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#1
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Problems with mechanical disc brake
I am currently building my new bike and have decided on mechanical disc
brakes (road version) from Avid with Ultegra STI levers. My problem now is that after doing all the adjustments the brakes felt rather soft (spongy?) - I could pull both levers all the way to the handle bar with only relatively weak effects. Seeing a lot of flexing in the brake cables, we replaced the housing (so far only for the rear brake) with housing from a shifting cable and found a marked improvement in performance. The brake acts much more directly and blocking the wheel was no problem (as I would have expected from the reviews I have seen). I checked back with AVID's web site and found they have a "compressionless Flak Jacket cable housing", however their (former) German distributor did not even know about this housing and expected any "normal" brake vable housing to work ... So my question would be if others had similar experiences and what kind of housing do you use? Thank you in advance for any help or suggestions Benno |
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#2
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Problems with mechanical disc brake
On Thu, 22 Jul 2004 09:34:32 +0200, Benno Pütz
wrote: I am currently building my new bike and have decided on mechanical disc brakes (road version) from Avid with Ultegra STI levers. My problem now is that after doing all the adjustments the brakes felt rather soft (spongy?) - I could pull both levers all the way to the handle bar with only relatively weak effects. Seeing a lot of flexing in the brake cables, we replaced the housing (so far only for the rear brake) with housing from a shifting cable and found a marked improvement in performance. The brake acts much more directly and blocking the wheel was no problem (as I would have expected from the reviews I have seen). I checked back with AVID's web site and found they have a "compressionless Flak Jacket cable housing", however their (former) German distributor did not even know about this housing and expected any "normal" brake vable housing to work ... So my question would be if others had similar experiences and what kind of housing do you use? Thank you in advance for any help or suggestions Shifter cable housing is not safe to use for brake cable; it can collapse under that much tension. It sounds like the first cable housing was merely a very poorly made type; there are many good ones available, and you can probably trust what is used by the people at your local bike shop. It's also possible that the calipers are improperly adjusted. Check the clearance between the fixed pad and the disc; if it's too large, the brakes will not fully engage despite large amounts of lever travel. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts. |
#3
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Problems with mechanical disc brake
On Thu, 22 Jul 2004 09:34:32 +0200, Benno Pütz
wrote: I am currently building my new bike and have decided on mechanical disc brakes (road version) from Avid with Ultegra STI levers. My problem now is that after doing all the adjustments the brakes felt rather soft (spongy?) - I could pull both levers all the way to the handle bar with only relatively weak effects. Seeing a lot of flexing in the brake cables, we replaced the housing (so far only for the rear brake) with housing from a shifting cable and found a marked improvement in performance. The brake acts much more directly and blocking the wheel was no problem (as I would have expected from the reviews I have seen). I checked back with AVID's web site and found they have a "compressionless Flak Jacket cable housing", however their (former) German distributor did not even know about this housing and expected any "normal" brake vable housing to work ... So my question would be if others had similar experiences and what kind of housing do you use? Thank you in advance for any help or suggestions Shifter cable housing is not safe to use for brake cable; it can collapse under that much tension. It sounds like the first cable housing was merely a very poorly made type; there are many good ones available, and you can probably trust what is used by the people at your local bike shop. It's also possible that the calipers are improperly adjusted. Check the clearance between the fixed pad and the disc; if it's too large, the brakes will not fully engage despite large amounts of lever travel. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts. |
#4
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Problems with mechanical disc brake
Werehatrack wrote:
On Thu, 22 Jul 2004 09:34:32 +0200, Benno Pütz wrote: I am currently building my new bike and have decided on mechanical disc brakes (road version) from Avid with Ultegra STI levers. My problem now is that after doing all the adjustments the brakes felt rather soft (spongy?) - I could pull both levers all the way to the handle bar with only relatively weak effects. Seeing a lot of flexing in the brake cables, we replaced the housing (so far only for the rear brake) with housing from a shifting cable and found a marked improvement in performance. The brake acts much more directly and blocking the wheel was no problem (as I would have expected from the reviews I have seen). I checked back with AVID's web site and found they have a "compressionless Flak Jacket cable housing", however their (former) German distributor did not even know about this housing and expected any "normal" brake vable housing to work ... So my question would be if others had similar experiences and what kind of housing do you use? Thank you in advance for any help or suggestions Shifter cable housing is not safe to use for brake cable; it can collapse under that much tension. I should have added that this was only done to allow a quick check of the suspicion mentioned, not as a long-term solution. It sounds like the first cable housing was merely a very poorly made type; there are many good ones available, and you can probably trust what is used by the people at your local bike shop. I actually build it at my LBS so I would not have questioned their choice of housing. It was the mechanic who suggested swapping the housing to see if anything would improve ... It's also possible that the calipers are improperly adjusted. Check the clearance between the fixed pad and the disc; if it's too large, the brakes will not fully engage despite large amounts of lever travel. I think I did that ... But I'll make sure to check it during my next visit, probably tomorrow. |
#5
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Problems with mechanical disc brake
Werehatrack wrote:
On Thu, 22 Jul 2004 09:34:32 +0200, Benno Pütz wrote: I am currently building my new bike and have decided on mechanical disc brakes (road version) from Avid with Ultegra STI levers. My problem now is that after doing all the adjustments the brakes felt rather soft (spongy?) - I could pull both levers all the way to the handle bar with only relatively weak effects. Seeing a lot of flexing in the brake cables, we replaced the housing (so far only for the rear brake) with housing from a shifting cable and found a marked improvement in performance. The brake acts much more directly and blocking the wheel was no problem (as I would have expected from the reviews I have seen). I checked back with AVID's web site and found they have a "compressionless Flak Jacket cable housing", however their (former) German distributor did not even know about this housing and expected any "normal" brake vable housing to work ... So my question would be if others had similar experiences and what kind of housing do you use? Thank you in advance for any help or suggestions Shifter cable housing is not safe to use for brake cable; it can collapse under that much tension. I should have added that this was only done to allow a quick check of the suspicion mentioned, not as a long-term solution. It sounds like the first cable housing was merely a very poorly made type; there are many good ones available, and you can probably trust what is used by the people at your local bike shop. I actually build it at my LBS so I would not have questioned their choice of housing. It was the mechanic who suggested swapping the housing to see if anything would improve ... It's also possible that the calipers are improperly adjusted. Check the clearance between the fixed pad and the disc; if it's too large, the brakes will not fully engage despite large amounts of lever travel. I think I did that ... But I'll make sure to check it during my next visit, probably tomorrow. |
#6
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Problems with mechanical disc brake
Benno P=FCtz wrote:
I am currently building my new bike and have decided on mechanical disc= =20 brakes (road version) from Avid with Ultegra STI levers. =20 My problem now is that after doing all the adjustments the brakes felt = rather soft (spongy?) - I could pull both levers all the way to the=20 handle bar with only relatively weak effects. =20 Seeing a lot of flexing in the brake cables, we replaced the housing (s= o=20 far only for the rear brake) with housing from a shifting cable and=20 found a marked improvement in performance. The brake acts much more=20 directly and blocking the wheel was no problem (as I would have expecte= d=20 from the reviews I have seen). This is potentially quite dangerous. Most modern shift housing uses=20 longitudinal wires, which makes it stiff, but not as strong as the=20 spiral-wound wire of traditional ("brake") housing. If you use indexed shift housing for a brake application, it will likely = work very well until it suddenly ruptures and the brake fails completely.= Check out my article on cables and cable prep: http://sheldonbrown.com/cables Sheldon "Sometimes You Need To Follow The Rules" Brown +----------------------------------------------------------+ | And what are all these mysteries to me, | | Whose life is full of indices and surds? | | x^2 + 7x + 53 | | =3D 11/3 --Lewis Carroll | +----------------------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide http://captainbike.com http://sheldonbrown.com |
#7
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Problems with mechanical disc brake
Benno P=FCtz wrote:
I am currently building my new bike and have decided on mechanical disc= =20 brakes (road version) from Avid with Ultegra STI levers. =20 My problem now is that after doing all the adjustments the brakes felt = rather soft (spongy?) - I could pull both levers all the way to the=20 handle bar with only relatively weak effects. =20 Seeing a lot of flexing in the brake cables, we replaced the housing (s= o=20 far only for the rear brake) with housing from a shifting cable and=20 found a marked improvement in performance. The brake acts much more=20 directly and blocking the wheel was no problem (as I would have expecte= d=20 from the reviews I have seen). This is potentially quite dangerous. Most modern shift housing uses=20 longitudinal wires, which makes it stiff, but not as strong as the=20 spiral-wound wire of traditional ("brake") housing. If you use indexed shift housing for a brake application, it will likely = work very well until it suddenly ruptures and the brake fails completely.= Check out my article on cables and cable prep: http://sheldonbrown.com/cables Sheldon "Sometimes You Need To Follow The Rules" Brown +----------------------------------------------------------+ | And what are all these mysteries to me, | | Whose life is full of indices and surds? | | x^2 + 7x + 53 | | =3D 11/3 --Lewis Carroll | +----------------------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide http://captainbike.com http://sheldonbrown.com |
#8
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Problems with mechanical disc brake
I have the avid for road on my bike. They work fantastically (very
strong). If you're having sponginess it sounds like the brake pads are not optimally aligned, if you can't get them close enough without rub on the pads, it could be that the rotor is warped (both of mine were warped from the manufacturer), they can be easily straightened with a set of pliers. Initial set up is not for the casual user or for a low quality LBS, these are precision parts and require expertise. I use stock (off the roll) housing for front and back, and I can lock the wheels like their glued to cement with one finger on each lever. "Benno Pütz" wrote in message ... I am currently building my new bike and have decided on mechanical disc brakes (road version) from Avid with Ultegra STI levers. My problem now is that after doing all the adjustments the brakes felt rather soft (spongy?) - I could pull both levers all the way to the handle bar with only relatively weak effects. Seeing a lot of flexing in the brake cables, we replaced the housing (so far only for the rear brake) with housing from a shifting cable and found a marked improvement in performance. The brake acts much more directly and blocking the wheel was no problem (as I would have expected from the reviews I have seen). I checked back with AVID's web site and found they have a "compressionless Flak Jacket cable housing", however their (former) German distributor did not even know about this housing and expected any "normal" brake vable housing to work ... So my question would be if others had similar experiences and what kind of housing do you use? Thank you in advance for any help or suggestions Benno --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.718 / Virus Database: 474 - Release Date: 7/10/2004 |
#9
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Problems with mechanical disc brake
I have the avid for road on my bike. They work fantastically (very
strong). If you're having sponginess it sounds like the brake pads are not optimally aligned, if you can't get them close enough without rub on the pads, it could be that the rotor is warped (both of mine were warped from the manufacturer), they can be easily straightened with a set of pliers. Initial set up is not for the casual user or for a low quality LBS, these are precision parts and require expertise. I use stock (off the roll) housing for front and back, and I can lock the wheels like their glued to cement with one finger on each lever. "Benno Pütz" wrote in message ... I am currently building my new bike and have decided on mechanical disc brakes (road version) from Avid with Ultegra STI levers. My problem now is that after doing all the adjustments the brakes felt rather soft (spongy?) - I could pull both levers all the way to the handle bar with only relatively weak effects. Seeing a lot of flexing in the brake cables, we replaced the housing (so far only for the rear brake) with housing from a shifting cable and found a marked improvement in performance. The brake acts much more directly and blocking the wheel was no problem (as I would have expected from the reviews I have seen). I checked back with AVID's web site and found they have a "compressionless Flak Jacket cable housing", however their (former) German distributor did not even know about this housing and expected any "normal" brake vable housing to work ... So my question would be if others had similar experiences and what kind of housing do you use? Thank you in advance for any help or suggestions Benno --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.718 / Virus Database: 474 - Release Date: 7/10/2004 |
#10
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Problems with mechanical disc brake
Benno Pütz writes:
Seeing a lot of flexing in the brake cables, we replaced the housing (so far only for the rear brake) with housing from a shifting cable and found a marked improvement in performance. The brake acts much more directly and blocking the wheel was no problem (as I would have expected from the reviews I have seen). Umm. Locking wheel is easy with dual pivots (one finger pressure is enough) and single pivots (might take two fingers). For that matter centerpulls, cantilevers and V-brakes can all lock of the rear wheel easily. |
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