay seller Ti Cycles has some really nice ones in stainless steel that are better than the original.
https://www.ebay.com/itm/Dropout-adj...n/182263111133
Mark Petry
Bainbridge Island, WA USA
One of the hidden aspects of Nuovo Record capacity is the Patent year... Campagnolo extended the distance from the upper attachment pivot to the top parallelogram links, a small amount but if you measure a Patent 70 (or earlier) to say a '74... not the same.
A reason why one who has a Nuovo Record mech curses a 28t, and another cakes it work.
#16
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I put SR cages on my NR rears and I've never had any capacity issues with 28t freewheels.
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where do you get spare SR cages?
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That is one beautiful Bianchi @satbuilder, you did a fantastic job on that one sir.
Rather than rush thru the final assembly, I have decided to take a different bike on today’s ride.
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That Nuovo Record rear mech is of very late design, or a hybrid, the jockey cage is like the last generation Super Record.
One of the hidden aspects of Nuovo Record capacity is the Patent year... Campagnolo extended the distance from the upper attachment pivot to the top parallelogram links, a small amount but if you measure a Patent 70 (or earlier) to say a '74... not the same.
A reason why one who has a Nuovo Record mech curses a 28t, and another cakes it work.
One of the hidden aspects of Nuovo Record capacity is the Patent year... Campagnolo extended the distance from the upper attachment pivot to the top parallelogram links, a small amount but if you measure a Patent 70 (or earlier) to say a '74... not the same.
A reason why one who has a Nuovo Record mech curses a 28t, and another cakes it work.
Something new to learn every day!
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Found by accident, was observing a few and noticed that the early units had a more refined shaping of the upper body surrounding the pivot / mounting bolt... whip out the calipers... sure enough different measures. The Secret Campy files...
#21
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SR cages are a different shape than NR cages. I've found cages only on eBay and have also bought SR rears that have damage and/or missing parts.
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