105 FD 5700 Trim Function

[SpokeyDokey]

Could someone please clarify my understanding of the trim function.

My FD is set up exactly as per the Shimano Techdoc relating to this item.

I can easily trim both front rings to go up and down all 10 rear cogs if I wish without any chain rub at all - not that I would want to use the cross chaining combos' of course.

My question though is this and I apologise for any dopeyness in advance.

When shifting up from the small chainring to the large no matter how far I push the lever there is always a little bit of movement that the FD can make further to the right that requires a further tiny push (ie slacken off on the lever and push again) to stop any rub should I be on my smallest rear cog.

Is this supposed to be how the upshift and trim works?

I understand (or think I do) the trim function with the little half shift inwards on the big ring and outwards on the small ring.

It's just this tiny little adjustment set-up that I was not really aware of. I am wondering if I have set the FD up wrong?

***

Sorry if the above is confusing.

 

[accountantpete]

Shimano were having a lot of problems with their left hand shifters. The manual confirms that the up shift from small to big chainring can be a two part affair with one big movement and a final short movement.

I'd try adjusting the cable so that the correct position over the big ring is reached on one go - so release cable, click shifter into position, position front mech where you want it and then tighten up on the cable. Then see if that affects the down shifting.



http://techdocs.shimano.com/media/t...0A/SI-6TH0A-002-ENG_v1_m56577569830702880.pdf

 

[SpokeyDokey]

Shimano were having a lot of problems with their left hand shifters. The manual confirms that the up shift from small to big chainring can be a two part affair with one big movement and a final short movement.

I'd try adjusting the cable so that the correct position over the big ring is reached on one go - so release cable, click shifter into position, position front mech where you want it and then tighten up on the cable. Then see if that affects the down shifting.



http://techdocs.shimano.com/media/t...0A/SI-6TH0A-002-ENG_v1_m56577569830702880.pdf

Thanks for that link ap and taking time to answer.

So looks like it is normal - it doesn't bother me as such; I was just wondering if it is normal or not.

 

[bobones]

You should be able to adjust it so the shift to the big ring is on first push. I would guess that you probably need to increase the cable tension.

The way mine works (5700) is that first click on pushing big lever is trim for small-small and the next click puts it up on the big ring. Depending on the stop screw position, the FD will retract a little from its outermost position when the lever is released, but it there should be no rub in big-small from this position.

Pressing the little lever once from here gives trim for big-big combo, and a further click drops to small chainring. You definitely shouldn't need to activate the big lever twice to move from small to big ring if everything is properly adjusted. If you increase the cable tension, you may find that the chain goes too far, but that can be fixed by tightening the stop screw. If the shifting action feels tight when activating the small lever then there is probably too much cable tension.

Quick and smooth front shifting with relatively short lever throw is probably what I like most about my 105 setup, but it can be tricky getting everything aligned and set up to minimise rub and have the trim and shifting working correctly.

 

[SpokeyDokey]

You should be able to adjust it so the shift to the big ring is on first push. I would guess that you probably need to increase the cable tension.

The way mine works (5700) is that first click on pushing big lever is trim for small-small and the next click puts it up on the big ring. Depending on the stop screw position, the FD will retract a little from its outermost position when the lever is released, but it there should be no rub in big-small from this position.

Pressing the little lever once from here gives trim for big-big combo, and a further click drops to small chainring. You definitely shouldn't need to activate the big lever twice to move from small to big ring if everything is properly adjusted. If you increase the cable tension, you may find that the chain goes too far, but that can be fixed by tightening the stop screw. If the shifting action feels tight when activating the small lever then there is probably too much cable tension.

Quick and smooth front shifting with relatively short lever throw is probably what I like most about my 105 setup, but it can be tricky getting everything aligned and set up to minimise rub and have the trim and shifting working correctly.

Thanks for your reply.

I have possibly have not explained myself very well?

The FD shifts from the small ring to the large ring easily with just one push.

My query was that when this change is made there is always approx' a couple of mm of further shift to the right available which has to be made with a slight second push of the lever. Only needed in the big ring/small cog combo to take care of slight chain rub.

The link from accoutantpete explains it perfectly and it looks like a normal feature of the trim function.

Everything works properly and exactly as you describe it was just this little feature that had me baffled!

 

[camtheman]

Bobones description is how I understand Shimano 105 to work. The outer adjustment screw setting on the FD and cable tension should allow you to get to the right position in one sweep. Yours sounds like the adjustment screw's too tight if you can't get onto the outer click. The trim function on the big ring is normally inward not outward.

By the way, I thought your explanation sounded right to me!

 

[SpokeyDokey]

Confused again!

Am I misunderstanding the small "X" movement here:

http://techdocs.shimano.com/media/t...0A/SI-6TH0A-002-ENG_v1_m56577569830702880.pdf

 

[SpokeyDokey]

Bobones description is how I understand Shimano 105 to work. The outer adjustment screw setting on the FD and cable tension should allow you to get to the right position in one sweep. Yours sounds like the adjustment screw's too tight if you can't get onto the outer click. The trim function on the big ring is normally inward not outward.

By the way, I thought your explanation sounded right to me!

I have just finished resetting the FD - started from scratch ie down to taking the FD off the seatpost.

Followed Shimano instructions to the letter and it is still the same.

From small to large chain ring goes in one big sweep. Leaves a slight rub on big ring / small cog combo.

Then a tiny (0.25") flick of the lever trims a couple of mm further to the right - so it appears to trim in both directions.

Have read and re-read the link from accountantpete and that appears to be the "x" movement that Shimano describe in column 3 here:

http://techdocs.shimano.com/media/t...0A/SI-6TH0A-002-ENG_v1_m56577569830702880.pdf

Unless someone tells me otherwise of course!

 

[accountantpete]

I still think you can get it to go in one.

Do the first sweep again.

The front mech is moved to the right but a tad short of perfection.

Without doing anything else undo the cable.

Then move the front mech by hand to the spot where it should be and then tighten up the cable.

That way you will get the front mech where you want it in one sweep of the paddle.

 

[camtheman]

I think you read the Tech Doc correctly but note the word "if"!

"If operation of lever a does not complete the
chainring shift stroke, operate lever a again
for the distance (X') to complete that part of
the lever stroke (X) which was short."

It depends on cable tension and outer stop positioning. It should be possible to set the cable tension a bit tighter and outer stop a bit slacker so you can go up from the inner ring and to the outer limit of the big ring in one go. but that means that whenever you use the big inner sprocket at the back, you'll have to trim inwards. I set up my Shimano to work the other way round because I'm a bugger for cross chaining big-big, and rarely use the big-small combo unless I'm going down a hill and they never last long enough to bother trimming! My Campag Centaur bike is exactly the same.

In the end, what matters is which way round works for you depending on where you tend to live most often in the cassette range. Like I said, I tend not to go down to the small sprocket.

I managed to "widen" the cage on my winter bike's FD with a large screwdriver so that I need no trim at all on that one!

 

[SpokeyDokey]

I think you read the Tech Doc correctly but note the word "if"!

"If operation of lever a does not complete the
chainring shift stroke, operate lever a again
for the distance (X') to complete that part of
the lever stroke (X) which was short."

It depends on cable tension and outer stop positioning. It should be possible to set the cable tension a bit tighter and outer stop a bit slacker so you can go up from the inner ring and to the outer limit of the big ring in one go. but that means that whenever you use the big inner sprocket at the back, you'll have to trim inwards. I set up my Shimano to work the other way round because I'm a bugger for cross chaining big-big, and rarely use the big-small combo unless I'm going down a hill and they never last long enough to bother trimming! My Campag Centaur bike is exactly the same.

In the end, what matters is which way round works for you depending on where you tend to live most often in the cassette range. Like I said, I tend not to go down to the small sprocket.

I managed to "widen" the cage on my winter bike's FD with a large screwdriver so that I need no trim at all on that one!

Thanks for reply.

I did note the word 'if' - looks like there is an option or at least two different solutions to two different set-ups; whether intentional or not! Not that Shimano make any attempt to explain things that well!

I did have a stab with the tension a tad higher and the stop opened beyond the recommended limit but then the inward trim function did not work so well.

I think I am happy with it just the way it is - it works fine how I have it set up and seems logical to me.

I don't use the last 2 smallest cogs much and like you this is usually on a downhill - no effort to flick the lever a quarter of an inch for this if needs be.

 

[SpokeyDokey]

Update:

Based on some replies being adamant that one sweep would do it, I persevered.

Basically I have followed the Park Tools website advice that adjusts chain tension slightly differently to Shimano.

Shimano: shift from small to large ring then trim. Following this adjust cable tension until the inner plate just clears the chain. Repeat and check.

Park Tools: shift from the small to large ring and adjust cable tension until the outside plate just clears the chain. Repeat and check.

Doing it this way plus adding in a sixteenth slackening on the H stop once the tension was correct has resulted in...

...one full sweep shifting up to the front ring with no rub in large ring/small cog. result.

Trim function also works well right across all cogs on both rings ie no rub at all. Happy!

Thank you for your advice.

 

[accountantpete]

Told you so










nice one.

 

[camtheman]

Er..you read the Shimano document for the FD adjustment the wrong way round. Sorry I didn't spot that before. The instruction says that the 0.5mm inner plate spacing relates to the low adjustment, not the top;

1. Low adjustment
Set so that the clearance between the chain guide inner
plate and the chain is 0 - 0.5 mm.

3. Top adjustment
Set so that the clearance between the chain guide outer
plate and the chain is 0 - 0.5 mm.

http://techdocs.shimano.com/media/t...SI-5LW0B-001-00-ENG_v1_m56577569830696762.pdf

But really glad you got it sorted out!

 

[SpokeyDokey]

Er..you read the Shimano document for the FD adjustment the wrong way round. Sorry I didn't spot that before. The instruction says that the 0.5mm inner plate spacing relates to the low adjustment, not the top;

1. Low adjustment
Set so that the clearance between the chain guide inner
plate and the chain is 0 - 0.5 mm.

3. Top adjustment
Set so that the clearance between the chain guide outer
plate and the chain is 0 - 0.5 mm.

http://techdocs.shimano.com/media/t...SI-5LW0B-001-00-ENG_v1_m56577569830696762.pdf

But really glad you got it sorted out!

No, I did that for the high and low adjustment.

The bit that was different was the cable tension adjustment.

Shimano advise shift to top ring, trim then adjust cable tension referencing inner plate clearance.

Park tools advise shift to top ring do not trim but then adjust cable tension referencing outer plate clearance.

***

Think I have that right? Could be wrong but it worked!