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#12
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Disc Brakes on Touring Bikes
There are a few concerns with disk brakes on touring bikes.
First, to accomodate the rotor, the hub flange spacing must be narrower. This will result in a wheel which is not as strong. Additionally, the front wheel will have dish. Second, the frame and fork need to be beefy to handle the torque from the brake. On the rear this just means extra weight. However, on the front, it also means a very stiff fork which will adversely affect ride quality. Third, it is difficult, but not impossible, to fit racks around many disk calipers. Fourth, there is evidence to suggest that a front disk brake can force a wheel from the dropouts unless there is some sort of secondary retention device (like lawyer lips) or other provision to prevent this. Fifth, there has also been some evidence that rim brakes can generate more sustained braking power and dissipate more heat prior to failure than most disk brakes. Rim brakes fail from excessive heat by blowing a tire off of the rim. Disk brakes fail frome excessive heat in a variety of ways: boiling fluid, warped rotors, melted plastic parts, glazed pads, etc. Generally speaking, rim brakes will tolerate a higher level of heat than most disk brakes. The best disk brakes in this regard are those with heavy, large diameter rotors. These can be superior to rim brakes in heat dissipation. The main advantage of disks in mountain biking is performance in muddy conditions when rim brakes would be packed with mud. This generally isn't an issue for touring bikes (unless off-road touring). Both rim and disk brakes need to clear the braking surface of water before effective braking can begin so there is no clear advantage for either in the rain. Todd Kuzma Heron Bicycles Tullio's Big Dog Cyclery LaSalle, Il 815-223-1776 http://www.heronbicycles.com http://www.tullios.com |
#13
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Disc Brakes on Touring Bikes
Todd Kuzma:
Fifth, there has also been some evidence that rim brakes can generate more sustained braking power and dissipate more heat prior to failure than most disk brakes. Rim brakes fail from excessive heat by blowing a tire off of the rim. Disk brakes fail frome excessive heat in a variety of ways: boiling fluid, warped rotors, melted plastic parts, glazed pads, etc. Generally speaking, rim brakes will tolerate a higher level of heat than most disk brakes. Blowing a tire off a rim is a catastrophic failure with rim brakes, not good when going down an incline, whereas a warped disk rotor will not have as dramatic an effect. A disk brake system is better in this respect. |
#14
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Disc Brakes on Touring Bikes
RE/
And BTW non-original pads won't fit. There is an auxiliary spacer spring that fits around the pad material tightly. Avid shapes their material to allow it to fit. Non-originals were caught by 2001 model magnetic mounting example and have not "fitted" their material exactly, resulting in the spacer spring not fitting, in my experience. Also, if you're using the Avids, take a couple of spare springs along with those spare sets of pads. I had one set of pads just fall out of the calipers on me - leaving behind a mangled spring. To be fair to Avid, I suspect I brought it on by incorrectly inserting the rear wheel once (the rotor probably caught the little tab that protrudes from the spring clip)...but it *did* happen..... Also, make sure you trim the cable ends close. One guy posted either here or in the MTB group that a friend did an endo at speed as the tail of the brake wire somehow got caught in the caliper body. ----------------------- PeteCresswell |
#15
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Disc Brakes on Touring Bikes
"Michael Dart" wrote:
Avid Mechanical ball bearing disc brakes are then next best thing to hydraulic discs and better than V's. Speaking as a 360 lb. rider who can use braking power and not just braking feel, and who's tried most every kind of brake, the order of those three brakes is reversed from a max. power standpoint. Cantilevers and Vs can stop harder, longer. And Avid mechanical brakes have the benefit of being tunable (through choice and/or adjustment of the lever) with regard to mechanical advantage. Hydraulic discs offer no leverage adjustment, and they become overheated just as easily as mechanical discs in an equivalent rotor size. People who don't actually use all their available braking power become impressed with the lever response of hydraulic discs and assume that their greater sensitivity to lever pressure means that they are more powerful than other brakes. They are not. They make a version for road bikes. They are quite simple and probably easier to set up and maintain than V's or Canti's. Easier to set up well than cantis, maybe. Easier than V-brakes? No way. If you have to seal your own hoses and bleed the system (such as when installing almost any unusual setup), any mechanical brake has simpler setup. One point the OP should note is that disc brakes make for a dished, weak front wheel. They reduce the amount of dish in the rear wheel, though, which is good. If the rear rack mounting issues can be worked out with a rear disc in place, then this might be an OK place to use a disc on a touring bike. You're better off with a canti brake, and a dishless wheel, in the front. Chalo Colina |
#16
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Disc Brakes on Touring Bikes
"Michael Dart" wrote:
Avid Mechanical ball bearing disc brakes are then next best thing to hydraulic discs and better than V's. Speaking as a 360 lb. rider who can use braking power and not just braking feel, and who's tried most every kind of brake, the order of those three brakes is reversed from a max. power standpoint. Cantilevers and Vs can stop harder, longer. And Avid mechanical brakes have the benefit of being tunable (through choice and/or adjustment of the lever) with regard to mechanical advantage. Hydraulic discs offer no leverage adjustment, and they become overheated just as easily as mechanical discs in an equivalent rotor size. People who don't actually use all their available braking power become impressed with the lever response of hydraulic discs and assume that their greater sensitivity to lever pressure means that they are more powerful than other brakes. They are not. They make a version for road bikes. They are quite simple and probably easier to set up and maintain than V's or Canti's. Easier to set up well than cantis, maybe. Easier than V-brakes? No way. If you have to seal your own hoses and bleed the system (such as when installing almost any unusual setup), any mechanical brake has simpler setup. One point the OP should note is that disc brakes make for a dished, weak front wheel. They reduce the amount of dish in the rear wheel, though, which is good. If the rear rack mounting issues can be worked out with a rear disc in place, then this might be an OK place to use a disc on a touring bike. You're better off with a canti brake, and a dishless wheel, in the front. Chalo Colina |
#17
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Disc Brakes on Touring Bikes
Jose Rizal wrote:
Blowing a tire off a rim is a catastrophic failure with rim brakes, not good when going down an incline, whereas a warped disk rotor will not have as dramatic an effect. A disk brake system is better in this respect. That's true although losing your brakes ain't no picnic. This reminds me of another issue. If you damage a rotor in an accident, you will have to remove it to continue. Not a big problem, but it has happened to mountain bikers. Todd Kuzma |
#18
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Disc Brakes on Touring Bikes
Todd Kuzma wrote in message ...
Fourth, there is evidence to suggest that a front disk brake can force a wheel from the dropouts unless there is some sort of secondary retention device (like lawyer lips) or other provision to prevent this. Four and a halfth, there is evidence to suggest that even if retention lips are present, the skewer can still be loosened sufficiently for wheel loss to result. James |
#19
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Disc Brakes on Touring Bikes
(Rick Warner) wrote in message . com...
snip Everybody seems to be concentrating on the mechanics of the brakes, levers, etc., but no one has mentioned one issue with discs and touring bikes: interference with racks! Not an impossible combination, but the standard mount will interfere with racks. Things gotta be moved to make it all work. - rick Old Man Mountain appears to have that solved: http://www.oldmanmountain.com/cold_s...ar_details.htm Jeff |
#20
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Disc Brakes on Touring Bikes
Todd Kuzma wrote:
First, to accomodate the rotor, the hub flange spacing must be narrower. This will result in a wheel which is not as strong. Actually, the resulting rear wheel may be less stiff laterally, but can almost certainly be built stronger (more load capacity) with less dish. Many tandem rear hubs have been built symmetrical or nearly symmetrical for this reason, though it means that flange spacing will be narrow. I am not convinced that disc brakes have any advantages on a touring bike, but in the rear at least, they will not compromise wheel strength. Chalo Colina |
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