Open letter by Vents regarding disc brakes **Graphic photos**

[Paul Ruinaard]

Hmm.

 

FWIW:  drum brakes are actually incredibly efficient as the principal they work on i.e. expansion in a drum allows for much greater braking forces. Just very heavy, fade really badly as heat builds up and they are difficult to maintain and tedious to disassemble.

 

So careful of the analogies. they stop cars quickly cause they work well. But not repeatedly well.

 

I reckon once you have the brakes, the tyres will develop - wider rims with more traction etc, as the rims are lighter. More traction in corners, higher corner speeds. It happens in every sport. Right now and in most cases tyres can be locked but that actually leads to an increase in speed so modulation is key.

 

ABS on bike brakes is easy once you have a battery. So safer for joe average as well who doesn't know about feathering.

 

But only major tour riders and commuters ride a lot  in the rain so we need to look at who will benefit. Its really at the pinnacle of the sport where small advantages will open up over others. That Aha moment which we are debating.

 

 

 

[Barend de Arend]

Exactly! I can remember stealing my dads old Corolla ages ago to take on joyrides. We would lock the wheels up at each corner pretending to be Colin McRae..... It had drum brakes, yet enough power to lock the wheels up. Yet discs perform better and are now the accepted norm.

 

Grip between tyres and the road is one of the factors to be considered. However there are other factors at play too. One cannot ignore things like better modulation, feel, confidence, consistency etc when talking about an over all better braking performance.

 

This is a nice real world test when the human factor is included.

 

 

That video is more about technique than technology.  Look at about 2:35 in.  Dan is clearly further back and lower.

 

I'd very much prefer a much more scientific test.  Say 10 stops in 10 minutes from 80 km/h, 90 kg bike + rider.  The repeated tests are for fade.  The speed is because that's what road bikes do on an alpine descent.  And different discs, different pads, different rims (including old fashioned leather on wood, for curiosity.)  These tests get done on cars all the time.

 

On that matter, same brakes, different tires: let's find out which tires are better.  That'd be useful too.  I know Continental and Michelin and Tour Mag actually test tire grip around corners.  Let's test stopping grip.  Then we can remove the "tires are the limit" question.

 

I'd prefer not to be an early adopter without more data.

 

But it is indeed not all about stopping power.  Modulation, feedback and consistency matter.  And technique.

[Patchelicious]

Hmm.

 

FWIW: drum brakes are actually incredibly efficient as the principal they work on i.e. expansion in a drum allows for much greater braking forces. Just very heavy, fade really badly as heat builds up and they are difficult to maintain and tedious to disassemble.

 

So careful of the analogies. they stop cars quickly cause they work well. But not repeatedly well.

 

I reckon once you have the brakes, the tyres will develop - wider rims with more traction etc, as the rims are lighter. More traction in corners, higher corner speeds. It happens in every sport. Right now and in most cases tyres can be locked but that actually leads to an increase in speed so modulation is key.

 

ABS on bike brakes is easy once you have a battery. So safer for joe average as well who doesn't know about feathering.

 

But only major tour riders and commuters ride a lot in the rain so we need to look at who will benefit. Its really at the pinnacle of the sport where small advantages will open up over others. That Aha moment which we are debating.

I think we can debate cars/drums/trucks/rims/rimjobs till we are blue in the face.

 

As it stands right now. From most of the studies, when it comes to over all braking performance, disk perform just as well to much better than rim brakes depending on conditions and road surface.

 

All the other cool tech advancement that you mention will come, and I hope that it does, but like you said only when disks are accepted.

 

So the question we need to ask is, why the hell doesnt the UCI allow them.

 

If it's a safety thing, then surely there is a solution.

If it's a "riders feel left out" thing surely there is a soltuion.

If it's a compatibility thing, again there is a soltuion.

 

There is a soltuion, but knee jerk reactions and blanket bans on good tech is not it.

[Patchelicious]

That video is more about technique than technology. Look at about 2:35 in. Dan is clearly further back and lower.

 

I'd very much prefer a much more scientific test. Say 10 stops in 10 minutes from 80 km/h, 90 kg bike + rider. The repeated tests are for fade. The speed is because that's what road bikes do on an alpine descent. And different discs, different pads, different rims (including old fashioned leather on wood, for curiosity.) These tests get done on cars all the time.

 

On that matter, same brakes, different tires: let's find out which tires are better. That'd be useful too. I know Continental and Michelin and Tour Mag actually test tire grip around corners. Let's test stopping grip. Then we can remove the "tires are the limit" question.

 

I'd prefer not to be an early adopter without more data.

 

But it is indeed not all about stopping power. Modulation, feedback and consistency matter. And technique.

I agree.

 

Making the test too short and too "scientific" jeez can't believe I said that, removes some of that "confidence factor" that is so important to real world speed. With your reference to cars tests, Car mag does this, and crappy cars can stop almost as quickly as sports cars in the standard 100kmh to 0 test, even though the one can inspire confindence and therefore lead to quicker corner entry speeds, later braking etc.

 

I think a test like taking a large data set say 30 riders. And have 15 descend a long pass on standard brakes first and then on disks. While the other 15 first do it on disk and then standard brakes. All on same tyres, same pressures, time of day and temperature. Then measure the differential.

 

This could be quite conclusive, but I think t will just reinforce what many know already. That the confidence that disks give, allow for faster descending. Guys that I know who went to disks have all improved their going downhill Strava PRs, they put this down to confidence, and not braking power.

 

Maybe some of the guys with disk can weigh in here.

[lechatnoir]

I prefer the way a disc bike looks to a bike with rim brakes. and if that's enough to make me want to ride it more, then all other arguments are moot. IMHO of course. I try to not let facts get in the way of these matters...   

[raptor-22]

The chaos of disc introduction is thanks to the way it was introduced. The majority of pro riders don't want it on grounds of safety, aesthetics, reliability , wheel change delay, compatibility between brands.

When we read between the lines all they want us to be consulted and fur there to be stsndards in place that regulate certain key dimensions. As it currently stands mtb systems are increasingly incompatible between brands. Simply swapping a wheel is not as easy as it was . You almost have to swap like for like to achieve the same performance. What happens if Mavic support is required in a road race? Will they have a compatible hub spacing with compatible cassette spaced correctly to work on s bikes that may have different disc rotor diameters or even brake surface depth? There's no stsndards to govern any of this development and for the racers that's s major problem. Would they want to risk having to wait for a team car and losing a race just because the component sponsor wants to show case disc brake technology? No. The gain isn't worthy of the risk to the ability to stay in the race .

 

The other issue and it's one I've noticed before with rigid carbon forks is differential flex in the fork legs . I could feel that different flex under hard braking. It's subtle because it's gradual so maybe unnoticeable in the heat of battle but it's still slightly unnerving to feel the bike want to drift left under hard braking . The thru axle is supposed to take care of that but under my 85kg arse it's a problem .

All current standards for bicycle forks have been developed for forks equipped with caliper brakes . Mtb forks standards don't apply here and generally the manufacturer doesn't have as tight a weight target as the designer for road forks would have.

 

There's a lot to be considered besides just performance and that's the main thrust of resistance including the political issues the pros are leveraging

[Pure Savage]

I prefer the way a disc bike looks to a bike with rim brakes. and if that's enough to make me want to ride it more, then all other arguments are moot. IMHO of course. I try to not let facts get in the way of these matters...   

 

You are going to LOVE mountain bikes

[Pure Savage]

I agree.

 

Making the test too short and too "scientific" jeez can't believe I said that, removes some of that "confidence factor" that is so important to real world speed. With your reference to cars tests, Car mag does this, and crappy cars can stop almost as quickly as sports cars in the standard 100kmh to 0 test, even though the one can inspire confindence and therefore lead to quicker corner entry speeds, later braking etc.

 

I think a test like taking a large data set say 30 riders. And have 15 descend a long pass on standard brakes first and then on disks. While the other 15 first do it on disk and then standard brakes. All on same tyres, same pressures, time of day and temperature. Then measure the differential.

 

This could be quite conclusive, but I think t will just reinforce what many know already. That the confidence that disks give, allow for faster descending. Guys that I know who went to disks have all improved their going downhill Strava PRs, they put this down to confidence, and not braking power.

 

Maybe some of the guys with disk can weigh in here.

 

I agree.

 

Making the test too short and too "scientific" jeez can't believe I said that, removes some of that "confidence factor" that is so important to real world speed. With your reference to cars tests, Car mag does this, and crappy cars can stop almost as quickly as sports cars in the standard 100kmh to 0 test, even though the one can inspire confindence and therefore lead to quicker corner entry speeds, later braking etc.

 

I think a test like taking a large data set say 30 riders. And have 15 descend a long pass on standard brakes first and then on disks. While the other 15 first do it on disk and then standard brakes. All on same tyres, same pressures, time of day and temperature. Then measure the differential.

 

This could be quite conclusive, but I think t will just reinforce what many know already. That the confidence that disks give, allow for faster descending. Guys that I know who went to disks have all improved their going downhill Strava PRs, they put this down to confidence, and not braking power.

 

Maybe some of the guys with disk can weigh in here.

 

The great US of A is compiling a report on all crashes in the US certified events and noting how many injuries arose from each part of the bike. There is about ten years of data they say. Therefore if there is a problem this large scale test will pick it up.

 

Has nobody else watched the latest GCN show? 

[SwissVan]

Just go ride your bike tomorrow the rim brakes will work just fine...like they have for the last [ ?? ] years. Discs are just another excuse to push up the price of new bikes.

[Barend de Arend]

Just go ride your bike tomorrow the rim brakes will work just fine...like they have for the last [ ?? ] years. Discs are just another excuse to push up the price of new bikes.

 

That's exactly why I want more data.

 

Weight is easy.  Aero took a few years before there were confirmed tests.  You would think if disc brakes were better, manufacturers would have no problem presenting data.

 

Right now discs are being heavily influenced by confirmation bias.

 

We all want brakes to stop us in emergencies.  We feel safer.  So we want better brakes.  I want better brakes.  But at some point better brakes just mean my soft parts hit the stem quicker.

 

None of this matters until I put money down for a new bike.

[Barend de Arend]

The chaos of disc introduction is thanks to the way it was introduced. The majority of pro riders don't want it on grounds of safety, aesthetics, reliability , wheel change delay, compatibility between brands.

 

I agree fully with this.

 

I also know that the pros use tubulars, and most of us use clinchers.

[Pure Savage]

I agree fully with this.

 

I also know that the pros use tubulars, and most of us use clinchers.

I also know all pro's are paid to ride bikes and promote manufacturers new tech

[rudi-h]

i'm set on buying my next road bike with disc brakes, just because i like it.  I've been to CL Fourways and Bike basement and they don't have a single disc brake roadbike on display, not even in the R150k class...

 

wonder why they won't bring it in?  Its great tech for us non-racers.

[Danger Dassie]

Just go ride your bike tomorrow the rim brakes will work just fine...like they have for the last [ ?? ] years. Discs are just another excuse to push up the price of new bikes.

 

Yet there are a slew of gravel/road bikes specced with discs in the mid and lower range that cost far less than many comparable and high end bikes that do have rim brakes. 

So that straw argument is a wash.

[GrahamS2]

BTW, disc brakes gained popularity not because of greater stopping power bu because of ease of maintenance. 

Not true at all. Disc brakes gained popularity due to the ability to modulate braking force more effectively, and thus the ability to utilise anti-lock braking systems.

 

Braking efficiency, particularly on a light weight vehicle such as a bicycle, is not determined by outright braking force available - all brake types have the ability to lock wheels... Discs are superior with regards to the ability to modulate braking force and to be consistent in all conditions. 

[Pure Savage]

I found out why the UCI banned disc brakes, can't blame them!!

 

 

 

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