Cannot shift to lowest gears despite limit screw adjust
 

Hi, my first posting to this forum and I cannot seem to find previous postings matching this problem.

Bike setup:
-Ultegra 53-39 crankset
-105 rear derailleur
-10 speed sprocket[LIST]
-Tiagra STI 10 speed shifters

Problem:
I cannot shift to the two lowest gears on the sprocket despite fully loosening the low limit screw. When on the #8 cog I can shift through one more index, but the derailleur will not move to the #9 cog. The inside cable tension is super tight after the final attempt at shifting, but the derailleur simply will not budge further. When I purchased this bike it was billed as a 10 speed, but the derailleur simply doesn't seem to have the range needed to reach the two lowest gears. Any ideas what might be the problem?

Thanks!

I would suggest that you forget everything you've done to your RD so far and start over.
Here's a pretty useful instructional video: http://www.youtube.com/watch?v=SkzvfCaIbyQ

Edit: Forget the above (keep the link for future reference). If the bike is new, and you bought it recently, take it to the shop that sold it to you. It's their problem, not yours.

Is this on both chainrings?

There are also at least two version of the Shimano 105 derailleur, the version 5501 is 8 and 9 speed compatible, the version 5600 is 10 speed, you may have the wrong model fitted?

http://www.chainreactioncycles.com/M...x?ModelID=2654

http://www.chainreactioncycles.com/M...?ModelID=13595

8-, 9- and 10-speed cassettes are all about the same overall width, so even if it was an 8-speed RD, it should work with 9- or 10-speed. Can you make the RD move over by hand (forget about the cable). Maybe it just needs a little oil at the hinges.

So...Tiagra shifters are 10-speed now? Shimano's website still lists them as 9-speed: http://bike.shimano.com/publish/cont...e-st_road.html

If you detach the cable from the derailleur will the derailleur move all of the way across the cassette?
If so then the problem is with the cable, cable housing, or shifter.
When you say lowest do you mean smallest cog or biggest cog? Technically the lowest gear is the largest cog on the cassette.
Follow the instructions for adjusting derailleurs found at: http://www.parktool.com.

Al

+1, I thought Tiagra was 9 speed

Good catch, 9-speed. I did not know that and it would explain the OP's problem.

As mentioned above, start over BUT if still no joy:

Bent derailleur hanger? Park makes a tool, a bit pricey for personal use, but your LBS should have one, that will check for this quickly. Bend or replace if it's out of line. No amount of adjustment can compensate for a out of line hanger, IMHO.

Hi All,

Thanks for the great advice. After manually shifting the derailleur I found that I could not get past the 7th sprocket, even with the high limit screw backed out completely. I'm assuming the derailleur is defective which probably occurred last year during a spill in rain (I replaced the bent hanger). All this time I never bothered fixing this b/c I assumed the shifting was related to the limit screw settings and I sort of liked not having the ability to get in the granny gears on the hills along my commute route (made for a better workout). Anyhoo, I replaced with a spare Ultegra derailleur and all is well again. Thanks again for all the help, and the video.