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Why disks ?(5 posts)

Why disks ?Steve Bailey
Dec 1, 2002 7:06 PM
Disk brakes is the topic.

I spent 2 days this past weekend with some friends that have spanking new FS mountain bikes. One a Jamis, the other a Specialized. Both bikes have disk brakes.

A third rider had a year old Specialized with V brakes, while I was on my 7 year old ProFlex 855, upgraded to XT canti's (from LX). Thus, I got to try 3 different bikes over the course of the ride, my own canti equipped, the V brake bike, and a disk brake bike.

I could certainly feel the difference between canti's and V's, but not so much between V's and disks. I was concerned that the 2 disk bikes had no posts for mounting any kind of canti or V brake and both disk bikes used hydraulic brakes. I also felt that the disks had too sensitive a feel (novice user here), going from nothing to stopped, which might be useful sometimes, but are also seemingly devoid of moderation. That concerned me.

About 1/3 of the way thru the 2nd day of riding, the Specialized lost the rear brake. Apparently the housing screws loosened , draining all the fluid. The rider continued to ride as it was not a hilly course and she could stop OK with just the front (are you there Sheldon ?).

My only thought, after 14 seasons of mt. biking was "What's the big deal with disks ?".

I know they have a reputation for good stopping power in wet conditions, but who does a lot of mountain biking in wet conditions ?. My experiences have always kept me out of the muck and mud, if not to save the trail, which is a good enough reason, but to avoid having to spend a minute of cleaning for each minute of riding.

Thus I don't have much need for brakes that have wet braking superiority, but I understand that others might.

So here's the pro's and con's as I see it:

Pro's to disks: - Terrific stopping ability - Great when wet

And that's all I could think of...

Con's: - Mechanically suspect - Much more difficult to fix in the outback - No real standard, I.E., Hydraulic and mechanical versions, Shimano VS. the others, International, etc.. - Too much stopping power - I.E., nothing between stopped and moving - no "slowing" as a factor of hand pressure on the lever. - No ability on some bike designs to convert to V's or canti's. - The front forks (Fox shocks in both cases) seemingly is beefier then I expected, I suspect a requirement for less play in the individual legs due to the very tight tolerances in the disk assembly (as opposed to canti's), thus the fork - and bike, is heavier - No weight savings for little gained (opinion)

All thoughts appreciated

Steve "Not converting anytime soon" Bailey
Gee Steveo, I won't be converting my Ultegra arches..Lone Gunman
Dec 1, 2002 7:13 PM
to disc brakes antime soon either after that story.
re: Why disks ?divve
Dec 2, 2002 8:00 AM
In the dry discs indeed offer little advantage over rim brakes. However, in the wet or during long descents there's a considerable advantage. Especially, in consistency of braking power. Where I ride it's not always uniformly dry or wet in all places. You can always rely on discs to slow you down enough when you have to suddenly hit the brakes after charging down a trail and incidentally going through a puddle or two. With rim brakes on the other hand you risk overshooting your braking point when you aren't prepared for your rims still being wet or dirty. This does happen at times and makes for very strange bike handling:)

"No real standard, I.E., Hydraulic and mechanical versions, Shimano VS. the others, International, etc"

There's one standard; IS2000. Get brakes that are IS2000 compatible and you can mount them on any modern frame or fork (one of the few exceptions is Manitou). Functionally it isn't really relevant that they aren't all from the same make or work by the same principle. It does however offer you more choice as a consumer. For the same reason one can choose from a wide range of tire and saddle manufacturers.

"Too much stopping power - I.E., nothing between stopped and moving - no "slowing" as a factor of hand pressure on the lever."

That's very dependent on the make and type of brakes you tested and the pad material. If you want good modulation try some Magura Marta brakes with the stock pads or the new XTR03 brakes with resin pads. They offer a great range between light touch and full stop.

"The front forks (Fox shocks in both cases) seemingly is beefier then I expected, I suspect a requirement for less play in the individual legs due to the very tight tolerances in the disk assembly (as opposed to canti's), thus the fork - and bike, is heavier"

Again that depends on the fork you have, mine has only 1 leg so I don't have to worry about the other and it's only 3lbs (more than 1/2lb lighter than any Fox version). Having said that disc brakes including the required sturdier wheel build are still slightly heavier than V-brakes, unless you resort to things such as aluminum rotors.
here' why discs are here to stay....MrCrud
Dec 2, 2002 8:14 AM
I agree so some degree with your points, but they do need some refinement. The total weight penatly for the usual dics brake setup is about 80gr per wheel. As far as cons go, i think it stops here. In terms of power, you get used to the modulation after a few rides. Discs also dont fade nearly as much when they heat up. You also dont have to change pads as often. Once a year is plenty, and some people can stretch it up to 2 years. Discs are here to stay and i think the trade-offs are very worth it.

Cheers!

Mr.Crud
re: Why disks ?JFST
Dec 2, 2002 9:02 PM
You need to consider how much maintain biking can change from place to place to really understand why disc brakes are the way to go. In many aspects you are correct. Discs don't make that much of a difference on mostly dry, flat trails with relatively short downhill sections. You really learn to appreciate them when you ride trails that have very long descents that last for several minutes (or even hours) at a time and you need to keep braking to maintain control. Rim brakes will eventually overheat and cause some really scray fading. You can even wear down a new set of rim pads in less than one ride on some situations. They also stop in ANY condition. Rim brakes drastically loose power in wet or mud in comparison.
About them being too touchy and sensitive to lever input is a common misconception to people who try them at first. Discs offer MUCH better modulation over rim brakes which are very hard to fine tune in comparison giving a more on/off feel to braking. The difference is discs require much lower lever force. They are meant to be able to provide as much braking power as possible with the least amount of effort from the rider. With just one finger you can make the brake slow down the bike as little or as much as you want. People who ride discs for the first time tend to work them like they would with a rim brake lever and squeeze the lever to tight causing that feeling almost being thrown over the bars and thinking the braking force is too violent. As far as maintanance is concerned a *properly installed* hydraulic setup is the lowest maintenance brake system of any kind. The key is they need to be installed and bled properly which is unfortunately something that is not done very often even on factory setups. Haydro's never need housing to be cleaned, cables to be changed or greased, pads to be adjusted, and pads last much longer. Bleeding is only required every 2 to 4 years and pads will usually last well over a year. A properly installed setup should never leak absolutely any oil or get contaminated.