Shimano Nexave rear derailer adjustment

[der_amerikanische_freund]

Hello all,

I'm trying to install a Shimano Nexave T400 rear derailer on my 2025 Atlantis. It's the first time in my life I try to install one such thing, I may have chosen too big a task, but I wanted to give it a go.

I have read on the user manual that the chain must be placed on the largest cog, and I have diligently done so. What would the next steps be? I'm running Silver2 shifters, so I guess I have to place the shifter all the way inwards. I'm running them on the upper side of the bars as thumb shifters so that would be the shifter position that corresponds to the largest cog if I've understood it correctly. Then adjust the H and L screws as required. Since this is not indexed shifting, would that be all that needs doing?

Kind regards

[Michael Connors]

You should adjust the inner L screw before installing the cable. You don't want to risk having the chain go into the spokes. The shift lever should be in the slackest position when you fix the cable to the derailleur. Leave a couple inches of extra cable in case you need to readjust.  Here is a video of Eric Marth installing the same derailleur (starts around 19 minutes in)

https://www.youtube.com/watch?v=muQgJiZtzwY

[Michael Connors]

Some additional details in case you haven't adjusted a derailleur before:

Adjust the inner limit screw with the chain on the inner front chainring.

Adjust the outer limit screw with the chain on the outer chainring.

(For low normal derailleur) I start out with the outer limit screw too tight, and adjust it after the cable is attached.

For both inner and outer limit screw adjustments, start with the chain audibly rubbing on the next cog,

and adjust 1/4 turn at a time until the noise stops

[der_amerikanische_freund]

Thank you for the info, Michael.

I have eventually managed to install and adjust it myself without much issue. I did send the chain to the spokes on a couple of occasions even after adjusting the L limit screw beforehand, but I'm a newbie so can't really trust my judgement. I took the bike for a quick ride around my local park to ensure everything ran smoothly and I think it does, but I may have been too excited to notice anything wrong, so I should check again tomorrow. I really like the lever motion in these Rapid Rise derailers, it feels more natural to push harder to get to a harder gear, and to be able to move to an easy gear more easily.

I also had to readjust the front derailer, which I wasn't expecting to do. I would have thought the chainline would remain the same but I did have some rubbing on the larger ring. I guess when you change one component in the drivetrain the whole system must be re-adjusted. It actually took me longer to adjust the front derailer than the rear, which is ironic considering the part I was changing was the rear mech.

Another thing to note is that even though the derailer is rated to 34T max cog, I'm running it on a 42T cassette. I did use a SunRace tab extender just in case, but I get the impression it may have worked without it.