shifting problems

JimboPlob

Hi

I purchased a 2nd hand bike that had full dura ace group set (very nice).

The rear deralliur wasnt shifting very well so I replaced the cables. It is now shifting much better but still having a few minor issues.

1) I can get it to go from the small to big rings just fine, but then has issues when trying to shift back to the smaller rings (the deralliur moves, just not quite enough, mainly noticeable in the middle gears)

2) If I fix the above, by reducing tension on the wire, it then struggles to shift from small to big cogs.

The chain is new, the inners/outers are new, the H&L screws are set fine, cassette looks fine and the deralliur/hanger doesn't appear to be bent in any way.

Any ideas???

MrChuck

What's the loop of cable entering the derailleur look like?
It sounds like drag in the cables, I saw you'd replaced them but if the turn is too tight or doesn't enter the mech itself smoothly there might still be enough drag for it to struggle.

JimboPlob

I have made the loop quite big. Bigger than it was before and a little bigger than on my other bikes..

Buckled_Rims

Looks like a cabling issue to me. Don't forget that new cables also stretch so that can hamper any investigation. Me, I'd take all the cabling off and clean it. Blast the outer hose with air in case grit is lodged inside. Pay attention to how it's attached in the hoods. Lube the parts inside the hose. Try again. I know it's a hassle but I've been there, and swore with frustration as well but did sort it out ;-)

JimboPlob

I will take a look again at the way the cable exists the shifters and enters the deralliur, Is there any way to shape the outer so that the cable enters better?

The outers are all brand new, so would be surprised if there was a problem with those.

Twostage

Sounds to me like you've attached the cable to the wrong side of the clamp on the derailleur.

JimboPlob

I am not sure what to try next. I have changed the inner and outer twice now but still having shifting problems. The chain is new and the cassette is also new but still brings problems.
It seems like either the shifter or rear derailleur isn’t working properly i.e. it doesn’t seem to move the required amount.

The hanger doesn’t look bent and nor does the derailleur. Could it just be the spring in the derailleur is old and not powerful enough, or the shifter isn’t doing its job properly. As mentioned, it all dura ace 7800 kit.

Any advice?

Thanks

andrewjoseph

Undo the cable from rear mech pinch bolt. Hold cable in finger and pull. change gears. can you feel the cable moving in and out all the way up and down the gears. if not then it is a cable issue.

if yes then it may be an indexing issue. make sure the shifters are all the way to the proper end of the run before bolting the cable back, then re-index.

JimboPlob

- Cables are all brand new - replaced twice already
- The cables move freely
- The rear deralliur moves, but it just doesn't seem to move consistently to shift between the gears i.e. it seems to be either set to go from small to big without problems but then is lousy at coming the other, so i reduce tension, then I have the opposite problem...

Twostage

JimboPlob wrote:

- Cables are all brand new - replaced twice already
- The cables move freely
- The rear deralliur moves, but it just doesn't seem to move consistently to shift between the gears i.e. it seems to be either set to go from small to big without problems but then is lousy at coming the other, so i reduce tension, then I have the opposite problem...

I repeat myself - It sounds like you have the cable attached to the wrong side of the pinch bolt on the DR. If you have it on the wrong side it will behave exactly as you describe.

JimboPlob

The wrong side?

I have attached it on the back at the bottom...

Twostage

When you attach the cable it can be either side of the bolt that holds in place and you need to make sure you attach it to the right side. There is normally a right way and wrong way. I took a guess at which dura ace dr you have and with this one http://techdocs.shimano.com/media/techd ... 610603.pdf the correct way depends on the shifter.
Check the documentation for your actual model and make sure the cable is routed correctly round the pinch bolt.

JimboPlob

I have the 7800 version, but I get the jist. I have looked up that and will ensure I bolt it as per the docs.

Thanks for that!

Also took a look at park tools website, and my jockey wheels could maybe do with replacing. I looked on CRC and the dura ace specific ones are quite pricey. Is there really much difference between those and other brands?

Thanks

andrewjoseph

JimboPlob wrote:

- Cables are all brand new - replaced twice already
- The cables move freely
- The rear deralliur moves, but it just doesn't seem to move consistently to shift between the gears i.e. it seems to be either set to go from small to big without problems but then is lousy at coming the other, so i reduce tension, then I have the opposite problem...

Yes, I appreciate that, but sometimes you can feel when the cable is binding by holding the cable between your fingers and shifting through the gears. Have you done that?