t-cycle
07-02-05, 02:25 AM
Including the obvious, like cracked or broken cables, what are other signs for the need to replace a cable? Thanks.
Bicycle Mechanics - Cable Concerns
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Wordbiker
07-02-05, 03:03 AM
Simple: Poor function. Cables are always pulled in one direction by hand pressure, and by spring pressure for the return. If they don't return easily, try the following:
For derailleur cables, shift to your largest cog or chainwheel, and without turning the cranks, shift all the way back again. This should give you enough slack to release the cable housings from slotted braze-on stops. Now slide the freed housing back and forth and check for any snagging. Inspect the inner cable for rust, fraying or kinks. You may want to replace it if you find any. For brake cables, just release the brake at the wheel and use the same procedure.
For housing, replace if it is cracked, kinked or broken. Also pull the ferrules and inspect the ends of the housings. Shimano SIS cables are a bundle of longitudinal wire strands. If these are not flush with the end, they can intrude into the inner wire hole in frame bosses and cause binding. Brake housings cut at an angle will kink and bind the inner wire when the brake lever is pulled, even if ferrules are used. For the cleanest cut possible with any cable housing, use a Dremel cutoff wheel, or file them down after cutting with a cable cutter, and reshape the inner lining with a small awl before replacing ferrules.
I like to use Moly Disulfide lubes for cables, but use your favorite "dry" lube before placing all the ferrules back into the bosses.
For derailleur cables, shift to your largest cog or chainwheel, and without turning the cranks, shift all the way back again. This should give you enough slack to release the cable housings from slotted braze-on stops. Now slide the freed housing back and forth and check for any snagging. Inspect the inner cable for rust, fraying or kinks. You may want to replace it if you find any. For brake cables, just release the brake at the wheel and use the same procedure.
For housing, replace if it is cracked, kinked or broken. Also pull the ferrules and inspect the ends of the housings. Shimano SIS cables are a bundle of longitudinal wire strands. If these are not flush with the end, they can intrude into the inner wire hole in frame bosses and cause binding. Brake housings cut at an angle will kink and bind the inner wire when the brake lever is pulled, even if ferrules are used. For the cleanest cut possible with any cable housing, use a Dremel cutoff wheel, or file them down after cutting with a cable cutter, and reshape the inner lining with a small awl before replacing ferrules.
I like to use Moly Disulfide lubes for cables, but use your favorite "dry" lube before placing all the ferrules back into the bosses.
neil0502
07-02-05, 10:28 AM
Including the obvious, like cracked or broken cables, what are other signs for the need to replace a cable? Thanks.
No sarcasm intended here, but . . . if you're asking (and without refering to your other post for more detail), I'd just replace 'em. New cables are cheap.
Just a thought....
No sarcasm intended here, but . . . if you're asking (and without refering to your other post for more detail), I'd just replace 'em. New cables are cheap.
Just a thought....
MudPie
07-02-05, 10:42 AM
Basically, I replace cables when the shifting action is no longer smooth. There seems to be a point where I can feel excessive drag, slow response, and just general poor performance. For me (mountain biking) I replace them about once a year. I replace them before there is any physical damage to the cable. I guess I look at cables as a maintenance item.
With new cables, you'd be amazed at the difference!
Wordbiker gives some great tips.
With new cables, you'd be amazed at the difference!
Wordbiker gives some great tips.
Michel Gagnon
07-02-05, 07:03 PM
I think the Original Poster had all the reasons for replacing cables in his post: broken strands, frayed cable...
Basically, two points are worth checking : near the shifter and where the cable is bolted into the derailleur.
Another cause for concern : if the cable or housing was kinked, either because it was misrouted or used improperly. In that case, I remove the cable from its housing and remove the kink. So far, I observed that problem in a 20-year old bike where the brake housing was squashed during a repair (non-aero lever), and on 2 or 3 friends' bikes that I repaired. Only once did I need to replace the housing and cable.
As for not-smooth operation, it's often related to rust. I remove the cable from its housing, scrub it with fine-grit sandpaper, oil it and re-insert it. Most times, it works.
Basically, two points are worth checking : near the shifter and where the cable is bolted into the derailleur.
Another cause for concern : if the cable or housing was kinked, either because it was misrouted or used improperly. In that case, I remove the cable from its housing and remove the kink. So far, I observed that problem in a 20-year old bike where the brake housing was squashed during a repair (non-aero lever), and on 2 or 3 friends' bikes that I repaired. Only once did I need to replace the housing and cable.
As for not-smooth operation, it's often related to rust. I remove the cable from its housing, scrub it with fine-grit sandpaper, oil it and re-insert it. Most times, it works.