Boz1984

About a month ago I purchased my first road bike (first bike in a long time actually), a C'dale Synapse 2.
Ive been having this problem that may just be a simple thing to fix, but due to my lack of experience it worries me.

The bike is equipped with a Shimano 105 RD/FD, Triple.
From this point on, please excuse me if it sounds like I have no idea what im talking about... cause i dont...

Anyways, on to the problem:
If I am in either of the two smaller chainrings, my chain will skip between gears in the rear up, down, up up up, down down, up, or at least thats what it seems. I know it is shifting gears on me, but the direction it prefers seems to be random. This symptom is easily repeatable, but mainly only happens when Im climbing, and really putting into the crank.

Does anyone have any ideas on what this could be? Simple fix like chain stretch, or RD out of alignment?

Thanks in advance for any help I can get!

-Boz

vpiuva

Sounds more like a cable tension (adjustment) issue, but first rule out a stiff link in the chain. While off the bike, watch your rear derailleur as you spin the crank backwards slowly. If you have a stiff link you'll see it back there.

slowandsteady

It is typical for the cables to stretch in the first few months on a new bike. Your bike shop should adjust your RD for you for free in this case. But, it is a good thing to know how to do anyway. The best description I have found is on the park tool website.


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

DMF 

It could also be a bent rear dérailleur hanger. See slowandsteady's advice for how to deal.

Chains don't stretch, btw. They do wear - and get longer - but the symptoms aren't as you describe. Now's the time to find out how to test the level of chain wear, while you're at it.

slowandsteady

Is this a brand new bike or used? There is no way a chain is going to "stretch" in a month. Now, the cables will stretch in a month.

Boz1984

Great guys, thanks for the advice.
Like I said, I dont really know what Im talking about, I just thought I had read someone talking about chain stretch.

Ill look into what you guys recommended.