Chain length choices...
 

Small (triple) ring, small cog.
Would you use Pic A, Pic B, or something else?

PICTURE A
https://cimg0.ibsrv.net/gimg/bikefor...681b9adfc9.jpg

PICTURE B
https://cimg1.ibsrv.net/gimg/bikefor...f3bc338dbd.jpg

I may be misunderstanding you, but usually one starts with big to big, not small to small. See Park Tools method for a conservative approach, or look at Sheldon Brown's method.

I only have Campagnolo, and they recommend small- small. Photo A looks about right. You are 'half linking' in Photo B.

Good catch on the half-linking!
Yes, I was also leaning towards Photo A.

I'd go with pic A.

From personal experience I know that RD will stretch a helluva long ways and wouldn't worry about it, but I always look at big/big too before making the final cut. I still end up with some setups that really stretch the hell out of short cage RD, but I'm always determined to cram a 32T cog under them. :fred:

The BIG/big method gives the shortest possible chain, but it isn't always optimal for shifting, IME. I prefer the Shimano method, especially for GT cage derailleurs. To do this, when you put the chain into BIG/small (highest gear), the jockey wheels of the rear derailleur should be in a vertical line. Always double check both BIG/big and SMALL/small to make sure the chain is long enough, and not so long that it can rattle against itself. (the latter state can be fudged if necessary with triples.)

I'd take a wild guess and say that 'A' is closest to this method.

Note that Shimano's/Campag's methods are only really applicable to gearing choices actually specified with the original complete groupsets.

For anything outside their ranges, you are on your own.

I always check the big/big chain length for general information, as well as the small/small. Longer chain often shifts best as mentioned by Salamandrine.

I didn't know that!
I only have one bike with a Campy drivetrain, and for that one I've just matched chain length to the previous chain.

Boy or boy, I am totally confused by this. I can only assume that I do not understand the explanation. If I go small to small, what happens when I go big to small? Seems to me that there would not be enough chain.

I almost always go big-big, ensuring that I will not stretch-load the chain. This has worked OK for me for many years, however...

More recently, I have found that my interest in vintage road bicycles trends towards pre-1970 offerings. This means that I will be using old school transmissions, such as a Campy Gran Sport chain jumper. Going big-big is safe but the shifting and chain tension/slack is not working well at all.

Umm... doesn’t appear to be on the small cog? :foo:

I've apparently been sizing my chains wrong this whole time.

I always did small small and as long as there was tension in the RD and the chain didnt rub on itself then that was that. I figured having the longest possible chain made cog adjustments easier in the future. I will go make penance now.

h
https://cimg3.ibsrv.net/gimg/bikefor...83d73c3c0b.png
ttps://www.campagnolo.com/media/files/035_35_Technical%20manual%20-%20%2010s_chain_%20Campagnolo_Rev00_09_16.pdf

Why are we talking Campagnolo when this is a Shimano derailleur. Go big-big +2
Works with my triple and a 105 gs long cage 49x46x30 and a 11-36 cassette

Both methods work. The SRAM/Shimano method is sizing for just one cassette in the rear. The Campagnolo method works with any size in the rear, so more useful if you swap wheels. The Campagnolo method gives you the longest possible chain, which, as mentioned above, gives the best shifting.

Learn something every day! I like that "staple" fixture!

Great info, thanks for the replies.
Clearly, different strokes for different folks!

Drivetrain is 52/42/30, 12-25, and is all Shimano 5500 except for a 5603 FD.
I went with A, and chain length seems good.

Now, though, I've developed a different problem...it is reluctant to drop down into the 12 cog.
Limit is fine, and the RD is clean and lubed.

Also, the FD dropshifts hard...should I suspect this is normal?

UPDATE: Shifting is better, but not yet perfect. Using the micro-adjuster, I believe that loosening it tightens the cable, and vice-versa. So, if it hesitates a bit climbing up the cassette, that means I need a slightly tighter cable, right?

Dropping down the cogs is usually fine, trouble spots seem to be in the smaller 3 or 4 cogs, and usually when climbing up the cassette.

67tony Did you check your chain line?

If the RD is reluctant to drop to the smallest cog(s) I'd take a look at the cable up inside the brake/shifter. If it's frayed it won't let the RD travel to it's most outboard position. I've seen that on a couple Shimano set ups and it was a telltale sign that the cable was soon to break. If the cable is good I'd look at lubing the shifter mech itself. I can't help you with that, it's wheel with wings stuff for me or nothing ;)

I have always held that the goal is to have optimally crisp and reliable shifting over the useable range of gears. The short-short method rarely accomplishes this, in my experience. I'm not saying 'never', though. Again, the goal is optimally crisp shifting for whatever combination of kit you have.

Does Campagnolo know what they're talking about? I have no idea, and don't care.

Do you?
https://cimg3.ibsrv.net/gimg/bikefor...fae2d4c90.jpeg

I've used the big-big+2 rollers for about 40 years now on everything when I cut a chain for someone else. For my personal use I do big ring-next to biggest cog+2 rollers cos it shifts faster and and I never use the big-big anyway. On everything. Been doing it on Campy since about 1977
JMO of course

So if big-big =2+2 is shorter and small-small is longer. How much difference is there?

Oh and when is the B screw adjusted?

Check your derailleur hanger alignment. If they are bent inward, it can cause this symptom. This is so common that it's almost to be expected. It's nice to have the tool for this, but you can improvise with a spare wheel.

When that is sorted out, do the limits next. I prefer to adjust the limit screws while in friction mode if available, or by pulling on the cables if not. When this is dialed in, then dial in the cable length to adjust the indexing. I suppose because I started in the friction era, this order feels more comfortable.

RE the FD, hard to say. Could be normal. Old non ramped and pinned chainrings were not nearly as smooth shifting as modern ones. Is the FD height set at one penny from the big chainring? Angle adjustment good?

I have a tendency to ask too much of my drive trains. On this account I like big big. If it wont pull up all the slack in little little I don't care. I'll never be there.

Agree. No matter where I start when adjusting chain length, I make sure that the chain and rear mech work well in the gears actually used, which never includes big/big nor small/small.