Help with Tiagra Downshifts...

drewesq

Hi all

I'm pretty new to all of this <12 months, so please forgive any mistakes!

I bought a Caad X last year, for me it has been great, it is comfortable and it has let me really enjoy my cycling. However, I have had an annoying issue since I got the bike last year that I can't seem to get right and wondered if it was something I could get advice from here about...

When downshifting on the rear, I don't always get the gear, if I do 1 click it sometimes gives me the gear and sometimes I have to do another half click for it to find the gear. It has only really become more of an issue recently as mu riding has improved and I'm doing longer distances and it sucks becauses it forces me to lose a lot of speed and momentum when I need it to say climb a hill.

I don't have this issue on my MTB, so I don't think it is my technique at fault, also when the bike was set up it was done professionally and I have even taken it back to the pros for this and all I can say is when it is on a stand the gears work perfectly.... they just don't when I am riding

Does anyone else have this issue, or better yet, has anyone else managed to fix this issue?

Really hope I can get some help with this

Thanks

Andrew

KINGGARY

Sounds like you simply need to wind out the barrel adjuster on the rear mech, your cables may have stretched slightly or your chain line may be different under load than on a stand.
Plenty of videos online or park tools website has some good tutorials.
I have tiagra on my winter bike and it does seem to need regular tweaking as opposed to ultegra or 105.
I have also found under heavy load holding the shifter for a second in the shift position rather than just clicking and releasing can be beneficial.

drewesq

Thanks KingGary!

I'll certainly try this later, would be ace if it was something simple as that!

keef66

In contrast I have 9 speed Tiagra on my winter bike and find it easier to set up / require less fine tuning than the 10 speed 105 on the summer bike.

Sounds like you just need a bit less cable tension (If by downshifting you mean moving to a bigger sprocket / easier gear) so just screw the rear mech barrel adjuster in a quarter of a turn at a time till it works as it should.

If that doesn't appear to work, the other possibility is the cable fraying inside the shifter. (happened twice on my 105's). On an externally cabled bike there's an easy way to have a look without unclamping the cable from the rear mech:
Put the bike in it's lowest gear (biggest sprocket)
Then without turning the pedals but while maintaining tension on the cable, keep clicking the shifter all the way to the other end.
You should by now have enough slack in the cable to lift one of the sections of outer from it's stop on the frame, and this will allow you to push the inner back through the shifter so you can easily see if it's fraying near the nipple. Best to catch this early; fragments of wire in a Shimano shifter can be terminal and hence expensive.

ravey1981

keef66 wrote:

Sounds like you just need a bit less cable tension (If by downshifting you mean moving to a bigger sprocket / easier gear) so just screw the rear mech barrel adjuster in a quarter of a turn at a time till it works as it should.

Other way around, to go up the block you need to wind the adjuster out, ie add more tension to the cable.

trailflow

Try lubing the shifter internals and derailleur pivots with spray grease/oil.

drewesq

Thanks all! I loosened the rear barrel adjuster and it works a treat now... thanks

Now need to change the front fork on my MTB!

Record11Ti

I agree with the barrel adjuster thing. But, something to know. It is almost a 1 to 1 on most rear Der's. And, it is also a 1mm thread pitch on the barrel. So, you can eyeball the chain and see how far you are off (in the work stand or what ever) One HALF turn of the barrel should be 1mm of travel on the cable, thus 1mm of travel on the chain wheel (yes the upper does have side to side, lower does not). I would refer to Sheldon Brown for more tips.

drewesq

Record11Ti wrote:

I agree with the barrel adjuster thing. But, something to know. It is almost a 1 to 1 on most rear Der's. And, it is also a 1mm thread pitch on the barrel. So, you can eyeball the chain and see how far you are off (in the work stand or what ever) One HALF turn of the barrel should be 1mm of travel on the cable, thus 1mm of travel on the chain wheel (yes the upper does have side to side, lower does not). I would refer to Sheldon Brown for more tips.

I have no idea what any of this means!

nferrar

I'd say this is more likely cabling (either too tight a bend somewhere or dirt in the housing causing stickiness). It sounds to me like the indexing is OK (no mention of issues on upshifts and it sometimes downshifts fine) so messing with the barrel adjuster could just create another problem. The problem you are getting is when you're making the cable slacker hence why the inner cable dragging/sticking could lead to it not always shifting properly first time