Tiagra Front Shifting Question

[dr_gn]

I’ve been on my new Boardman ADV 8.9 for the first time today. It’s got hydraulic discs with Tiagra shifters. I’ve only ridden mountain bikes previously. It’s great, but I can’t figure out the front shifting: to shift from the small to large chainring, no problem move the large lever, but to shift down I need to click the smaller lever twice. It’s as if it’s made for three chainrings coming down, but two going up. Can anyone enlighten me please?

[gazza285]

It doesn’t have just two positions, one for each chainring, but it has two positions per chainring, close together, to allow slight adjustments preventing the chain rubbing on the front derailleur when the chain is at each end of the cassette.

[dr_gn]

gazza285 said:

It doesn’t have just two positions, one for each chainring, but it has two positions per chainring, close together, to allow slight adjustments preventing the chain rubbing on the front derailleur when the chain is at each end of the cassette.

Ok, so there’s no way of dropping to the small chain ring in one click? I must be bypassing the first position when shifting up because I’ve not noticed an extra step. I guess the same way you can shift down several gears at the rear with one action?

Thanks.

[lufbramatt]

Yep its the "trimming" position to stop chain rub at either end of the cassette.

I'm sure my 105 shifters will drop the chain on to the lower chainring with one click, (although needs moving through 2 "clicks" to go to the big chainring) you might need to push the lever to the extreme of its travel or tweak the cable tension slightly to move the mech cage slightly closer to the frame. As the cables stretch this may happen by itself.

I find bikes are never 100% right from the shop and need a bit of fiddling here and there.

[Matt_N]

lufbramatt said:

Yep its the "trimming" position to stop chain rub at either end of the cassette.

I'm sure my 105 shifters will drop the chain on to the lower chainring with one click, (although needs moving through 2 "clicks" to go to the big chainring) you might need to push the lever to the extreme of its travel or tweak the cable tension slightly to move the mech cage slightly closer to the frame. As the cables stretch this may happen by itself.

I find bikes are never 100% right from the shop and need a bit of fiddling here and there.

Yeh sounds like the trim / cable tension is not quite correct, when in the big ring you can trim up to push the mech a bit further out, but it should normally drop to the inner ring with just one click.

[dr_gn]

Matt_N said:

lufbramatt said:

Yep its the "trimming" position to stop chain rub at either end of the cassette.

I'm sure my 105 shifters will drop the chain on to the lower chainring with one click, (although needs moving through 2 "clicks" to go to the big chainring) you might need to push the lever to the extreme of its travel or tweak the cable tension slightly to move the mech cage slightly closer to the frame. As the cables stretch this may happen by itself.

I find bikes are never 100% right from the shop and need a bit of fiddling here and there.

Yeh sounds like the trim / cable tension is not quite correct, when in the big ring you can trim up to push the mech a bit further out, but it should normally drop to the inner ring with just one click.

Mine doesn't lock in the trimmed position (further out) on the big ring. It's not limited by end stop either, so I don't know what's going on there. Definitely two clicks to drop down.

First click to go up from small ring isn't enough to engage the large chain ring either.

[lufbramatt]

Postions should go (closest to frame to furthest):

1- low trim
2- low gear
3- high trim
4- high gear

to shift gears from low to high the mech should be moving from 2-4, so the mech should be locking in the most extended position. I think there is slightly too much tension on the cable which is throwing the indexing out slightly.

[dr_gn]

lufbramatt said:

Postions should go (closest to frame to furthest):

1- low trim
2- low gear
3- high trim
4- high gear

to shift gears from low to high the mech should be moving from 2-4, so the mech should be locking in the most extended position. I think there is slightly too much tension on the cable which is throwing the indexing out slightly.

Thanks I'll double check tonight. It's not working like that at present: "2" isn't low gear, "1" is low gear. "2" seems irrelevant at present which is why I asked.

[lufbramatt]

Hopefully whoever put the bike together wound the barrel adjuster out a turn or two before setting it up so you can create some slack in the cable without having to undo the pinch bolt on the mech. Front derailleurs are some sort of dark art to set up right.

[nurseholliday]

lufbramatt said:

Postions should go (closest to frame to furthest):

1- low trim
2- low gear
3- high trim
4- high gear

to shift gears from low to high the mech should be moving from 2-4, so the mech should be locking in the most extended position. I think there is slightly too much tension on the cable which is throwing the indexing out slightly.

That doesn't make sense, because in the small chainring, you'd be expected to normally use the big sprockets on the cassette (lower gears), so you'd trim away from the frame to reduce chain rub when using the smaller sprockets on the cassette (higher gears), and vice-versa.

It should be:

1- low gear
2- low trim
3 - high trim
4 - high gear

[lufbramatt]

Yea I guess either position could be called the trimming position, but the mech will change gear going from 3 > 2 then you'd "trim" it as you move to bigger sprockets at the back. Depends what way you're looking at it. Was just trying to explain the positions

From shimano manual

Edited by lufbramatt on Monday 11th June 15:31

[Your Dad]

dr_gn said:

Anyone else troubled by this photo?

[nurseholliday]

lufbramatt said:

Yea I guess either position could be called the trimming position, but the mech will change gear going from 3 > 2 then you'd "trim" it as you move to bigger sprockets at the back. Depends what way you're looking at it. Was just trying to explain the positions

From shimano manual

Edited by lufbramatt on Monday 11th June 15:31

Sorry, didn't realise you were quoting the manual! I stand corrected, or firmly put back in the box.

[dr_gn]

lufbramatt said:

Yea I guess either position could be called the trimming position, but the mech will change gear going from 3 > 2 then you'd "trim" it as you move to bigger sprockets at the back. Depends what way you're looking at it. Was just trying to explain the positions

From shimano manual

Edited by lufbramatt on Monday 11th June 15:31

Do you have s link to the technical/installation manual please? The user manual is useless.

[lufbramatt]

http://si.shimano.com/#/en/search/Series?name=TIAG...

Setup is in the front mech docs (FD-****) rather than the shifter docs.

[lufbramatt]

nurseholliday said:

lufbramatt said:

Yea I guess either position could be called the trimming position, but the mech will change gear going from 3 > 2 then you'd "trim" it as you move to bigger sprockets at the back. Depends what way you're looking at it. Was just trying to explain the positions

From shimano manual

Edited by lufbramatt on Monday 11th June 15:31

Sorry, didn't realise you were quoting the manual! I stand corrected, or firmly put back in the box.

no worries, I did have to go and find that pic to check I'd remembered it right!

[dr_gn]

lufbramatt said:

http://si.shimano.com/#/en/search/Series?name=TIAG...

Setup is in the front mech docs (FD-****) rather than the shifter docs.

Thanks!

[The_Jackal]

Your Dad said:

Anyone else troubled by this photo?

Yes!! It's not even a case of OCD, just not being careful with your equipment.
Future gear change problems to come?

[nurseholliday]

Your Dad said:

Anyone else troubled by this photo?

In court I got to use this line, which caused a little titter:

"I don't agree, because the location you're suggesting the collision took place has 2 signposts next to the road, that would mean after the collision and during the ensuing incident, I could have left my bike leaned against one of those signposts, however I distinctly remember having a quandary about having to lay my bike down on the pavement, as I hate having to do that.

[dr_gn]

The_Jackal said:

Your Dad said:

Anyone else troubled by this photo?

Yes!! It's not even a case of OCD, just not being careful with your equipment.
Future gear change problems to come?

Yeah the front mech not quite touching tufted grass could well have caused the pre-existing issue.