What to do if you can’t dial in your rear derailleur…

I’ve been writing about a component upgrade for the Venge over the last few days… I installed 10sp Ultegra derailleurs and shifters, and got done just this morning. The 105 components that were on the Venge won’t go to waste, either. My Trek 5200 triple is about to become a compact double (as soon as my chainrings get here).

So I had everything installed yesterday but couldn’t get the rear derailleur to dial in. Starting, as we do, in the smallest cog, I’d tighten the barrel adjuster to get the derailleur to shift up the cassette. When I got to the second biggest cog, though, it wouldn’t shift back down the cassette. I’d loosen the adjuster to get it to go back down and once I got to the last gear, it wouldn’t go back up. Rinse and repeat for fifteen minutes…

I walked away rather than busting my bike into little, tiny, pieces. To thine own self be true. I am a hothead.

This morning, I came to the realization that there’s only one explanation: there’s a hitch in the cable, inside the frame somewhere. This explains why the derailleur will only dial in one way (either up or down the cassette, but not both). The cable is getting hung up just a little bit…

The trick is figuring out where, because relieving that will be the only way to fix the problem.

I had a fair idea for my problem. There’s a couple of guides that route the cables around the bottom bracket. There are cable guides that cover the cable to keep them clean underneath the bike. When I ran new guides, I ran the one for the rear derailleur long because “if some is good, more should be a lot better”. Damn, I’m such a drunk!…

Anyway, I loosened the bolt holding the cable to the derailleur and stripped everything down. I pulled the housing, cut it in half and slid it back on, using a scrap piece to help slide it through the frame.

I put everything back together, and… Bingo.

The cable housing was bumping into the guide at the cable exit in the chain stay, back by the derailleur. That was holding the cable up just a fraction of a sixteenth of an inch, so the derailleur couldn’t be dialed in both up and down the cassette.

Once I cut the cable guide down. The cable could move freely and everything worked. I had to think logically (often a problem with me) to get around the cable hangup. What would cause the derailleur to dial in one way and not the other? The cable’s gotta be hanging up somewhere. Then, where are the logical places this could happen?

It’s always best to start at what I did different. Chuckle.

Now I get to turn my attention to the Trek… With the bike’s external cable routing, it’ll be a TON easier. I can’t wait to see how much weight I lose with the 16 years’ newer components.

UPDATE! I almost forgot the “why” of all of this! My 16 pound Venge is now a 15 pound Venge! Worth it!

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