Bicycle Mechanics - Shimano Sora drivetrain problem

We were working on a friend's Trek 1000 road bike yesterday and we ran into a very strange problem. Her front derailleur would shift but it would take a lot of force to push the handle over to make it shift. :confused: We checked the cable tension and adjusted that both ways (tight/loose) but it would not cure the problem. We also checked the cable, the shifter, and the derailleur, but all seems ok. It's not supposed to be this hard to shift the front derailleur.

She did not have this problem before. We were trying to fix a rubbing chain problem (the chain was rubbing on the front derailleur, on the middle chainring, at all speeds) by increasing the cable tension and adjusting the Hi/Lo stops. After we fixed the rubbing, this problem came up. The front derailleur seemed bent inwards a little, which caused it to rub on the chain.

Is it something that we missed?

I assume that it is hard to shift the derail through all three positions? If it is only hard to shift it to the outer (big) chainring it is probably an outer (high) limit problem. The limit screw is holding the derailleur just shy of the catch in the shifter making it hard to get into gear. IF that is not the case then are you sure that the cable did not come out of its guide on the bottom bracket shell? It needs to be in that groove so that the friction is low and so that it shifts properly. Also check to make sure that the front derail is not broken or damaged (bent or broken linkage, etc) For other suggstions I will need to think a while.

-Ryan

I checked the BB rail and it's on track. It's traveling through all gears, and I even backed out the two Hi/Lo screws all the way to make sure it wasn't hitting the stops, but the hard shifting is still there. It feels like the cable gets really taut (sp?) when the big chainring is active, but has little tension when the little chainring is on. I guess that's normal. There's just a LOT of resistance when going from the small to the biger chainrings, and the difficulty increases as the chainrings increase in size.

The system was working fine before we started tinkering with it, so I don't think the derailleur is broken.

Any more suggestions are truly appreciated. :)

Lets just go through some front derailleur basic setup tips:
1. Put the rear derail in the big cog so that the chain is all the way to the left.
2. Take the cable loose from the front derail and set the inner limit so that is comes as close to the chain as possible without rubbing it. This will be a little farther in (left) on the Sora components than on other shimano components because the Soras generally have trouble shifting into the small chainring.
3. Once the limit is set then pull the cable taut (not tight) just so the slack is taken out of it and secure it in the cable anchor. It goes above the bolt not below it. Be sure that the shifter was in the low chainring position when you secured the cable obviously.
4. Test shift the derailleur and adjust the outer limit far enough out to allow the chain to travel to the small cog in the rear without rubbing in the big chainring, but not too far or else it will overshift.
5. Obviously the front derail should be lined up with the chainrings- not crooked. Although in some cases where trouble is had with the derail shifting to the lower chainrings a slight angle with the rear of the cage toward the inside can be helpful.
6. The front derail should be a few mm above the chainring for optimal shifting-too high and the "bumps" in the cage do not contact the chain correctly. Too low and it hits the chainrings.

I guess all the cable housings are seated correctly in their frame stops and such. Also the cable head is not out of place in the shifter? and the cable is not kinked causing extra friction in the housing?

-Ryan

We inspected the entire cable, and it looks good, except for the portion where the clamp has caused some damage on the cable. The cable head is in place.

You mentioned that the cable should be routed on top of the cable anchor. Can you post a pic of this setup? The cable anchor on this derailleur secures the cable from the bottom up. Perhaps this is the problem? Maybe we're pulling the derailleur the wrong way. I don't have the bike here or else I'd post some pics for ya. If the problem's still on next weekend, I'll be sure to post some pics.

I have a bike with SORA and I had this exact problem (although mine is a double not triple chainring) and it lasted all but one day....then disappeared. Wasn't all the time either, just sometimes :p dunno what the cause is!

Brendon
:beer:

I followed the instructions for adjusting the front derailleur since ours was rubbing on the chain. The advise worked beautifully. The cables were just replaced and evidentally had stretched some. Pulling the cable taught was all that was needed. Thanks all for your insight.

With this kind of thing, I like to follow the problem through the system to see where the problem is. Put a bunch of slack in the cable (You can do this by simply taking the housing off the frame or by disconnecting the cable) Then hold the cable in your hand and shift the shifter. If the shifter shifts without all that extra tension you have ruled out your shifter and you can check the first section of housing etc. If you have no extra tension in the system by the time you finally get to the derailleur and the tension reapears when you set up the system again, then your problem is either in your derailleur or a mystery.

If it was my bike I'd spritz the shifter's innerds with WD40 and follow it up with a blast of compressed air. That'll often work wonders on STI shifters.

If your girlfriend uses sports drinks... check the bottom bracket cable guide and clean it out. If the drink bottle is left open and slops liquid on the downtube (or seat tube if it is mounted there), it can run down to the guide and cause it to gunk up. It's amazing the difference cleaning it out can make to front and rear derailleur shifting. In my case, the front shifter seemed to have jammed entirely, until I cleaned up the BB.

Plus, I haven't got access to my Sora-equipped road bike right now, so I am not sure if the Sora cable is supposed to run *over* the roller that's about an inch or inch-and-a-half under the clamp. Check to make sure the cable is over this if it is there. That can have an influence on the effort required to shift.

Hi, I too have just followed through advice and there seems to be a small improvement in rubbing of chain on front derail. However, whereas inner limit adjuster screw seemed to be very sensitive, the outer limit one did nothing at all when chain on big front and small back. Am I missing something really obvious?
Would welcome any suggestions.