This is my first rebuild, and as I was cleaning the rear derailleur I found this. I'm wondering If it is a concern and should be replaced or if it is more cosmetic and wont affect the function. This is two shots of the same cog.

it's mainly just going to interfere with the dust shield, so if that was the only thing wrong I'd just carve it clean with a knife...but coupled with the tooth-wear: I would replace the pulley (probably both since they will both be worn).

Who needs teeth? Lots of Huret derailleurs were made without them!

OK, I'll bite ()
It's a fair question: Huret pulleys were toothless, (they also used loads of tiny ball bearings)...but everybody else, including the aftermarket pulleys, all have teeth.
So was Huret the only mfg. that got it right?
Has anybody tried running their Campy, Shimano, Suntour, Sram, etc. RDs with the pulleys ground smooth...and what happened?

Good questions, and I don't have answers. But once takingcontrol lubricates the chain, freewheel, and pulleys, he will know if the drivetrain has adequately low friction. My guess is that worn teeth don't matter on derailleur pulleys.

But one thing makes me scratch my head: how do you wear out teeth on derailleur pulleys?

Hi unworthy1 !
It ran OK. It was a worn freewheel combined with a new chain that caused big problems.

I've run a good 1,500+ miles on my 1961 Campagnolo Gran Sport RD w/the original steel, toothless pulley wheels.

It has been coupled - at different times - with a SACHS freewheel (7 speed, narrow), a cheap, Chinese-made Royal Enfield 5-speed freewheel (half step), and a Shimano 600 freewheel (6 speed, narrow). Two different Sachs/SEDIS chains have been run on it (first replaced due to wear).

To this day, I have no complaints, except for the parallelogram spring being too strong - it generally shifts just as well, if not crisper, then a Nuovo Record. Your mileage may vary.

If you care to see video of one of my NR's and the GS, see:
https://www.youtube.com/user/cudak888...72CD01BE2E06E2

-Kurt

This is from the bianchi I just bought. other then a loose BB (slight) this is the only problem I have found.

I believe only the early '60s Huret RD jockey wheels rode toothless. Later on they added teeth to their pulleys. I imagine there is an improvement in the chain not skipping off the pulleys with teeth, as opposed to those without. But this is just my guess.

My early 1950s vintage Campy "Gran Sport" has toothless metal pulleys with ball bearings. Maybe Huret just kept doing it right longer than anyone else?

I have a very early Campy Gran Sport rear derailleur (I see John just beat me to it!!!) which came new with toothless steel pulleys on ball bearings. The purpose of the pulleys is to guide the chain onto the proper rear sprocket, and to enable taking up chain slack. Teeth aren't really needed. Decently free bearings are needed. If those blemishes and marring cause some friction when you get them back on teh cage, just trim them off with an Xacto knife.

Clean and lube the bearings.

I had forgotten about those early Campy GS pulleys that were also toothless, but now that Pastorbob mentions it I do recall that Huret went to teeth on first one pulley and then both. I guess the teeth aren't absolutely needed for best performance, but I try to keep mine and replace worn pulleys when possible, maybe I'm just being fussy.

[QUOTE=pastorbobnlnh;9633475]I believe only the early '60s Huret RD jockey wheels rode toothless. Later on they added teeth to their pulleys. I imagine there is an improvement in the chain not skipping off the pulleys with teeth, as opposed to those without. But this is just my guess.QUOTE]

The Duopar I had was toothless. I don't know the history of the duopar, but I know that nobody was making titanium bicycle parts in the early '60s. Only the government could afford it.

This Record was also toothless. It also had ball bearings. The improved Nuovo Record had bushings. Go figure.

Overbrushing.