Poor disc brake performance

[Yellow Saddle]

@Yellow Saddle, as always, thanks for such a comprehensive reply!

It's an interesting point you make about holding on a hot brake and that (if I've read correctly) that could introduce some vibration - or shudder(?) into the equation. I've noticed an increase in shudder over the last month or so and I do typically hold the front brake on at stop signs, lights etc. Not a problematic amount but I'll ensure that the next pad change is a more thorough one and I'll report back.

It is my experience that Hy-Rd's feel a bit "spongy" compared to most other brake systems I've tried. It's neither here nor there for me, I have plenty of modulation and I have about 1 cm between bar and lever at full lockup.

Yes, holding a hot brake is one of the problems. Holding a hot brake is a nice way of expressing it. I've just stolen the phrase.

 

[mythste]

Yes, holding a hot brake is one of the problems. Holding a hot brake is a nice way of expressing it. I've just stolen the phrase.

Glad I could help

 

[DWM]

The frustrating thing for me is that I have done my best not to do any of the things that were listed that can cause glazing. I'm a bit of nerd so when I buy something I do a lot of research. This is my first bike with discs so I read all about them, and therefore I bedded in the pads/rotors, haven't dragged the brakes (instead using short, sharp braking), don't stop with the brakes applied, have been very careful to avoid contamination etc. I will obviously have to try harder!

Cheers

Dave

 

[DWM]

I think the issue persists.

Over the weekend I fitted a new rotor (a Formula solid rotor) and new pads (resin) and tried to bed them in yesterday. Went for a ride up and down the local Bristol hills (5 miles, 750 ft up/down), and followed all the advice online that I could find. The result is certainly no better, and possible even worse than before! A photo of the rotor after that ride is attached.

I won't get a chance to use the bike again until Thursday. Am I likely to find an improvement then (after everything has cooled down etc), or is it back to the drawing board?

Cheers

Dave

 

[Yellow Saddle]

A couple of issues.

When buying new discs, try and find some with some surface area instead of these filigree, lacy ones like that in your latest photo. That's not your problem though, that presents with other problems.

The disc surface looks OK - perfect in fact on the little bit of metal that survived the drillium disease.

What pads did you use? Metal or resin? Edit: Missed "resin" in your post.

And then, why don't we start fresh and you describe the symptoms and bedding in method, in case there's something amiss there.

 

[Tim Hall]

A couple of issues.

When buying new discs, try and find some with some surface area instead of these filigree, lacy ones like that in your latest photo. That's not your problem though, that presents with other problems.

The disc surface looks OK - perfect in fact on the little bit of metal that survived the drillium disease.

What pads did you use? Metal or resin?

And then, why don't we start fresh and you describe the symptoms, in case they've moved on.

Ahem.

and new pads (resin)

(of course he mayhave added that bit later)

 

[Yellow Saddle]

Ahem.
(of course he mayhave added that bit later)

Probably not, I skimmed too fast I think.

 

[mythste]

Humour me here, Stand the bike on its back wheel (as if you were wheeling it through a gate) and pump the brakes for a few minutes. The bedding in period (as in, brakes installed to brakes working as they should, not just the scientific hard braking bedding in period) with HYRDs has been weird in my experience. as @nickyboy can attest, when I went from having no brakes at all to full lock in the space of half a mile, about 20 miles into a ride!

Perhaps the standing it on it back shuffles some things round in the hydraulic reservoir, I dont know - but you'll feel something catch, I'm at least 58% sure of it.

 

[Pale Rider]

I've always been underwhelmed with the braking performance from the Magura hydraulics on my Rose trekking ebike.

Matters worsened when an occasional feint judder from the front became more than occasional.

My local bike shop suggested a change from 160mm to 180mm rotor as a first step.

This was done last Friday, and after 50 miles at the weekend I can say the judder has gone and the braking performance is improved, not by a lot, but by enough to satisfy me.

I don't doubt many users are pleased with their Magura brakes, as are the riders who have the same brakes as the OP.

But his basic problem seems to be lack of performance, and it seems to me a bigger rotor would likely result in an improvement.

 

[DWM]

@mythste - I will give this a go and report back!

 

[DWM]

@Pale Rider - thanks for your comments. I would rather not go down this route if I can avoid it. The fact that others have reported that their 160mm HyRd's work well indicates that there is something amiss with my set up.

 

[Pale Rider]

@Pale Rider - thanks for your comments. I would rather not go down this route if I can avoid it. The fact that others have reported that their 160mm HyRd's work well indicates that there is something amiss with my set up.

I agree, some very experienced cyclists on here say the brakes can work well, so yours should be able to be made to perform.

Another thought, might be worth trying the rear calliper on the front which could rule out - or in - a calliper problem.

I admire your tinkering patience, I'd have lost my temper with the job long ago.

 

[Kajjal]

Logically you have changed the rotors and pads so that rules those out. One thing you have not tried is bleeding the brakes but normally they would feel very spongy or the lever would go straight to the bar. You could try disc brake cleaner, i just spray on the muc-off cleaner, turn the wheel with the brake on, give it a short while and then get up to speed and brake hard a few times until they stop making any noise. The only other parts are cables and levers which should just work. Appart from that it is just the normal align caliper properly by eye and make sure everything is done up properly.

Other than that find a good bike shop or potentially a warranty claim.

 

[DWM]

I tired pumping the brakes for a few minutes last night, and other than a slightly sore forearm, didn't notice/feel anything change. I didn't get a chance to ride the bike (and probably won't until Friday due to a busy week at work).

@Pale Rider - I hadn't considered swapping the calipers around - I think this is definitely worth a try.

@Kajjal - I don't think they need bleeding, although I may try and carefully top up the reservoir a bit as apparently this can reduce the characteristic long lever travel common with HyRd's, which should allow the pads to bite sooner. Other than that everything appears well aligned, the inner cable looks OK, and the outers are compressionless. I do have some Muc-Off brake cleaner so could also try that.

Failing all of this, can anyone recommend a decent bike shop in Bristol? I have always carried out my own maintenance so have never had to use one before.

Cheers

Dave

 

[Yellow Saddle]

I tired pumping the brakes for a few minutes last night, and other than a slightly sore forearm, didn't notice/feel anything change. I didn't get a chance to ride the bike (and probably won't until Friday due to a busy week at work).

@Pale Rider - I hadn't considered swapping the calipers around - I think this is definitely worth a try.

@Kajjal - I don't think they need bleeding, although I may try and carefully top up the reservoir a bit as apparently this can reduce the characteristic long lever travel common with HyRd's, which should allow the pads to bite sooner. Other than that everything appears well aligned, the inner cable looks OK, and the outers are compressionless. I do have some Muc-Off brake cleaner so could also try that.

Failing all of this, can anyone recommend a decent bike shop in Bristol? I have always carried out my own maintenance so have never had to use one before.

Cheers

Dave

Since you have new pads and discs on there I would advise against using brake cleaner until everything works. Topping up wont work. The system is such that even if there is the absolute minimum fluid in there to make it work, it will still work exactly as good or bad as when it is full of fluid.

When breaking them in, did you do about 20 stops from light to heavy, one brake at a time until you could feel an improvement?