Disc brakes vs. 'normal' brakes??

[GrasB]

Now surely any loss in feel is related to how much tension is transmitted through the cable - if the cable tension is low (i.e. travel is long) then very little feel is lost because the cable friction and compression effects are minimal. This is why V-brakes typically feel much better-modulated than cantilevers or caliper brakes, even with identical cable runs and the same overall mechanical advantage.

However the best mechanical rim brakes never stacked up to hydraulic rim brakes for modulation or feel despite using the same pads. The same is true for disc brakes. The best long pull systems are okay but aren't comparable to a really nice hydraulic setup.

IOW, a hybrid cable/hydro disc can still have good "feel" if properly designed.

You can get okay feel but not good to great feel. Also you're stuck with high tension short pull road leavers which voids part of your rational above.

When a hydro disc overheats, the wheel can lock or skid - you don't necessarily "roll through".

I've not seen a setup like this. I think you have this the wrong way round, on a mechanical setup this is more likely to happen. On hydraulic system to you need to bin the res (which means manual adjustment of the pad clearances) or have a really badly designed caliper.

 

[GilesM]

You have a cable in the system... the merits of hydraulics have just been rendered almost completely mute. the SRAM Red solution gives you hydraulics from lever to pads.

The main advantage of the hydraulic brakes on mtbs is the huge stopping power with minimum input power, great being able to brake with one finger, a few people have said that they have enough stopping power with cable rim brakes as they can easily lock the wheels up, I used to think the same, however braking power is more to do with how quickly you can reduce your speed to a point where the wheels will start to lock, and how this can be done with minimum effort on the brake lever, braking with one finger really helps you to keep full control, especially on rough ground. The Hope CX brakes are reported to be very good as the power required at the master cylinder is very low with respect to the stopping power, hence the small loses due to the short length of cable before the master cylinder do not really reduce the actual power at the caliper. The feel and modulation of brakes on a bike comes more from being very aware of the bike, you feel the wheels locking through all contact points, not just the brake lever, and can respond to this feel.

I assume the car in the avatar is yours, starngely the only other people I ever hear talk about modulation of brakes are those who drive the more interesting sports or race cars.

 

[GrasB]

The problem is that as you get onto harder & harder surfaces the more braking performance depends on feeling how hard you're pushing the friction surfaces not just the grip limits. The former can only be felt through the braking system, the latter can be felt indirectly by other means. So while for CX hybrid systems may well be fine, when it comes to feeling what's going on when you get to fast flowing tarmac then you have a problem. This is EXACTLY what I've found when trying a hybrid system, there's detachment from the friction surface which makes it hard to feel how hard you're actually pushing the brakes so holding a certain friction level is interesting.

 

[GilesM]

The problem is that as you get onto harder & harder surfaces the more braking performance depends on feeling how hard you're pushing the friction surfaces not just the grip limits. The former can only be felt through the braking system, the latter can be felt indirectly by other means. So while for CX hybrid systems may well be fine, when it comes to feeling what's going on when you get to fast flowing tarmac then you have a problem. This is EXACTLY what I've found when trying a hybrid system, there's detachment from the friction surface which makes it hard to feel how hard you're actually pushing the brakes so holding a certain friction level is interesting.

Maybe, I'd only be sure if I actually tried the different systems, and whenever I get on a bike without hydraulic disks, my first thought on steep descents (on or off road) is usually, more stopping power would be nice.

 

[snailracer]

...You can get okay feel but not good to great feel. Also you're stuck with high tension short pull road leavers which voids part of your rational above...

Maybe that's why our impressions differ, I am used to discs on MTB's, which have been designed for long-travel levers. I can imagine a lot of road/CX discs are hastily adapted MTB systems, which try to adapt disc brakes designed for long-travel MTB levers to the short-pull road/CX levers.

...I've not seen a setup like this. I think you have this the wrong way round, on a mechanical setup this is more likely to happen. On hydraulic system to you need to bin the res (which means manual adjustment of the pad clearances) or have a really badly designed caliper.

No shortage of those.

 

[Happiness Stan]

I would have thought you don't have disc brakes on road race bikes because of the increase in rotating mass created by the disc and the mounting.

 

[GilesM]

I would have thought you don't have disc brakes on road race bikes because of the increase in rotating mass created by the disc and the mounting.

The discs are very light, and no reason why they would not get a lot lighter if the top road teams started to use them, Carbon Fibre discs on a bike, cool

 

[Rickshaw Phil]

I would have thought you don't have disc brakes on road race bikes because of the increase in rotating mass created by the disc and the mounting.

Not necessarily as the rims could be made lighter since they wouldn't have to have a braking surface, which would most likely even it out.