sgg0513

I recently got a used Trek for a fairly good deal. It had Ultegra derailleurs on it, and it shifts fairly well for being an older model. So, I ran into a bit of an odd quirk, it shifts perfectly fine to the largest ring on the front derailleur if I have the bike lifted off the ground on a stand, but the moment I start riding it refuses to shift to that largest ring in the front derailleur. Everything else shifts fine, and the bike works great! So, I was wondering could it possibly be chain wear on the bicycle? I couldn't really find anything on this when I tried to look it up. I figured I might as well ask here. If you need any more information feel free to ask, and I will try and provide the information to the best of my ability. I am a bit new to road cycling, so bear with me!

IslandTimePE

Have you done any adjustment to the front derailleur? If not, first thing to check is your derailleur upper limit crew. Under the pressure of riding, it needs to push the chain over a bit further than when under load to move up.

There are plenty of videos on the web if your search for front derailleur adjustment that will show the details of the process.

A new chain never hurts though....particularly if you don't know how many miles are on the current chain.

Ifind oOlder derailleurs should shift just as well as new ones if properly adjusted.

Iride01 

You buy it used from a shop or an individual? I don't know from experience, but I'd think a shop would look at it and adjust it for free even used if they sold you the bike. Just like most do for new bikes. If you are a newbie rider.... it's still possible you are doing something wrong.

sgg0513

I've been riding mountain bikes and hybrids for a while, but new to road bicycles. It was sold through a shop in as-is-condition. The owner of the bike asked to sell it off, so I don't believe they looked at it too specifically. I'll probably just drop by there tomorrow on my way to work and ask for a quick adjustment. I assume it won't run too much, as it seems to just be the front derailleur.

Leisesturm

Maybe too much load on the chain when shifting?

Andrew R Stewart 

Ultegra is pretty non specific as to features, the name having been used for a few decades now. Do the rings have shift gates, ramps, lift pins? What's the ring teeth counts? What are the part #s?

Shifting well with no stress on the drivetrain (as in pedal pressure) is fairly easy for worn, old, even misadjusted systems. Add pedal pressure and it all goes to pot. Good shifting technique makes up for a lot. Andy

2manybikes

This !! ^^^^^

sgg0513

Okay, well a few things. After having looked up a bit more about the gear sets and such. Fronts are 105s, though I couldn't find any specifics on them per say. The rear is ultegra, I do believe them all to be ramps. My technique should be fairly decent. There are no hills where I live and my cadence is pretty strong and I'm at a fair speed for shifting. It's a 2004 I do believe, so a bit older for sure. As far as teeth go, 39/53. It's a Trek 2200 if that helps (probably does not.) There is a good bit of rubbing coming from the chain and the front 105s which I did seem to adjust out.

CadenceCrazy

I still have a 2004-ish Trek 2300 with the original Ultegra ders. Other than a lot of new chains, everything else is stock and shifts sweetly. Unless something is physically broken or extremely dirty, your front der should work fine fine with some knowledgeable TLC. In the worst case, a new der and cables won't break the bank!
The 2300 is now my rain bike and has seen a fair share of scuzzy weather.

Retro Grouch 

Double or triple?

I could teach a chimpanzee to adjust a rear derailleur but fronts can be a bit more cantankerous. Since you've been fussing with it for awhile without a solution, I'd recommend starting over completely.

disconnect the shift cable from the derailleur and pretend you are installing the derailleur for the very first time. Park Tool, among others, has a good set of step by step directions to follow. Now here's the trick: Assume nothing. Start with the position of the derailleur on the set tube. Don't skip any steps and do all of the steps in order. Every adjustment that you make can affect subsequent adjustments. My experience has been that step 1 - the position of the derailleur on the seatpost, is absolutely critical.

le mans

if your getting the large crank cog when it's not under load.. but aren't under load, perhaps the stops are set ok,
try screwing out the barrel cable adjuster a little while riding, it's on the shifter cable end, see if that will make it change to the large cog

fietsbob

This... whtn are you demanding the chain be forced off one chainring onto another?

sgg0513

Okay! Finished finals and I finally took it to the local bike shop where they let me use their stand. So, after fiddling with it for a good twenty minutes I found that the front derailleur had been positioned way too low. It refused to let the chain switch up to that one under pressure and even started acting up under no stress. I watched a few videos and ended up readjusting it and it shifts fairly well now. It seems like the person who owned it before me had attempted to adjust it. I found a few sharpie marks from where the old adjustment had been (trying to mark the positioning).

Andrew R Stewart 

So how long was the ft der lower then best? And when did you note the poor shifting? While stuff does wear, shifting technique also goes a long way too "It refused to let the chain switch up to that one under pressure" Andy

rumrunn6

I have experienced different shifting on a repair stand compared to actual riding. so after any adjustments, I always ride the bike, to be sure the adjustments are confirmed, in real life, so to speak