CliffordK

It is rare that I'll break a derailleur. For a used one, watch that the cage isn't nearly worn through, and you aren't missing pieces like the cage bolts.
Precisely. As long as the cable pull is moderately compatible with the levers, it doesn't make much difference.

I think a couple of Suntour derailleurs have the reverse pull. I haven't used one, but it always seemed like an interesting feature worth trying. I'm not sure why it never took on.

The Golden Boy 

As covered in the previous posts- that's not always the case- the sculpting on some modern derailleur cages will not pick up from a ring it's not designed to pick up from. Drag it all day across the chain- it's not picking up.

CliffordK

I had that happen with an older Shimano Alivio or Altus derailleur, triple.

Used, well worn stuff, I don't know the history of the bike/cranks/derailleur. My interpretation was that the derailleur not only didn't pick up the chain, but actually folded over the top of the chain and effectively trapped and prevented the chain from hopping up.

I ended up raising the derailleur by about 1/4", and it was able to shift through all the gears.

It is a point, however, that not all derailleurs are made equal.

Many of the cheaper Vintage bikes had a cable stop on the front derailleur which is rare on modern bikes.

Almost all road bikes are bottom pull, but MTBs (and cyclocross) can be either top pull or bottom pull.

A lot of MTB derailleurs take up more space behind the seattube than road derailleurs, and might not fit with road tires.

Double and Triple derailleurs have diverged over the years, and may not be compatible.

The Golden Boy 

That's so true!

Just in my experience with the DA 7803 and 7700 derailleurs-

First, based on my experience with every other FD ever, I would have expected the triple to work flawlessly.

Second, I would have NOT expected the double derailleur to work through all 3 chainrings. I just being anal/dorky about having DA derailleurs on there.

Randybb

Thanks everyone. I got a brand new Cyclone MII all set up on the bike, and also switched on my 53/42 crankset. It's so interesting to open up a 40 year old box...

The cyclone looks really similar to the superbe FD, and by hand I can't tell which one weighs more. However it is significantly longer than the superbe, and it was a bit tricky to set up. I typically align the outer FD plate to be perfectly parallel with the outer chainring, but when I did that, I got rub in every gear except big-smallest and small-biggest. So I angled the back end of the derailleur a little bit towards the frame, and now I can run through 7 of 8 gears without trimming the FD. It seems to shift well, but I've got the bike in the trainer so unclear how it'll hold up in the real world, I expect it'll do great.