teokiatuan

So i was adjusting my fit on the bike today, fiddling around with saddle fore/aft, when i noticed something was wrong with the rear derailleur:

The readout on the right Tiagra shifter says its on the lowest gear, but it actually is on the second highest gear. Shifters have no click to them when i try to shift to a higher gear, and i can't shift to a lower one because according to the readout it already is in the lowest.

I've tried shifting the chain with my bare hands, but it shifts back to the second highest on its own.
I've also tried fidding with cable tension, that doesn't help either.

Anyone have any clues?

Thanks
Teo

FBinNY 

It sounds like it's a cable tension adjustment, or possible a limit screw problem, but your description is unclear.

Let's start at the beginning.

If I get you, your lever says 1 and your chain is on the second largest (or second lowest sprocket). Is that correct? If not disregard what follows.

Step one, check the RD by applying direct pressure to the mechanism while pedaling (on a stand, or with friend holding the wheel off the ground) and see if the RD will shift to the largest sprocket. It should, and not go beyond sending the chain over between the cassette and the spokes. If yes, proceed, to step 2.

If not, your "L" limit needs adjusting, and given your limited experience, I suggest you let the LBS do this this, especially if it's a new bike and under warranty. If you want to adjust the limits yourself, there are a number of good tutorials by Sheldon Brown, or at the park tool site. Limit screw adjustment is easy, but an error can cost you the RD, rear wheel, derailleur hanger, or worse, so make sure it's done right.

Step two, since your lever says 1 the chain should be on the largest sprocket. See if when you go to 2 the chain drops to the third sprocket, and so on down the line. If so it's because the cable is too slack by an amount equal to the space of one gear. You can double check bu going back to 1 and plucking the bate wire away from the frame and seeing if that makes the last shift happen. Yes, good go to step 3.

step three, turn the cable adjuster on either the lever, or derailleur to take up slack and make the RD shift one sprocket. This can be done in any gear. If you've turned the adjuster as far possible without it coming off without solving the problem, turn it (both RD and levers) all the way back in, shift to high gear, loosen the cable anchor nut, pull down the all the slack in the wire and re-tighten. Now try again, shift the lever one click and adjust the cable tension until the chain moves to the correct sprocket. Now you should have the lever number corresponding to the actual gear throughout the range, and need only fine tune the cable adjustment for smooth effective shifting in either direction. This means a bit of trial and error adjustments of about a quarter turn or so.

Good luck.

teokiatuan

Thanks for your reply, but i can't shift at all, which pretty much means i can't try any of your suggestions yet.?

Uh oh...

FBinNY 

First loosen the cable adjuster a bit to create a bit of slack, and see if it'll let you shift to a higher gear. If not try again while gently pulling the wire away from the frame. If it's jammed and you can't get the lever to shift at all in either direction, it's likely an internal lever problem, and it's time for a visit to the LBS.

teokiatuan

Tough luck. Tried it, doesn't work...

Thanks FB.

operator

https://www.parktool.com/repair/readhowto.asp?id=64

Start from square #1.

DOS

You might try flushing the shifter out to see if its just gummed up. Otherwise it seems like shifter mecanism is toast. If you disconnect the cable form derailleur and shift the levers up an down, do you get any clics at all from the shifter?

HillRider

First, the readout" (Optical Gear Indicator, aka OGI is what I assume you are referring to) does not really tell you where the shifter is positioned, it's just a guide that can be misleading if it's not set correctly. As Operator recommended, go to the Park Tools web site and go through the set-up and adjustment procedure starting at the very beginning. In the future, ignore the OGI.