Sticky brakes

[Tin Pot]

I seem to be suffering this on two bikes now, fixed the first by replacing the entire brake caliper.

The one I'm complaining about now is new though, TRP rear brake for Argon18. It's a weird caliper on the underside of the chainstays. Internal cabling, through a steel bend that hold the calipers together. A bit like this:

It had a new gear cable, but I've replaced it partly to see if it fixed this, partly because it was already fraying.

I've played with all the screws I can, but the only effect is to clamp the wheel tighter. I have to push the right brake out to 'reset' it.

It seems to be the right brake pad primarily but neither release. The right brake pad holder has a screw that levers the pad closer or further from the rim. And another screw I can't figure out what it does.

I'm down to thinking it's the cable sticking somewhere, but I've straightened the cabling and the spring functions on the brake arms it just doesn't seem to be strong enough.

Any ideas?

 

[Tim Hall]

Does it spring open if you remove the cable? If yes, that points to a cable issue. If no, the pivots on the brake are the main suspect. Take it apart, taking photos as you go, clean it all up, dob a bit of grease in obvious places and reassemble, referring to the photos you took earlier.

 

[Tin Pot]

Does it spring open if you remove the cable? If yes, that points to a cable issue. If no, the pivots on the brake are the main suspect. Take it apart, taking photos as you go, clean it all up, dob a bit of grease in obvious places and reassemble, referring to the photos you took earlier.

Yes it springs open.

The cable is new Campag, prelubed.

The outer is new, steel, Clark.

Bike has never been ridden bar on a turbo.

 

[Yellow Saddle]

Is the brake in question a bit like the one in the photo or exactly like the one in the photo. I'm after whether it is a V-brake or a cam brake.

 

[Tin Pot]

Is the brake in question a bit like the one in the photo or exactly like the one in the photo. I'm after whether it is a V-brake or a cam brake.

The only difference I can see is that there is no cabletie added to mine.

Could it be the Clark steel outer itself? (Also new) its routed through the aero bar out and into the body then out as you see in that photo.

 

[Yellow Saddle]

The only difference I can see is that there is no cabletie added to mine.

Could it be the Clark steel outer itself? (Also new) its routed through the aero bar out and into the body then out as you see in that photo.

OK, you have to start isolating things.
Release the cable from its anchor bolt on the brake caliper. Have someone hold the bike for you and crouch down next to the bike on the side where your back brake sits. Now pull on the cable at the bottom and manipulate the lever at the bar. The movements should be smooth. It will be a bit tricky to do because the noodle is loose. Perhaps just pull the noodle down and work with the cable directly out of the housing. However, the noodle is a big suspect, so try and assess it with the noodle in place. You may need 4 hands. Once you are happy with the cable's performance - it must be ABSOLUTELY smooth (which is not something I associate with Clarks products BTW). The noodle's nylon liner must be intact and slide smoothly as well. Now move to the levers. Manipulate them and see if they move freely on their pivots. If not, remove, clean and grease. The problem has to be within those two things you've now tested.

Some general notes. Brakes in that position are always troublesome. One reason is obvious - it is close to road grime although yours has been on a trainer. Secondly, a trainer is bad news for bicycles. You sweat a lot on trainers and sweat destroys cables, bearings, seatposts, handlebars (yes, even under the tape) and paintwork. It is imperative to keep sweat off the bike. Your brakes are neatly in place for sweat dripping down the downtube and seat tube, to settle and eat away.
The third problem is the awkward angles of the cable and noodle in that confined space. It is not optimal at all.

 

[Tin Pot]

OK, you have to start isolating things.
Release the cable from its anchor bolt on the brake caliper. Have someone hold the bike for you and crouch down next to the bike on the side where your back brake sits. Now pull on the cable at the bottom and manipulate the lever at the bar. The movements should be smooth. It will be a bit tricky to do because the noodle is loose. Perhaps just pull the noodle down and work with the cable directly out of the housing.

Yep did this last night, it's smooth but not effortless.

However, the noodle is a big suspect, so try and assess it with the noodle in place. You may need 4 hands. Once you are happy with the cable's performance - it must be ABSOLUTELY smooth (which is not something I associate with Clarks products BTW). The noodle's nylon liner must be intact and slide smoothly as well.

Threading through the noodle is a hassle, the first few times I couldn't do it at all and had to removed the liner first then replace it. Now I can force a cable through without doing that with firm pressure.

You could be right, I'll focus on this.

Now move to the levers. Manipulate them and see if they move freely on their pivots. If not, remove, clean and grease. The problem has to be within those two things you've now tested.

Yes they're new and fine, smooth. The lever clicks back but the cable pokes out as though not under tension.

Some general notes. Brakes in that position are always troublesome. One reason is obvious - it is close to road grime although yours has been on a trainer. Secondly, a trainer is bad news for bicycles. You sweat a lot on trainers and sweat destroys cables, bearings, seatposts, handlebars (yes, even under the tape) and paintwork. It is imperative to keep sweat off the bike. Your brakes are neatly in place for sweat dripping down the downtube and seat tube, to settle and eat away.
The third problem is the awkward angles of the cable and noodle in that confined space. It is not optimal at all.

Agreed - the brake has housing to cover all the moving parts.

The bike is covered in towelling on the turbo, and I usually have a deprecate towel for my face.

It is An Embuggerance that's for sure, I may have underestimated the various finicky b'stard
things involved with tri bikes. Had my fitter help out on a few things, which cleared up some lack of knowledge on my part, but sadly didn't ask him to look at the brakes. Doh.

 

[Tin Pot]

Hmm, so further testing I think I need to lubricate the noodle somehow.

1. I detached the brake and connected it only to the right brake - that works fine.

2. I remove the noodle, removed the liner, threaded it through again and pulled against the brake lever operation. Removing the liner was no different.

3. I connected both callipers, and get the problem again.

4. In that state, all together, I manually pressed the brake callipers together. They released fine.

What should the noodle liner be lubed with?

 

[Yellow Saddle]

Hmm, so further testing I think I need to lubricate the noodle somehow.

1. I detached the brake and connected it only to the right brake - that works fine.

2. I remove the noodle, removed the liner, threaded it through again and pulled against the brake lever operation. Removing the liner was no different.

3. I connected both callipers, and get the problem again.

4. In that state, all together, I manually pressed the brake callipers together. They released fine.

What should the noodle liner be lubed with?

Any grease will do, but once you grease it, you'll have to grease it frequently since grease in that position will get contaminated and, the nature of a cable moving in a sleeve doesn't replenish grease. In other words, in high pressure spots it will be sliding dry after just a few uses of the brake. The grease continuously move away from those spots and can't be replenished. That's why those liners are made from soft, smooth material that doesn't require grease.

However, you are caught between a rock and a hard place. The sharp bends and high tension in the brake cable in that noodle area requires less friction than what a good noodle can deliver.

I used to treat those by frequently replacing the noodle or manufacturing a new noodle liner from cable liner used in frames where the cables run internally. This liner tubing can be purchased in lenghts. Unfortunately the liner in a noodle isn't just a piece of tubing, but it is flared at the one end. I used a hot instrument to shape it.

 

[Tin Pot]

Any grease will do, but once you grease it, you'll have to grease it frequently since grease in that position will get contaminated and, the nature of a cable moving in a sleeve doesn't replenish grease. In other words, in high pressure spots it will be sliding dry after just a few uses of the brake. The grease continuously move away from those spots and can't be replenished. That's why those liners are made from soft, smooth material that doesn't require grease.

However, you are caught between a rock and a hard place. The sharp bends and high tension in the brake cable in that noodle area requires less friction than what a good noodle can deliver.

I used to treat those by frequently replacing the noodle or manufacturing a new noodle liner from cable liner used in frames where the cables run internally. This liner tubing can be purchased in lenghts. Unfortunately the liner in a noodle isn't just a piece of tubing, but it is flared at the one end. I used a hot instrument to shape it.

Now that's going to be a hassle

Cheers though.

I'll try the manufacturers, this doesn't seem to have been experienced by other owners.

 

[Yellow Saddle]

Now that's going to be a hassle

Cheers though.

I'll try the manufacturers, this doesn't seem to have been experienced by other owners.

Ha. I think you won't find a single owner who hasn't had trouble with those brakes. And if they say they haven't, they are simply too mechanically insensitive to know there is a problem.

 

[Tin Pot]

Ha. I think you won't find a single owner who hasn't had trouble with those brakes. And if they say they haven't, they are simply too mechanically insensitive to know there is a problem.

Well I've seen complaints on adjusting them and stopping power, but not in getting them functioning whatsoever!

Thought I'd be able to resolve this this morning and ride. TT on thursday.

Might call an LBS, although they're all road focussed.

 

[Yellow Saddle]

Well I've seen complaints on adjusting them and stopping power, but not in getting them functioning whatsoever!

Thought I'd be able to resolve this this morning and ride. TT on thursday.

Might call an LBS, although they're all road focussed.

How can anybody complain about them stopping the bike when they can easily be locked-up, skidding the wheel? If you can't skid the wheel with them then there's something seriously wrong. They modulate/operate poorly and erratically but stop as expected.