Portis

I wonder if anyone else has experienced this? I have used a couple different set of Shimano EF 29 index shifters on a couple of my mountain bikes for some time. I wonder if these shifters are causing my problem.

I used to have these shifters on both of my bikes, recently i upgraded one bike to a better set. The bike with the better shifters seems to shift fine at all times. However the bikes with the EF29 shifters have always seemed to have a problem from time to time in the middle of the cluster when down shifting. IOW, sometimes when you try to from shifter setting 6 to 5 or 4 to 3 it often doesn't shift and then i have hit the shifter again to get it to go.

I can adjust the indexing using the outer cogs as per Parktool website but there instructions deal with using the two outer cogs. The shifters always work fine on these cogs, it is the more inward cogs that have trouble.

The odd thing is that this doesn't happen all of the time. Sometimes i can mess with the cable tension and get it to be right on. Other times, i can't seem to get it to make any difference and the symptom is still there. I have increased the tension many times to the point where it gets to tight and still i keep having this trouble.

Is this a problems with these shifters or am i just not getting my tension correct???