Before you start: We’re addressing only road bikes here. (Mountain bikes, while similar, can present different problems and complexities.)
Shifter types: At this writing, there are three common road shifters in use; Campagnolo, Shimano, and Sram. There are some variations within each of these manufacturers. Before tackling a re-string, it is best to familiarize yourself with the correct procedure for your specific shifter.
NOTE: Technical data is not readily available for all shifter types and models. If you can not find the correct information for your specific product, you would be wise to seek assistance from a mechanic at your local shop. Hint: Be prepared to pay for this instruction. It will be worth the small investment.
Supplies (typical):
2 each shifter cables
2 each brake cables
Approximately six feet of shifter cable housing
Approximately six feet of brake cable housing
6 to 14 shifter housing ferrules
6 to 10 brake cable ferrules
2 shift cable end tips
2 brake cable end tips
Tools:
Cable cutter
Housing cutter
Metric Allen wrenches in 4mm, 5mm, and 6mm sizes.
Note: In some applications a 10mm combination wrench and/or a 9mm combination wrench may also be necessary.
“Third Hand” cable puller
File or (optional but really nice to have) bench grinder.
Now, here’s a good question: Did your bike ever work well with the old cables and housings? If the answer is “yes,” skip the next part, and go down to “Cutting and sizing.” If the answer is no, then you need to do some investigation, and possibly some careful measuring.
First, invert the bicycle, and look under the bottom bracket. You see there a thing called a “cable bridge” or cable guide. Is it filthy and partially clogged with spooge? Or is it possibly worn? If dirty, clean it, if worn, go get a replacement to have ready for when you take the old cables off.
Now look at your cable routing. Are any of the housings stretched way tight? (Too short.) Or are housings possibly looped way out and too long? This is your opportunity to correct either of these situations.
Cutting and sizing:
NOTE: If you haven’t done this before, it’s a good idea to replace the cables one at a time. That way there is less chance of confusing the routing of each cable.
Take the appropriate housing (brake or gear) and lay it alongside the existing one on the bike. This measures the housing. Now cut to length.
For brake housings: After cutting, inspect the ends of the housing. Likely there is a curl of the metal jacket bent inward. Use a file or bench grinder to grind the end flat, smooth, and free of intruding curls of metal. Then open the hole with a sharp pointed tool, such as a scratch awl.
For gear housing: The supporting metal jackets in gear housing run along the length of the housing, so there will not be an intruding curl of metal. However, it is not unusual for the cutting process to close the inner liner off. Again, use a sharp pointed tool to open the inner liner.
Once the housings have been cut to size, go to the next step.
Removing the old cables: Cut the ends off of the old cables. Loosen the pinch bolts at the derailler or brake. Go ahead and cut the cable in as many places as is convenient. Remove the old bar tape (if necessary. See LINK for this process.) Remove the old cable and housing.
Install the new cable in the control. Follow the manufacturer’s procedure for this.
Install the ferrules on the Ends of the housing. Notice, not all housing ends require ferrules. Let the old housings be your guide in this.
Thread the cable through the front most housing.
Move the housing into the appropriate receptacle in the control.
Insert the housing into the appropriate cable stop on the frame.
Shifter cables:
- Front Derailler cable: In almost all applications there will be only one housing, going between the control and a cable stop on the frame. Then the control wire runs freely, down to the left hand channel in the “bridge” below the bottom bracket. As the wire exits the rear of the bridge, it will go up and be secured under the pinch bolt of the front derailer:
- Rear Derailer cable: In a typical application, the cable will go through a housing between the control and the cable stop on the frame. Then it runs freely along the frame to the right hand channel of the “bridge.” Usually, after the cable exits the rear of the bridge, it will travel back along the underside of the right chain stay. Then it is threaded into a housing section. This section is fitted into a cable stop, forward of the rear derailler. The rearward end of the housing fits into an adjuster barrel on the rear derailer. The cable goes through this adjuster barrel, and then under the pinch bolt.
Brake Cables:
- Front Brake: This cable is ordinarily attached to the left brake lever. Follow the manufacturer’s procedure for inserting the cable into the brake lever. Run the cable through the housing. The housing will stop in the receptacle in the front brake lever. Then the housing will be secured against he handlebar. Finally, the cable is threaded through the adjuster barrel or the front brake, and then the housing is inserted into the adjuster barrel. The cable is secured under the front brake pinch bolt.
- Rear Brake: This cable is ordinarily attached to the right brake lever. As with the front brake, insert the cable into the lever by following the manufacturer’s recommended procedure. Then thread the cable into the housing, and the housing into the receptacle in the control lever. The housing will run along the handlebar, and then to a cable stop on the frame. The cable then runs feely along the frame, until it is threaded into a rear housing section. This housing is then fitted into the rear cable stop, on the frame. The cable, emerging from the rear housing section, is fed through the adjuster barrel on the rear brake, and then the housing is inserted into the adjuster barrel. Finally the cable is secured under the breare brake pinch bolt.
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