Shimano 105 triple, front reluctant change up to middle

[flat tyre]

I've got Shimano 105 triple (10 speed) on one of my bikes. I'm finding that it's a bit messy when changing up from the smallest front ring to the middle. I don't think it's anything to do with the cable tension as I've tried to adjust this to solve the problem but it hasn't. At present if anything I think I may have too much cable tension as there is a bit of chain rub when using the smaller end of the rear cassette, although this can be trimmed out with the shifter lever. The front does change up but I usually have to move the shifter until it clicks and then release it and then shift up it up a bit more to get the chain to move up. Anyone got any clues?

[pwa]

When the mech passes over the big ring, what is the gap between the outermost plate of the mech and the teeth of the ring beneath. It normally ought to be about 3mm if you are using exactly the rings the mech was designed for.

When you look down on the mech and the rings from above, does the mech seem to be parallel to the rings, as far as you can tell?

What ring sizes are you using? 30/40/50?

[Brucey]

if the FD is the exact correct model for that chainset, with those chainrings, then a common cause of this problem is that the FD is set too high. If the FD is not the exact correct one for that chainset and those chainrings, all bets are off, pretty much.

Also I can't remember the trim click protocol on those shifters; IIRC there are two positions for the middle ring, but I can't remember if you always have to downshift to get leftmost one. If you do then the upshift from the small chainring always goes to the rightmost trim click on the middle ring.

cheers

[flat tyre]

Thanks for replies. I just went to check the derailleur alignment and it seems to be pretty well spot on and about 3mm clearance at the closest point when it passes over the big ring. The chain rings are the standard ones that came with the the crankset (pretty sure that they are 30,40, 50). May be I just have to go up to the middle chain ring trim position (that's what I seem to do to get it to change), but I would have thought that it would change up to that position in the first place and then click back to re-trim for lower gears.

[peetee]

How worn are each of the chainrings and the chain?

[flat tyre]

How worn are each of the chainrings and the chain?

Bike, and hence the chainrings, has done about 15,000 miles. The chain has done about 1,500 miles. Chain ring looks ok. Only other thing is that I recall that the middle ring was replaced at about 7,000 miles with a Shimano branded replacement due to some damage incurred. Is it possible to get the chain ring relative position wrong when re-assembling the crankset? I don't know what the correct technical term is but there are chain catchers on the chain ring, is it possible to get these in the wrong place?

[rotavator]

Is there any chance that the FD is bent? That was the problem with mine when I last had a shifting problem like yours.

[mikeymo]

I've just put a NOS 105 nine speed triple on mine.

At the moment I have 48-38-24 chainrings and a 11-34 cassette. The shifters are Sora drop bar, current version, FD R3030.

Shortly before I put the 105 FD on (used to be Sora), I replaced the middle ring, the old one had lost a tooth. I put a better quality one on than was there originally, and the chap at Spa (where I got both original and replacement) advised me to put 0.45 spacers on the "improved" replacement middle ring.

On an initial test ride, I dropped the chain a few times, though usually off the big ring. The change up from inner to middle, the one you're having trouble with, was sometimes problematic. But you mention trim - my experience is that I have to go right to end of the shift, i.e. including the trim, to make the shift successful. The thing I've found about the upwards trim, is that I can barely feel it in the shifters. So I feel the first click, but I haven't actually gone all the way to the end (including the trim). I can't find it now, but I remember a Shimano doc that basically explained trim such that you always shift past the trim, and then trim back, if you need to. If that makes sense.

With my original setup, using Sora FD, everything seemed to be perfect, so I never actually used the trim. And also in those days I spent practically all the time on the middle ring. Now that I'm trying to use the inner and outer chainrings more, I've become a little more acquainted with trim, and this is what I've found works. It means moving up a chainring is a big move, but I don't have problems now.

So from my little experience I would say:

1. Maybe your middle ring needs spacing towards the frame (as per Spa's suggestion), or

2. Go the "full distance" when changing up, including the trim.

[Brucey]

105 10s triple would be either FC-5603
https://si.shimano.com/api/publish/storage/pdf/en/ev/FC-5603/EV-FC-5603-2440B.pdf
or FC-5703
https://si.shimano.com/api/publish/storage/pdf/en/ev/FC-5703/EV-FC-5703-3004B.pdf

chainrings would be 30-39-50 in either case

FC-5603 middle chainring has a 'pip' on it which goes behind the crank. FC-5703 has no feature for timing that is equivalently clear. However the shift pins are unevenly spaced



I believe that in the photo above the RH crank should be positioned at the half past three position.

The SI techdoc for FD-5603
https://si.shimano.com/api/publish/storage/pdf/en/si/5JN0D/SI-5JN0D-001-ENG.pdf
indicates the trim click protocol; when you shift from small to middle, you should 'land' on the RH trim click, and have to trim back to get the LH trim click. It also specifies the FD clearance over the big ring; 1-3mm. IME upshifting is noticeably improved when it is nearer 1mm than 3mm.

If you have replaced the middle chainring then I suppose it is possible that you don't have the exact correct 39T chainring; a 39T middle ring for a triple is a very different thing vs a 39T inner ring from a double.

cheers

[flat tyre]

Thanks everyone for the replies and suggestions. I'll have a look at the chainring to see if I can identify which one is fitted.

[deckertim]

Thanks everyone for the replies and suggestions. I'll have a look at the chainring to see if I can identify which one is fitted.

I've exactly the same issue. Thanks everyone for these tips, hopefully will work for me too.