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Im having trouble deciding if upgrading to disc brakes is a good idea and with that which ones would anyone recomend.
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I went thru a similar thought exercise a few years ago. I needed new wheels (because the walls were getting thin due to the rim brakes) and figured if I bought new wheels I may as well get new brakes. I had the attitude that disc brakes were more gimic than anything, but I thought I would give them a try, especially if it meant not having to buy another set of wheels for a long time.
I bought the Avid mechanical discs, mainly because they were cheap and I didn’t find a lot of people saying bad things about them. I have been a happy camper ever since. With discs I don’t have to worry about keeping the rims clean, the braking action is consistent, even after crashing thru a muddy puddle, riding in the rain, etc. I don’t even think about stopping to give my brake squeezing muscles a break on long downhills anymore. The pads last forever; I’ve got a few thousand miles on them and still have lots of life left.
I’ve never ridden with other discs enough to be able to say which ones are best so I will leave the critiques up to the gear-heads, but I will say that I think it is well worth it to switch to discs.
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All I’ve got to say is that I LOVE MY HYDRAULIC DISC BRAKES!
I used to have serious problems with carpel tunnel when I was riding a hard-tail with v-brakes…Numbness in my hands and fingers, pain on long downhills, etc. I tried everything including brake boosters, softer pads, different gloves, different grips, even mechanical disc brakes…None of it seemed to fix the problem. Ever since I’ve had my hydraulic disc brakes, I haven’t had even a twinge of numbness or tingling.
Rim trueness isn’t as critical with discs, but that can lead to trouble with breaking spokes if you’re not paying attention.
I’ve heard all the talk about how hydraulic disc brakes aren’t field-servicable and that’s true. I’ve blown one hydraulic line, bent a rotor, frozen the master cylinder plunger, and lost pressure (due to a faulty bleeder valve) on the trails. But I still had at one brake to make it home (just having the front brake makes it challenging to ride but it’ll still stop the bike). I carry a bleed kit in the car when I go out of town…just in case. But the benefits out weigh the downfalls in my mind.
A set of pads will last me about 500-1000 miles (depending on terrain) and I try to keep an eye on them. I’ve ruined one rotor because I waited too long to change the pads and got caught on a long downhill with metal-on-metal. When they start to get low, I carry an extra set on the trail. Mud and snow can eat through ’em pretty quick.
I guess you’ve got to ask yourself if it’s worth the extra weight. I think so, but that’s just my opinion and I’ve never been weight-conscious when it comes to my bike. You may get a different answer if you ask an XC racer.
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As a moderate rider, in GA, I really didn’t see the need for disc brakes, but since moving out to Golden, yeah.. I could see how they would be helpful. Long descents = very tired forearms. Cost has come down a bunch too and you can probably find a used pair if you check craigslist. I’ll probably switch.
Still, I think for a new bike, I’d rather invest the money in the frame and components 1st, disc brakes 2nd.
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I have found some good disc brakes and was wondering how to mount them on my frame. The frame I have is disc brake capatable and has some mounts. Just wondering if anyone knew. I am thinking of purchasing some Avid mechanical brakes.
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They’re very easy to mount. A couple of bolts into the frame (most of the time you have to use the adapter), center the brake housing on the disc, reroute the cable and use zipties if necessary to secure it, then just adjust the distance between the pads and the disc based on where you want the brake to grab. The Avid mechanicals have a red knob on each side of the brake housing that you turn to get the pad the right distance from the disc. Piece of cake!
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The key part of the last reply being “adapter”. Depending on the style of mounts on your bike, it may be necessary to buy an adapter to get the brakes to fit. The fronts probably won’t be a problem, but the backs may be.
What kind of bike do you have (year, make, model)?
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I have a 2006 Gary Fisher Marlin that appears to have the mounts on the frame.
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I suspect that a new bike like that shouldn’t have any compatibility problems with your brakes. The older Treks used a mount (I forget the name) that required an adapter — I would be surprised if your new bike will need one.
Worst case is if you do need an adapter then you will just have to make a trip to the local bike shop. Most good shops should have one in stock.
Go for it, man!
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Love the Avid B.B’s. Went with Mech’s after seeing so many hdro’s in the shop.
Riding is life all else is waiting
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I have ridden a couple of fast downhill rides, the last one where I descended 1000+ meters in 10 KM, where my back brake has oveheated. (it slightly rubs after heating). This past ride I heard some strange noise from my rear brake and I looked down. I actually saw the rotor was warped as the wheel turned. I was using both brakes, but the back overheated. Back at the camp it appeared OK, but I am a bit concerned. I have noticed the front rubbing after a fast downhill but never as bad as what the back just did. I run Shimano XTR disks with an 8″ rotor on the front and a 6″ on the back.
Should I change the rotors to 8″ instead of the current 6″? or is this just a problem with disk brakes?
Are there better rotors that dissipate heat a bit more, or are less susceptible to warping?
Anyone had a similar problem?
Thanks
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I would think that the front would be the first to overheat, but with a larger rotor… You shoudl probably get a larger one in the back, as I think it will solve your problem. Scratch that. 😀 That happens to all rotors, we had that happen on our van.
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Ok I think I am about done, I have a question on how the disc brakes get on the bike and was wondering if you need special hubs that attach to the discs for them to work.
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Yes, you definitely have to have disk brake hubs that are compatible with your rotors. If your wheels are old and beat up you may as well get completely new wheels. Otherwise, if you already have a nice/expensive set of rims you could get them rebuilt with disc hubs.
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"MountainNomad" wrote
I have ridden a couple of fast downhill rides, the last one where I descended 1000+ meters in 10 KM, where my back brake has oveheated. (it slightly rubs after heating). This past ride I heard some strange noise from my rear brake and I looked down. I actually saw the rotor was warped as the wheel turned. I was using both brakes, but the back overheated. Back at the camp it appeared OK, but I am a bit concerned. I have noticed the front rubbing after a fast downhill but never as bad as what the back just did. I run Shimano XTR disks with an 8″ rotor on the front and a 6″ on the back.
Should I change the rotors to 8″ instead of the current 6″? or is this just a problem with disk brakes?
Are there better rotors that dissipate heat a bit more, or are less susceptible to warping?
Anyone had a similar problem?
Thanks
At Downieville I heat the back disk up some, cause I steer and balance the bike with it in loose rock and shale. 8 inch would be great but do not want to spend the money for a couple of runs a year.
Riding is life all else is waiting
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"bensf" wrote
Or maybe squirt some cold water on it when you see it getting hot. That happens to all rotors, we had that happen on our van.
Don’t do that! 😮
On car/truck disc rotors, they’re plenty thick, and won’t distort if they get wet when hot……
But if you quench a bike rotor, and it’s hot enough, it WILL warp.I’ve gotten my rotors hot enough to feel the heat from ’em just standing next to them.
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Sorry for that bad advice. 😳 I took into consideration on what you said, and now I’m wondering if after going down a big enough hill to heat up your rotors you go through a big puddle. Could that warp them?
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Car rotors wear with time. but I do not have lots of miles on the set. How long should I expect the rotors to last?
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"bensf" wrote
Sorry for that bad advice. 😳 I took into consideration on what you said, and now I’m wondering if after going down a big enough hill to heat up your rotors you go through a big puddle. Could that warp them?
Nah, just a splash here and there won’t hurt them….. But a constant stream of water from a camelbak or faucet likely would.
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"MountainNomad" wrote
I have ridden a couple of fast downhill rides, the last one where I descended 1000+ meters in 10 KM, where my back brake has oveheated. (it slightly rubs after heating). This past ride I heard some strange noise from my rear brake and I looked down. I actually saw the rotor was warped as the wheel turned. I was using both brakes, but the back overheated. Back at the camp it appeared OK, but I am a bit concerned. I have noticed the front rubbing after a fast downhill but never as bad as what the back just did. I run Shimano XTR disks with an 8″ rotor on the front and a 6″ on the back.
Should I change the rotors to 8″ instead of the current 6″? or is this just a problem with disk brakes?
Are there better rotors that dissipate heat a bit more, or are less susceptible to warping?
Anyone had a similar problem?
I always have rubbing problems on long downhills. Sometimes just a slight rub at the end of the downhill, sometimes a squealing brake, and sometimes even a grinding sound. My rotors show the tell-tale signs of extended heating (i.e., discoloration of the rotor). I think the rubbing has to do with the heat expansion of the rotor, pads, and hydraulic fluid. If you run tight clearances between the two, a slight warp on the rotor will be more noticeable after it’s been heated up for a while. Another issue is the material composition of the rotor and pad. Soft materials make for more stopping power, but more stopping power = more friction, and more friction = more heat. That’s where the 8″ rotor has the advantage over a 6″ by increasing the mass and surface area of the rotor. Although their angular velocities are the same, the linear velocity at the caliper of an 8″ rotor is faster so less force is needed to dissipate the same amount of energy via friction. The energy is imparted into a larger mass which is able to absorb more heat and dissipate it quicker. The more holes there are in the rotor, the greater the surface area/mass ratio (meaning a greater dissipation rate), but there is less mass and less contact between the pads and the rotor leading to the friction being concentrated on a smaller area. Does the benefit of a higher surface area/mass ratio outweigh the loss in mass? I guess that’s the question the designers are trying to figure out.
Okay, enough Mr. Science for today 😉 Sometimes I think I’ve got too much time to think about these types of things on the trails.
If the warpage gets too bad I’ll tweak the rotor a little by hand (make sure your hands aren’t greasy) to take out the wobble. I’ve had to use this ‘field-service’ technique after bailing off the bike and watching the rotor hit a rock.
I would guess a rotor should last at least a few thousand miles.
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Also, if a rotor is slightly out-of-true, overheating it will make the warp more noticable. It will return back to nearly straight after cooling, but once it’s been heated and cooled enough times, the alignment of your rotors will be permanently off.
Having the incorrect shims between the mount and caliper can also contribute to a noisy, or ineffective brake.I’ve yet to overheat my 7″ Magura rotors to the point where they stop grabbing, but they do start to complain…. loudly. A swap to 8″ discs is coming soon in my bike’s future.
If you’re not that concerned with weight, your bike’s frame is compatible, and your budget large enough, I highly suggest running the largest rotor possible. Almost all aftermarket rotors are also Galfer rotors and cross-drilled as well. IIRC, Shimano and Hope are two of the only companies that still use non-Galfer rotors.My wife just bent her Avid rotor this past weekend, and an LBS employee was able to put enough love on it to get her back onto the trails…. 😎
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