Author Topic: Let's talk Hydraulic brakes  (Read 6877 times)

quixoticgeek

  • Mostly Harmless
Re: Let's talk Hydraulic brakes
« Reply #100 on: April 08, 2021, 03:49:20 pm »

My other bike is a Brompton... The brakes are... more of an idea, than a useful part of the bike...

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

Re: Let's talk Hydraulic brakes
« Reply #101 on: April 08, 2021, 04:17:16 pm »
Bah.  You should try going back to a rod braked bike in the wet!  :o

Hot Flatus

  • Mediocre polyglot.Scoutmaster and nudist
Re: Let's talk Hydraulic brakes
« Reply #102 on: April 08, 2021, 04:17:39 pm »
I'm on the point of needing a new rotor for one of my bikes. It is a bike that has always had 140mm Shimano freeza rotors, apart from nov-april this last year when I used a dynohub wheel which had a steel 160mm rotor on it.

...and I've come to a few conclusions about this. I noticed that the Freeza rotors don't last that long, certainly in comparison to solid steel rotors. I also noticed that when I let a Freeza rotor wear to the limit I saw a crack appear. Turns out they have a relatively thin steel coating on an aluminium core...hence the freeza bit I suppose, because it must be about heat dissipation. I don't really like the thought of that crack in the steel coating.  I also noticed that the solid steel rotor doesn't ping after heavy braking. In fact, I'd forgotten about the pinging until I removed the steel rotor and put the freeza rotor back on.  But most of all I haven't noticed any improvement in braking since I put the Freeza back on.   Plus the Freeza rotors are almost double the cost of steel ones.

So, I'm going to go on the hunt for a sold steel rotor and ditch the Shimano ones.

Re: Let's talk Hydraulic brakes
« Reply #103 on: April 08, 2021, 04:25:41 pm »
Very much the experience of this fella:

https://youtu.be/utMchnpW1vo


Hot Flatus

  • Mediocre polyglot.Scoutmaster and nudist
Re: Let's talk Hydraulic brakes
« Reply #104 on: April 08, 2021, 04:46:28 pm »
Interesting, thanks!  :thumbsup:

Now I know which rotor brand to go for. Hadn't occured to me to look at Campagnolo. Just got to check that there aren't compatibility issues, but he seems confident using them with Shimano calipers. Got a bit scared when he started talking about heat transferring into the hubs, boiling your bearing grease, and expanding the hub shell but I suppose that is more likely on mountainous terrain rather than the short descents we have here. I've never knocked mine out of true either, despite many trips in the car, just that annoying scraping or pinging sound after prolonged braking.

How many discs did he say he gets through in a year?   :o

TimC

  • Old blerk sometimes onabike.
Re: Let's talk Hydraulic brakes
« Reply #105 on: April 08, 2021, 04:59:15 pm »
For my main bike (Kinesis GFTi), I have a few sets of wheels depending on the time of year and what I'm using it for. Right now, it has a pair of Mavic Crosslights on with cheapish 6-bolt 160mm discs. For my use, they work just as well as the Shimano Freezas I have on the summer Hunt wheels. Incidentally (having just checked), the 'floating' feature of the Freeza/Hunt combo doesn't. Float, that is. They're as solid as the 6-bolt discs. Probably need to look into that before those wheels go back on...

Hot Flatus

  • Mediocre polyglot.Scoutmaster and nudist
Re: Let's talk Hydraulic brakes
« Reply #106 on: April 08, 2021, 05:04:20 pm »
Yes, it was swapping back from steel rotors to freezas a week ago that got me thinking, and then a conversation with my riding partner, Steve, who was also getting pissed off with his discs. I'll give the Campag rotors ago and report back in a few weeks.

Cudzoziemiec

  • Eating all the pies and drinking all the tea.
Re: Let's talk Hydraulic brakes
« Reply #107 on: April 08, 2021, 05:18:19 pm »
It's news to me that they're meant to float. But before worrying about that or about heat dissipation and so on, I'd probably do better to give mine a clean.
Riding a bike through a city is like navigating the collective neural pathways of a vast global mind.

Re: Let's talk Hydraulic brakes
« Reply #108 on: April 08, 2021, 05:37:33 pm »
I’ve been happy with Hope floating rotors.
We are making a New World (Paul Nash, 1918)

Re: Let's talk Hydraulic brakes
« Reply #109 on: April 08, 2021, 05:48:09 pm »

My other bike is a Brompton... The brakes are... more of an idea, than a useful part of the bike...

J

I’ve never got this complaint. I’ve always found them super effective (2013 spec with Shimano pads).

FifeingEejit

  • Not Small
Re: Let's talk Hydraulic brakes
« Reply #110 on: April 08, 2021, 06:29:39 pm »
It's news to me that they're meant to float. But before worrying about that or about heat dissipation and so on, I'd probably do better to give mine a clean.

The "floating rotor" thing is just that the mounting spider and brake surface are different bits of metal, they don't really float but expand at different rates, which apparently helps with cooling and performance or something that probably only matters in Downhill MTB.



TimC

  • Old blerk sometimes onabike.
Re: Let's talk Hydraulic brakes
« Reply #111 on: April 08, 2021, 07:34:36 pm »
It's news to me that they're meant to float. But before worrying about that or about heat dissipation and so on, I'd probably do better to give mine a clean.

The "floating rotor" thing is just that the mounting spider and brake surface are different bits of metal, they don't really float but expand at different rates, which apparently helps with cooling and performance or something that probably only matters in Downhill MTB.


Floating discs in most applications actually do float. It's news to me that they don't on a bicycle wheel. I shall research it!

Cudzoziemiec

  • Eating all the pies and drinking all the tea.
Re: Let's talk Hydraulic brakes
« Reply #112 on: April 08, 2021, 08:09:18 pm »
Is the float supposed to be tangible to the finger or do they only float under braking pressure?
Riding a bike through a city is like navigating the collective neural pathways of a vast global mind.

Re: Let's talk Hydraulic brakes
« Reply #113 on: April 08, 2021, 08:12:22 pm »
Interesting, thanks!  :thumbsup:

Now I know which rotor brand to go for. Hadn't occured to me to look at Campagnolo. Just got to check that there aren't compatibility issues, but he seems confident using them with Shimano calipers. Got a bit scared when he started talking about heat transferring into the hubs, boiling your bearing grease, and expanding the hub shell but I suppose that is more likely on mountainous terrain rather than the short descents we have here. I've never knocked mine out of true either, despite many trips in the car, just that annoying scraping or pinging sound after prolonged braking.

How many discs did he say he gets through in a year?   :o

My pleasure - it's a great channel. I'm an engineer too, albeit software, but really interested in the mechanical properties of metal, which is his day job. I love it when he pokes hole in cycling marketing bollox with a big stick of maths.

I think he lives in Malaysia now - so he has some pretty big hills, it is very warm, and very wet: He says the wetness, and more the road grit it brings onto the pads, accelerates wear significantly.

Re: Let's talk Hydraulic brakes
« Reply #114 on: April 08, 2021, 08:18:42 pm »
Is the float supposed to be tangible to the finger or do they only float under braking pressure?

The disc should be mounted on pins half connected to the spider - this is what allows a little bit of float. I don't have a bicycle floating disc in front of me to check - but that is how they work on my motorbike.

The motorbike pins don't move under finger pressure - and I wouldn't expect the bicycle ones too either AND I would be worried about warping: They are so thin!

The theory is rather than bending your disk towards the pads - everything stays in the same plane, which gives  the pads the greatest surface area to operate even when new: Rather than being slowly chamfered to match the slight angle of fixed disks being bent a little under the force of the callipers slightly offset to the actual centre of the disk.

This would have been better described with a picture  ;D

Hot Flatus

  • Mediocre polyglot.Scoutmaster and nudist
Re: Let's talk Hydraulic brakes
« Reply #115 on: April 08, 2021, 08:21:21 pm »
Interesting, thanks!  :thumbsup:

Now I know which rotor brand to go for. Hadn't occured to me to look at Campagnolo. Just got to check that there aren't compatibility issues, but he seems confident using them with Shimano calipers. Got a bit scared when he started talking about heat transferring into the hubs, boiling your bearing grease, and expanding the hub shell but I suppose that is more likely on mountainous terrain rather than the short descents we have here. I've never knocked mine out of true either, despite many trips in the car, just that annoying scraping or pinging sound after prolonged braking.

How many discs did he say he gets through in a year?   :o

My pleasure - it's a great channel. I'm an engineer too, albeit software, but really interested in the mechanical properties of metal, which is his day job. I love it when he pokes hole in cycling marketing bollox with a big stick of maths.

I think he lives in Malaysia now - so he has some pretty big hills, it is very warm, and very wet: He says the wetness, and more the road grit it brings onto the pads, accelerates wear significantly.

That makes sense. Those conditions melt everything. There was an Australian guy talking about common failure of HT2 cranks, (cue anxiety for me)  but it turns out its really only happening in the southern hemisphere.

I've seen some PeakTorque vids, mainly last year when I had just bought a Supersix HiMod, was googling reviews and found him reviewing his. Agree with you about him lambasting marketing bollocks. I much prefer him to Hambini because his ego doesn't seem to come into things.

Cudzoziemiec

  • Eating all the pies and drinking all the tea.
Re: Let's talk Hydraulic brakes
« Reply #116 on: April 08, 2021, 10:01:55 pm »
Is the float supposed to be tangible to the finger or do they only float under braking pressure?

The disc should be mounted on pins half connected to the spider - this is what allows a little bit of float. I don't have a bicycle floating disc in front of me to check - but that is how they work on my motorbike.

The motorbike pins don't move under finger pressure - and I wouldn't expect the bicycle ones too either AND I would be worried about warping: They are so thin!

The theory is rather than bending your disk towards the pads - everything stays in the same plane, which gives  the pads the greatest surface area to operate even when new: Rather than being slowly chamfered to match the slight angle of fixed disks being bent a little under the force of the callipers slightly offset to the actual centre of the disk.

This would have been better described with a picture  ;D
That's actually very clear, thanks.
Riding a bike through a city is like navigating the collective neural pathways of a vast global mind.

TimC

  • Old blerk sometimes onabike.
Re: Let's talk Hydraulic brakes
« Reply #117 on: Yesterday at 12:20:02 am »
Floating discs on motorbikes are exactly as trundle describes. The disc itself 'floats' on the bobbins that connect it to the bell, spider or cage that is fixed to the hub, and the bobbins allow a small amount of lateral movement of the disc to ensure that the braking effort is applied equally by the pistons on either side of the calliper. A cheaper setup allows a single-piston calliper to apply a balanced pressure to the disc. The float is often quite noticeable, particularly on racing discs which will often rattle on the bobbins. An alternative way of achieving centralised pressure is a floating calliper, which is kind of similar to the way a single-pivot rim brake (should) avoid distorting a wheel under braking. The two-piece construction is about heat dissipation.

When I raced in karting (250 ICE, for those in the know), the discs floated on the axles using a connector not dissimilar to the Shimano centrelock system, and again the movement was distinct and sometimes noisy. Hence my assumption that they worked on a similar principle on bikes. But, looking closely, it appears that there's a compressible washer on the bobbins that allows a tiny amount of lateral movement on the spider and, as trundle says, it's not detectable by finger pressure - and floating disc of this type are available on both 6-bolt and centrelock mounts.

I have my doubts that this kind of float is particularly worthwhile on a bicycle (I think the hydraulic balance in the calliper will do all the self-centring needed), or that the heat dissipation properties of Icetech Freeza rotors are needed for most YACF-style riders. But they look nice, and often that's all that's needed!

Re: Let's talk Hydraulic brakes
« Reply #118 on: Yesterday at 10:32:37 am »

I have my doubts that this kind of float is particularly worthwhile on a bicycle (I think the hydraulic balance in the calliper will do all the self-centring needed), or that the heat dissipation properties of Icetech Freeza rotors are needed for most YACF-style riders. But they look nice, and often that's all that's needed!

You are spot on with the hydraulic self-centering with dual piston callipers  :thumbsup:


Re: Let's talk Hydraulic brakes
« Reply #119 on: Yesterday at 02:04:05 pm »
... or that the heat dissipation properties of Icetech Freeza rotors are needed for most YACF-style riders. But they look nice, and often that's all that's needed!
Don’t forget the m in half m v squared.

Re: Let's talk Hydraulic brakes
« Reply #120 on: Yesterday at 02:05:36 pm »
... or that the heat dissipation properties of Icetech Freeza rotors are needed for most YACF-style riders. But they look nice, and often that's all that's needed!
Don’t forget the m in half m v squared.

Have to say that occurred to me too, but I was more charitable;)

Or perhaps the v being squared more than compensates (other than on the hills...)

citoyen

  • Occasionally rides a bike
Re: Let's talk Hydraulic brakes
« Reply #121 on: Yesterday at 04:38:03 pm »
An alternative way of achieving centralised pressure is a floating calliper

You could do this by forgetting to tighten the mounting bolts after you've loosened them slightly to centre them on the disc.

I may have done this accidentally once. Or twice...

NB not a serious recommendation.
"The future's all yours, you lousy bicycles."

Re: Let's talk Hydraulic brakes
« Reply #122 on: Yesterday at 07:11:06 pm »

I had a total loss of braking mid way through a January 200 using Juin-Tech cable/hydro hybrids (a bit like a cheap rip off of the TRP hybrid ones). Both brakes. They had been an absolute bugger to set up, and I had been having to adjust them mid ride, every ride.
...
 Brakes went in the bin. Never really got to the bottom of the issue, but lost faith in them.

That sounds pretty alarming.
I’ve found they set up easily enough and don’t need much attention, so far. But I suspect I go less far than you.
For me the advantage was in the levers. But I’m picky about them.

TimC

  • Old blerk sometimes onabike.
Re: Let's talk Hydraulic brakes
« Reply #123 on: Yesterday at 10:06:46 pm »
... or that the heat dissipation properties of Icetech Freeza rotors are needed for most YACF-style riders. But they look nice, and often that's all that's needed!
Don’t forget the m in half m v squared.

As a heavier-than-average rider, I never forget it!

Talking of motorcycle floating discs, my brother turned up at my house this afternoon on his new BMW RS1250R. It was definitely possible to move the discs on the bobbins, so I think that the 'floating' description of the Shimano discs is perhaps stretching the truth.

FifeingEejit

  • Not Small
Re: Let's talk Hydraulic brakes
« Reply #124 on: Yesterday at 10:28:17 pm »
Floating discs on motorbikes are exactly as trundle describes. The disc itself 'floats' on the bobbins that connect it to the bell, spider or cage that is fixed to the hub, and the bobbins allow a small amount of lateral movement of the disc to ensure that the braking effort is applied equally by the pistons on either side of the calliper. A cheaper setup allows a single-piston calliper to apply a balanced pressure to the disc. The float is often quite noticeable, particularly on racing discs which will often rattle on the bobbins. An alternative way of achieving centralised pressure is a floating calliper, which is kind of similar to the way a single-pivot rim brake (should) avoid distorting a wheel under braking. The two-piece construction is about heat dissipation.

When I raced in karting (250 ICE, for those in the know), the discs floated on the axles using a connector not dissimilar to the Shimano centrelock system, and again the movement was distinct and sometimes noisy. Hence my assumption that they worked on a similar principle on bikes. But, looking closely, it appears that there's a compressible washer on the bobbins that allows a tiny amount of lateral movement on the spider and, as trundle says, it's not detectable by finger pressure - and floating disc of this type are available on both 6-bolt and centrelock mounts.

I have my doubts that this kind of float is particularly worthwhile on a bicycle (I think the hydraulic balance in the calliper will do all the self-centring needed), or that the heat dissipation properties of Icetech Freeza rotors are needed for most YACF-style riders. But they look nice, and often that's all that's needed!
250 ICE, that's a gearbox class isn't it?

So fast that most tracks had a straighter bit for you that was rather unimaginatively known as "the gearbox straight"

I don't remember many meets with anything faster than JICA or Senior TKM.

Sent from my BKL-L09 using Tapatalk