Zoom mechanical disc brake question

[John F]

I have just replaced my Zoom pads with Clarks VX organic disc pads.

Despite my carefully setting them up, they are the same as the original in terms of performance, ie a bit spongy and not especially powerful.

Is this to be expected or is there a different type of pad that would improve things?

 

[trex]

Usually, it's the flex in the outer cable or the worn crimps at the end of the outer cable that make the brakes feel spongy. You can check if the outer cable moves when you squeeze the brakes.

two factors improve disc brakes performance: degreasing the rotor and make sure that the caliper is lined up so the pads are perfectly parallel to the rotor.
I usually remove the caliper from the frame, clean and degrease the rotor with soap and hot water then adjust the fixed side so that the gap between the two pads are about 3mm before refitting. Don't tighten the allen bolts right away, squeeze the brakes so that the pads line themselves to the rotor first. Make sure that the rotor is in the middle of the gap before tightening.

 

[Deleted member 4366]

What did you do to set them up carefully? Watch the disc in the caliper as you pull the brake. If it moves sideways, you haven't set it up correctly.

 

[Alan Quay]

+1 for degreasing the rotor. If you installed the pads on a greasy rotor, you may need to remove them and give the a rough up with sand paper.

Then you need to bed them in. Get the bike up to 15mph, and brake hard as you can. Come to a complete stop. Repeat 10 times. The heat will get them bedded into the rotor.

 

[John F]

I spent a long time setting them up, and think they were spot on. i.e. fixed pad as close as possible to the rotor then tweaking the moving one. I also centred them by applying the brake with the callipers loose.

Rotor is in good nick, and cleaned with turps first.

I suspect it's simply the cable, though having done a few miles yesterday it does seem to have improved in this respect somewhat.

This only leaves a nagging worry that it may not be as powerful as I anticipated in an emergency, so I wonder whether there is simply a "better" pad available for my brake?

 

[trex]

ceramic pads are best, then sintered, then organic.
So, next step up is sintered.

 

[Deleted member 4366]

Sounds like you've done everything right, but the proof is whether you can see the disc move. You didn't mention that!

If the disk doesn't move significantly, then you should try sintered pads. Alternatively, upgrade to a hydraulic one. This one should sort you out. You don't need a brake switch because you have one on the back brake.

http://www.chainreactioncycles.com/avid-elixir-1-disc-brake-2014/rp-prod67752?utm_source=Google&utm_medium=Shopping&utm_name=UnitedKingdom&gclid=CjgKEAjwwuqcBRCSuoivmIPnkwQSJACpqj3kPYU1Oz_wQfgleeRv1AnMLI7SkRWcjccJZog9MIl61fD_BwE&gclsrc=aw.ds

 

[trex]

+1 for d8veh's suggestion of hydraulic upgrade.
hydraulic brakes are not luxury if you ride over 15mph. You'll never want to go back to cable operated brakes again.

 

[Geebee]

I don't understand the issues people have with cheap mechanical disc brakes, I have an MTB that if you followed the above advice of braking as hard as you can from 15 mph you would go over the handle bars as both wheels would lock up wet or dry, same for my trike it will lock both front wheels with ease, luckily it has a very long wheelbase so won't lift the rear.
I can't really see a need for more powerful brakes as the limitation for me is always traction or keeping from going over the bars?

 

[Deleted member 4366]

We all started on cable disc brakes. Then we tried hydraulic ones. There's absolutely no comparison, and, as Trex says, there's no way back. It's not so much the power, it's more the control and confidence. You should try some on your bike. Their not expensive.

 

[RobF]

I spent a long time setting them up, and think they were spot on. i.e. fixed pad as close as possible to the rotor then tweaking the moving one. I also centred them by applying the brake with the callipers loose.

Rotor is in good nick, and cleaned with turps first.

I suspect it's simply the cable, though having done a few miles yesterday it does seem to have improved in this respect somewhat.

This only leaves a nagging worry that it may not be as powerful as I anticipated in an emergency, so I wonder whether there is simply a "better" pad available for my brake?

Try lightly abrading the discs with emery cloth.

Or an old mountain bikers' method, which is to deliberately smear the disc with mud and let the grit in the mud do the job.

 

[cwah]

I have the zoom hydraulic disc brake and they are not that great.

I have to bleed them every few weeks.. maybe because it's not sealed properly.

And getting spare part has to be done via chinese sellers only.

 

[trex]

cwah, if you buy from China, try tektro auriga next time.

 

[Deleted member 4366]

I have the zoom hydraulic disc brake and they are not that great.

I have to bleed them every few weeks.. maybe because it's not sealed properly.

And getting spare part has to be done via chinese sellers only.

It must be leaking or have some other fault. I've never had to do any service to any of mine. I have Juicy, Shimano, Tektro and Avid.

 

[trex]

can you comment on the features of these brands?

It must be leaking or have some other fault. I've never had to do any service to any of mine. I have Juicy, Shimano, Tektro and Avid.

 

[Deleted member 4366]

The Tektro Auriga E-comp has a switch. Apart from that, they're all much of a muchness. I've recently fitted some of those Shimano ones where the lever works the gears as well as the brakes. They make kit installation very easy because they take up less space on the handlebars.

 

[John F]

Sounds like you've done everything right, but the proof is whether you can see the disc move. You didn't mention that!

If the disk doesn't move significantly, then you should try sintered pads. Alternatively, upgrade to a hydraulic one. This one should sort you out. You don't need a brake switch because you have one on the back brake.

http://www.chainreactioncycles.com/avid-elixir-1-disc-brake-2014/rp-prod67752?utm_source=Google&utm_medium=Shopping&utm_name=UnitedKingdom&gclid=CjgKEAjwwuqcBRCSuoivmIPnkwQSJACpqj3kPYU1Oz_wQfgleeRv1AnMLI7SkRWcjccJZog9MIl61fD_BwE&gclsrc=aw.ds

re disc movement - as the fixed pad is as close as I could get it to the disc and the moving pad thus pushes the disc onto the fixed pad then I have an acceptable min disc movement right?

As pads are cheap (are the better ones more expensive?) I think a change of pad type might be easiest. Can't be bothered faffing about with sandpaper, I don't have to do that with my car!

 

[Deleted member 4366]

If your fixed pad is close to the disc, then you should hardly see the disc move when the other one squeezes it. Movement should be less than 1mm.

 

[John F]

If your fixed pad is close to the disc, then you should hardly see the disc move when the other one squeezes it. Movement should be less than 1mm.

That's what I've got. Conclusion
1) Cable too easily compressed
2) Better pads would help
3) Try a hydraulic and hope the maintenance doesn't increase!
4) Stop worrying and ride slower!

 

[Deleted member 4366]

You'd be very unlucky to have problems with a branded hydraulic brake, which is guaranteed from Chainreactions. Cwah bought his from Ebay. Maybe it was a cheap Chinese imitation with leaking seals. Who knows?