Front Derailleur - 3 to 1 issue

[dhd.evans]

My front derailleur is having a bit of an issue, jumping from gear 3 to 1 when trying to transfer 3 to 2. This only seems to happen in the lower to middle gears on the rear cassette, but whilst topped out at high gear it shifts normally.

Shifting up and down is fine on the rear cassette. Shifting up on the front rings are fine too.

Vital Stats:
Rear Cassette - SRAM 11-28t 8 speed
Rear Mech - Shimano 105 Medium Cage
Front Mech - Triban 'Microshift' ownbrand.
Crank - Sora triple
Outer ring - Shimano 105 52t
Middle Ring - Shimano Sora 39t
Inner Ring - Shimano Sora 30t
Brifters - Triban 'Microshift' ownbrand

Things i've done:
- Reset the front mech alignment and tension in the cable
- Indexed the rear cassette

The issue of jumping 3 to 1 persists. Any solutions?

 

[raleighnut]

You still need more tension in the cable, select gear 2 at the front and tension the cable until the shifter is central on the middle ring ( chain on 4-5 at the back)
Cable tension is the only possible adjustment of the middle ring position.

 

[dhd.evans]

You still need more tension in the cable, select gear 2 at the front and tension the cable until the shifter is central on the middle ring ( chain on 4-5 at the back)
Cable tension is the only possible adjustment of the middle ring position.

Will give this a shot later; tried fiddling with the barrel adjuster earlier, but ended up with an issue where going 1 to 2 on the shifter didn't even move the mech.

 

[raleighnut]

Some of those 2 piece barrel adjusters seem to work backwards, but you may have reached the end of its adjustment in which case back the adjuster right off then select 1 on the front shifter and the ring on inner ,undo the cable clamp and remove most of the slack then retighten the clamp. This will give you adjustment back on the barrel adjuster.

 

[dhd.evans]

Tweaked, but no joy. Could this be a brifter issue? Brifters have seen about 2500mi on them (two replacement gear cables and one replacement brake cable).

 

[boydj]

I've had this issue with Campag shifters and mechs when installing them on a frame. The problem comes when there is not enough movement in the mech between the lower limit and the upper limit, so that the mech just passes the middle ring when releasing from the big ring - or the position of the mech is not quite right.

First thing is to get the height and alignment of the mech right - clearing the big ring by a couple of mm and approx parallel with the chain when it's in the middle ring and a middle cog. Then set the limit screws on the mech so that they just avoid the chain dropping - again with the chain on a middle cog, after the initial setup with the chain off - in order to maximise the amount of movement available. Finally, attach the cable with the shifter in the small ring position. I use pliers to pull the cable taut and this is usually enough. I'd recommend fitting a chain-catcher on the downtube since there is a risk of chain drop if you are already on the big cog when dropping from the middle to small chainring.

There is a trial and error element to setting a triple front mech. It's not easy to get it spot on. To get the position of the mech just right it can be useful to watch the mech closely to see where the chain hits when a change is made in order to make sure that the nudge points (bulges) in the mech are being hit correctly.

 

[rb58]

^^^^^ This.
Unlikely to be the shifters, more likely cable tension or mech set up.