Unanswered Spongy Mechanical Disc Brakes

[Williamson]

The brakes on my Kogan Fortis eBike have become spongy and ineffective. Admittedly they're are an entry level brake with a mechanical (cable) operation, but they have lost effectiveness. Bike has only done around 650km. I'll get down the garage soon and strip and check 'em, in the meantime (as this is my first foray into bicycle disc brakes), anyone on here want to provide any advice or tips on what I should be looking for?

 

[dave_uk]

Save yourself time and effort and replace them with hydraulic brakes, take a look at Clarks Clout1 MTB brakes - they are a full replacement. They work well, and will be a major improvement from your old cable brakes.

 

[VWsurfbum]

Sounds like you need to realign the calipers and turn the non-moving side out to be closer to the disc.

 

[Williamson]

Save yourself time and effort and replace them with hydraulic brakes, take a look at Clarks Clout1 MTB brakes - they are a full replacement. They work well, and will be a major improvement from your old cable brakes.

I'll check with my local bike shop, but I suspect converting to hydraulic will cost me more than the bike. My main point is that the brakes worked reasonably well, but don't now.

 

[Williamson]

Sounds like you need to realign the calipers and turn the non-moving side out to be closer to the disc.

Mmmm ..... worth a try.

 

[2WheelsNot4]

I'll check with my local bike shop, but I suspect converting to hydraulic will cost me more than the bike. My main point is that the brakes worked reasonably well, but don't now.

I know its going to sound obvious, but im not taking the piss. New pads ?. I mean 650km on a single set is within limits, but they must be getting towards the end of life at that.

Another thing to consider is cable stretch.
On that point are the levers traveling far before they make contact with the rotor ?. Which could indicate the cables have stretched(and they do)
Loosen off the cable clamp brake caliper end, slip a couple of playing cards thick between pads and rotor and then pull the cable tight before re-tightening. When you take the cards out, distance should be set.

As to working 'reasonably well' No offence intended, but low priced bikes have very low priced parts, which arent really suitable. One way to know if in that emergency situation is to get up to speed and do the death grip on the levers for as sudden a stop as possible. Its usually all very well with gradual stopping, coming up to traffic lights or a turn when you're basically just bimbling along. But when the need for a sudden stop is required, you need to know they can stop you safely.
My original 4 pots(shimano 501) are ok for bimbling, and the front bites, but the rear is not so good and while a gradual slow to stop they're fine, i knew in the emergency situation they wouldnt have stopped me. Swapped to Hope V4's, because its nice to know in that unseen situation,they're up to the mark

 

[dave_uk]

... when you're basically just bimbling along.

I like that

 

[Williamson]

Effort to adjust brake calipers turned to disaster last Sunday when I applied too much force and caused some damage. Whiskey Tango Foxtrot, I reckon it's gunna be expensive.

Laptop out, onto eBay, found a replacement bit, but had to buy disc, calipher (with pads) and brackets. Purchased two, wanted front and rear to match - AU$40, if that's the only wallet damage, I'll be happy.

Package arrives Thursday midday, another WTF moment with two boxes, each box with a pair of discs, caliphers (with pads) and brackets. What am I gunna do with two sets disc brakes? Anyway approximately 30 minutes to fit and adjust, test ride this AM. Verdict new replacement brakes are better than the OEM brakes.

Happy customer here!

Re. an hydraulic set-up, this would have required new brake levers with a micro switch to cut-off electric motor when applying the brakes. In my view not worth the cost and effort on an entry level bike, particularly for me as I'm going for an upgrade in the near future.

 

[urastus]

Ahh, folk here have probably forgotten about cables and cable housings. It dependes what sort of cable housings you have. Some are lined with plastic. The plastic can wear with grooves, which of course will increase friction. You will feel this as "sponginess". Some housings are lined with teflon, and some are just steel lined in a tightly bound spiral. You can lube the steel lined ones - even crc or something will free them up. For the other plastic and teflon lined ones, you just have to replace them. This is more of an issue for brake cables - much more force.

 

[Williamson]

I only know cable brakes. The eBike is my first with disc brakes, the next will be an upgrade to get hydraulic brakes, and a better overall bike.

Re. lubing the cables, in my bike shop days (owner and chief mechanic) when assembling a new bike, standard practice was to remove brake and gear cables, smear them with grease and reinsert them into cable outers (with or without a teflon sleeve), and adjust them. Yes, this took a little longer to get 'em ready for sale, but it was just plain old fashioned good practice.