SouthFLpix

I wonder if anyone would be able to offer me some advice on an issue I'm having. While riding I am able to upshift just fine during any situation, but often the downshift will not 'take' unless I am pedaling very slowly. As a work-around I usually have to either shift down twice, or hold the grip shifter down toward the lower gear, but not actually shift. For example:

Say I am in 5th gear and want to shift to 4th.
I move the grip shift to 4, but the gear does not change.

I can either shift again to 3, which would then take 4th gear, or
I can move the shifter slightly below 4th gear (but not to the point where it clicks to 3) until I feel the shift take place.

I am a total novice when it comes to bike mechanics. I've never done anything more complex then changing a tire, but I am looking for some assistance here. My bike is a Giant Cypress DX, 2007 with a grip shifting system.

operator

If a simple reduction of cable tension either via the pinch bolt or the barrel adjusters don't work then do the full procedure here.

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

Retro Grouch 

Actually, with grip shift, it almost certainly needs a "skosh" of ADDITIONAL cable tension. Look for a barrel adjuster where the cable exits the shifter and turn it counter clockwise about 1/2 turn. My bet is that'll fix it.

Cable housings seat and cables stretch a bit as a bike breaks in. Cables never need a cable tension reduction because they never shrink.

SouthFLpix

Wow, way above my head guys, but I gave it a try. Using the derailer pinch bolt first I loosened the cable, which made the problem much worst. Then I tightened it as much as I could, which seemed to improve the problem a bit. I did not see any 'barrel adjuster' to tighten the cable, so I tightened it in a very awkward way by loosening the rear derailer pinch bolt and then pulling the cable tight with a pair of piers while I tightened the bolt. I feel that it would work better with just a bit of extra tightness, but I am unable to do this by hand.

Like I said, I see no adjustment for tightening the shift cable. Is it possible that the adjustment for this is inside the grip shift? Please bear with me, this is definitely all new to me.

ICycleALot

My experience with grip shifters is a little limited, but on some systems the barrel adjuster might be on the rear derailleur itself, or on the cable guides on either the down tube or the top tube (wherever the cables are on your bike), or sometimes you'll have an adjuster in both places. I suppose it's possible that your bike might not have one, but if you still can't find it, just swing by a shop and ask someone to point it out for you, I'd bet it's there.

SouthFLpix

Wow, thank you so much! I finally found it and with just a small adjustment now the bike is shifting perfectly. The local bike shop would have probably charged me $35-$50, just for this 5 minute adjustment, so you definitely saved me a lot of money. Thanks again!!!

Berre

Irregular shifting is usually the result of a cable problem.

Outer cables should be 'clean' cut, either with a special cable cutter or with a dremel cutting tool. Take care of grinding cable ends completely flat, so they will fit snug in cable stoppers. No "sponginess" is allowed when it comes to correct shifting.

BTW, cables should be the correct lenght: not too short, not too long either. Most bikes come with cables way too long.

Read Sheldon Brown about installing cables.