disc brakes- what's the big deal?
i see many saying "disc brakes are essential..." etc, but i don't really get it. i have v-brakes on my old gary fisher and they stop me instantly, even when ripping downhill. is it a weight thing or what? can someone set me straight?
Concrete wall stops you instantly.
Dirt Rag Extraordinaire
There are lots of advantages to disc brakes on a mtb:
i. Disc brakes work really well. It's the difference between grabbing two handfuls of brake lever and skidding to a halt, or using one finger and almost doing an endo straight over the bars.
ii. Don't heat-up as quickly and fade like v-brakes.
iii. Work much better in the wet.
iv. Rim brakes are dependent on perfectly true rims, disc brakes aren't. You're much less likely to ding a disc rotor than you are a rim.
v. Disc brakes look cool.
"You go up the hill, you go down the hill."
V-brakes are great. I have one bike with disc brakes, and one with V-brakes. They both work well for me. Disc brakes have some advantages, but if v-brakes are working for you, don't worry about it. V-brakes are usually lighter than most disc brake setups.
I'll let others talk about why discs are better.
^^ nailed it. (edit, the second post above mine lol)
And also you get more control (modulation) regarding how much speed you wanna shave off and when you're going down some rough stuff, it's easier to get the exact amount of braking force you need with disc brakes rather than rim brakes because you don't have to pull much on the levers and you get constant feel.
Plus they won't wear out your rims, be better in wet/mud/sand condition (winter too), looks better with no brake tracks on the rim, they usually last longer between maintenance (pads replacement/adjust and cleaning) and they are more predictable under a lot of weather conditions.
But they cost more, are a bit heavier, can be very annoying if they start to squeal and sometimes are a mess to adjust if your rotor isn't straight or if your frame is not perfect either. They can make a big vibe wobble and turn you crazy, etc. Personally I'd run disc brakes over rim brakes on all my bikes if I had the money or disc compatible frame and hubs.
Originally Posted by NicoleB28
Creek crossings in below-freezing temperatures make for "interesting" braking performance from rim brakes. If you plan on never dealing with heavy mud or accumulating ice, enjoy your rim brakes!
disc brakes work regardless of the condition and also last longer.
Not much mud, ice, or even hills in South Florida. I've kept a rim brake on the rear wheel on my HT because I see no need for the expense or additional weight. It's the POS Tecktro that came on the bike. Works beautifully, especially in the rear because there's not nearly as much need for modulation. After four years and a few thousand miles I finally had to replace the pads a couple months ago.
When I bought my current mountain bike, with Avid BB5s, I thought, "What's the big deal?" But I did notice that they lose much less performance when trails are wet. So that's pretty cool.
I put hydraulic discs on that bike later. I didn't realize how much more stopping power it's possible to have! And the lever effort is much less. They also don't require attention to keep them working well as often.
One of my road bikes has disc brakes too now. My last commuter was about to need some new rims because of wear from braking. I broke the frame before spending money on wheels, so at least I didn't do that in the other order.
My attitude is that disc brakes are cool, cool enough to want a new mountain bike to already have them installed. But I don't think it makes much sense to upgrade an older bike to discs most of the time. Since a different hub is required, it's a pretty expensive change.
"Don't buy upgrades; ride up grades." -Eddy Merckx
I'll add that, since discs can be made from stainless without too much weight/inertia penalty compared to rims, you can use aggressive friction compound on pads compared to the pads for rim brakes without causing excessive wear. That's probably where most of improved wet performance comes from.
Magura used to make hydraulic rim brakes. It was like having 559mm disc in effect, but it was still plagued by aluminum-compatible pads (less friction coefficient), frame deflection, aforementioned bent rims, etc. Maybe they still make those - many trials riders still use rim brakes in the back if I'm not mistaken.
big reasons why I prefer discs when I can get them:
- better modulation, which makes it easier to scrub a little speed with slight lever grab
- light lever action, resulting in less hand fatigue
- less fiddly. mechanicals still require adjustment for pad wear, but pad materials last longer so they don't need to be adjusted immediately after a long downhill. hydros automatically adjust for pad wear, so they are practically a "set and forget" item once you get them dialed. at least, my 10 year old Magura Julies are.
- they don't wear out your rims over time. rotors can be replaced when they wear out without re-lacing a whole wheel.
- they are more tolerant of slightly out of true or dinged rims.
- they are more tolerant of bad weather, wetness, dirt, etc
- good ones are expensive. BB7's are good and affordable, but they are heavy and more fiddly than good hydros.
- if you have an old bike, you can't just slap them on as an upgrade
- rotors contaminate easily with skin oils or lube. if you contaminate your rotors/pads, it can be a real PITA to get a clean start again
- pads for some brands can be hard to find at an LBS. every brand has its own pads. they are not interchangeable.
- raw stopping power isn't really that much higher than comparable quality rim brakes unless you get a model designed for downhill riding
- some brands/models are notoriously susceptible to awful noises (see Avid turkey warble thread)
- many brands have different rotor and pad size specs that reduce compatibility. For example, Avids use a wider brake track on the rotor than Shimano. Mixing Avid and Shimano disc brake rotors/calipers creates niggling incompatibilities that need to be addressed.
- fade can be an issue especially for hydros, because heat from the system doesn't dissipate well and reduces effectiveness. good ones with appropriately sized rotors for the application don't have this problem.
- the biggest one I hear about is how discs are not as field repairable as vees. especially hydros. First, I haven't heard of a single case of a busted hydro brake out there. nowhere. for that matter, I can't say I've ever heard of a busted cable disc brake. I'd say discs are mechanically simpler and have less to fail than vees or cantis. I rode for about 4 years on vees before I went with discs on a new bike. my vees DID break a couple of times, forcing me to limp out with one (or no) brakes. I have been using discs for 10 years now, with only minor fade as a complaint.
Do you have friends who ride with disc brake? If yes try it on technical or steep descend. You should be able to tell the difference right away.
Originally Posted by cwininger
Your rim brakes may be able to lock up your wheel and stop you instantly, but that is hardly the point. Locking a wheel up isn't some genius invention. Honestly, I hate locking a wheel up while riding-you lose traction. Disc brakes aim to achieve a brake that will last. Brakes fade on long downhill runs, and modulation can lose its strength. Disc brakes aim to achieve a brake that is not effected by the quality of the rim, whether out of true or dirty. They also aim to dissipate heat more effectively, and in the case of new Shimano brakes-I am a fan. Hydraulic disc brakes have pistons that progressively close in as the pads wear out, so you don't need to adjust cable tension like you do when v brakes fade. Of course everything is always consistent, so your mileage may vary. I don't think I could ride the way I do with rim brakes.
Thanks to all for the informative answers. sounds like it's probably worth the upgrade if/when i become a more technically proficient rider (and when i get a newer bike that's atcutally set up for discs.)
good stuff from everyone... except this guy
it does remind me though, that there is usually a d-bag in every room.
Originally Posted by vanamees
I just set up a pair of new xt v's on a friends bike with new xt levers and the best stiffest possible housing and slickest cables, and compared to my formulas they are a complete joke. Discs actually stop you. And you have modulation. I remembered v's being good back in the day until I got hydro rims. But now in a comparison the v's just don't cut it. I only ride pavement though. V's are not completely useless but discs are way more powerful. And once you tasted the power there is no turning back.
Originally Posted by cwininger
Rule #9 // If you are out riding in bad weather, it means you are a badass
Originally Posted by iheartbicycles
Both my current bikes have disks. My '05 Marin has Shimano mechanicals, my '12 Trek has Shimano hydros.
When I bought the Marin back in '06, I thought disks were cool, but like the OP I was satisfied with the cantis on my '95 Marin (pre-V). The canti's stopped great, not like the sidepull calipers I grew up with on my first few dept store bikes.
So, as I was working with a small budget (under 500), I had eliminated disks as something I was looking for. Well the Marin had disks, and being a leftover, was discounted a few hundred bucks. It fit perfectly into my budget. After the first ride, I thought "holy crap, these brakes are great!". From that point on I was sold, and over time I grew to like them even more.
What's said above is true - it's not about being able to lock up the wheel, what's great about the disks is how you can modulate them and keep them right on the threshold of locking up. I was talking to a guy yesterday I met on a ride, and he asked about the disks, and said his V brakes worked great. I explained about modulation, and compared them to ABS brakes on a car. Even with my mechanicals, I can get them to the point where I can actually HEAR the tire slowing on the pavement, yet it's not quite locked up. I do all street riding with this bike, and I think that stopping power has saved my bacon at least once or twice this summer.
And as far as maintenance, I've done NOTHING to those brakes since I bought it six years ago. No adjusting cables, no adjusting pads to get them closer to the rim to compensate for wear or to change the angle, and no grooved up rims.
When I was 16 or 17 I had a canti-braked Univega that I took to a ski resort in NH one summer that was EXTRMEMLY muddy. By the end of the day, my pads were shot and the rims were all grooved up from the mud. And not to mention all the fade and cramped hands from squeezing the levers harder.
As far as the hydros on my Trek, I can't comment. I've only ridden it around the block, I'm waiting for my new pedals to come in before I start really riding it. They feel "ok", I'm sure I'll realize how much better they are once I ride it more extensively.
Not every rider needs disc brakes but in some technical trails they definetely are an advantage specially going when going down, being able to stop with much more power and using literally one finger is a must for me, on my previous hidraulic brakes my hands were numb at certain stages because of pulling the lever so much, with better brakes I definetely forgot that thing.
Your weight matters a lot too, if you're fine on vbrakes you will be just fine
And remember when it comes to stopping power... Rotor size > Brake Model (depending on brake model)
I tested 2012 xt hydros with like.. 130mm rotors and they definitely didnt stop as well as the 2012 slx brakes with something like 180mm rotors.
Or maybe they could stop in the same distance but it sure felt harder.
No, not worth it as an upgrade.
Originally Posted by cwininger
If you get a new bike in a pricepoint that's actually going to give you more than you've got now, it'll be a nice change. But you have to spend quite a lot, especially if you're picky about hubs and wheels, to upgrade from rim brakes to disc brakes. Unless you have disc-ready wheels, which are pretty rare.
"Don't buy upgrades; ride up grades." -Eddy Merckx
pads wore out too quick for me on v brakes. but i do tend to ride really fast then do hard braking at the last moment.
i enjoy the back wheel breaking loose and sliding around as well and i've went through two tires since may
i got disc brakes now though and love them. just longer pad life in my eyes, the weight is not an issue to me. the way i see it, the heavier bike, the better the workout
+1 If your rims aren't worn out and you don't have any heartache like, " man, I wish I didn't have to use all these fingers to pull this lever," then hold what you got until you experience any of the challenges expressed. When the frustration is greater than the financial impact to you, go ahead and order a new bike that is suited to the type of riding you do. I'm from Florida and my v-brake bike was fine until I moved to TN. It was still fine, but I got a little more serious about it and had the cash to buy a new bike, so I did. Don't feel like you have to have them.
Originally Posted by DavyRay
I've had a disc brake bike for all of 72 hours on my new to me Blur LT but I love the discs so far. I'm a heavy guy (265) and my V-brakes on my '97 Stumpy worked great when the rim was true but there were many times when I had to adjust them on the trail so the lever would pull almost to the bar because the rim had gotten out of true. Besides that they just stop better, more control, easier lever pull, etc. What's not to love? I'll never go back. I raced motocross years ago and these feel right at home, so nice to have that same combo of modulation and power again on a bike without the constant adjustment.
There's no comparison between rim brakes and disc, especially hydros. Hydros require barely any pressure to stop and can stop on a dime in wet or dry. They might weigh a little more, but the extra weight is worth it, IMO.
I prefer cantilevers to disc brakes.
Hydro discs have more consistent modulation in any/all conditions; that's the only real difference I notice.
As far as "power" it's much easier to lock the wheel (generally not a desirable thing) with a squeeze of my canti brakes than with my discs.
Its a fashion thing mostly. Disc brakes are more modern. Hearing reasons why v brakes despite being lighter, are not good is similar to ppl justifying $4000 purses.
Problem is. Since parts are all now disc compatible, better to go with disc cuz its available.
sent from one of my 4 gold leafed iphone4s's
Last edited by bob13bob; 08-27-2012 at 01:01 PM.