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PostPosted: Sun Aug 26, 2012 7:43 am 
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WAIT... Don't people want BIGGER disk rotors for better braking? Isn't the Rim as big as you can get? Also aren't we comparing apples to pears when it comes to rim vs disc brakes, I've used cable disc and its useless, hydro disc is amazing though. Cable rim braking is good, I assume that hydraulic rim brakes will be better (cervelo p5 owners)?

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Posted: Sun Aug 26, 2012 7:43 am 


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PostPosted: Sun Aug 26, 2012 11:01 am 
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airwise wrote:
So that's no then.

Most of us haven't. Closest I've got is 20km descents on a cross bike with Force, 23c tyres and BB7's.

Of course rim brakes will always be lighter but if you want to descend quickly for 10km, you really don't want a super light and unaerodynamic bike in the first place.



Really..? Have you every raced motorcycles or cars before.. I like disk brakes when im needing to get rid of 180kph at the end of a 2km straight for the first gear hairpin at the end. Lighter is alway, alway always better...

And the mass attached to the wheels is the most important place to loose weight..

A heavier wheel will have a higher gyroscopic effect, making the whole bike resist Turning into the corner, wanting to stand up under brakes which will agian make it resist turning into the corner under brakes into the corner ( yes you can acutally brake all the way up to the apex of a corner ). Will carry more inertia( resist desecration ) and spin up slower...

I totally reckon that my 5.3kg bikes best attributes are its high speed cornering ( 60-90kph ) and manners under brakes...


You would be very surprised just how far you can lean a wheel set up bike with a decent set of tires over..

If the roads you ride are that poorly surfaced that... Blah blah blah... Just buy a MTB. Its what you really want anyway :roll:

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PostPosted: Sun Aug 26, 2012 4:20 pm 
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I'm sorry, but the gains of a few grams at the wheels is negligable. And the case can be made that the rim can be lighter, so the weight would be a bit heavier, but better balanced, so most of your argument immediately goes out of the window ;)

Sugarkane, I understand you don't like Discbrakes but to start saying that anyone who needs it better can buy a CX bike is ridiculous. There are perfectly fine reasons for discbrakes even on good surfaces: RAIN.


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PostPosted: Sun Aug 26, 2012 4:37 pm 
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Saying that any of us NEED them is ridiculous... Sorry mate

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PostPosted: Sun Aug 26, 2012 4:58 pm 
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sugarkane wrote:
Saying that any of us NEED them is ridiculous... Sorry mate


need is relative :)

None of us needs a sub-11 kg bike, sorry mate ;)


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PostPosted: Sun Aug 26, 2012 7:57 pm 
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Location: Glermsford, Suffolk U.K
I still make the point that the MTB had the very same discussiuon 20 years ago. Now the road community is having the same discussion. There are very many polarised opions based on little practical experience. what practical experience is based one system, Avids meachicals and inferenace and postulations from MTB systems. It a bit like judging all MTB disc system on some of Hayes early efforts my how they have improved.

There are solutions to the problems identified by Leanord Zinn we just have not seen them yet. There is much polarised opinion here. those of us who want to try them on the road do not need to just by a CX or MTB. I already have the MTB.

Also the arugument that the rim is a big disc does not hold or MTB's would not be using disc brake systems but they do for the wet weather performance, braking modulation, performance in mud/grit which kills rim pads and for the braking performance particulalary during decents. For road disc brakes I do see the potential of some technologies from motorsport finding there way in to deal with heat like ceramic/carbon discs (which will deal with weight as well) and pads that can deal with the heat build up already exist - high performance cars use them.

A road brake disc system will not be same as a MTB system as the requirements are different the solutions will be different. Also the disc brake used on touring bike or tandam will have different requirements and different solutions to a brake used on race bike used for high speed decents.

Also no one needs discs brakes, somepeople still drive/race cars with drum brakes, would you use one a daily transport in all weathers? I wouldn't and I like old cars.

Next year one of my aims is to build up a disc brake equipped race bike and start experimenting what works and what does not on the wheel front. Again I don't need to do this but I want too. Maybe road discs brakes will flop and never take off but there is alot of judgement about a product does not even exsist properly yet.

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PostPosted: Mon Aug 27, 2012 12:08 am 
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Franklin wrote:
sugarkane wrote:
Saying that any of us NEED them is ridiculous... Sorry mate


need is relative :)

None of us needs a sub-11 kg bike, sorry mate ;)



Haha true
I'll be in when you can build a sub 6kg bike with out to much drama
And the industry starts embracing formula 1 tech.

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PostPosted: Mon Aug 27, 2012 2:32 am 
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I am 92 kg @ 6'4" and I love to go downhill fast.

In the rain going down a big hill (or emergency stopping in the city) the current brakes just don't work well enough for me (alu clinchers, carbon wheels of any type).

In the dry, current brakes do not work well enough for me (carbon clinchers - not sure about carbon tubulars. They could be better for alu clinchers.)

For those guys who say, "don't need 'em" I would like to suggest they strap 30kg onto their bike or back and do those same braking manoeuvres as they did before and see if they wish for better brakes. The fact of physics is that the force required for stopping is much greater for heavier guys.

Stopping from 60km/h in 6 seconds requires a force of 277 newtons for me vs 186 newtons for a 60kg rider. Or think of it this way skinnies: next time you stop at 100% and take a sigh of relief, think of the fatties that would require their brakes to work 65% better to stop in the same distance. (for formula see: http://answers.yahoo.com/question/index ... 510AA7UwPs)

Yes they have drawbacks, but until I either drop 30kg or find a rim type braking system that works 68% better, I just can't put myself in your position to see how you are happy with braking performance of road bikes.

------

I realise that tyres play a large part in adhesion and that discs are not as aero and will weigh more. But bring them on - front wheel only as a compromise.


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PostPosted: Mon Aug 27, 2012 11:00 am 
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Location: Lancaster, UK
sugarkane wrote:
I used to race production 250 gp class motorbikes


so did I sugarkane :wink: Really.

sugarkane wrote:
I would still ride around the outside of you any day and any conditions


big words sugarkane, big words. I'd be careful what you assume fella. I was riding the Maratona last year and came up behind a bloke with the number 34 on his number plate. Guess what - it was Kevin Schwantz - you gonna ride round the outside of him too?


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PostPosted: Mon Aug 27, 2012 12:53 pm 
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maddog 2 wrote:
sugarkane wrote:
I used to race production 250 gp class motorbikes


so did I sugarkane :wink: Really.

sugarkane wrote:
I would still ride around the outside of you any day and any conditions


big words sugarkane, big words. I'd be careful what you assume fella. I was riding the Maratona last year and came up behind a bloke with the number 34 on his number plate. Guess what - it was Kevin Schwantz - you gonna ride round the outside of him too?



Haha not likely, I stay away from motorbikes these days they are just to dangerous and I enjoy riding way to fast..
I love fast tech descents on the pushy though and always looking for a hill big enough to push well into the 100kph bracket down.

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PostPosted: Wed Aug 29, 2012 9:06 am 
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sugarkane wrote:
[
Really..? Have you every raced motorcycles or cars before.. I like disk brakes when im needing to get rid of 180kph at the end of a 2km straight for the first gear hairpin at the end. Lighter is alway, alway always better...

And the mass attached to the wheels is the most important place to loose weight..

A heavier wheel will have a higher gyroscopic effect, making the whole bike resist Turning into the corner, wanting to stand up under brakes which will agian make it resist turning into the corner under brakes into the corner ( yes you can acutally brake all the way up to the apex of a corner ). Will carry more inertia( resist desecration ) and spin up slower...

I totally reckon that my 5.3kg bikes best attributes are its high speed cornering ( 60-90kph ) and manners under brakes...


You would be very surprised just how far you can lean a wheel set up bike with a decent set of tires over..

If the roads you ride are that poorly surfaced that... Blah blah blah... Just buy a MTB. Its what you really want anyway :roll:


It would be interesting to take you on on an Alpine descent on your super light bike. I'm a crap cyclist but not many come past me heading downhill - very few motor powered vehicles seem to keep up either. Having said that I don't take switchbacks at 60-90kph. I don't know anyone that does in the real world either :wink:

If you are worried about heavier wheels resisting cornering then discs will most likely be ideal for you - dedicated tubular rims (the part that creates the inertia) can most likely be built remarkably light without the need for a braking surface.

With regards to motor racing, have you ever raced motorbikes or cars on a downhill only course? I've not ridden motorbikes - seen too many idiots in plaster or coffins to consider it :) I would say however that stability in the wind would strike me more as a consequence of aerodynamics in motorsport than weight - if your motorbike weighed 6kg I suspect it might be a different matter.


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PostPosted: Wed Aug 29, 2012 12:18 pm 
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Joined: Wed Dec 01, 2010 4:29 am
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Yes, bring on road bikes with hydraulic disc brakes. Perhaps the caliper mechanism could also house the brake fluid, which can be cable activated from the STI/Di2 levers :-)

Yes, to completely remove the dishing issues with rear wheels, bring on 11 to 14 spd Internal Geared Electric/Di2 Race Hubs with quick release skewers and dual chainrings, ie Shimano 11spd Alfine Di2 but with Di2 dual chainrings :-)


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PostPosted: Wed Aug 29, 2012 12:32 pm 
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Posts: 265
not so good review...

http://road.cc/content/news/64505-eurob ... first-ride


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PostPosted: Wed Aug 29, 2012 2:08 pm 
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airwise wrote:
sugarkane wrote:
[
Really..? Have you every raced motorcycles or cars before.. I like disk brakes when im needing to get rid of 180kph at the end of a 2km straight for the first gear hairpin at the end. Lighter is alway, alway always better...

And the mass attached to the wheels is the most important place to loose weight..

A heavier wheel will have a higher gyroscopic effect, making the whole bike resist Turning into the corner, wanting to stand up under brakes which will agian make it resist turning into the corner under brakes into the corner ( yes you can acutally brake all the way up to the apex of a corner ). Will carry more inertia( resist desecration ) and spin up slower...

I totally reckon that my 5.3kg bikes best attributes are its high speed cornering ( 60-90kph ) and manners under brakes...


You would be very surprised just how far you can lean a wheel set up bike with a decent set of tires over..

If the roads you ride are that poorly surfaced that... Blah blah blah... Just buy a MTB. Its what you really want anyway :roll:


It would be interesting to take you on on an Alpine descent on your super light bike. I'm a crap cyclist but not many come past me heading downhill - very few motor powered vehicles seem to keep up either. Having said that I don't take switchbacks at 60-90kph. I don't know anyone that does in the real world either :wink:

If you are worried about heavier wheels resisting cornering then discs will most likely be ideal for you - dedicated tubular rims (the part that creates the inertia) can most likely be built remarkably light without the need for a braking surface.

With regards to motor racing, have you ever raced motorbikes or cars on a downhill only course? I've not ridden motorbikes - seen too many idiots in plaster or coffins to consider it :) I would say however that stability in the wind would strike me more as a consequence of aerodynamics in motorsport than weight - if your motorbike weighed 6kg I suspect it might be a different matter.



Only raced down hill on the road.. Lighter bikes ( motor bikes ) corner better cause the stress the tires less..
I take the stwich backs at the speed most people do I just brake very late and very hard..
My front pads last me around 1200kms..
Racing teaches you to brake where you need to not any earlier..

All I'm saying is I like riding very fast down tech descents.. And my rim brakes do the job plenty fine.. Wet or dry and I leave the brakes very,very late some times..
It puts a smile on my face :mrgreen:

If disks on roadies are really gona be developed well, we'll need muchI softer tires.. And they arn't gona last long or be cheap..

Ohh and I'm not in untill the disks are carbon..

Steel disks fade. When pushed really hard..
That is a Shity feeling.. When you go for the brakes hard and nothing happens.
Carbon rim brakes won't and don't fade. Sure there are plenty of other problems with over heating carbon rim brakes but there are plenty of differnt and just as awful issues with overheating disks..

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Posted: Wed Aug 29, 2012 2:08 pm 


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PostPosted: Wed Aug 29, 2012 2:34 pm 
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sugarkane wrote:
Steel disks fade. When pushed really hard..
That is a Shity feeling.. When you go for the brakes hard and nothing happens.
Carbon rim brakes won't and don't fade. Sure there are plenty of other problems with over heating carbon rim brakes but there are plenty of differnt and just as awful issues with overheating disks..



Okay, now that you've established that you know nothing about brakes...


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