rapidreview

I am pretty new to road biking and I have a total newb question. I have a CAAD9-5 with the compact Shimano 105 12-27 compact rear cassette. On my last ride, I noticed some trouble shifting into the lowest gear - the chain just does not seem to "settle" in and there appeared to be some appreciable lateral movement of the chain, so I just upshifted into 1-2. I don't know if this is related or not, but when I was trying to adjust it after my ride, I noticed that my shifter will not allow me to shift into the lowest (largest) cog. Is there a problem with my rear derailer? Aren't I supposed to be able to ride that cog??? Thanks all.

-Jon

DOS

Is than issue that you think has been a problem since you've owned the bike and are just noticing; or is it a new development? Best guess is that you need to tighten up the cable just a bit but some adjustment of of the low gear limits crew might be in order. https://www.parktool.com/repair/readhowto.asp?id=64

rapidreview

Hey thanks for the link. I've only had this bike for a couple weeks, so I'm not sure if this problem came with the bike or if it was something I caused. I tried adjusting the lower limits and to no avail - I still cannot shift into my lowest gear. It's as if I physically cannot push the shifter anymore. Is there something else I can adjust to get my shifter to shift to my lowest cog? Thanks.

DOS

I suggest you set the shifter so derailleur is on smallest cog, then disconnect cable and start from beginning setting up the derailluer. If you are running out of clicks before you run out of cogs, and you are sure the limit screws are correct, its likely that the shifter was not set properly when cable was attached. The shifter needs to be shifted all the way lowest gear when cable is attached, otherwise shfter will be out of sinc with the derailluer (e.g dreailleur will have chain on smalles cog while shifter is set on second gear). Once you are sure you have shifter set on lowest possible gear(i.e. no more clicks) ; follow Park tool directions for attaching cable and adjusting tension and screws.

edited toadd; meant to include, since bike is new, take it to shop you bought it from and have them fix it. If you are determined to diy, follow above.

well biked

Go through the whole RD adjustment process in the Park link provided above. It sounds like you may need more cable tension. It's a fairly common problem.

The tension is off so much that starting in the smallest cog, two, instead of one, clicks are required to make the first shift from smallest cog to next-to-smallest cog. It then shfits fine until that last shift (to the largest cog). By that time, you've used up all your clicks, you're using the click that's supposed to shift into the largest cog to shift into the next-to-largest cog. No way will it shift to the largest cog.

rapidreview

Thanks everyone. Since my bike is still fairly new, I am going to take my bike to the shop and have them look at it - hopefully they can show me what they're doing so I can learn first hand how to adjust for future reference. Thanks for all the quick replies!