0
How to Upgrade Your Frame with Continuous Cable Routing
Riding your mountain bike in dusty conditions has an adverse affect on cable performance. Dust enters cable at their openings and ratchets itself all into the cable housing, impairing shifting and braking performance.
The mechanism for dust entering the cable is not by air movement but by ratcheting. Imagine the dust particles as roughly-shaped balls. The dust settles on the exposed inner cable and when the cable is actuated, is pulled into the outer cable. Once the cable is released, the relative movement between the inner and outer is different and the slack inner allows the dust that was initially moved in, to remain inside. With the next actuation it moves deeper inside and so on.
By the end of a four or five hour’s ride the dust easily penetrates up to 80 mm inside the cable. The dust and cable grease forms a sticky paste and your cable starts to perform poorly which in turn means your brakes and gears perform poorly.
With disjointed cable outers where the inners run nakedly along the bike’s frame, there are several points of entry, worsening the situation. By running one continuous cable outer all the way from your gear shifters or brake levers to the component itself, you eliminate most of the problem. Another way of improving cable performance is to fit ferrules with seals. Unfortunately the inner cable is not perfectly round but daisy-shaped and seals don’t fit perfectly around them, still allowing dust to enter and roll underneath. Some manufacturers make a brake cable ferrule that’s slightly longer than standard ones and feature a blank cavity at the end where the inner cable exits. This blank cavity prevents ratcheting of dust to a large extent.
Preparing your frame for continuous cable routing.
Things you should know
1) A botched procedure could harm your frame. Work carefully and methodically. The fastest way is not the best. Follow these procedures carefully and think before you do anything.
2) A successful procedure does not affect the structural integrity of your frame. Cable stops are welded onto the frame’s tubing and provide far more metal to work with than frame tubing. By filing and finishing off the hole for the cable you will eliminate stress risers that could propagate cracks. Sharp nicks should be rounded off and polished out.
3) A successful procedure will not void the guarantee on your frame NO MATTER WHAT THE MANUFACTURER TELLS YOU OR WRITES IN ITS DOCUMENTATION. The South African Consumer Protection Act makes it unlawful for the manufacturer to refuse a non-modification related guarantee. In other words, if you file your cable stops and a month later the frame cracks at the bottom bracket, the guarantee (whatever it was in its original form), will still be valid.
4) This is not a gonzo procedure valid only for hard-core MTBers who sleep in the bush and live off energy bars. It is a sensible procedure that should really become standard procedure in frame manufacturing. Naked cable routing is neater, doesn’t scratch the frame so much and weighs less.
5) Continuous cable routing is not perfect. The cables tend to rattle against the frame and scratch it. That’s life, you can’t have your cake and eat it. However, this is a MTB we’re talking about, not a pampered roadie machine.
Tools and consumables you’ll need.
1) A set of needle (rat tail) files. Can be purchased from good hardware shops for between R40 for a Chinese set to R400 for a set of Canadian Nicholson files.
2) Duct tape. This is to protect the frame.
3) A short piece of cable housing for continually testing the size of the hole. You may need gear and brake housing - they’re not the same diameter.
4) Cable cutter or side-cutter.
5) New cables – inner and length of outer housing.
6) Cable ferrules for finishing off the ends.
7) Workshop stand or girlfriend.
8) 6-pack of Windhoek Light.
Tools you should NOT use
1) Drill – electric, hand, air, atomic, whatever.
2) Angle grinder (not really needed unless you’re working on a Morewood or Ellsworth).
Why not just drill it?
2) Because a standard twist drill will get stuck in the existing slot on the cable stop and rip out, from the frame, a chunk of precious aluminium the size of a R5 coin.
OK, lets get cracking.
1) Remove the relevant cables. Loosen the anchor bolts on both the front and rear derailers and pull the gear cables right out and discard. Throw away the various bits and bobs of cable housing.
2) Stick a piece of duct tape either side of each cable stop and double up until you have an area of about 100mm covered each side of the stop. This is to protect the frame from scratches. Raleigh owners needn’t bother.
4) Constantly check if the hole is big enough for the cable housing. You want a tight fit to help eliminate rattle and scratch problems.
5) Once the hole starts to form, you’ll want to pick a round file and progress with that.
6) When the hole is the right size (tight fit for the cable housing), finish it off by rounding all edges and eliminating any sharp edges or grooves.
7) Go on to the next cable stop until you’ve done them all. Do not make the mistake of sizing a stop with a brake cable when you’ll be threading a gear cable through it and vice versa, they’re not the same size.
8) Now do the obvious, feed a length of cable outer from origin to destination, get your bend right at the handlebars, seat-stay and derailers. Cut the cable, finish off the edges, install the ferrules and feed through the inner cable.
9) Adjust your gears and brakes.
10) Go ride.
