Mechanical Cable Actuated Disc Brakes

[PedalUma]

It takes skill to maintain cable or mechanically actuated disc brakes. There is an inside pad which is fixed that needs constant adjustment in a click as its surface thins, and there is a moving outside pad which also needs to be tightened regularly with pad erosion and cable stretch. Having something white or bright below the caliper when the bike is upside down will help a lot. View through the pads to see the gaps on either side of the rotor. Minimize those gaps and true the rotor each week. Ideally the gap on each side will be less than 1/2 the thickness of a business card. There are thin stainless gigs for this. Mechanical disc brakes are a pain even for the most seasoned bike mechanics. You are not the only one.

 

[fooferdoggie]

It takes skill to maintain cable or mechanically actuated disc brakes. There is an inside pad which is fixed that needs constant adjustment in a click as its surface thins, and there is a moving outside pad which also needs to be tightened regularly with pad erosion and cable stretch. Having something white or bright below the caliper when the bike is upside down will help a lot. View through the pads to see the gaps on either side of the rotor. Minimize those gaps and true the rotor each week. Ideally the gap on each side will be less than 1/2 the thickness of a business card. There are thin stainless gigs for this. Mechanical disc brakes are a pain even for the most seasoned bike mechanics. You are not the only one.

yep plus I don't know if the discs were more prone to warpage back then but I seemed to have a lot more warps then I do now. Now they stay pretty flat. except for the Shimano ice-tech rotors they tend to be warped out of the box and warp in use.

 

[gromike]

I've had my Trek 7.2 for something like twenty years and it has cable pull disc brakes. It's been a mid-drive electric for two years, and I've never had a problem with the brakes.
And now you guys have got me worried! Time to check those twenty-year-old pads, I guess.

 

[Aushiker]

I deliberately installed mechanical disc brakes on my Salsa Mukluk because of the remote riding I do. It is much easier to do an emergency fix than with hydraulic disc brakes (I learnt that from experience.)

 

[fooferdoggie]

I've had my Trek 7.2 for something like twenty years and it has cable pull disc brakes. It's been a mid-drive electric for two years, and I've never had a problem with the brakes.
And now you guys have got me worried! Time to check those twenty-year-old pads, I guess.

well if the pads are 20 years old your not using them much so no worries.

 

[gromike]

Not yet, at least.

 

[mrgold35]

Mechanical brakes on my two 16 Radrovers. I was constantly adjusting the cable tension and pad placement monthly. The cheaper brake cable started to have broken strands at the calipers and brake pull. It started to become liability issue for emergency stops at speeds +15 mph because I wasn't sure of stopping power. Replaced with plug-n-play Spyke TRP mechanical calipers and Jagwire MTB cables (cable only, reused Rover's brake cable sleeve). I had L/R brake pad adjustments, only needed to adjust my pad distances/pull tension only as the pads wore down, and I had predictable consistent emegency stopping power.

Side Note: The wife's 2018 Radcity Step-Thru had a similar type of mechanical shift cable as my Radrover brakes. It stopped working a few years ago because it oxidized, was rusted inside the cable sleeve, and I couldn't shift the gears. Replaced with CNC Pro slick polished/coated bike shifter cable and back to normal with more precise shifting (no clicking, skipping gears, up/down shifting twice for one gear).

 

[indianajo]

Mechanical brakes on my two 16 Radrovers. I was constantly adjusting the cable tension and pad placement monthly. The cheaper brake cable started to have broken strands at the calipers and brake pull.

I've been warning newbies about cheap imitation steel cables in Rad and other bargain brands for 6 years. It was amazing when I bought a yuba bodaboda in 2017, and did not have to adjust the cables every 2 weeks. I had been riding Diamondback and Pacific, kiddie bikes for people with short legs, like me. In the $200 bike category, lots of lead, tin, copper, in the "steel" cables and spokes. Rad was the same stuff. Yes a set of Jaguar, clarks, or other slick stainless cables can really improve a piece of **** bike like a Rad. Slick housings help too.
Lots of posts about stretched spokes in early Rads, too. Rad sent some woman in Scotland new spokes one at a time. So she had to have the shop re-true the wheel ($75 here) every week or two.
The rate of posts to the Rad "known problems" thread on the brand forum has really decreased in the last 3 years. Perhaps they realized that spending $2 more to buy real parts instead of garbage was cheaper than paying Seattle residents to answer the phone for complaints and ship $8 boxes of garbage over & over. The yuba cables & spokes came from ***** too, just they were not garbage.
BTW the tektro 160 mm disks that came with the Yuba, are still great, and unwarped. I change front pads every 2000 miles. Tighten caliper for wear every 1000 miles.

 

[Aushiker]

Replaced with plug-n-play Spyke TRP mechanical calipers and Jagwire MTB cables (cable only, reused Rover's brake cable sleeve). I had L/R brake pad adjustments, only needed to adjust my pad distances/pull tension only as the pads wore down, and I had predictable consistent emegency stopping power.

That is what I fitted to my Mukluk. No issues so far.

 

[sc00ter]

That was the first thing I replaced on my Rad when I had it, the brake cables. The Tektro brakes were great one adjusted but the cables, yuck, constant adjustment. I know good cables from my bmx days so I ordered some fancy pants ones from a bmx supply company. The added bonus was I could do colored housing. Never had to mess with cable stretch again. I still stand behind mechanical brakes being as good as hydraulic brakes one you understand the basics and get 'em dialed in correctly.

 

[mrgold35]

This is what my original Rad brake cable looked like before I changed it our to Spyke TRP brakes and Jagwire MTB coated brake cables. The 5-6 inches of coiled up broken strands were jammed into the 1.5 inch space of the brake handle and causing the motor cut off to active intermittent. No fun riding up an 2 mile steep incline during summer with a headwind and the motor cuts out. Never seen this before and haven't had this issue with my other Rad Power ebikes with the standard brake cables.

 

[PCeBiker]

My ebikes have hydraulic brakes but my shifter cables are mechanical.
I oiled the shifter cables when the bikes arrived.

Some say that it isn't necessary and some say it's bad (attracts dust that enters the cable), but I've been dealing with rusty cables for 50 years and I've learned to keep them lubed.

I remember buying new cables that came with different lugs on either end. (barrel and bell shaped)

You'd cut the end off that you don't need, but I could never cut the cable clean enough to feed it into the cable housing. One or two strands would catch, bend over and bind.

I still struggle with it.
Lately, I've been using a rotary tool with a cutoff disk to cut the cable then a drop of crazy glue to help hold the strands together.

 

[Ben J]

If you're looking for an easy upgrade, there are now hybrid hydraulic/mechanical brake calipers now. Basically the master cylinder is right at the caliper so your mechanical brake setup is unchanged but the actual calipers are hydraulic.

 

[PedalUma]

Great points made by all. Good housing and quality cable make all the difference. I like to shove the drop needle down new housing and get some CLP oil in there. It does not oxidize or get gummy. With my new job we only sell bikes with hydraulic brakes but work on all of them. Saturday a woman with a new riser bar wanted a longer through-frame rear brake housing. What I did to make it easy was to pull the old housing then feed the new housing over the old cable, using the old cable to route through-frame. Then I used CLP and fed the new cable. The CLP needle tip also expands the housing where it was cut.

If you're looking for an easy upgrade, there are now hybrid hydraulic/mechanical brake calipers now. Basically the master cylinder is right at the caliper so your mechanical brake setup is unchanged but the actual calipers are hydraulic.

We did that recently with a gigantic trike that had a cable splitter. It worked very well.

 

[PCeBiker]

I've got this cool tool for injecting oil into an installed cable,..
You insert the spray tube from your spray can into the injector port.

It's sized for automotive cables though, so it's too big for my bike cables.

 

[PedalUma]

This Park Tool video has good information with references and links.

youtube park tool mechanical disc brake adjustment - Google Search

I also like stainless pad alighnment tools. They are half the thickness or less of a business card. If tightening always pulls only one way then that is when I will use a business card. I like the 'crank inside and outside all the way' as a centering technique, then I can back off to a bare whisper of rub at the start of a long ride for maximum tightness. I will guess that about half of the kids riding MacFox style moped bikes cannot stop because of brakes requiring service.

 

[m@Robertson]

You folks who are changing out crap cabling for quality cables should also invest in replacement cable housing. There is a huge difference in cheapo vs. 'compressionless' housing (the better Jagwire stuff meets this standard). The difference is felt in the cable pull. Compressionless housing keeps you from having to squeeze the lever extra distance thanks to the housing flexing. Or something. I stay away from cabled brakes but I remember on my Envoy mid tail putting in quality housing made an enormous difference to the efficacy of the rear brakes given their long run back on the extended frame.

I'll still rely on hydraulic brakes every time. Install the right brakes and and you only touch them when the pads wear out. There's a reason the cheaper ebike manufacturers have jumped on the hydro bandwagon, and its all about liability. The added maintenance needed for cabled brakes on a heabvy ebike that goes faster is something an experienced cyclist can be counted on to perform, but not the typical DTC ebike consumer. So they go out of adjustment and then we get accidents that highlight the poor brake choice. We all know the one I am talking about, that killed a child and singlehandedly caused the industry shift.

 

[PedalUma]

@m@Robertson, how true. On shift cable the strands of wire run the length, not radially, like most brake housing. I have about 19 feet of non-compression brake housing, but it is 5.3mm, too thick for an internal application so far, it has linear strands. It would be ideal for a long bike. Yes, that is why we only sell bikes with hydraulic brakes, convenience and safety for the average person. RAD Power bikes have started shipping DTC with hydraulic brakes. Some mom with a RAD Wagon would not typically adjust mechanical brakes before a ride, because the kid is clean and fed and headed to school and she is headed to the office. It is an urgent need that most people are not aware of to put at the top of their list. We see people with hydraulics that take the pads to the backing so the pistons leak. Someone should invent a stainless return spring clip with a 1.2mm gauge that screams when it touches the rotor for childless cat ladies and those looking to make some nocturnal cat soup. You could probably just bend one of the legs of each side.

Edit: I just did it on a stainless pad spring expansion clip. I slightly curved in the ends of two legs, using a needle-nose vice-grip, one on each side about 1.3mm on a new set of pads as a wear indicator. It will scream like a cat trailing a fire from its tail! Should that be the leading or trailing edge? I suspect leading will make the most noise. I will run it by the guys at work in the morning. See, productive stuff can come from EBR.

 

[PCeBiker]

,.. Someone should invent a stainless return spring clip with a 1.2mm gauge that screams when it touches the rotor

Some replacement brake pads for my different cars had squealer tabs like that,..

Should that be the leading or trailing edge?

Each pair of pads had one pad with a squealer.
I remember wondering about leading or trailing.
I think I ended up with one of each because the squealer tabbed pad had to go on the inside of the caliper, so it was leading on one side of the car and trailing on the other?

I think trailing would have more of a fingernails on a chalkboard effect?

 

[Chargeride]

They, do, there a thick metal plate behing the pad that makes a grinding noise, the longer you leave it, the louder it gets, when pedestrians grimace, you know the rotor is beyond repair.