vicyclist

I'm working on an old Trek 2300 with 600 Ultegra brifters. I'm stumped. The trim clicks work only when shifting the front derailleur up from the small chainring to the large. Try to trim when on the large ring and the shifter makes one big click and drops the chain all the way to the small ring. I've flushed out the shifter mechs and relubed them. When there's no tension on the cable I can feel/hear both trim clicks when shifting both up and down, but put tension on the cable and it jumps straight to the small ring instead of trimming. When it does that, it's a pretty good "snap", which makes me think I've got too much tension, but even screwing the barrel adjuster all the way in doesn't seem to make a difference.

Any help would be appreciated.

70sSanO

Yep, that how that shifter works. The trim allows you to run the small-small, but won’t trim down to run the big-big.

But you should still get 7 of the 8 cogs while riding in the large chainring.

John

Edit added: My response was incorrect as I read 2300 and associated it with ST-2300 shifters, not ST-6400 Ultegra 600 shifters.

vicyclist

Are you sure? The RX100 shifters on my 2100 of the same era has trim for both rings...four shift positions...and this seems to have the same. With no tension on the cable I'm hearing/feeling intermediate clicks just as I do with the RX100.

70sSanO

I re-read OP’s post. I saw 2300 and thought of Shimano’s ST-2300 STI shifters.

Disregard my earlier response.

John

70sSanO

Not to leave you hanging...

https://si.shimano.com/pdfs/si/SI-87G0C-000-00-ENG.pdf

John

vicyclist

Thanks, John. It's interesting that these instructions from Shimano start the adjustment process on the large chainring. Every other bit of info I've come across on front derailleur adjustment—granted it's all general, not specifically Shimano—begins with the small chainring. I'll see if this makes a difference.

55tele

Try loosening the cable tension…

vicyclist

Thanks. I retensioned the cable at the pinch bolt with the chain on the small ring and left it a little looser than seemed right. It's not there yet, but it's better. If I'm very careful pushing the lever, I can hit the high trim now. Half a turn on the barrel adjuster to add tension and it's gone. Oddly, it won't return to the full high position from the high trim; I've got to drop all the way down to the small chainring, then shift back up. I recall having this issue with a 105 shifter of the same vintage when the grease was gummed up. These 600 shifters haven't been used in years and didn't work at all when I received them. I left them sitting in kerosene for an hour...which turned black...let them dry, then relubed them. The 105 was similar after relubing...hitting the high trim was finicky and took care with the lever at first, but after a couple hundred kilometres it loosened up and worked properly. I think I'll ride it for a week and see if the same thing happens, then do more fine-tuning.

55tele

I think you’re on the right track….Had exact same issues with my DA 7400 STI front shifter and when I did my WD40 flush followed by TriFlow lube it was all good…

it’s sort of ironic that if you don’t cross chain, you can set things up so that you don’t need to trim much if at all….At least on 8 speed….