Shimano Tiagra Front Mech

jimbob 2705

Hi All,

I have just bought my first road bike which is a Specialized Allez Elite 2008, which I bought secondhand.

I have assembled it tonight and taken it for a short ride (it was dark).

The problem seems to be that the Shifter has 3 shifts/gears but only 2 chainrings, and it only shifts at the extremes - so at 1 or 3 on the shifter (so basically 2 shifts each time). Is this correct?

Also, when on the inside chainring the chain seems to rub against the Tiagra Front Mech. How can I fix this?

Thanks and ATB

James

rake

thats called trim, the small click doesnt shift but moves the mech slightly to avoid chain rub. when its rubbing on the granny ring, move the lever only say half way or so, it will trim the mech slightly over. you can see in the daytime.

jimbob 2705

rake wrote:

thats called trim, the small click doesnt shift but moves the mech slightly to avoid chain rub. when its rubbing on the granny ring, move the lever only say half way or so, it will trim the mech slightly over. you can see in the daytime.

Ok thanks.

So it is meant to have three adjustments on the shifters?

So basically just half shift?

Thanks and ATB

James

jimbob 2705

Just went outside for a little ride now, and I have found that there almost seems to be four shifts (some seem larger than others).

I found that if I do the half shift (or trim?) it won't rub when on the small chainring and the biggest sprocket at the back, but when I change to the smallest sprocket on the back it will then rub again.

Should it be doing that?

Thanks and ATB

James

rickwiggans

Tiagra shifters, at least some I had once, are designed to work as doubles OR triples. Hence four clicks.

jimbob 2705

rickwiggans wrote:

Tiagra shifters, at least some I had once, are designed to work as doubles OR triples. Hence four clicks.

Well that's sort of good news then.

So are mine working fine or do I need to adjust them?
I will maybe try and record a video tomorrow, and post it up so you can see what I mean - but I feel this might be quite difficult.

Is there a good guide somewhere which would help me to adjust/setup my front mech?

Thanks and ATB

James

Twostage

My tiagra is one of the old double/treble shifters. Moving 'down' from a treble configuration to a double is just a matter of adjusting the high and low limit screws to reduce the range. Half clicks are perfectly normal. For instance if you are in the big ring at the front and you want to go down to the big ring at the back you have to trim (half click) to stop the chain from rubbing against the derailleur.

rickwiggans

Try youtube. Lots of good demos on there. Also Shimano's tech docs quite good

migrantwing

I have the new Shimano (5700) 105 shifters, and they are exactly the same, jimbob. You just have to fine tune the hi/lo limits. A pain in the a**, but the trim is a good option to have.


Tiagra: http://techdocs.shimano.com/techdocs/bl ... ID=jnO4Gv0

jimbob 2705

Thanks for all the helpful replies!!

Does anyone knbw what model tiagra I have, as there seems to be quite a few different models? It is on a Specialized Allez Elite 2008. I have looked but I can't see any model numbers on the tiagra parts.

Thanks and ATB

James

rake

probaly 4500.
http://bike.shimano.com/publish/content/global_cycle/en/us/index/products/road/tiagra/product.-code-ST-4500.-type-.st_road.html

desweller

Chances are that, if it's been transported in a box, the mech needs aligning as well.

jimbob 2705

Thanks for all the help everyone!

I aligned/adjusted the mech so it was in the right place and clearance. I moved the low adjustment of the front derailleur so that the chain wouldn't rub on it, but after this the rear derailleur seemed to be playing up, so I decided to have a little fiddle with that (Stupid mistake!).

I seemed to have the front sorted, but the back wouldn't change onto the highest/biggest cog. I set the low and high adjustment as best as I could (to the shimano manual). It still didn't seem to want to go into the biggest cog, then it stopped going onto the smallest cog.

After some fiddling with the low and high adjustment, I have now got it so it works fine - Thank god!!

The bike seems to working Ok/fine now, but I don't think the front derailleur/mech is right :

It now seems to have only 3 shifts, and it doesn't seem to shift all the way to the right (the little red bar on the shifter) like it did before. This is how I would of expected it to come before, but I am not sure if it is right now.
It doesn't seem to have the 'trim' on the larger front cog. Right or wrong?

Also, it has now gone back to rubbing when in certain gears on the back - but I know how to adjust this now BUT the problem there seems to be now is that the low adjustment won't take it far enough from the chain. Any ideas?

I am going to have another look tomorrow night hopefully.

Thanks and ATB

James

Twostage

Low adjustment is a combination of low limit and cable tension. If the cable is too tight then it will be held higher than the low limit. You will have a barrel adjuster on the downtube which will allow you to loosen the cable tension.

The setup guide from the shimano tech docs take you through it step by step and if you follow them exactly they work fine.

tonye_n

Dual purpose shifters (such as Shimano Sora, Tiagra, old 105) are a bugger to tune up with triple chainrings.
I find that when it goes wrong (such as after you change cables or are re-installing after transporting the bike) it is better to loosen the front mech cable and start from scratch.
All the other posters are right about it being a matter of getting the low/hi limit screws set properly on the front mech.

Be carefull though, because the shifter internals are plastic for the Tiagra. If the mech is limited for double shifting and you keep on trying to force the shifting to 3rd ring without properly adjusting the limit screws you could break the shifter permanently.
Once the plastic stopper in the shifter internals break it is a replacement job. There are many stories of this with tiagra/105 shifters.

The shimano techdocs are sometimes a bit short on detail.
I find that if I start from scratch using the directions on Park Tools I never go wrong.
http://www.parktool.com/blog/repair-hel ... djustments

desweller

tonye_n wrote:

Dual purpose shifters (such as Shimano Sora, Tiagra, old 105) are a bugger to tune up with triple chainrings.
I find that when it goes wrong (such as after you change cables or are re-installing after transporting the bike) it is better to loosen the front mech cable and start from scratch.
All the other posters are right about it being a matter of getting the low/hi limit screws set properly on the front mech.

Be carefull though, because the shifter internals are plastic for the Tiagra. If the mech is limited for double shifting and you keep on trying to force the shifting to 3rd ring without properly adjusting the limit screws you could break the shifter permanently.
Once the plastic stopper in the shifter internals break it is a replacement job. There are many stories of this with tiagra/105 shifters.

The shimano techdocs are sometimes a bit short on detail.
I find that if I start from scratch using the directions on Park Tools I never go wrong.
http://www.parktool.com/blog/repair-hel ... djustments

After breaking one 105 shifter this way I have set the replacement up so that it shifts using the top two positions rather than the bottom two. It does mean that the cable goes a bit slack if you click into the bottom two positions on the shifter, but there's not enough there to be in any danger of getting tangled up; seems to work OK so far.