cable disc brake performance

[spitfire4v8]

Her indoors has treated herself to a canondale road bike .. gumtree special and fully believable that it was only ridden a couple of times, it's immaculate despite being 3-4 years old.

Thing is, the cable disc brakes are dreadful in terms on stopping power. The idea of having the bike with the discs was to avoid the lack of stopping power you have with rim brakes after having ,say, ridden through a puddle of water, but the discs have that lack of power even in the dry.

A quick bit of googling suggests the brakes need to bed in, but also that there are organic or sintered pads (I don't know what it has currently, only had the bike 2 days).

Other googling also suggests that whilst the hydraulic versions of disc brakes are indeed better, the cable versions are actually pretty good (contemporary reviews don't highlight a braking deficiency) - so is it just a case of riding the bike in the hope the brakes improve? Or are there pads out there with more initial bite …

Spec is canondale synapse 2017 / tiagra / Promax Render R brakes according to online (should have looked what's on before leaving home this morning)

any ideas ?

[Bill]

Are the cables running smoothly and are they properly adjusted? Mine needed significant tightening up after a couple of rides.

[spitfire4v8]

Yes the cable action feels fine, not draggy or sticky or hard to pull initially, but you have to put a LOT of effort into the lever to get any sort of braking reaction, like the discs/pads have oil on them, but they don't.

[Justin S]

Quick search digs this up
• Mechanical Disc Brake
• Cold Forged 6061-T6 Aluminum Alloy Caliper Body
• Dual-Pad Adjustment Via one Inboard Dial
• Render Is Compatible With Linear-Pull Brake Levers
• Render-R Is Compatible With Road Brake Levers
• Sintered Pads; Compatible With Avid® BB5 Pads
• Meets or Exceeds ENM Standards
• Designed in USA/Made in Taiwan

Just asking about the adjustment on them. Has that been set up ? I know cable brakes have a pivot arm and if not set up too well, can loose the leverage, if that makes sense. Its also saying sintered pads. I would try putting some water on the discs and doing some braking to bed the pads in a bit more as well.

[Bill]

It sounds like either something is jammed or the pads are contaminated. AIUI/IME cable discs work fine but the modulation isn't as good as hydraulics and they need more fettling.

If it's no better activating the brakes via the lever on the caliper then I'd take some sandpaper to the pads and some cleaner to the discs. The pads may be glazed.

[spitfire4v8]

Thanks for the replies

pads may well be glazed .. apparently there's a bedding in procedure just like car discs, so a light cleanup with emery and go and do the bedding in procedure again and see how it goes.

currently binge watching you tube videos on caliper set up.

Good to know that the cable brakes can be made to perform well, just need to apply some new knowledge to this bike now.
cheers.

what are peoples thoughts on type of pad material to use ? The bike a is a commuter and weekend machine - punishing the brakes on long downhill sections won't be a priority, good stopping power from cold will be..

[itsnotarace]

A long lever action before engagement sounds like pad to disc distance adjustment. You basically want the pad as close to the disc without it dragging or making noise

There should be an adjustment screw that will allow you to fine tune the process. You may need to loosen the brake caliper a fraction on both bolts so that you can centre the caliper between the two pads. Grab a handful of brake with the 2 bolts loosened and then retighten the 2 bolts.

[Bill]

itsnotarace said:

A long lever action before engagement

Isn't he describing lots of effort rather than lots of travel?

[spitfire4v8]

Yes the lever travel is not excessive, but the effort required to make the bike slow is excessive

[itsnotarace]

Bill said:

itsnotarace said:

A long lever action before engagement

Isn't he describing lots of effort rather than lots of travel?

Sounds more like simple adjustment than lack of friction by the way the issue has been described, pad compound has very little effect on dry braking - should be able to fully lock the wheel in either dry or wet conditions. Compound mostly effects longevity of pad life / wear rates

[spitfire4v8]

I will make sure all surfaces are thoroughly cleaned and re-adjust and report back, might be the weekend before I get to do it now.

thanks all.

[hantsxlg]

I have a 2020 synapse 105 with cable disc brakes. The braking was awful (as in non-existent!!) until I bedded in the discs. If everything else looks ok and you suspect the bike is hardly used I'd Google how to bed in disc brakes and give that a go.

[RobDickinson]

I had cable disk brakes on a bike and they needed constant adjustment to work.

Replaced the levers and calipers with a drop in cheap hydraulic system and its much better.

[dontlookdown]

Yes bedding of discs and pads, plus regular adjustment, is key to getting the best from cable discs. They are a bit of a compromise but better than rim brakes imo - at least they do not wear the rims.

As far as pads go, stick with regular resin for ordinary use. The harder pads last longer but at the cost of wearing the discs faster instead.