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NeoRetroGrouch
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6,493 Posts
Discussion Starter · #1 ·
This happened some time ago, but was as hard to find as the recent loose lockring post.

A friend bought a new C’dale and, after riding it a few times, asked me to take a look at it because the rear would start jumping after a few miles of riding. She said that she had it back to the shop several times and that after riding a few miles it would start jumping again every time.

I looked and the rear was in need of adjustment. I adjusted the barrel adjuster and thought, “The shop couldn’t figure that out?” All was well.

The next time I saw her she said that it started jumping again after riding a few miles just like after the shop fixed it. I threw it on my roof rack and took it home with me.

I put it on the stand, cranked it by hand and the rear couldn’t decide which cog it wanted to be on. It was trying to go to a smaller cog like the cable was too loose. There was no adjustment left on the barrel (also none on the down tube adjuster). I turned both adjusters about two threads from all the way in and reset the cable attachment. I adjusted the RD and went for a ride - not easy on a very small flat bar road bike :). 12 miles later it was again trying to shift to a smaller cog.

When I got home, I lifted it onto the stand and, by pure luck, the problem was obvious. What was happening?

TF
 

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NeoRetroGrouch
Joined
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6,493 Posts
Discussion Starter · #6 ·
ChuckUni said:
was the cable housing collapsing at one of the ends?

hrm...dunno!
I think you got it!

The reason that it was obvious when I picked up the bike was because I was stabbed by the little housing wires sticking out of the down tube cable braze-on. The bike had been assembled with no ferrule at the down tube and it was pealing back the housing cover a little every shift which would make the cable 'effectively' longer. Put ferrules on the cables and all was well.

TF
 

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Polka Power
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1,348 Posts
TurboTurtle said:
I think you got it!

The reason that it was obvious when I picked up the bike was because I was stabbed by the little housing wires sticking out of the down tube cable braze-on. The bike had been assembled with no ferrule at the down tube and it was pealing back the housing cover a little every shift which would make the cable 'effectively' longer. Put ferrules on the cables and all was well.

TF
Nice!

I only know this because I did this with brake cables once. I installed barrel adjusters without cable ends. It looked like the barrel itself would make a great cable end...nope. A little less brake with every pull.

I didn't know if the deraileur would have enough cable tension to do that. Apparently it does.
 

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Get me to In&Out
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5,419 Posts
Another thing I have seen cause this is when the cable housing itself twists with the adjustment. It essentially winds up like a poorly built machine built wheel. First ride and half the spokes lose tention. Same thing here. The housing twists and works great in the stand then after a few dozen shifts, it unwinds and releases the tension and is back where you started.
 
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