I've got a 7 speed Athena rear hub on an older bike of mine. I suspect the freewheel cogs might be worn out, because after installing a new 10sp Veloce crank and 9sp SRAM chain, I get really bad skipping when any torque is applied. This skipping doesn't occur along the entire range of cogs, though; just in the middle three, which are used most often.

I suppose my question is whether this skipping is an obvious sign of cog wear, and if the freewheel needs to be replaced, what kind of threading is used on that style of hub? I think the hub itself is from 1987/88.

One more thing: I'm not entirely sure about the freewheel causing skipping, because before installing the new chain and AFTER installing the new crankset, the chain skipped.

Rule of thumb: Replace the freewheel and chain together. Some espouse two chains before a new freewheel is needed but I have heard others (much more serious riders than I) say they should both be done together. Regardless, if the application of torque causes skipping, and the RD is properly aligned, then stick a fork in it, it's done.

Installing a new cassette or freewheel means also installing a new chain - as the old chain has 'stretched' to match the shape of the worn-out cassette/freewheel. And you need to get the chain at the correct length. This can be found about 1/3rd of the way down this page:

https://sheldonbrown.com/derailer-adjustment.html#chain

Alright, so it looks like this just has to be replaced. Trouble is, you go into a shop asking for a 7 speed freewheel, and they laugh you out the door...

We're missing the most important piece of information, the brand of the current freewheel. English and Italian hub/freewheel threading is close enough that you can mismatch the two. However, it does cause some damage to the threads and you should not switch back and forth between English and Italian threaded freewheels.

Oh, sorry - it's a Maillard.

Just curious, but could the skipping be caused by having the narrower 9spd chain on an old style freewheel? I didn't know if the modern 9spd cassettes had thinner cogs than the old freewheels. I would think the new chains would also be designed with the modern shift ramps in mind.

I actually saw a new 9spd freewheel on a website the other night. Can't remember where, I was surprised someone was making such a thing! I have had good luck with a new Sunrace 7spd freewheel, they aren't very expensive.

HThe chain could be a problem, but a small one at worst, just so long as it seats correctly. Yes, you need to replace your freewheel. I like my IRD freewheel and have no complaints, it's a quiet thing though they're kind of expensive.
And you may be talking about the 9-speed freewheel for the BionX system. That's a whole nother beast, there.
-Gene-

Funny coincidence, I was looking at 7 speed freewheels on eBay today.

here ya go

Are you certain its a freewheel and not a freehub?

**edit**
this part is english threaded... i just realized we dont know the threading you have

Since it is Maillard, it is probably English threaded, as I don't believe they made Italian. Similarly, I don't believe that Campagnolo still offered French hubs, this late in the game, but it should not be dismissed, as Maillard definitely offered French freewheels. You're going to have to remove the freewheel anyway, so determining the difference is easy. An English threaded Maillard freewheel will have a rectangular punch mark on the back of the body. Alternately, the Campagnolo hub should be marked with the thread standard, either 1.37 x 24 for English or 34.7 x 1 for French. French and English are totally incompatible, so whether you identify the hub or freewheel thread, the other component is the same.

BTW, Sheldon has an excellent article on chain/cog wear, with photos to aid identifying all the various combinations of worn and new cogs and chains. https://www.sheldonbrown.com/chains.html