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Cannondale F7 Disc 2008 Gears Shifting Poorly Above 10 mph: Troubleshooting Tips?

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Discussion starter · #1 ·
I just purchased a 2008 Cannondale F7 Disc from craigslist a couple days ago. I've taken it out for a couple miles on trails and a couple more on neighborhood streets, and I keep noticing that any time I am riding at speeds greater than about 10 mph my gears shift very poorly: it takes several crank revolutions for my chain to transition into the next gear. This happens on both derailleurs, but usually only in the higher gears.

So my question is what is causing this issue/is this just a component quality issue or is there an adjustment that I can make?

Thanks!!
 
#2 ·
You should be able to get reasonably good performance out of the stock components, if they're not too worn out. However, shifters and derailleurs are definitely sensitive to tuning.

Since the bike's about four years old, the first place I'd look is the chain. It's not worth trying to tune a bike if the chain's trashed.
Chain Maintenance

If the chain's fine and things are dirty, clean them! I usually just drag my chain through a dry rag for several revolutions, but if the chain rings and cassette are gnarly enough, you should clean them too. Clean the derailleurs while you're at it. There's not always much you can do about the actual pivots, but at least get the dirt off the outside.

Relube the chain. There are endless debates about what to use, and I don't care to get into it. :p Just so long as it's something designed to stay on a part, not WD-40 or a solvent.

Now, on to the derailleurs.
Park Tool Co. » ParkTool Blog » Front Derailleur Adjustments
Park Tool Co. » ParkTool Blog » Rear Derailler Adjustments (derailleur)

If you don't have any luck, you may be overdue for new cables and housings. Get your LBS to help you with that. They're not particularly expensive, but they should be cut correctly, and to the right length.
 
Discussion starter · #4 ·
Thanks guys for the quick responses!

I've adjusted the back derailleur--it's shifting great now. The trouble I'm having is with the front derailleur. I'm using Park Tool Co. » ParkTool Blog » Front Derailleur Adjustments[/url] to guide me, and I'm currently attempting to adjust the limit screws. But it seems I'm having quite a dilemma; I have my chain set on the largest cog and smallest chainring, with the cable tension loose, and I'm trying to adjust the low-limit (outermost screw), but I'm not seeing any movement in the derailleur. I also thought, "well, maybe it could be the innermost screw", and I tried that one as well...but still, no movement!

I don't know where to go from here??
 
#5 ·
From the right angle and if everything's clean, you should be able to see into the mechanism. Your derailleur may have hit another hard stop, like the seat tube or part of the pivot.

Is the chain dragging on the inboard side of the derailleur cage? If not, don't worry about it unless you find screwing in the low limit screw never starts to work.
 
Discussion starter · #6 ·
Hmm..I think it's time to go to the LBS. I got the chain to quit rubbing against the outermost part of the front derailleur (problem I was having all along) by losing the cable tension on the barrel adjuster. However, just when I thought I had it all fixed, I shifted from the biggest chainring to the middle and the cable tension went completely loose. Now it obviously won't shift any more, and the barrel adjuster looks broken? The cable tension won't stay in the shift no matter what I do to try to twist it in with the barrel adjuster....

: (
 
#8 ·
This sounds backwards to me. Can you take a picture? I'm wondering if you were dialing the barrel adjuster out of the shifter, increasing tension. If you go far enough, you can unscrew it completely. Should be fixable, you just need to get the threads started again.

However, I think it's easier to learn to maintain a bike that's already working well than it is to learn by tuning up one that isn't. So going to your local shop could save you some time and aggravation, and I don't think there's all that much to gain if you're just getting frustrated.
 
#12 ·
In the first pic - nothing wrong, the housing is just supposed to be held in by cable tension anyway.

In the second pic, I can't tell. The barrel adjuster has two parts. The outer part, with the four little splines, has a spring that pushes it against the shifter. So if the barrel adjuster is unscrewed all the way, the spring will push the outer part over the inner, threaded part. If the barrel adjuster is broken, it will look the same. Try pulling back the outer part, toward where your hand is in the pic. That might reveal something useful.

The fact that you can do that at all indicates that the cable tension is way too low. So also have a look at where it's attached to the front derailleur and see if it has slipped. Where you tighten the cable fixing bolt on the derailleur over the cable, the cable gets flattened. So if that flattened part is visible, it's slipped.

If nothing's damaged, screw your barrel adjuster in all the way and then back it out maybe one complete turn. Make sure the shifter is in its lowest tension position. Pull as much cable as possible through the cable fixing bolt on the front derailleur and then tighten it, a bit more than last time. :p Pick up wherever you got stuck in the Park Tool instructions, or use Shimano's instructions. Those are also good, although they can take a little more puzzling out, and are available from their web site.
 
Discussion starter · #13 ·
So the problem is I am bike illiterate. I had what I assume to be the high limit screw tightened all the way down (because from earlier I was trying to differentiate between high and low limit screws, since there are no H/L letters). Well I loosened what I thought to be the high limit screw, and now it shifts. Before, the derailleur wouldn't even move when I tried to shift to the 1st chainring? Hmm....lol I have no idea what I'm doing : /!!

Thank you for all your help!
 
#14 ·
Just take it slow. Almost nothing on a bike is hidden, so you can often see the other ends of things like limit screws, and the surfaces on the derailleur link that they press on. A flashlight helps.

Anyway, glad you got this part sorted out.
 
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