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Discussion Starter · #1 ·
I'm about to mount an old Campy Super Record Triple crankset (52/42/32), I have the longer BB axle (NR BB) and I'm running a 13-21 7spd freewheel.

My question is: Should my NR (patent 83) Rear handle that, or should I start looking for a SR Rear?

I know this is not the ideal setup but I'm trying to get by with what's in my garage.

Thanks in advance.
 

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Might work. With the narrow-range freewheel and your triple you need 28 teeth wrap capacity, which may be just outside the specs of the derailleur. Size the chain just long enough for the big-big combination, and you might have slack only in the smallest 2 or 3 cogs with the granny ring. And you avoid those combinations anyway, right?

Won't cost you anything to try it. If it doesn't work you can look for another der.
 

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SilverStar said:
I'm pretty sure this will work as long as the chain is sized correctly. NRs are pretty forgiving...
They're not at all forgiving of too short a chain. But the Ops only slightly over capacity and as long as he makes sure the chain is long enough for the 52/21 combination in case he accidentally shifts into it, the system will tolerate excess slack in the 32/13.

The nice thing is the largest cassette sprocket is 21t eliminating jockey wheel height problems with any chainring.
 

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Discussion Starter · #5 ·
JCavilia said:
Might work. With the narrow-range freewheel and your triple you need 28 teeth wrap capacity, which may be just outside the specs of the derailleur. Size the chain just long enough for the big-big combination, and you might have slack only in the smallest 2 or 3 cogs with the granny ring. And you avoid those combinations anyway, right?

Won't cost you anything to try it. If it doesn't work you can look for another der.
What's wrap capacity and how is it calculated?
 

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d26818 said:
What's wrap capacity and how is it calculated?
It's the amount of chain slack the idler cage can take up. It's given in the RD specs along with the larges sprocket with which it'll work.

To find out how much you need, add the difference between largest and smallest chainrings, to the difference between the largest and smallest cassette sprockets.

On your bike that's 52-32 + 21-13 = 28t

Even if you never plan to ride the extreme crossed over combinations, it's important that the chin is long wnough for the large/large combination and that the RD can take up all the slack when you go to the small/small combination, though in a pinch you can cheat a bit on the small/small side as long as you don't expect to use it.
 
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