I just picked up my bike last week, newly built up with DA 7900. I took it out for a test spin and found that I could not shift from small ring to big ring. When I tried to shift, the chain would go around the big ring, but when I released the lever, the chain went back to the small ring. I tried SEVERAL times, no success, then chain just would not stay on the big ring.

I called my mechanic and he said 7900 is a little different and just to shift a little harder. I have very small hands and can't shift any harder than I already am. In order to shift from small to big ring, I literally had to reach over with my right hand and yank the lever hard - then the chain stayed on the big ring.

I'm so disappointed that I have not taken my bike out again. Anybody else have this issue? I never had this problem with 7800.

I just can't believe that to be correct. I'd check the cable routing to be sure it's not incorrect and then be sure that there is sufficient cable tension, so you're not moving the cable but getting no FD movement. The shift cable should not be slack when it's in the little ring.



https://bike.shimano.com/media/techdo...9830651786.pdf

Thanks, I'll check the cable routing. I took a look at the tech doc and perhaps the problem is that I'm shifting the same way I did with my 7800 lever. The doc shows lever "a" being shifted from the bottom - which is what I did when I reached over with my right hand and pulled the lever from the bottom when the chain finally stayed on the big ring. Could it be because I'm also inadvertently shifting lever "b" at the same time I'm trying to shift lever "a"? It just seems so much harder to shift.

I'm also thinking my mechanic did not utilized the "short reach" feature on the new 7900 shifters like I asked him to.... sigh.

More reasons why I use Campy. It's actually cheaper and the new ultrashift levers are great. Of course, I do all my own mechanical work.

limit screw

Take it back to the shop that did the work. First have them adjust the reach. With the reach adjusted you'll have a better chance of using the levers properly.
Also if you are able to get the chain up to the large ring only if you use an excessive amount of force it may be that the limit screw has been turned in a bit too much. A 1/8 or 1/4 turn out may be all that is needed. The shift cable may have also "stretched" due to improper set up of the cables and housing. If you paid money for the job take it back and have them set you up right. If a bike I worked on was not working properly I would not think twice about taking a look at it.

Took the bike back in today. Turns out the screw for the "reach adjust feature" was not turned all the way. After the screw was all the way turned, it helped with the reach and now at least I'm able to shift to the big ring (however, still way more difficult than it should be). The mechanic said he has heard lots of dissatisfaction regarding the difficutly in shifting with 7900.

Note to Shimano: Your new "Reach Adjust" feature is a load of crap. There is absolutely no difference in reach from the prior 7800 shifters. The reason I bought 7900 was specifically for the "Reach Adjust" and now I wish I had stayed with my old 7800, or better yet, gone Campy. Live and learn.

Oh, thank you to all who replied!