Bicycle Mechanics - Shimano 105 front brifter seizes on Large ring

Custom Steel with Shimano 105 triple brifters - a 3-4 of years old.

Took my old bike out for a ride after leaving it forelorn in the basement (using my new Madone mainly since October) and went for a ride. Going along in the middle ring fine. Changed to large ring and then it would not shift back down. It appeared that the downshift mechanism was seized. No action - that is the lever would not move. Of course, it happened on a rising grade. Managed to get it to finally shift after futzing with it for about 3 minutes off the bike. Same thing happened a bit later. Was careful to finish my hilly loop without moving to the large ring. The middle and small rings worked fine repeatedly, both up and down.

Was just down in the basement with it up on a stand. It appears to be shifting but may be catching a bit if I don't immediately release the "inner or smaller" brifter lever. I do recall getting a new chain on this not long before moving to the new bike. Oh, it is a 9-speed, I believe, but customized to only 8 in the rear (xt mt stuff moved from a rusted custom road frame that had bar-end shimano. There were no problems prior to this for those 3 or 4 years. Possibly the new chain had/has something to do with this?

I am not much of a bike mechanic, frankly.

I'd lube everything well with a can of T9, preferably the spray. If you have the spray, hose out the inside of the shifter with the T9 as well, it often "fixes" issues with Shimano shifters not engaging or sticking. Its pretty gross the stuff that will come out of a used shifter. Also, its a possibility your cables are in bad shape and have become semi-seized in their housings. Might look into that and see if the cables are sliding freely as they should.

Try loosening the high limit screw on the derailleur about 1/8 turn.

Some mechanics set the high limit screw by shifting into the big/little combination and then turning the screw down until it stops. When they do this, sometimes the derailleur gets bound up in the big ring and won't shift out of it just as you described.

Try loosening the high limit screw on the derailleur about 1/8 turn.

Some mechanics set the high limit screw by shifting into the big/little combination and then turning the screw down until it stops. When they do this, sometimes the derailleur gets bound up in the big ring and won't shift out of it just as you described.

i do that sometimes...but then i always make sure the bike shifts smoothly on the test ride. i don't crank it down on the limit or anything, just until it barely touches, and then back it off a tiny bit. but yeah, that's what the problem sounds like to me...i should know, i'm one of the guys who causes it. ;)

Since they was in storage, the lubrication may have dried up. Brifters are not unlike watches in terms of precision. If they are dirty or the lube has dried up, they won't work worth a damn. If the various above suggestions don't work, you may need to take them off, soak them in a bucket of hot water/Simple Green solution, blown them dry and lube with a good quality lube such as T9 or Tri Flow. Let us know the results. That's the only way we know what works.

I've solved all of my brifter problems, forever, by installing a pair of these suckers on my bike... :D

But seriously, the other posters have offered good advice. I've solved my sticking brifter problem by removing the levers, and literally soaking in WD-40 overnight. I'm sure many other methods will work, also.