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PostPosted: Wed Jan 02, 2013 8:48 pm 
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As far as I know, sram are developing hydraulic rim brakes for the road, not hydraulic disc brakes. Hydraulics have advantages over cables for both rim and disc brakes, but that doesn't mean that hydraulic disc brakes are better than rim brakes.

Braking on an MTB and braking on the road are two very different scenarios - speed on the road can be a lot higher, and tyre contact patch is a lot smaller. While modulation is a good thing in any situation, the amount of braking "power" available can be too much. If you can lock the front wheel easily, then you have too much power, and not enough traction, which is not a good situation. In that case, you either need more traction so that the wheel doesn't slide, or less power to avoid locking it in the first place. If you do have a good traction/power ratio, then as soon as front wheel braking begins to lift the rear wheel off the ground, you've found the limit of it - braking harder in that case will not stop you any faster.

Good road rim brakes with decent levers, cables, pads and rims, together with a decent set of grippy tyres, are perfectly adequate for any and all situations, and while they have some drawbacks, they don't have as many as discs do right now.


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PostPosted: Wed Jan 02, 2013 8:53 pm 
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foz wrote:
As far as I know, sram are developing hydraulic rim brakes for the road, not hydraulic disc brakes. Hydraulics have advantages over cables for both rim and disc brakes, but that doesn't mean that hydraulic disc brakes are better than rim brakes.

Braking on an MTB and braking on the road are two very different scenarios - speed on the road can be a lot higher, and tyre contact patch is a lot smaller. While modulation is a good thing in any situation, the amount of braking "power" available can be too much. If you can lock the front wheel easily, then you have too much power, and not enough traction, which is not a good situation. In that case, you either need more traction so that the wheel doesn't slide, or less power to avoid locking it in the first place. If you do have a good traction/power ratio, then as soon as front wheel braking begins to lift the rear wheel off the ground, you've found the limit of it - braking harder in that case will not stop you any faster.

Good road rim brakes with decent levers, cables, pads and rims, together with a decent set of grippy tyres, are perfectly adequate for any and all situations, and while they have some drawbacks, they don't have as many as discs do right now.


I read an article on the development of the C59 disc and Colnago's collaboration with Formula developing the disc brakes. As you said Formula had to reduce the power of the disc brakes fitted to the C59 as the bikes brakes kept locking up too easily.

I think the main advantage of discs is the minimal wear to wheel rims and the reduction of brake fade in hot (unlikely in the UK) and wet conditions rather than the increased stopping power in 'normal' conditions.


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PostPosted: Wed Jan 02, 2013 9:11 pm 
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foz wrote:
As far as I know, sram are developing hydraulic rim brakes for the road, not hydraulic disc brakes. Hydraulics have advantages over cables for both rim and disc brakes, but that doesn't mean that hydraulic disc brakes are better than rim brakes.

Braking on an MTB and braking on the road are two very different scenarios - speed on the road can be a lot higher, and tyre contact patch is a lot smaller. While modulation is a good thing in any situation, the amount of braking "power" available can be too much. If you can lock the front wheel easily, then you have too much power, and not enough traction, which is not a good situation. In that case, you either need more traction so that the wheel doesn't slide, or less power to avoid locking it in the first place. If you do have a good traction/power ratio, then as soon as front wheel braking begins to lift the rear wheel off the ground, you've found the limit of it - braking harder in that case will not stop you any faster.

Good road rim brakes with decent levers, cables, pads and rims, together with a decent set of grippy tyres, are perfectly adequate for any and all situations, and while they have some drawbacks, they don't have as many as discs do right now.


http://www.bikeradar.com/road/news/arti ... ook-35887/

Hydraulic road discs are inevitable, any manufacturer that ignores them will be going out of business.
That's why I wondered about Campagnolo, if they have the mindset that rim brakes are fine they won't have a market in a few years time.
They don't have the experience from mountain bikes like Shimano and SRAM so need to catch up quickly.


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PostPosted: Wed Jan 02, 2013 9:16 pm 
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There might be some reduction in brake fade from the pads, but what happens if the brake fluid boils, which from what I've read can happen quite quickly on a road bike?

Brake fade on rim brakes shouldn't be a problem anyway, if proper braking technique is used.

If the overall braking power is the same between rim and disc brakes, and both have sufficient modulation, then is there really any advantage in "normal" riding conditions? Frames and forks need to be made stronger to take the different braking forces applied to them, and designed to take brake hoses. I don't think there's a weight advantage either (and there's probably a disadvantage with discs). Suitable brake levers need to be developed too (I think the maguras are for TT only at the moment, but sram seem to have a reasonable design on the way).

Don't get me wrong, I love modern technology as much as I love the old stuff, but creating something just because you can, or just because your marketing department think you should, or because your customers think it's what they need, doesn't make it a good product.


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PostPosted: Wed Jan 02, 2013 9:21 pm 
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I know they're on the way, and for cross I can see their benefits, but I'm still not convinced they're an improvement for road riding. I've still yet to read anything that convinces me - I've seen no arguments that make them better overall than rim brakes, and quite a few that make them worse.


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PostPosted: Wed Jan 02, 2013 9:35 pm 
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I am currently building a road/cyclocross bike with discs .

Going to use bb7 road for the brakes .


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PostPosted: Wed Jan 02, 2013 9:50 pm 
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I'd like to know how it turns out, especially when braking on long and/or steep descents. Have you got a build thread for it?


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PostPosted: Wed Jan 02, 2013 10:36 pm 
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I don't think the locking up argument really carries too much weight. I don't brake any harder or lock up more when using discs. In fact I maybe lock up less as the modulation is very good on hydraulics. It is just a case of adjusting your braking technique.


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PostPosted: Wed Jan 02, 2013 10:44 pm 
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1. All aerodynamic advantage advances with wheels over the last 15 years, will most likely be instantly wiped out by sticking on a disc and associated extra spokes for the required strength. When pro time trials/sprints can be won by 10th's of a second - thats a big factor.

2. Surely the point of road cycling is actually to try not to slow down so not sure of the advantage of discs is beneficial.

3. I'm very surprised no-one has picked up on the fact that the grip dynamic is completely different on a road bike in that you have a much smaller tyre contact patch with the road and I'd think grabby discs would actually be more dangerous in wet/icy conditions.

I can see them coming for the more leisure orientated bikes, its going to be an interesting next few years but there are a lot more implications compared to MTB's....that rear axle width will need looking at ,also the necessary strength and associated extra weight in beefing up those forks/stays will need a rethink.

Campag will have no issue as they'll just sub contract an existing manufacturer to assist. Look how slick there EPS is compared to the rather clunky Di2...Jeez if Avid can get it right?!


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PostPosted: Wed Jan 02, 2013 11:27 pm 
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will start a thread now .


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