Disc brakes on road bikes

[sevenfourate]

Because you have a big lump of metal ( the disc) on one side.

An offset gyroscopic effect ? I’d imagine the wheel / tyre / hub would far outweigh (sic) a 100g brake-disc……..

 

[Alex321]

Because you have a big lump of metal ( the disc) on one side.

It really isn't that big a lump, compared to the weight of the wheel as a whole, and being at the centre of the wheel will have much less effect than a similar weight nearer to the rim would.

 

[Webbo2]

It really isn't that big a lump, compared to the weight of the wheel as a whole, and being at the centre of the wheel will have much less effect than a similar weight nearer to the rim would.

So when I go in to our out building to get my bike as soon as I move it, the front wheel always turns/ swings to the left. The same when I wheel it through the back gate pushing it by the saddle.
As my hoses are internal there is nothing causing any resistance to the slight weight of the disc.

 

[Dogtrousers]

It really isn't that big a lump, compared to the weight of the wheel as a whole, and being at the centre of the wheel will have much less effect than a similar weight nearer to the rim would.

It's a question of balance. The weight just has to be a smidge more on one side.

 

[Mike Ayling]

4/6, B: room for improvement

I've got six bikes with hydraulic discs from Shimano and Tektro. Only one of the Tektro* bikes squeals in the wet and then only for a few seconds until it's warmed up. The Shimano have been near silent in all conditions.
* edited to correct: that bike has a SRAM gears not brakes

Well so you say.
We were on holiday at our son's home at Heist op den Berg in Belgium on the first week in June and we walked around the corner to see a professional bike race. Most of the team cars were recognisable from the Tour de France so I assumed that they were riding on some decent bikes. There was a circuit with five laps and we set up at a T junction to watch. On one of the laps there was a rain shower and the screeching of brakes as the peleton slowed down for the corner was deafening!

 

[Dadam]

Well all I can say in my statistical sample (my bikes), only 1 in 6 squeals, and then only briefly. Maybe some pads are worse than others. Google suggests sintered pads are worse than organic ones, so it might have been that. Also, it sounds likely that they hadn't braked much before the T junction so there was a bunch of riders with cold wet discs which could well squeal until heated up and the water dispersed.

Anyway it's not correct to say all disc brakes are noisier in the wet.

 

[Mike Ayling]

Well all I can say in my statistical sample (my bikes), only 1 in 6 squeals, and then only briefly. Maybe some pads are worse than others. Google suggests sintered pads are worse than organic ones, so it might have been that. Also, it sounds likely that they hadn't braked much before the T junction so there was a bunch of riders with cold wet discs which could well squeal until heated up and the water dispersed.

Anyway it's not correct to say all disc brakes are noisier in the wet.

Well all I can say in my statistical sample (my bikes), only 1 in 6 squeals, and then only briefly. Maybe some pads are worse than others. Google suggests sintered pads are worse than organic ones, so it might have been that. Also, it sounds likely that they hadn't braked much before the T junction so there was a bunch of riders with cold wet discs which could well squeal until heated up and the water dispersed.

Anyway it's not correct to say all disc brakes are noisier in the wet.

Four of the five laps were dry and there was no screeching on dry discs.
Your six items are not a statistical sample!

 

[Chislenko]

Why would the weight of the discs make any difference to the wheel turning?

Or to wheeling the bike by the seat (not that I have ever really done that)?

It just does Alex. On a rim brake bike there is no weight at the front so the wheel stays straight. On a disc brake bike the weight and position of the disc makes the wheel turn usually to the side where the disc is mounted. When lifting it back onto the wall mount you have to employ a different strategy to lifting a rim brake bike.

Two hands on the top tube on a rim brake, very easy, one on the top tube, one on the handlebars on a disc brake, not so easy.

 

[gcogger]

Four of the five laps were dry and there was no screeching on dry discs.
Your six items are not a statistical sample!

I can add another 4 samples (from my wife and I) - no screeching, just occasionally a brief noise when first braking in the wet.
I suspect Dadam is correct in that it's the sintered and semi metallic pads that are noisy. Ours have all been organic/resin types, but the pro cyclists use sintered.
Edit: perhaps we need a forum survey on noisy brakes

 

[Binky]

My experience of riding with lots of cyclists who have disc brakes are they squeal in wet and the dry, far worse than rim brakes.
I'd say in my experience of riding rim braked bikes it's rare for them to squeal, it's not rare for discs to.

 

[Alex321]

It just does Alex. On a rim brake bike there is no weight at the front so the wheel stays straight. On a disc brake bike the weight and position of the disc makes the wheel turn usually to the side where the disc is mounted. When lifting it back onto the wall mount you have to employ a different strategy to lifting a rim brake bike.

Two hands on the top tube on a rim brake, very easy, one on the top tube, one on the handlebars on a disc brake, not so easy.

I can't say I've noticed, but it may be that I just automatically hold by the stem without thinking about it.

I'll think about it as I'm storing the bike tomorrow when I get to work - the bike storage in our office has racks like these, so I have to lift the bike to almost vertical.

 

[Ming the Merciless]

There is much more to brakes, than whether you can get them to lock up a wheel. Being able to lock the wheel doing not inherently make them good brakes. Hell, I could lock up a wheel by sticking a stick through the spokes.

 

[Alex321]

My experience of riding with lots of cyclists who have disc brakes are they squeal in wet and the dry, far worse than rim brakes.
I'd say in my experience of riding rim braked bikes it's rare for them to squeal, it's not rare for discs to.

I have hardly ever heard them squeal in the dry.

We had 13 of us out for a club ride on Sunday, 3 with rim brakes, 10 with discs, and I did not hear a single squeal from anybody's brakes in the entire 37 miles.

In the wet, yes they often do. Though even then, only for a couple of seconds each time.

 

[Binky]

I have hardly ever heard them squeal in the dry.

We had 13 of us out for a club ride on Sunday, 3 with rim brakes, 10 with discs, and I did not hear a single squeal from anybody's brakes in the entire 37 miles.

In the wet, yes they often do. Though even then, only for a couple of seconds each time.

I'm thinking of Mallorca this year and I was descending off Puig Major and it was deafening! Some no doubt due to hire bikes not maintained etc but I have definitely heard discs howling in the dry plenty of times.

Anyway, my point is which I'd say was fair is it's rare for rim brakes to squeal, far less rare for discs in wet or dry.

 

[rydabent]

Cyclist the cling to rim brakes remind me of firemen on diesel locomotives. Lost cause. And------------the mfg are now pretty much geared up on producing disc brakes.