Got a bike problem with the front Shimano 105 derailler.

[fuzzybabybunny]

I've got a Fuji with Shimano 105 front derailler and three chainrings. Going from the smallest chainring, I used to be able to go

shift (now in middle chainring)
shift (now in largest chainring)

Now my bike is doing something like this:

shift (now in lower part of middle chainring)
shift (now in upper part of middle chainring)
shift (now in largest chainring)

downshift (drops all the way back down to the smallest chainring, unless I downshift with a really quick tap)

Any idea what's going on?

 

[everman]

You might need to adjust it, this should help: Text

 

[fuzzybabybunny]

Originally posted by: everman
You might need to adjust it, this should help: Text

Thanks. I've done all the adjustments there, I just don't know where there's now an extra index...

 

[Brutuskend]

Originally posted by: fuzzybabybunny
I've got a Fuji with Shimano 105 front derailler and three chainrings. Going from the smallest chainring, I used to be able to go

shift (now in middle chainring)
shift (now in largest chainring)

Now my bike is doing something like this:

shift (now in lower part of middle chainring)
shift (now in upper part of middle chainring)
shift (now in largest chainring)

downshift (drops all the way back down to the smallest chainring, unless I downshift with a really quick tap)

Any idea what's going on?

Sounds like cable stretch to me.
The second position is totally reliant on cable tension while the upper and lower rely in part on the stops on the dérailleur.

If it's not going up into the second gear in the first "click" then your cable has more than likely stretched and needs to be tightened. There is often a in line barrel adjuster where you can take up cable slack (on the newer brake shifter combos) or there will be a barrel adjuster on the down tube where the down tube shifters would normally mount.

Edit: I have seen people get and extra click when cable tension is too slack too. Check it out...

 

[JulesMaximus]

I'm so glad I run a Campy drivetrain and only have doubles on my bikes. :thumbsup:

 

[Dessert Tears]

Is it possible that the shifter internals have been fouled, e.g. have you ridden in the rain at any time?

Your problem sounds like it could be different symptoms of a problem I had with my RSX shifters. The shifting was sticky - it would refuse to shift and sometimes get stuck between index positions. Basically, one or more spring-loaded parts were getting stuck open or shut, making shifting in the affected direction impossible. The tooth that snapped into the index positions was also sticking at non-index points occasionally.

I fixed the problem by flushing the shifter with WD40, then I smeared grease over the internals for weather protection. I had to remove a plastic dust shield to access the internals, but I broke it on removal.

 

[herbiehancock]

Honestly, it sounds like you finally got your front STI shifter's cable tension right and found the trim positions in the shifter. Shimano triple road systems are indexed and when the chain is on the middle chainwheel there are two positions for the front derailleur in order for the chain not to rub on the front derailleur cage when it is on the smaller or larger rear sprockets.

Read the large single-paged multi-languaged paper that comes with the front derailleur and the STI shifters. Both detail the trim function for the center chainring in the STI shifters. If youdon't have either, your local LBS should have one, or be able to open a front der. box or STI box and let you look at the paper in it.

Alternatively, you can go to the Shimano website, Europe version (the U.S. version does not have as much tech. info as the EU website does, unfortunately) and download a.pdf that explains the trim function.

Having trouble locating the triple 105 service instructions, but there's a link to the Sora STI's, which have the same function: (See pg. 3, right side)

http://bike.shimano.com/media/cycling/t.../ST/SI-6JR0A_v1_m56577569830538833.pdf

 

[Dessert Tears]

Originally posted by: herbiehancock
Honestly, it sounds like you finally got your front STI shifter's cable tension right and found the trim positions in the shifter. Shimano triple road systems are indexed and when the chain is on the middle chainwheel there are two positions for the front derailleur in order for the chain not to rub on the front derailleur cage when it is on the smaller or larger rear sprockets.

Read the large single-paged multi-languaged paper that comes with the front derailleur and the STI shifters. Both detail the trim function for the center chainring in the STI shifters. If youdon't have either, your local LBS should have one, or be able to open a front der. box or STI box and let you look at the paper in it.

This sounds right - I hadn't realized that the 10spd 105 STI (ST-5600) are front double/triple shifters. I run them on a double, and I was wondering what the extra position beyond my large chain ring was for.

Shimano links (the PDFs are their print materials):
http://bike.shimano.com/catalog/cycle/p...d=1408474395181419&bmUID=1162526522780
http://bike.shimano.com/media/cycling/t.../ST/SI-0024A_v1_m56577569830563505.pdf
http://bike.shimano.com/media/cycling/t.../ST/SI-6KD0A_v1_m56577569830563506.pdf