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I've got a 2nd hand bike to play with as I've never been into bikes. When I got it the brakes only stopped while I wasn't on it. I stripped the bike down for cleaning and I re-attached the brake cable but the right lever is creating too much slack. I've tried creating more tension by pulling the cable through the housing and then tightening the cable but on release it gives too much slack again.

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    Second photo suggests that the inner cable is not clamped properly in the pinch bolt on the rotating arm, and that the outer cable is not routed "smoothly". Can you look closely there and see if you can do it differently? Compare with the back caliper which may give you some better ideas. Another photo from the side might help too. – Criggie Jul 4 '19 at 11:57
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    Note on the side: That pedal on the red bike is badly damaged and needs replacing, in case the bike is yours. – Carel Jul 4 '19 at 13:11
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    Have you adjusted the pads? The brake cable probably only activates the outer pad, the inner pad needs to be adjusted as the pads wear down. refer parktool.com/blog/repair-help/mechanical-disc-brake-alignment – mattnz Jul 4 '19 at 19:54
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    Can we please have a picture (or two) showing the full cable run from the lever to the caliper. – mattnz Jul 4 '19 at 20:59
  • Ok. This is the front ibb.co/qJjw829 ibb.co/t211GnD and the back ibb.co/QdhSLch ibb.co/whwK8Zq ibb.co/5r78XK3 – jay Jul 4 '19 at 21:49
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Your actual rear brake looks like a electric scooter brake, I would ask whoever you got this bike from if they done any mods or maintenance on it.

1st Image Curries Electric Scooter Brake

Unfortunately I don't think any form of adjustment will get you any sufficient braking.

2nd Image Artek Vigourous Brake (Bike)

You can see from the second image the different cable route designed for use on a bike, generally the cable is fairly straight from the nipple to the clamp.

My suggestion is first find out if the brakes were replaced, and secondly if they were replaced which I suspect they're, you need to get the correct brakes installed for efficient and safe braking.

Artek Vigourous brake sets can be bought for £25 a set front and rear.

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  • I've gone through ideas in this thread and I've adjusted the lever, tightened the pinch bolt with the cable under the washer and while it stops dead when I'm on pushing it, it doesn't stop when I'm on it. – jay Jul 4 '19 at 19:21
  • Does your back brake match your front brake, same make / design? I personally think you have a scooter brake on your rear which is why the cable doesn't route properly. Normally bike brakes have a nipple the cable runs through then clamps under or through the arm look at my second image above for a bike caliper – Dan K Jul 4 '19 at 19:53
  • Honestly think this is a red -herring and nothing to do with teh problem. The cable routing would be correct if the cable was coming directly down the fork leg.The fork has IS mounts and the caliper is an IS caliper so fits. – mattnz Jul 4 '19 at 20:11
  • Both brakes match. Here is a picture of rear (same as front) but from another angle. ibb.co/6bLXbp0 – jay Jul 4 '19 at 20:35
  • @Jay both calipers match, however both brake levers are different. This leads me to believe nothing on the bike is standard, chances are levers are wrong along with cables, and regardless of what others say I still think they're the wrong calipers for the bike. Can you please provide a side on view of the bike or tell us bike name so we can find out what originally came with the bike – Dan K Jul 5 '19 at 4:35
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I suspect there is something wrong with your cable routing. The second picture in particular is indicative of this as the housing is arriving at the caliper at the wrong angle. Inspect the cable route from lever to caliper, making sure the housing is properly inserted into the lever and caliper, and any frame attachment points.

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  • I suspect it's the wrong caliper altogether as noted above in my answer, that's why the cable routing is all wrong – Dan K Jul 4 '19 at 14:57
  • Disagree about the caliper - if the cable was routed straight down the fork to the caliper, it would be a direct pull on the activation arm. Either way, the problem is travel and cable routing does not affect travel. – mattnz Jul 4 '19 at 19:51
  • @mattnz his rear caliper is from an electric scooter, where do you think I got image 1 from? It's from an electric scooter website not a bike website. Also even if the caliper was mounted vertically the caliper arm would then be on backwards to be at right angles to the cable – Dan K Jul 4 '19 at 19:58
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It's not clear from your explanation whether the cable is slipping where it's attachedd or if the slack is coming from somewhere else. I'm going to start with the former.

In your photo, the cable is pinched between the bolt head and the washer below it. This setup has only a small flat surface area for gripping the cable, so it is easy for it to slip unless you tighten it so much that the cable is flattened. The proper routing is under the washer. The cable should lie in the groove that is just to the right of the washer. The groove helps ensure that the cable is secure and pulling from the correct angle. Disc brakes pull with a high leverage ratio, so it is easy to generate enough force to cause the cable to slide if it is not properly secured.

So, 1)loosen the bolt until the washer can be raised up enough to slide the cable beneath it.

2) pull the cable taut. Check that the end of the cable housing is seated properly at the brake lever.

3) tighten the bolt while keeping the cable taut. Make sure the bolt is very tight.

You may even need to move the lever arm slightly before tightening in order to get enough cable tension to brake properly. There should also be a pad position adjustment on the back side to adjust the position of the stationary pad.

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