disk brakes.. - Page 2

DISC BRAKES ARE HEAVY

and they do not give you more stopping power, disc brakes give good modulation something that is not needed on a road bike. Oh and if you realy want them on a road bike then just use a mtb frame and hubs, a 700c rim will fit easy. the front fork wont be very aero though, but then who cares.

You get some of that back in a disc specific rim which can be lighter. We already have bikes that are struggling to meet the UCI 6.8kg limit and that are being artificially weighted (a powertap or srm as an example). As materials evolve (and assuming the 6.8kg limit remains in place) there is every possibility that disc equipped bikes could be at or around that limit.

Disc brakes absolutely give better stopping power in certain situations. Wet / muddy etc etc.

--brett

No disc brakes do not give better stopping power, think about it a rim brake has the ability to lockup and skid the wheel, so how then do disc brakes improve tyre traction, they dont do they, disc brakes are more powerful but the governing factor here is tyre traction. and last time i tried my "you beauty" v brakes in wet muddy conditions they locked the wheel too? Disc brakes give better modulation ( for dummies that means better feel)

[QUOTE=Insaneclimber]DISC BRAKES ARE HEAVY[QUOTE]

Are you sure?

I've MTB Magura disks according to internet: weight 747g per pair including levers and cables...

...and a pair of Ultegra at 335g for the brakes and 490g for the levers (couldn't find the weight of the cable). Perhaps the comparison isn't fair because the Ultregra include a gear control.

I just looked this up on the internet so perhaps the numbers need checking.

Canyon have a prototype 6.8kg bike with twin front disks.

I'd have thought that disks are heavier, hence all the MTB racers have V-brakes in the dry but would be interested in the evidence.

Stop using your brakes, it's lost power

Please. Anyone who has done any kind of white knuckle descent with standard road bike rim brakes (Ultegra/DA as an example) in wet conditions will tell you that it's virtually impossible to lock the wheel.

Two weeks ago I raced in abysmal heavy rain conditions the descents were more than a little scary and after one short descent into a hard left, rider after rider was unable to wash enough speed off running it through the corner. I had the lever locked in as hard as it would go and the wheel was a very long way from locking.

I've done enough long technical off road descents on my mtb with Hayes HFX-9 Carbons though all kinds of crap conditions to know that in the wet they are an order of magnitude better than *any* rim brake I've ever used.

--brett

I don't know what disc brakes you have used but they are most certainly more powerful when you step up to dual piston hydraulics (the standard for XC. all the way from entry level)

To get good stopping power, they must be bedded in though, and you must be using reasonable pads (like any brake).

And locking the wheel is pointless. It prematurely wears your tyre, it gives you less stopping power, and less traction (it gives you less stopping power because of the lower traction, but also makes the back end harder to control).

The modulation in disc brakes makes them easier to use in technical situations, but they also have greater power and don't wear down your rims in the wet, have better pad life, tolerate out-of-true wheels, etc. etc. Though they weigh more, the difference is fairly small and I'll sacrifice some weight to have peace of mind that I'm using brakes that can stop me extremely quickly under any conditions.

Also, the front gives you more stopping potential so locking your back wheel is next to pointless.

__________________
BMC SL01
SRAM Force


thank you crank n' cycles...If you are ever in SW WA, take a trip to Crank N' Cycles.

I wasn't talking about locking the back wheel? i ment the front. i am suprised to hear that a roady ran out of brakes in the wet.Was that with carbon rims? i cant comment on that as i havent had a road bike for more than 10 years. My XC bike has v brakes and iv never run outa brake, even on a 1 hour descent on a NZ mountain. But the point about rim wear is a worry, i have had a rim become so hot that the sides softened and beacame concave, which scared the hell outa me.

I still think that discs on a road bike would be a waste? but i am starting to change my mind. considering how easy it would be to put them on there why is no one doing it? maby it is just because of the twisting motion on the fork?

From my own experience I think V-brakes are stronger and will resist fade longer than disc. On a 35 degree descent (pavement) I couldn't seem to get enuf power on the fronts to sufficiently stop my bike and I was using hayes nine hydraulics on hayes nine 6" rotors. The rotors were scorching hot to say the least making it all the more difficult to lock the front tires. Altho it wasnt my intention to lock the fronts but I would have had more confidence if I could have had more power on the fronts.

My other bike with Alex DA16 rims and cheap tektro V-brakes, the brakes were definitely stronger inspiring more confidence in the same downhill pave.

I installed 8" alligator rotors on the front using the same Hayes Nine calipers and its the same story with the hydraulics. I'll be experimenting on different brake pad compounds to see if that will give me more stopping power.

On a different note, I use yellow cork brake pads for my reynolds carbon wheelsets in my road bike. The pads came with the wheelset and I replaced the stock rubber pads that came with the 07 Record skeleton calipers. Initially I hated the lack of power of the cork on the carbon rim. However, as they bedded in I found the power to be almost as strong as normal rubber pads on aluminum rims.

__________________

I agree that discs on a road bike would be a complete waste. Heavier and not carrying nearly the benefits of discs off road.

HD I hope you mean 35%, 35 degrees is 70%.

I've never run out of brakes using avid juicy 3s. I do alternate a bit between front and rear, but if I ever get the urge to be thrown pointlessly over the front, I can at the light touch of a lever. The other mtb in our family (a BMC fourstroke, which is alas, not mine ) has avid juicy 3s and 180mm rotors and they feel crap compared to my 160s. Same pads. Modulation is handy in the dirt though.

__________________
BMC SL01
SRAM Force


thank you crank n' cycles...If you are ever in SW WA, take a trip to Crank N' Cycles.

Like I said, you can't race on them so manufacturers aren't likely to build them.

I read an article on a pro who wintered in N.California (maybe Levi?) and who had a converted cyclocross bike with discs for his winter training rig. Raved about how great it was. I think for the average Joe thats a big investment for a bike to simply train on for part of the year.

--brett

You can get most (90-95%?) of the "benefits" of this sort of rig by converting only the front end to disc. If you really wanted to, you can probably get away with it for under A$450 at retail prices (or a LOT less if you know where to look). It should be even less in the US/UK (but maybe not EU).

All you need is a fairly inexpensive steel/alloy disc fork, avid bb7 disc caliper (road version), a cheap disc hub laced to a rim, and a little bit of know-how to put it all together.

Its still a large investment, but not prohibitively expensive if it's wet enough where you are to justify it.

n

What about disc brakes on a touring bike? Most of you are comparing them to road bikes. I'm trying to build something for a trans-America trip. There are a lotta mountain ranges in-between the two coasts that I’d like to have some stopping power on. Especially with all the added weight I’ll be carrying in gear. I've been looking at touring bikes and haven't seen any that come with discs. Why not?

Giant makes a touring bike with disc brakes. But I am not sure on availablity. So far as I know, they only advertized it for a year to two. I could be mistaken.