And, just like your other red herrings, it is likely not an issue. I’ve adjusted hundreds of these kinds of brakes and have never had trouble adjusting the fixed pad adjuster. I didn’t even know they were a thing on some brakes until this thread. Just like the spherical washers, it’s mostly a nonissue and certainly not something that helps to address the problem.

'Sorry guys, I know there are too many of the same pictures, which is getting confusing. I've already adjusted the 2mm Allen key; it's very flimsy with an Allen wrench, and it only unscrews about 1 revolution. Is that normal? But still, the bike isn't stopping. its at about 50% The pads are clamping onto the rotor, no problem; I think it's contaminated. I'm thinking of buying new brakes from AliExpress, either identical or from another brand, or is that not possible?

the set screw only keeps the Adjuster in position, it will NOT adjust the brakes.
the adjustment is done via the 5mm allen hole on the inner side of the caliper, after you loosen the 2mm set screw... and that set screw should be able to un-thread completely from the caliper body, but that white corrosion (AKA: Aluminum rust) is preventing it from turning more than one rev.

lightly re-tighten the 2mm set screw After finishing your adjustment..

a better plan is to take the bike to a qualified mechanic now, and save yourself from causing irreversible damage.
i'm seeing way too much confusion from you about what is a basic tune up thing, and SAFETY related.

Before you go abandoning the brakes, look at the procedure I linked to in post 7. You’ll have to modify it a little because your brakes are slightly different from the BB7 but the procedure is much the same. The small set screw doesn’t do much and I’d be surprised if it is even engaged against the pad adjuster.

Thanks to all of you for your help I won't take up anymore of your time i will get it sorted either by myself 😁or a pro

You aren’t taking up time. Many people here have loads of time to waste. Check out a chain lube thread sometime:rolleyes:

Keep asking questions, we’ll keep answering.

Here is a manual for JAK. Not the best of wording or understandability, IMO. But that's common for the small budget manufactures. There is useful information in it. Such as what measurement the pads need replacing by. https://classic-cycle.de/media/pdf/M...AcWKmlQZW2FPpF

Also, here is a Youtube video about them. No speaking, but it does show some key things if you dwell on it a little and have some DIY ability and mechanical inclination. You can look for other YouTube videos that might have verbal commentary to explain more.


You also need to see if there is a barrel adjuster on your shift lever for the cable. As well, the one on the brake body looks all the way in, so maybe too slack a cable that doesn't pull enough. I don't remember if you ever said what condition the brake pads are. They should be checked to see that there is enough pad material on them. If the legs of the retainer spring are the same thickness as the pad next to them, then it's well beyond time to change the pads.

SOP with cable operated disc calipers is to take up the slack with the pad adjuster, and use the cable adjuster only for light wear and fine tuning the lever feel - if you're using much cable adjustment it's time to slacken it off and screw in the pads.

Caliper parts
 

Hi just came across identical brakes on aliexpress and noticed they should come with two pad retainers see top right my brakes don't have these I think they are missing could this cause the issue I'm having with bike not stopping properly thanks..
https://cimg8.ibsrv.net/gimg/bikefor...d0e3b25ba7.jpg

those "pad retainers" are temporary inserts for when you remove the wheels from the bike.
they have nothing to do with brake "strength".

i use shortened carpenter's wood shims here, if the pads can fall out easily... MOST bike calipers now have built-it pad retainers.. magnets, a clip, or a pin...

Success
 

Success, guys! I managed to sort it. I did some hard riding yesterday — constant braking; hard, you call it bedding in. It has made a big difference. How long does it take to fully bed in new pads? Another issue: when I shift into the easiest gear, it slips off the centre chain rings. Does the back wheel need pulling back, or are the teeth wearing out on it? One thing I noticed: the front handlebars I think are too low how high should they be As of now, they are at the lowest level, as is the seat. I'm reaching down when riding straining my back slightly...

If your caliper is properly aligned and pads converge on the rotor symmetrically, then bedding-in happens very quickly - a couple of hard stops and you are done. But if there are alignment issues, then it might take much longer. You are basically filing down your pads to conform to the demands of improper alignment. They will file down and conform eventually... but it is not the right way to do it.

if the seat post and steering stem are "all the way down", and your knees are not nearly straight when you pedal, then the bike's frame is too big for you. or the seat post is now too low in the frame.
if you set the handle bars too high, it effects your knee angle too, and can cause more pain as your lower back is forced to bend with every pedal stroke.

here's a rather cool method to find a decent starting point on seat height...

the pic labeled "high" in the cover shot is actually about where the knee angle should be, for most riders.
as you pedal, your foot points down some, changing that knee angle... if you are flat foot on the pedal, the knee nearly straightens out, and you lose power when the leg is straight.
getting the seat height correct is a perfect way to make riding your bike funner and less exhausting.

as to the bars' height... the best is almost level with the seat, if the frame is the coirrect size for you... i've watched people get caught in the ever-higher loop many times, thinking a higher bar will make their back pain vanish... it does not.
the pain gets worse as bars become too high for the rider, and their hips begin to hurt from rocking back and forth more too.
Most of the "Wallflower Bikes" i see with no tire wear have the bars jacked all the way up, and super-wide seats installed that cause painful chafing too.

Glad to hear that your brakes are now working better!
they will now bed in a bit better, after more miles/kilometers of riding.
and i ALWAYS do some stretching exercises before a ride... ALWAYS... i'm 67, and have numerous past injuries to deal with, none of which were caused by bicycles.
:thumb:

Is this brake cable in a more sensible position now when not being pulled?

If not, I don’t think you’ve addressed the root cause.

Mtb headset
 

Hi guys again now ive sorted brakes How are these headsets adjusted as i need to raise it a bit but as never seen this type before is it just allen keys needed thanks..
https://cimg5.ibsrv.net/gimg/bikefor...41cceeda47.jpg

That is NOT an "adjustable height Steering Stem."
those allen screws keep the stem and HEADSET BEARINGS correctly adjusted and aligned.

Oh never heard of one that can't be adjusted I'll have to lower seat then to level it off thanks..

My wheels are 26inch with 26x1.95 tyres can I put 26x2.25 or 26x4.00.

2.25... Probably... but they may rub while riding.. the rim and tire move around some while you ride... 1/4" clearance, all around, at rest, is a good rule of thumb.

4".. not a chance. that's Fat Tire bike stuff, and your bike isn't a Fat Tire bike.

Your headset does allow a (very) small amount of vertical adjustment of the stem height by means of moving the spacers.

Unfortunately, all of the spacers are already under the stem, which means that the only choice is to move the spacers above the stem, which would drop the stem lower.

That's a problem of your leg and core strength, it will improve with time as you get used to riding the bike, the important thing is to get your saddle height something near correct for pedaling efficiency. Generally sport bikes will have the bar set a couple inches lower than the saddle, racers can have a drop of six inches, some more sedate riders like zero drop. Having the bar higher than the saddle is "comfort bike" territory for the old and infirm who like to sit too low for pedal efficiency, on huge squishy saddles. Even I manage two or three inches of drop, despite being old and overweight with a bad back and generally unfit.

Chain drop: probably a front derailleur adjustment thing, possibly exacerbated by bent chainring teeth. Worn chainrings usually slip rather than dropping the chain.

Bedding in: just a few hard steady applications of the brake, easing off and not stopping while it cools down. Basically you're just transferring a thin even layer of friction material from the pads to the rotor - it's the rotor that you're conditioning, not the pads.

I missed read it it said 2 40 yeah 4 would be insane.