flyingcamel2021

Hello everyone.

My bike is a road bike with dual-pivot caliper brakes and concealed cabling. I recently replaced my brake cables with Jagwire Road Pro cables.

Now my front brake works fine, but only one caliper of my rear brake moves, the other caliper is stuck.

I think that the problem is that the cable housing is too stiff, the cable housing emerges from the top tube and immediately goes into the caliper arm, which doesn't leave enough housing outside to allow it to flex, thus not allowing the other arm to move. If the cable housing was more flexible, then I think that both arms could move independently. As a temporary fix, I've forcibly bent the brake cable with a cable tie. This helps a bit by increasing the bend in the cable housing. if I hold the cable right next to the top tube and pull the brake lever, both arms move.

So, I'd like to know if there's any way to fix this problem without cable ties and other quick fixes? Would running the cable housing through the top tube help? Or should I try to find a more flexible cable housing? Or should I try to increase the length of cable housing from the top tube to the caliper arm?

I tried to upload a photo but it won't allow me since I'm a new user.

Andrew R Stewart 

"Or should I try to increase the length of cable housing from the top tube to the caliper arm?"

This is the first thing I think of. Andy

dsbrantjr

This is one of the many downsides and few (to me) upsides of through-the-frame cable routing. Call me old-fashioned....

oldbobcat

The last one. The cable stops or ferrules at the ends of the top tube will prevent the first one, and quality housing is pretty similar in flexibility anyway.

This means, of course, you will need to replace the truncated cable with a new one. I find an old spoke to be invaluable for fishing out the end of the cable and threading it through the hole in the frame. Also, you can get plastic "cable liner" tubing to guide the new cable through the frame. And while you have the brake cable disconnected, clean the caliper pivots thoroughly, lubricate with a couple drops of light oil, and center the centering screw(s).

flyingcamel2021

Thanks everyone, the problem is solved. I took it to the most experienced cycle mechanic I could find. He took apart the rear brake, cleaned everything up and put it back together. I don't know what exactly he did but both arms pivot now.

jgwilliams

Yes, I've had exactly the same. It's probably been like that for a while and you didn't notice until you installed the new cables.

mikeonbicycle

you can improve these dual pivot brakes,older types and even brand new ones,,my new brakes were spongy out of the box new so i decided to take them apart for a tune up,i replaced all nylon spacers with metal ones,greased up all pivot points,and put in a smaller spring,now i have very nice brakes,Should not have to do this stuff with brand new brakes but like everything else they cut costs,those black nylon washers crush and split and causes these brakes to stick even when new,the two major adjustments on these types of brakes are the long bolt and the shorter side bolt,if either of these bolts are too tight the brake will not even work,there is not much else to them really

FBinNY 

Disconnect the cable and hold it in your fingertips in the same place as it meets the brake. Now be the upper arm and move down as it would.

Doing this, experiment with loop distances to find the one that resists least. That's the sweet spot.