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I purchased a 2013 GT Karakoram 4.0 a few months ago. Granted I have been pushing the envelope with this bike; however, I have been having some shifting issues. I have not wrecked the bike, nor have I thrown it down. It is garage kept, cleaned after every ride, and hung up for safe keeping.
In fact, just yesterday, my shifter cable was dangling so loosely, I had to waste valuable dirt time getting it back in place. Furthermore, my investigation revealed my low and high gear shifter screws on my front derailleur were completely tightened. I had not noticed this before until I really started getting into some major uphill climbs and needed to shift frequently.
Today, a shift failure caused a near serious crash when my chain shifted completely off the cassette in the middle of the woods. Fortunately, I was biking with a great buddy who helped me out. But, we were still left scratching our heads wondering why a new bike would have those issues.
Is this some quirky manufacturer error or just some shipping issue when the bike came off the truck. I know the bike was serviced before it put out on the floor. Could it be someone on a test ride jacked something up? I don’t know. I am wondering if anyone else has had a similar experience. What did you discover was the culprit?
Love to hear your feedback.
Ericka–Sgt29er
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The adjustments need to be done while you are rotating the pedals in the forward direction and shifting sprockets. The simplest way to do this is to put the bike upside down (resting on seat and handlebars). Then rotate the pedals with one hand, and switch gears to see the results (still rotating pedals).
The derailleur works by pulling against a spring. Look at your derailleur and try to shift. If your derailleur does not move, then the cable is too loose and not pulling against the spring. Loosen the cable clamp screw, and grab the cable with a needle nose plyer. Pull on it until you get some spring tension on it, and then tighten the cable clamp screw. Do not pull until you completely compress the spring or else it will make the cable too tight. Try to shift again to see if derailleur moves.
If the L and H screws are adjusted wrong, then:
1. If the L screw is OUT too far…
When shifting to low, the chain will try to go past the low sprocket.
2. If the L screw is IN too far…
When shifting to low, the chain will not go far enough onto the low sprocket.
3. If the H screw is OUT too far…
When shifting to high, the chain will try to go past the high sprocket.
4. If the H screw is IN too far…
When shifting to high, the chain will not go far enough onto the high sprocket.I know that this was a bit of a lengthy explanation, but I hope that this helps.
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This actually helped a lot. It took me a bit to get things aligned. One culprit was dirt that worked its way underneath the H and L screws. When I tried to shift, the derailleur did not move which is what accounted for the loose cable.
Thanks for the help since that seemed to cure the issue.
You rock!
Sgt29er
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Awesome! I am glad I was able to help…
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