I am riding a 1999 Trek 5000 with primarily Ultegra 6503. I have recently replaced my shifter cables. Lately, I've noticed that the chain will down shift heavily and unexpectedly when I put load on the chain (climbing, or getting going from a stop), it will also jump gears when I hit bumps. This occurs almost exclusively when I am in the middle ring. I had to ride all of the cobbled sections of the Paris-Roubaix challenge in the small ring because I just don't have big ring power and the middle ring was causing too many problems. I cannot duplicate these issues when I have the bike on the indoor trainer, it only seems to occur outdoors.

Additionally, I've noticed that frequently I can move the right shift lever and there will be no tension in the lever. Sometimes it will take two or three movements to the left for me to feel that it is catching the cable. When I pull the shifter back into tension, the above mentioned chain jumping is less frequent.

I hope I am describing the issue well and that someone can help shed some light on the issue. Thanks in advance.

It is a little confusing what you are describing, but it suggests to me one possibility:

Maybe your derailleur (rear, I'm guessing is where you're getting the problems) is not freely swinging back in the return direction, or the return spring is not strong enough. It may be that you are downshifting (pulling cable), then upshifting perhaps multiple gears, and the derailleur executes fewer actual shifts, and then sits there with a loose cable for a while. A jolt like a bump or a sudden increase in pressure from stomping on the pedals, might shake it loose and execute the delayed shift.

This would explain the 2nd paragraph, but I don't think I can see how it would have anything to do with middle front chainring vs outer.

To get some terminology clear, you say the chain will 'down shift heavily' -- I think you must mean upshift, i.e. shift to a harder/faster gear (which does involve a smaller rear cog, which is maybe why you called it 'down'shift). The derailleur return spring is always pushing in the upshift direction, so this is the direction that RD 'want' to move. A RD cannot move by itself in the downshift direction (to a bigger cog) because it would have to stretch or break the cable. UNLESS you have a (pretty uncommon) bottom-normal derailleur, in which case the return spring does indeed push towards downshift, and the cable pulls the derailleur to upshift.

To test my theory, ride around a parking lot. Shift all the way up (hard/fast gear, small cog). Then downshift one gear at a time, sensing carefully by sound, sight, and feeling, that the chain shifts one cog each time. Then upshift one gear at a time. Does each upshift come promptly and shift by only one gear? If I am right, then it will take 2 or 3 upshifts to achieve just one gear of upshift, at which point the cable will be slack and the derailleur spring pushing (weakly) resulting in additional delayed upshifts.

And if I am right, the likely solution is to lube the derailleur pivot points. You say you have replaced your shifter cables, did you also replace the housing? Friction in the housing would also explain this. You can also try to drip some drops of thin lube into the housing and work the cable back and forth to distribute; but if the housing is old/kinked, or if there is maybe torn lining inside, or rusted metal, the housing may just need to be replaced.

This issue is usually related to the shifter slipping back. But the devil is in the details, and I can't suggest apscifics without knowing more about the shift levers, including things like age and condition.

It's also helpful to know if this ever happened before you replaced the cables, or was perfect until you did, and started almost immediately after.

Did you replace just the inner wires or the outer housings as well? Sometimes new cables do not move freely in the groove worn into the housing by the old cable.

"Additionally, I've noticed that frequently I can move the right shift lever and there will be no tension in the lever. Sometimes it will take two or three movements to the left for me to feel that it is catching the cable. When I pull the shifter back into tension, the above mentioned chain jumping is less frequent." slewkowitz.


This sounds like classic Shimano STI shifter pod internals getting gummy/sticky and the tiny ratchet pawls no longer working consistently. Do you live near an experienced bike shop? If so then a visit and request to access your bike might offer you some insight to what sounds like a few different issues collectively happening at the same time. If this is the case I will not be surprised. Andy.

Hello again, and thank you for your suggestions. To add to my earlier post, I did replace the cable housing at the same time I replaced the cables. I have tried replacing the 6500 Derailleur with a 5500 derailleur to see if that would help and it did not.

I bought the bike used in Kosovo, what path it took to get there, I don't know. It was originally sold in Switzerland based on some shop stickers. The shifters are quite old looking, but I do not know much about their internals. 6500 was made between 1997 and 2005, so they are between 20 and 12 years old, and appear to have been in use for that whole time.

Take it to a shop and have the RD hanger checked for alignment. I was having a similar problem I couldn't figure out so I took it to the shop. They found the hanger was very slightly bent.

+1 search these forums for "wd40 flush" and you'll find it is quite common, and with your bike's long, unknown history, there's a good chance this is it.

Thank you all for your ideas. I am going to try flushing out the shifter. If that does not work for me, I will take it in to have the irreplaceable derailleur hanger looked at.

Flushing out the shifter helped with the looseness in the shifter! Thank you for the help with that. The chain still jumps down the cassette when I am in the middle chainring. I guess I had 2 separate issues occurring at the same time. I will get the derailleur hanger checked out, but I don't know why it would only occur when I'm riding outdoors and not on the trainer. I never have this issue on the trainer.

Thanks again!

riding outdoors, pushing with legs applies a lot more pressure to the drivetrain than turning it with your hands and the wheel spinning freely.

We must ride trainers differently, I use my legs and fluid resistance.

Have you measured your chain for wear? Is the middle ring on your crankset worn? Those could lead to issues with the chain jumping off of the middle ring.

Checking the DR hanger is a straight forward process, if you have the tool. I would expect any bike shop to have it.

Park Tool DAG-2.2 Derailleur Hanger Alignment Gauge