Compatibility of Tiagra derailleur with STX shifter?

[ed.to...@gmail.com]

My old mountain bike came with STX components in 1994. After a few years of nonuse due to mechanical issues, I'm fixing it up.

I got new "special edition" STX shifters to replace the worn ones, and the front shifter didn't work right anyway. The original front derailleur had turned into a lump of corroded metal as well, and the rear was pretty grungy. So I got Tiagra front and rear shifters.

Shifting the front requires a ridiculous amount of effort. I'll sprain my thumb. The Tiagra's return spring is pretty stiff, but the problem seems to be that the old STX front derailleur had a significantly longer, and bent-to-the-inside lever arm at the cable end. The Tiagra's cable attachment is a lot closer to the pivot point.

The cable runs under the bottom bracket as you'd expect, and the Tiagra is a bottom-pull, It just is very very stiff. It's not clear to me if the shifter should have a different amount of mechanical advantage for Tiagra versus STX. No chain on yet, so I don't know if the STX shifters are overshifting the Tiagra derailleur or not.

I have a set of seven-speed Exage shifters that I could use. My quick test showed that STX and Exage both seemed to move the cable a very similar amount per shift, so I don't think I'll get any improvement.

The cable casing from the shifter to the cable stay on the frame is old and can use replacing, but after that it's open cable to under the bottom bracket. That part of the cable hits pretty close to middle C so it's tight, and that's in the middle position. I'm not sure where to look. And I wonder if the Tiagra rear shifter will work okay with the rear STX shifter.

Any ideas?

[Ralph Barone]

I had a world of trouble with the Tiagra front STI shifter on my LHT (hard
to shift up and it would downshift from the outer chainring to the inner
one and always jump over the middle ring) until I realized the cable clamp
on the front derailleur had a little "tit" on it and that the cable was
supposed to go over that tit and not under it. So perhaps when you replaced
the front derailleur, you didn't get the cable attachment correct. Check
the drawings for your front derailleur before you abandon ship.

[ed.to...@gmail.com]

On Saturday, April 19, 2014 3:34:32 PM UTC-4, Ralph Barone wrote:

> I had a world of trouble with the Tiagra front STI shifter on my LHT (hard
> to shift up and it would downshift from the outer chainring to the inner
> one and always jump over the middle ring) until I realized the cable clamp
> on the front derailleur had a little "tit" on it and that the cable was
> supposed to go over that tit and not under it. So perhaps when you replaced
> the front derailleur, you didn't get the cable attachment correct. Check
> the drawings for your front derailleur before you abandon ship.

I'll take another look. I'm pretty sure I ran the cable correctly, through a groove. The shifter was new in box, with instructions, but cable attachment seemed to be assumed, and not described.

[Frank Krygowski]

I assume your cables are new and well lubricated.

I'd also double check all the cable routing details. I once was putting
up with frustratingly high lever force on some old friction bar end
shifters. I finally saw that the end of the cable housing was
mis-aligned at a stop, causing the inner cable to sort of scrape over
the edge of the housing.

--
- Frank Krygowski

[John B.]

I've got a set of XT shifters with matching derailers and the
front(L.H.) shifter is pretty stiff compared with the rear (R.H.). You
can flick back and forth with the R.H. shifter and hardly notice any
resistance but the Front you need to sort of get ready for it.

One thing you might try is to loosen up the derailer stop screw for
the large chain wheel side to be sure that you aren't trying to pull
against the stop.
--
Cheers,

John B.

[Sir Ridesalot]

Read the replies posted so far but didn't see any that ell you whether or not the shifters are compatible with the derailleurs. Are the STX shifters compatible with a Tigra derailleur on a MTB?

Cheers

[DATAKOLL MARINE RESEARCH]

WE DO WHAT WE CAN DO.....ASKING if someone has tried x with z when we haven't tried x or z separately but off course not together as who would try it ?

I ask the seller if I have x then can I buy z to go with then the seller ask z's distributor for advice passing it along...

best asking Goo for a second opinion.

http://goo.gl/iBT3zF

[ed.to...@gmail.com]

On Saturday, April 19, 2014 5:37:01 PM UTC-4, Frank Krygowski wrote:
> I assume your cables are new and well lubricated.

Cables are new. The derailleur snaps back when downshifted with a bang. I don't think it's a friction issue.

> I'd also double check all the cable routing details. I once was putting
> up with frustratingly high lever force on some old friction bar end
> shifters. I finally saw that the end of the cable housing was
> mis-aligned at a stop, causing the inner cable to sort of scrape over
> the edge of the housing.

Cable routing is a no-brainer. There's one length of housing, then it's all open wire.

On Wednesday, April 23, 2014 9:51:27 PM UTC-4, x wrote:
> WE DO WHAT WE CAN DO.....ASKING if someone has tried x with z when we haven't tried x or z separately but off course not together as who would try it ?

All the experience here, I was thinking someone might know if the cable pull was different on these Shimano components. I did not know, when I purchased them, that Tiagra was a "road bike" component. The road bike components may have smaller travel and different cable pull ratios.

> I ask the seller if I have x then can I buy z to go with then the seller ask z's distributor for advice passing it along...

That's my next step. The seller is a shop trying to clear out old inventory, although the owner did search for a derailleur through the collection, and he knows the bike. And sold me the STX shifters too.

> best asking Goo for a second opinion.
> http://goo.gl/iBT3zF

Yeah, and this thread is the top result, so I don't think that's going to help a lot.

....Ed

[Ralph Barone]

<ed.to...@gmail.com> wrote:
> On Saturday, April 19, 2014 5:37:01 PM UTC-4, Frank Krygowski wrote:
>> I assume your cables are new and well lubricated.
>
> Cables are new. The derailleur snaps back when downshifted with a bang. I
> don't think it's a friction issue.
>

If it "snaps back with a bang" when downshifting, you might be hard against
the stop, which would imply a pull ratio problem, either from the shifter
being incompatible with the derailleur or the cable being improperly
terminated at the derailleur.