Determining the correct chain length (52/36 with 12/29 11S cassette combination)

I have a Campagnolo Record groupset on my road bike where I want to replace the chain. My combination is 52/36 crankset with 12/29 (Chorus) cassette. I got a Campagnolo Record Chain 11-speed for this operation (this product).

I'm on a DIY mentality recently and trying to follow instructions given from Campagnolo official YouTube channel videos, GCN Campy videos and the manual came in the box. However, I wasn't be able to adjust the height as it was defined on the 3 sources, where the distance between lower sprocket's chain and the lower chain should be between 8 to 15 mms (when the chain is on the bigger ring and the smallest on the cassette). For my instance, this distance is way wider, maybe 2 to 3 cms.

To define better:

So I didn't see that as a big problem, guess the chain can make it with a couple of links missing, however when I put the chain on the small ring on the crankset, then the chain is too loose, it's simply swinging in the air.

So my confusion here is that it is already a short chain when it's for the big ring but it's too long for the small. What way should I follow to determine the correct length in this case?

PS: The latest bikeshop shortened my old chain and since then, I wasn't be able to use the biggest cassette with the big chainring (I know I shouldn't, but even if I went to that gear accidentally, the RD would stuck and I had to take the rear wheel off to fix the problem) and also my FD wasn't working properly since the short chain was causing much tension and it wasn't be able to move the chain to bigger ring when say the grade is more than 0. So I can't take the old chain as a ref.

• Follow the directions here: parktool.com/blog/repair-help/chain-length-sizing and remember, using a slightly longer chain is better than using one thats too short. In small-small, it is not surprising to have a non-taut chain. – Batman Apr 4 '17 at 21:08
• Most bike mechanics just cut the chain to be tight or nearly so for the large-large combo. The only time this is not reasonable is for very old bikes whose derailers lack enough "tooth capacity" to cover the full range. (Look up the "tooth capacity" for your rear derailer and compare it to the (large - small) tooth count on the front plus the (large - small) on the rear. If the tooth capacity is less than the total teeth then you'll need to compromise somehow.) – Daniel R Hicks Apr 4 '17 at 21:38
• Note that the measurement you're talking about above should be made with the small-small derailer settings. – Daniel R Hicks Apr 4 '17 at 21:42
• @DanielRHicks Checked the manual and the limits are okay. But yeah, I was measuring it wrong, thanks for that. The only trouble now is that it's a little bit slack for small-small combination but I guess I should leave it as it is with an acceptable tension. – kubilay Apr 5 '17 at 6:05
• @Batman Thanks, looks like I should ignore the little bit of slack for the small-small combo. Other than that, everything seems to be functioning well. In the ParkTool video, mechanic says that Campagnolo has the longest chain length in the industry, that's a relief... – kubilay Apr 5 '17 at 6:08

From the picture, it's clear you have a "short cage" rear derailleur. That could be a big contributor to the problem.

Rear derailleurs are rated for a certain maximum "capacity" that they can handle, which is the difference between the smallest total number of teeth and largest total. In your case, your system goes from 12+36=48 teeth to 29+52=81. This requires a capacity of 33T. Suppose your chain is almost snug when shifted into the 29 + 52 combination, so that the derailleur's tension pulley is almost horizontal, and then you shift into 12 + 36, the derailleur's tension pulley has to then pick up 33 teeth of slack.

A 33T range is about right at the edge of the capacity of a typical short cage derailleur, which is probably why you're having trouble setting things up to be okay at both extremes. It would be more comfortable with a middle cage length unit.

• With the new chain length, higher chainring and biggest sprocket are functioning -they weren't with the previous chain which was obviously short. Also according to Campy manual, the limits of the RD are correct. Suppose a bit of tension loss on chain when on smallest sprockets both won't be a trouble -I hope... PS: Manual link campagnolo.com/media/files/… – kubilay Apr 5 '17 at 6:01

Count the links on the old chain and use the same number of links on the new chain.

• Generally a good idea but doesn't help this guy - the old chain is either too long or too short already. – Criggie Apr 5 '17 at 4:53
• @Criggie He is replacing a chain and gives no indication the old chain was not fine. – paparazzo Apr 5 '17 at 11:26
• Last paragraph "PS: The latest bikeshop shortened my old chain <trim> So I can't take the old chain as a ref" – Criggie Apr 5 '17 at 11:56