Trek 820 rear brake cable replacement
12-31-17, 08:15 AM
#1
Trek 820 rear brake cable replacement
I have a mid 1990s Trek 820 (steel frame and rigid steel fork).
I want to replace the rear brake cable which is different from most as a single cable which splits into 2 cables at the rear triangle, one cable to each caliper. One of the cables is in a jacket.
Anyone know where I can find it online?
Thanks in advance.
I want to replace the rear brake cable which is different from most as a single cable which splits into 2 cables at the rear triangle, one cable to each caliper. One of the cables is in a jacket.
Anyone know where I can find it online?
Thanks in advance.
12-31-17, 09:28 AM
#2
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12-31-17, 10:34 AM
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12-31-17, 10:44 AM
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The split cable portion is really two different parts. The primary cable runs from the lever and into the link wire's "button". It takes a turn and then runs to the end on one canti arm (where there's an anchor bolt to clamp it). The second leg of the split is a short length of cable (the link) which runs from the "button" to the other canti arm end (where there's a hook to grab the cable end, like happens at the lever too).
These link wires come in a variety of sizes, different lengths of the link. This allows for fine tuning the cable pull and canti geometry as well as fitting around the bike's limitations (as in a small bike will need shorter link wires at the rear brake then a taller bike can use). Sometimes there's a letter (A, B, C and D) denoting the length differences. Either matching your old or dry testing one and then judging the best other sixe are the usual way to chose the best length.
Every bike shop I've worked in (or owned) have many of these on their shelves. We exchange them during repairs to achieve the best braking action and still fit the bike's dimensional limitations. We currently charge about $5 for over the counter sales but generally just even exchange them for repairs.
A straddle cable is a design where the primary cable stops at the "button", which is now better described as a clip with a cable anchor bolt and a hook for the straddle cable to grab onto with. The straddle cable runs from the hook ended canti arm, up to the pull up clip (straddle cable carrier), turn the corner at the clip and run down to the second canti arm and it's anchor bolt.
Both designs can work equally well. The link wire is an attempt to speed up assemble and reduce the set up range of the geometry. Shimano saw the need to reduce the ability to screw this up, as it is inexperienced assembly mechanics (as in most recently hired at the low end of the pay scale) that are commonly the people assembling bikes these days. Andy
These link wires come in a variety of sizes, different lengths of the link. This allows for fine tuning the cable pull and canti geometry as well as fitting around the bike's limitations (as in a small bike will need shorter link wires at the rear brake then a taller bike can use). Sometimes there's a letter (A, B, C and D) denoting the length differences. Either matching your old or dry testing one and then judging the best other sixe are the usual way to chose the best length.
Every bike shop I've worked in (or owned) have many of these on their shelves. We exchange them during repairs to achieve the best braking action and still fit the bike's dimensional limitations. We currently charge about $5 for over the counter sales but generally just even exchange them for repairs.
A straddle cable is a design where the primary cable stops at the "button", which is now better described as a clip with a cable anchor bolt and a hook for the straddle cable to grab onto with. The straddle cable runs from the hook ended canti arm, up to the pull up clip (straddle cable carrier), turn the corner at the clip and run down to the second canti arm and it's anchor bolt.
Both designs can work equally well. The link wire is an attempt to speed up assemble and reduce the set up range of the geometry. Shimano saw the need to reduce the ability to screw this up, as it is inexperienced assembly mechanics (as in most recently hired at the low end of the pay scale) that are commonly the people assembling bikes these days. Andy
01-01-18, 01:58 PM
#6
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Also , on the front wheel of cantilever brake mountain bikes , when the main cable broke , the transverse/straddle cable comes down on the tire,
Powered by both return springs .. and was enough to stop the wheel.. the other one, the brake fails open.. not flinging you over the bars..
Powered by both return springs .. and was enough to stop the wheel.. the other one, the brake fails open.. not flinging you over the bars..
