Installing 105 (5800) front derailleur

uad782
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Installing 105 (5800) front derailleur

Postby uad782 » Sat Jun 02, 2018 12:41 pm

Hi everyone,

Am just installing a 105 front derailleur onto my new Ti frame. These is no rubber padding on the derailleur so I have metal on metal. Is that ok?

Also it cam with a weird tool TL fc 68. I have read the dealers manual but wonder why I need to use this?

Thanks

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Duck!
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Re: Installing 105 (5800) front derailleur

Postby Duck! » Sat Jun 02, 2018 2:09 pm

I've never met a front derailleur with any rubber padding. Clamp-mount models usually include spacers to accommodate a range of tube diameters, but that's all.

The little tool is the determine the cable pull angle and the resulting position of the guide pin below the anchor bolt. Different cable pull angles can affect the smoothness of the derailleur shift, and setting the position of the guide pin helps correct it.

There's also a bit of a process for tuning the derailleur, because it needs a bucketload of cable tension. After you've set the height and angle of the derailleur, and use the brace bolt against the frame to stabilise it, wind the low limit in until the outer face of the cage aligns with the outer face of the big ring teeth. Ensure the shifter is set to the full low gear position - 11-sp. models need a second press of the release lever to fully release the cable and trim the derailleur. Feed the cable between the guide pin and anchor bolt, and pull the cable vertically along the outer side of the bolt. Pull hard, and tighten the bolt. Shift the rear derailleur to low gear (the big sprocket), and adjust the FD's low limit until there's .5-1mm clearance between the chain and inner derailleur plate. This final adjustment will get the last bit of tension you need.
I had a thought, but it got run over as it crossed my mind.

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Tim
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Re: Installing 105 (5800) front derailleur

Postby Tim » Sat Jun 02, 2018 3:20 pm

Duck! wrote:There's also a bit of a process for tuning the derailleur, because it needs a bucketload of cable tension.


I've developed a bit of a feel for these long-arm FD's. (5800, 6800 and 9000).
It's a three handed technique but works with a bit off manual dexterity and makes cable replacement simple.
Set all the heights, angles, stops etc as per Duck's instructions
Drop the FD cage down to it's lower limit.
Loosen the cable anchor bolt, make sure the cable is routed correctly and then pull the cable with a pair of pliers. I use fencing pliers which have a groove slotted down the length of the plier's jaws so it grabs but doesn't crush the cable.
With the same hand that's squeezing the pliers and pulling the cable upwards I drop my thumb down to the FD arm and push it inwards slightly towards the frame, still maintaining pull on the cable.
With the FD arm pushed inwards and tension still on the cable I just tighten the anchor bolt with the other hand (pre-armed with an Allen key).
...and Bob's your auntie. :D

Sounds rough but with a bit of judgement it works perfectly. Finer adjustments are then done with the inline barrel adjuster.
I use a similar method on the RD.
It makes cable changes quick and easy.
All I'm really doing is pre-tensioning the derailleurs before fixing down the anchor bolt and cable.

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Tim
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Re: Installing 105 (5800) front derailleur

Postby Tim » Sat Jun 02, 2018 3:28 pm

uad782 wrote:Also it cam with a weird tool TL fc 68. I have read the dealers manual but wonder why I need to use this?
Duck! wrote: Different cable pull angles can affect the smoothness of the derailleur shift, and setting the position of the guide pin helps correct it.


I tried the cable located in both positions on a FD5800.
Couldn't discern any difference so tossed a coin in the absence of the gauge tool.

uad782
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Location: Somewhere near Malabugilmah

Re: Installing 105 (5800) front derailleur

Postby uad782 » Sat Jun 02, 2018 9:12 pm

Thanks everyone

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Duck!
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Re: Installing 105 (5800) front derailleur

Postby Duck! » Sat Jun 02, 2018 9:43 pm

Tim wrote:
uad782 wrote:Also it cam with a weird tool TL fc 68. I have read the dealers manual but wonder why I need to use this?
Duck! wrote: Different cable pull angles can affect the smoothness of the derailleur shift, and setting the position of the guide pin helps correct it.


I tried the cable located in both positions on a FD5800.
Couldn't discern any difference so tossed a coin in the absence of the gauge tool.

I think it really depends on the cable line of individual frame models. On some, particularly if the cable angle is close to the guide line on the alignment tool, it doesn't really matter which side the guide pin is on. On others with more divergent angles, having the pin the wrong way for the pull angle can really make the derailleur quite jerky in its action. It doesn't seem to affect the interaction of derailleur, chain & rings at all, just the interaction of derailleur & shifter.
I had a thought, but it got run over as it crossed my mind.

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