2bridges1bike

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!

shelbyfv

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.

ARider2

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?

2bridges1bike

Yes I replaced the inner cable and outer housing. There is an unavoidable sharp bend at the bottom bracket due to the internal routing. Stops are secure.

The rotor is one year old, and has been used for about 2,000 miles of outdoor riding.

2bridges1bike

That is a good way to look at it, as a feature and not a flaw. I would feel a bit more confident on descents if the brake lever felt tighter though.

andrewclaus

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.

HillRider

+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?

Andrew R Stewart 

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)

2bridges1bike

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

2bridges1bike

Yes, I even tried closing the pads to the point were there was a slight rub in the rotor pads. It didn’t help much.

2bridges1bike

That is an interesting idea, may try it out if all else fails

Andrew R Stewart 

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)

'02 nrs

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?

DaveSSS 

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.

FastJake

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.

2bridges1bike

no flex in the lever though the pads could be a bit more ever soooo slightly more parallel, how would you adjust this?

Not sure what you mean regarding the cable housing ends being off

2bridges1bike

Interesting suggestion to use feeler gauges. Any thoughts if upgrading to the hybrid hydraulic calipers might resolve this issue?

2bridges1bike

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

tyrion

On IS mounted brakes, loosen the caliper bolts a little, squeeze the brakes levers, then tighten calipers back down with lever squeezed.

'02 nrs

[QUOTE=

Not sure what you mean regarding the cable housing ends being off[/QUOTE] see pic;

https://www.sheldonbrown.com/cables.html

Pop N Wood

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.

Geepig

If there is a sharp turn, maybe compressionless is not the answer?

rosefarts

Is it solid housing or is there a cable stop entering and exiting the frame?

DaveSSS 

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.

2bridges1bike

no cable stop