atrocious shifting on old shifters

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hamishm
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atrocious shifting on old shifters

Postby hamishm » Sun Oct 08, 2017 5:05 pm

I have an old bike with Shimano 6700. It's done plenty of km with this gear and just lives on my trainer now. But the rear shifting has been atrocious for some time and I'm hoping it can be improved. Last time I had a bike shop look at it they said the STI shifters were had it and they couldn't do any better.

It'll shift down from the biggest cog to the smallest cog perfectly. But once there it's reluctant to shift out of the smallest - the first click from the shifter gets me no movement at all (and the cable is quite loose). After that it more or less shifts ok all the way back to the biggest cog, although some shifts are reluctant.

I thought the cable was just way too loose but when I tightened it up, it'd jump from the 8th cog to the 10th (biggest), like it was way too tight - although then shifting from the smallest cog was ok. The cable looks like it's in ok condition throughout.

I'm missing something. Can anyone help? Was the 'had it' diagnosis correct?

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RonK
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Re: atrocious shifting on old shifters

Postby RonK » Sun Oct 08, 2017 5:50 pm

Sounds like a frayed inner cable jamming the mechanism. Replace it.
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Tim
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Re: atrocious shifting on old shifters

Postby Tim » Sun Oct 08, 2017 8:06 pm

6700 and 7900 need cabling and cable routing in perfect order to work properly.
That means new inner and just as importantly new outer cables. Good quality PTFE coated inner cable (not the polymer ones) and Shimano SP41 outer make a good combination.
The cable loop at the derailleur end must be cut to the correct length.
Check the cable guide under the bottom bracket isn't gunked up. I had shifting troubles on the rear with 7900. The cable had cut a groove in the plastic BB guide causing added friction and preventing accurate gear changes. I replaced it with a new one, problem solved.
New ferrules might help too.
I doubt the shifter is at fault. If it still clicks through the ten positions then I reckon there's nothing wrong with it. They're the sort of thing that either work properly or don't work at all. None the less it wouldn't hurt drowning them in something like WD40 and then re-lubing with a product such as Boeshield T9.
Obviously the rear derailleur has to be adjusted properly. In my case, by the book (RTFM before mindlessly fiddling).
hamishm wrote: Last time I had a bike shop look at it they said the STI shifters were had it and they couldn't do any better.

Some LBS people are full of it. :) Maybe get them to check the hanger alignment, assuming they know how to. :evil:
Last edited by Tim on Sun Oct 08, 2017 8:09 pm, edited 1 time in total.

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hamishm
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Re: atrocious shifting on old shifters

Postby hamishm » Sun Oct 08, 2017 8:08 pm

RonK wrote:Sounds like a frayed inner cable jamming the mechanism. Replace it.

I popped it out a bit (as far as the other end of the cable would allow) and it's definitely ok right at the head.

I went over it again. If I make it nice and tight then shifting near the small end of the cassette is ok but the big end is terrible; with it looser the big end is ok but the small end is terrible. Chain is new (couple of hundred kilometres at most), and I changed the cassette today too with no effect.

This is why my other bikes have di2 :-P

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Tim
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Re: atrocious shifting on old shifters

Postby Tim » Sun Oct 08, 2017 8:12 pm

hamishm wrote:This is why my other bikes have di2 :-P


Give me a mechanical problem over an electrical fault any time.
Cables are simple and cheap.
Electronics aren't. :D
If it isn't a simple cable problem you have, I'll eat my hat, and yours. :D
When your di2 stuffs up, throw it away, and go back to cables.

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Duck!
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Re: atrocious shifting on old shifters

Postby Duck! » Sun Oct 08, 2017 9:14 pm

+1 to Tim's advice: replace inner and outer cables, PTFE/Shimano "Optislick" inners (not the furry polymer-coated ones) and SP41 outer.

6700 and the closely related 5700 105 and 7900 Dura-Ace aren't the best-shifting systems at the best of times, and will really suffer badly if the cables are munted. I highly doubt it's a shifter problem; a worn or more likely gummed-up shifter will present itself with slipping past the ratchet points, and 6700 isn't old enough to start gumming up yet.
Last edited by Duck! on Sun Oct 08, 2017 10:27 pm, edited 1 time in total.
I had a thought, but it got run over as it crossed my mind.

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warthog1
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Re: atrocious shifting on old shifters

Postby warthog1 » Sun Oct 08, 2017 10:08 pm

I did thousands of ks on 6700.
Only time it played up was when the cable got work handened and frayed in the shifter mechanism.
Bits of broken wire got jammed in there and munted the shifting until cleaned out.

madmacca
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Re: atrocious shifting on old shifters

Postby madmacca » Mon Oct 09, 2017 4:40 pm

warthog1 wrote:I did thousands of ks on 6700.
Only time it played up was when the cable got work handened and frayed in the shifter mechanism.
Bits of broken wire got jammed in there and munted the shifting until cleaned out.


While the OP's current cable is OK, maybe bits of previous cables are in there somewhere?

tez001
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Re: atrocious shifting on old shifters

Postby tez001 » Mon Oct 09, 2017 5:34 pm

I have a 5700 groupset which has never shifted really crisp. It doesn’t have the ptfe and sp41 cabling so I might give that a try.

My 5800 and 4700 groupset with whatever cabling it has seems to be light years ahead in shifting.

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Cardy George
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Re: atrocious shifting on old shifters

Postby Cardy George » Mon Oct 09, 2017 11:35 pm

hamishm wrote:
RonK wrote:Sounds like a frayed inner cable jamming the mechanism. Replace it.

I popped it out a bit (as far as the other end of the cable would allow) and it's definitely ok right at the head.

I went over it again. If I make it nice and tight then shifting near the small end of the cassette is ok but the big end is terrible; with it looser the big end is ok but the small end is terrible. Chain is new (couple of hundred kilometres at most), and I changed the cassette today too with no effect.

This is why my other bikes have di2 :-P

Until a few months ago my roadie was my work horse commuter, and copped everything this area could throw up, rain, sand, you name it. And it worked really well. But then my 7900 started getting slow and was 'not awesome' for a good 12 months, to the point where I thought the derailleur hanger had come loose. It was just plain slow and sloppy in both directions, then about a month before it was relieved of it's commuting duties the ORIGINAL cable snapped, probably about an inch or so away from the shifter end, inside the lever where any fraying couldn't be seen. Put in a new cable and it was as good as new again. My point is there's hope.

My $0.05 is pull the cable out and have a good look for wires poking out along the whole length, including the outer sheath at the other end. I personally don't lube cables at all, but if you do make sure it hasn't gunked up, or rusted up. Any slightest thing foreign in the system will make it horrible.

Maybe new cable AND new outers as others have suggested?

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hamishm
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Re: atrocious shifting on old shifters

Postby hamishm » Fri Oct 13, 2017 9:13 am

I pulled the inner all the way out and it's definitely good, but the outer loop near the RD is kind of rusty. I'll replace it when I find some spare and see if that fixes it up. Thanks y'all.

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Duck!
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Re: atrocious shifting on old shifters

Postby Duck! » Fri Oct 13, 2017 10:34 am

That will be a contributor, but do the top sections too.
I had a thought, but it got run over as it crossed my mind.

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hamishm
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Re: atrocious shifting on old shifters

Postby hamishm » Sun Oct 15, 2017 1:09 pm

Duck! wrote:That will be a contributor, but do the top sections too.

I was hoping you wouldn't say that because I hate doing the bar tape :?

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Tim
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Re: atrocious shifting on old shifters

Postby Tim » Sun Oct 15, 2017 1:20 pm

hamishm wrote: ...I hate doing the bar tape :?


Just unwind it back to the shifter.
Replace the cable outer and rewind the tape.
I've done it tons of times and it works if you do it carefully.
Pro branded tape has a bead of silicone instead of adhesive on the under side. It unwinds and rewinds very well.

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hamishm
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Re: atrocious shifting on old shifters

Postby hamishm » Sun Oct 15, 2017 5:12 pm

Wow, it shifts like new with fresh Optistick cable. I should have done this years ago, except I only ride this bike on the trainer and it never seemed worth the effort. :oops:

Thanks all.

tez001
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Re: atrocious shifting on old shifters

Postby tez001 » Sun Oct 15, 2017 5:23 pm

hamishm wrote:Wow, it shifts like new with fresh Optistick cable. I should have done this years ago, except I only ride this bike on the trainer and it never seemed worth the effort. :oops:

Thanks all.


You've now motivated me to do the same. My bike mounted on my trainer has the 5700 groupset and its shifting is a bit sloppy.
Going to order a set of optislicks now

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hamishm
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Re: atrocious shifting on old shifters

Postby hamishm » Mon Oct 16, 2017 10:01 am

tez001 wrote:You've now motivated me to do the same. My bike mounted on my trainer has the 5700 groupset and its shifting is a bit sloppy.
Going to order a set of optislicks now

The thing about bikes is that bits wear out so slowly that you (or at least, I) don't notice.. shifting gets sloppy as the chain wears and the cables rust up and the cogs and chainrings wear, the clipless pedals get loose, the bearings wear etc. So when you finally do replace them it's always wow! I should have done that ages ago. Happens to me every time with a new chain.

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kb
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Re: atrocious shifting on old shifters

Postby kb » Mon Oct 16, 2017 1:11 pm

hamishm wrote:
tez001 wrote:You've now motivated me to do the same. My bike mounted on my trainer has the 5700 groupset and its shifting is a bit sloppy.
Going to order a set of optislicks now

The thing about bikes is that bits wear out so slowly that you (or at least, I) don't notice.. shifting gets sloppy as the chain wears and the cables rust up and the cogs and chainrings wear, the clipless pedals get loose, the bearings wear etc. So when you finally do replace them it's always wow! I should have done that ages ago. Happens to me every time with a new chain.

That reminds me... time for an eyesight checkup again :-)
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madmacca
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Re: atrocious shifting on old shifters

Postby madmacca » Tue Oct 17, 2017 10:05 pm

This thread has reminded me to finally install the Optislick cables that I have had sitting round for a couple of months, onto my 5700s. The change in the front shifting is like night and day.

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