Compressionless housing did not fix spongy cable disc brake
#1
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Compressionless housing did not fix spongy cable disc brake
Hello All
I just installed compressionless brake housing on my alloy Synapse. It completely got rid of of sponginess in my front brake, but didn’t help much with my rear brake. Are there any other options to help eliminate the sponginess in the rear brake?
The brake cable is internally routed and hooks up to a brand new trp spyre disc brake caliper. The housing is Jagwire KEB-SL
Thanks All!
I just installed compressionless brake housing on my alloy Synapse. It completely got rid of of sponginess in my front brake, but didn’t help much with my rear brake. Are there any other options to help eliminate the sponginess in the rear brake?
The brake cable is internally routed and hooks up to a brand new trp spyre disc brake caliper. The housing is Jagwire KEB-SL
Thanks All!
Last edited by 2bridges1bike; 12-29-20 at 06:28 AM.
#2
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I had those brakes and liked them. If everything is set up properly, it's probably the length of the cable causing the different feel front/rear. Not much to do about that. Spongy rear brake may save you from an embarrassing lock up. You could think of it as a feature rather than a fault.
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Assuming you replaced the inner cable and outer housing and you made sure connections are secure at all cable stops including where the housing meets up with the shifter. Also make sure there are gentle bends in the cabling rather than sharp turns. Finally, what is the age and condition of the rotor and brake pads?
#4
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Assuming you replaced the inner cable and outer housing and you made sure connections are secure at all cable stops including where the housing meets up with the shifter. Also make sure there are gentle bends in the cabling rather than sharp turns. Finally, what is the age and condition of the rotor and brake pads?
The rotor is one year old, and has been used for about 2,000 miles of outdoor riding.
#5
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I had those brakes and liked them. If everything is set up properly, it's probably the length of the cable causing the different feel front/rear. Not much to do about that. Spongy rear brake may save you from an embarrassing lock up. You could think of it as a feature rather than a fault.
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A few too many inches of housing from the lever to the frame may make a difference in feel. A loop can be too long, causing an unneeded change in direction.
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OP: Have you adjusted the pad/rotor clearance and alignment to minimize brake lever travel without rubbing?
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I would suggest an experiment- Run an external housiinged cable to the rear brake. Compare it's feel to the internal one. Then choose which you like and go with that. Andy (who really dislikes internal cable routing)
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AndrewRStewart
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#9
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The housing length is probably a bit in the short side, although I may take it to the lbs to get a second opinion of all else fails
#10
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+1 I have the same brakes and housing on a Surly Midnight Special with, fortunately, external cable routing. I was careful to minimize the cable run to the rear brake to just long enough to allow the bars to turn fully without pulling on the housing. Yes, the rear doesn't have quite the firm feel as the front but it's plenty solid.
OP: Have you adjusted the pad/rotor clearance and alignment to minimize brake lever travel without rubbing?
OP: Have you adjusted the pad/rotor clearance and alignment to minimize brake lever travel without rubbing?
#11
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That is an interesting idea, may try it out if all else fails
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2b1b- Thanks. I have used this type of alternative set up suggestion over the years for various problems and have found it sadly interesting how many people are reluctant, hesitant or unable to consider an experiment that they can do with no one else's help.
Like when one is young and wanting to spell a word. Mother says "look it up in the dictionary". Which is, of course, is about learning how to find answers then actually how to spell any one word. Andy (who still doesn't spell or write too well but thinks he get's his ideas out there just the same)
Like when one is young and wanting to spell a word. Mother says "look it up in the dictionary". Which is, of course, is about learning how to find answers then actually how to spell any one word. Andy (who still doesn't spell or write too well but thinks he get's his ideas out there just the same)
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flex?
while squeezing the lever look at the caliper.does it flex? are the pads centered to the rotor-each moving the same distance?are the pads parallel to the rotor? are the cable housing ends squared off?
#14
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I use feeler gages to be sure that both pads have the same clearance, to within .002 inch. I use Juin-Tech GT-F hydraulic/mechanical calipers that adjust on both sides, as pad wear occurs. The cable tension knob still has to be adjusted occasionally, to compensate for wear. My frames have internal routing with a housing conduit that runs above the spindle axle. The housing pushes in from the top tube to the chainstay, with a firm push. I have tried both yokozuna reaction and jagwire pro housing and prefer the jagwire, but neither is spongy.
#15
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Full-length housing is stupid and so are disc brakes. This combination will always feel less firm on the rear with a mechanical brake. Fortunately, the rear brake doesn't have a big job to do.
#16
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Not sure what you mean regarding the cable housing ends being off
#17
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I use feeler gages to be sure that both pads have the same clearance, to within .002 inch. I use Juin-Tech GT-F hydraulic/mechanical calipers that adjust on both sides, as pad wear occurs. The cable tension knob still has to be adjusted occasionally, to compensate for wear. My frames have internal routing with a housing conduit that runs above the spindle axle. The housing pushes in from the top tube to the chainstay, with a firm push. I have tried both yokozuna reaction and jagwire pro housing and prefer the jagwire, but neither is spongy.
#18
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Yes it makes sense that the rear would feel less firm, but it’s a huge difference and others here, who I hope learn from, have been able to resolve this issue
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squared off housing end.
[QUOTE=
Not sure what you mean regarding the cable housing ends being off[/QUOTE] see pic;
https://www.sheldonbrown.com/cables.html
Not sure what you mean regarding the cable housing ends being off[/QUOTE] see pic;
https://www.sheldonbrown.com/cables.html
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that is exactly what I do with my spyre brakes. Centers them perfectly every time, super quick and easy. Much easier to set up than the BB7's on my other bikes.
#24
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Another problem that can occur is the stiff cable housings fouling up the caliper centering and angle. I centered my calipers without the cables, actuating the lever by hand, then inserted the housing into the caliper. With the very stiff housing, this can be difficult.
I found that sqeezing the brake lever with the cable attached did not work because the rotors are not very stiff from side to side and the cable housing pushed with enough force to move the caliper.
Changing to hydraulic calipers is not likely to solve the problem and they are pricey at $250 for a pair of GT four piston calipers. I suspect the problem is mistaking freeplay for spongy.
I found that sqeezing the brake lever with the cable attached did not work because the rotors are not very stiff from side to side and the cable housing pushed with enough force to move the caliper.
Changing to hydraulic calipers is not likely to solve the problem and they are pricey at $250 for a pair of GT four piston calipers. I suspect the problem is mistaking freeplay for spongy.
Last edited by DaveSSS; 12-30-20 at 02:28 PM.
#25
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