Classic & Vintage - Max cog for NR rear derailleur?

Finishing up a vintage restoration project, and my initial attempt at pairing a 14-26 freewheel with a Nouvo Record rear derailleur (pat 84) was not very sucessful - upper pully making contact with the largest 2 cogs. I was under the impression that the derailleur could handle a 26t largest cog, but I have no idea where that impression came from, so thought I'd ask the experts. Will it work? If so, what do I need to do to get clearance between cog and pully wheel? No B-tension screw man - what's up with that (just kidding). If not, what's the biggest cog I can run? Thanks folks!

Did you put a new chain on? It may be too long. I use a NR on a 28 tooth paired with a half step chainwheel (3 tooth difference between the two chainrings). You might also try setting axle all the way back in the dropout.

26T for NR, 28T for SR. Depending on chain and hanger length, of course.

Yeah, I heard 26T for the NR, too. Interesting that someone has raised this subject; I just noticed that my earlier Campy rear derailleur, marked "Record" (chromed bronze & steel, c.1963-67) is actually marked "13-36", yet the pulley cage has exactly the same geometry as the NR.

Does anyone know if (or Why) there was actually a reduction in the capacity of the NR? ~ It really doesn't seem to shift any better or worse than it's predecessor.


By the way, my first generation long-cage "Rally" (c.1974) is likewise marked 13-36... (and also 36-54 - which would be Campy's NR Triple crankset's chainring range).

I'll give it a second attempt. Mkahrl - I was thinking about chain length (yes it is new) but didn't want to go too short. Axle in dropouts didn't occur to me (Doh!), and is probably the culprit. I'll give it a try and report back.

jw.

I use 28t on all my 3 NR bikes with no ill effect.

Depending on the chainring differential, 26 is the realistic max for a NR rear. Chain length has to be spot on if using a 52/42 or 53/42, in addition pulling theaxle back in the dropouts will assist, not my favorite but if one needs it, go rearward.

If the cage is hitting in the next smallest cog, lets say a 23 or 24... too much chain, there is another trick, the jockey cage has more than one hole for the tension spring to locate in, go to the hole that increases the "twist" of the cage, it will assist in taking up the slack when in the small/small, a gear that should be avoided as well as the big/big, but I think setting up a drive train to "work" in those extremes is rational.

Interesting - I'm having a similar problem with a NR shifter...and so far am unable to keep the pulley from grinding on the cog no matter what I do. Loss of spring tension, maybe?

By the way - that 13-36 doesn't mean 13 to 36 on the freewheel - it is the tooth the difference between your biggest and smallest chainrings for your front derailleur, and the total capacity of the derailleur: the tooth difference between your biggest cog and smallest cog + the front chainring difference.

13 front and 26-13 rear = 26 teeth. This is near the practical maximum, so they were being optimistic with the 36, i think. (a 36 tooth front triple would add six more...)

I'll give it a second attempt. Mkahrl - I was thinking about chain length (yes it is new) but didn't want to go too short. Axle in dropouts didn't occur to me (Doh!), and is probably the culprit. I'll give it a try and report back.

jw.

If you pull the axel all the way back in the dropout, you may get skipping on the smaller cogs due to insufficient chain wrap.

If you pull the axel all the way back in the dropout, you may get skipping on the smaller cogs due to insufficient chain wrap.

Wouldn't moving the axle all the way back increase the chain wrap - or is this a track-style dropout?

Wouldn't moving the axle all the way back increase the chain wrap - or is this a track-style dropout?

You're right. Now I'm wondering why mine developed a skip when I removed the spacers from my Simplex dropouts and it went away when I put them back. I thought I had it figured out, but that makes no sense at all. Never mind!

I didn't get much sleep last night. I'll spend half of tomorrow fixing what I screwed up today.