mozad655

I've replaced the wire and housing for the rear derailluer of my bike. All I have to do now is attach it to the bolt, but I can't seem to tighten the wire enough by hand. There's just not enough tension. Do I need a tool for this?

well biked

Move the shifter/rear derailleur to the highest gear (smallest cog position), with any barrel adjusters (derailleur, shifter, downtube, etc) turned within a turn or so of being turned all the way in. Take hold of the cable with your hand and simply pull the cable tight, maybe do this a time or two to make sure everything seats in the right place. Then, with the cable in your hand pulled taut, making sure the cable is feeding under the anchor bolt in the right way, tighten the anchor bolt. Once that's done, spin the drivetrain and see if you get a shift when you move the shifter to the next-to-smallest cog. If it won't shift at all, add some tension by turning barrel adjuster counterclockwise.....keep experimenting until you get smooth shifts all the way up the cassette or freewheel, and back in the other direction. You're trying to balance cable tension against the derailleur's return spring to find the "window" of adjustment that allows responsive shifts in both directions.

RubeRad

First off, you do have a barrel adjuster where the cable enters the derailleur, right? That is for tightening. Make sure it is screwed all the way in first, then secure the cable, then start unscrewing to tighten.

More tips:

It is possible to buy inline barrel adjusters that can give you more cable-tightening ability, even while riding.

It is possible to buy 'third-hand' bicycle tools that hold cable under tension while you tighten the bolt.

But, you shouldn't need to buy specialty products to install a derailleur cable.

When you secure the cable initially, try to get it as tight as you can to begin with. Lock some vise grips on the cable and pull with one hand while tightening the pinch bolt with the other.

Also, use the limit screw to push the derailleur in maybe half a cog-spacing, then attach the cable, then loosen the limit screw again to let the derailleur back out, that should add some more tension as well. You'll have to start from scratch with adjusting your limit screws, but it's not a bad idea to do that anyways when replacing cables.

RubeRad

This is important too; make sure all of the housing is seated where it's supposed to be, not riding up on the braze-on. And the cable properly in the cable guide under the bottom bracket.

RubeRad

Also don't forget; make sure your shifter is in high gear (to correspond with a most-slack cable, and the derailler in the outboard, small-cog position).

Reynolds 

The cable must not be tight when in the smaller cog and with the adjuster fully in, just shouldn't have any play or slack. Then you tune it with the adjuster.

HillRider

The tool you are referring to is called a "Forth Hand" and is used, as you said, to place a cable under tension. A "Third Hand" tool compresses brake caliper arms to allow attaching the cable to the anchor bolt.

mozad655

I'm fiddling with the housing now and I found a problem with the adjusting barrel by the rear derailluer.. How far is it supposed to go in? It seems that I can only get it a couple of mm in before it seems stuck. How far in to the attachment hole is the adjusting barrel supposed to go in?

leob1

You must be as old as I am. Most of the youngens don't know what a third hand is, or how it's used.

RubeRad

I would guesstimate 5mm of travel for the barrel adjuster? Maybe more? Is it possibly cross-threaded?

If your threads are ruined, then I think your options are (a) dial in cable tension perfectly after many tries so you don't have to adjust it, or (b) look for an inline barrel adjuster solution. Nashbar's is pretty cheap.

RubeRad

Haha, well I'm 43, but I've always gotten by with just my two hands...

FBinNY 

Actually, I do the exact opposite. I start with the lever in high, and make sure all fittings are properly settled. Then I shift to low by pushing the RD in by hand and let it hang there. (it moves out partway, but that's OK) I then attach the wire loosely. When I pedal the RD shifts back to high, with wire slipping out through the under-tightened pinch bolt, leaving me with an almost perfectly adjusted cable.

Sometimes I need a bit more slack, which I can get by plucking the bare wire like a guitar string.

I find that this is easier than trying to pull out all the slack.

HillRider

Probably older. I have two different Third Hand tools and hardly ever use either. The last time was on a set of particularly recalcitrant cantilevers. I also have a Hozan Forth Hand tool that came along with a used bike I bought years ago. It's really useful for tightening zip ties.

leob1

That's pretty much what I use mine for. The third hand is used if I have to work on a pre 1980 bike.

RubeRad

Now that's clever! (And I'd expect nothing less from you FB) I will try that next time I happen to deal with an RD cable.

anixi

This is about the only way one can install a "Rapid-Rise" rear derailleur. I don't bother when it's a regular high-normal derailleur though. I put it in to highest gear(smallest cog) and pull on the cable with a pair of needle nose pliers and tighten the anchor bolt. It seldom fails to get me in the ball park.
If I find that the cable is still too short after cycling through the gears, I go back to highest gear and retighten the cable.
BTW, the slipping cable trick is good for brakes: I undo the QR on the brake and let it slip a little and then try the clearance between pads and rim. It's a good way for me to avoid a 3rd hand tool which I believe is really great for newbies. HTH!

mozad655

Allright, using the barrel adjuster by the shifter levers, i've managed to tighten up the cable. But weird thing is that where it normally would start changing gears, nothing happens now. I can push the levers as much as I want, doing so does tighten/loosen the wire, but for some reason the gear remains the same despite wire movement.

RubeRad

Cable needs to be tighter. If you pull the cable away from the downtube with your hand, you should see how the whole system works, cable causes the RD to move inboard, releasing cable lets RD spring move the RD outboard. Especially if chain is off all becomes clear.

Gotta get that slack out so that first movement of shifter pulls the RD over one gear.

wheelreason

I do something weird too, but I find it easiest and quickest.

I set the upper and lower limit screws sans cable as usual, then I screw the barrel adjuster all the way in, and back it out 1 1/2 turns.
now I move the dlr to the 2nd cog, and finger pull the cable and tighten it. That's it. Done. 90% of the time I don't even need to trim with the barrel adjuster. What I can't figure out (nor do I care to) is why it works equally well with everything from 7 to 11 speeds.

RubeRad

Yah, that's the kind of thing I meant with the limit screws, but I guess if you just push the RD over by hand to get the chain to hold it on the 2nd cog, that's easier.

sunburst

great description, and very timely for me. I've got to adjust a finicky XC Pro RD I just cleaned and reinstalled.

Grand Bois

I think you'll find that the excellent Shimano instructions that come in the package say about the same thing. I was impressed when I finally got around to reading them.