bigfred 

I think I've tried it all. My wifes new to her 2010 Shimano 105 equiped compact double doesn't seem to have a high trim. Well, it does, sort of, ....not. Shifting from low to trim is fine and then onto high is fine. Coming back down from high, it has a half click, but doesn't move. Then it has a harder than I would expect full click and comes down to low without further drama.

I've set the hi and low limits and adjusted cable tension for approximately 2-3mm of clearance between cage and chain when cross chained from small ring to small cog. I've exposed the shifting mechanism and liberally sprayed it down with CRC. Let that dry, then gave it a good dose of PTFE spray.

So, am I missing something? Or, does 105 just not have the same functionality that I'm accustomed to with Ultegra? The click is there. It seems odd that there would be a detent in the mechanism that did nothing. And, while the wife has adjusted to the harder/heavy full click to shift down, it seems odd that this would be more difficult than it was on her previous Tiagra kit.

There's not much that she asks for from her bike. That the gears work properly is one of those things. I need to get this sorted.

Thanks,

CACycling

Sounds like too much cable tension. Cable only needs to be tight enough to move the FD against the high limit screw. Too much tension could give you the symptoms you are experiencing.

bigfred 

I would agree. That's what my preliminary searches on here led me to believe. However, I've adjusted the cable tension to maintain clearance on the small ring/ small cog combo. Is there an independent means of adjusting both?

shelbyfv

You may have to accept some chain rub in the small ring and one or two smallest cogs. I think some Shimano instructions even admit this.

bigfred 

Voila, we seem to have a winner. But,.......that just seems wrong. It's not that it even really needed the hi trim position. It could cross chain big ring to largest cog without rubbing. It was just the really heavy click that it took to get it to shift down. Adjusted the barrel adjustment for slight rub in the small ring/ small cog combo and it seems to be working correctly. Hmmfff

There we have it. Time for a test ride. Thanks.

dsbrantjr

bigfred: Why concern yourself with how your drivetrain works in cog/ring combos you won't (or shouldn't, anyway) use? Think of the chain rub as a signal to use a more reasonable and less-wearing drive combination.

bigfred 

Mate, look at original post "wife's bike". Have never managed to get her out of the habit of exhausting the cogs in either direction before shifting the front ring. She has erroreously claimed that is how I originally taught her. Which is the furthest thing from the truth. Sometimes, I believe she does it and says that just to wind me up a little. Anyhow, you're correct. Maybe she can use the chain rub as in indicator that she "should" already be in the big ring.

Test ride around the block proves the front is working well. Now, onto the back.

Seems to shift up(? from smaller to larger cog) without issues. But, doesn't shift from largest cog to next cog. Requires a double down shift and jumps the second cog, going directly to third. On the small cog end, doesn't shift into smallest cog without delay. Rattles along for a while and then finally drops. If I adjust the cable tension down any, then it doesn't shift up well at all. Can see a fine adjustment of the small cog limit screw potentially fixing that. But, what about the shift from largest cog to second?

Thoughts everyone?

CACycling

The FD position for the small chainring is set by the limit screw, not cable tension. Adjust the cable tension for the big ring and trim functions.

bigfred 

FD small ring/ large cog set with limit screw. FD sm ring/ small cog set with cable tension whilst in trim position. FD large ring/ small cog outer limit set with limit screw. It appears my mistake was in setting the small ring/small cog tension while in the trim position I was moving the cage outboard sufficiently that it wouldn't rub the chain at all. With a bit of chain rub on the cage in the small/small/trimmed state everything now seems to be functioning correctly. The high trim funcition is there and it requires a much lighter touch/click to shift from large to small ring.

BobLoblaw

Re the rear shifting. The shifter could be out of sync with the cassette. Shift to the bottom cog while continuing to shift the shifter and pulling gently on the cable. When th shifter stops clicking my guess is there will be some slack in the cable. Tighten it up and you should be set.

BL

oldbobcat

First, the easy one. Yes, loosening the outer (high) limit screw a little bit can ease shifting onto the smallest cog. The concept is to align the derailleur pulleys slightly to the outer edge of smallest cog. This allows the chain to slam down with some vigor.

Regarding the reticence about going down the cassette, the culprits (in order of increasing complexity) can be either friction, a misaligned or bent derailleur, or a worn derailleur with too much play in the pulley and body bushings. Friction can be caused by frayed, dirty, or corroded cables or housing; a kink in the housing or cable; or the housing "pigtail" (the loop where the cable connects to the derailleur) being too short. Having a derailleur hanger alignment tool at my disposal, hanger alignment is the symptom I like to check and correct first.

By the way, congratulations on being able to use high trim with a light touch. There are lots of shop mechanics who can't get this right.