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#212
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Why do some forks and frames have brake rotor size limits?
On Monday, October 30, 2017 at 9:39:55 AM UTC-7, Joerg wrote:
On 2017-10-29 12:57, wrote: On Sunday, October 29, 2017 at 10:02:12 AM UTC-7, Joerg wrote: On 2017-10-29 09:45, wrote: On Saturday, October 28, 2017 at 8:09:18 AM UTC-7, Joerg wrote: And grandpa has driven his cars without safety belts yet survived ... For people who do not shy away from unpaved roads or use a lot of singletrack and ride in the rain there is a much more extreme issue: Wet mud. There is NO brake the is proof against wet mud. In fact it is perhaps worse on a disk since the additional pressure of the pads can turn the silicon present in most muds into cutting instruments that on rim brakes cuts into the rubber show rather than the hard and thin disk pad. Actually, no. I've had mud literally dripping from the calipers which had become barely recognizable brownish blobs. The only thing that happens is that they make an awful grinding noise just like muddy rim brakes do. With the two major differences that they still come on full force immediately and that this grinding does not eat up aluminum. Aluminum as one of the braking surfaces plain does not make any sense, certainly not in a muddy environment. A downside of bicycle disc brakes is that in contrast to most motor vehicles the rotors have "vent holes" and weight weenie spiders. This results in rather fast heat-up and in "brake mousse" when you plow through thick vegetation on an overgrown trail. Mashed star-thistle and other weeds get shredded and a sort of pulp develops which cakes up in the holes of the rotor. It doesn't diminish the brake force but lets of a bad stench. One of the reasons why I carry a Swiss Army knife in a pocket. Not in a pannier, so I can whip it out in seconds. This also helps in poking out the giant mud clump that forms behind the BB and can prevent the rear wheel from turning. Joerg - that additional noise is wear. Sure. However, the rotors last thousands of miles, cost around $20 and take only minutes to change. The pads cost $2/pair for ceramic-based material (like motorcycles have) and last around 1000mi depending on turf and weather. That is way more hassle than with a motor vehicle but way less hassle than swapping out a shot rim. I started riding again in fall 2013, using an older model MTB with almost zero miles on it. By the end of 2013 it had around 1000mi on it and the front rim looks horrible. The problem in our area is this: Mud contains granules of decomposed granite. Rubber pads need water diverter grooves and the granules lodge in these grooves. They also pierce the rubber itself and lodge in there. When pulling the lever that lets of a horrid grinding noise. Coming down a hill you have to keep the brake engaged and you can literally hear the rim being tortured all the way to the bottom of the hill. On flat surfaces you have to stop and pry out the granules. On a rainy day that means stopping every few miles. I stand by my opinion that rim brakes are inadequate for any serious MTB riding. Well, perhaps it was from older parts but I saw a significant number of MTB riders walking their bikes back off of hills. Those were the older cable pull brakes so that might have been when they were still developing the proper compounds. https://www.youtube.com/watch?v=Wdb7KEc7xJI This is comparing an 11 speed Ghost with an aluminum el-cheapo Raleigh. This was a highly unfair test to begin with: On the climbing test the Raleigh had an eight speed compact that simply didn't have the correct gearing. And the bicycle size and set-up was entirely wrong. On the braking test it was hydraulic disks against what appeared to the the old-fashioned long throw brakes. There was so much bend in the brakes that you could bottom out the lever. On the TT again the problem was that there simply wasn't the proper gearing.. And since the Raleigh wasn't sized correctly it was nearly impossible to get into an aero position. Personally in the brake test I believe my Skeleton brakes would have finished not exactly with the disks but really close. There is no flex to speak of in my brakes and while I think I could lock the front wheel and allow the rear wheel to rise off of the ground there is absolutely no day I would do such a thing. My bikes are set up similar seating position to the Raleigh. But I could merely change the stem to gain a position such as the Ghost. I personally don't give much credit to the aerodynamics of a frame. |
#213
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Why do some forks and frames have brake rotor size limits?
On Monday, October 30, 2017 at 9:48:34 AM UTC-7, Joerg wrote:
On 2017-10-30 08:33, wrote: Joerg, heroics can also be described as riding a really heavy bike such as yours at any pace above mild. That's not heroic because it doesn't come with additional risk. Over time you just build up a lot of leg muscle. This also helps for rides with the road bike like yesterday. I rode along a canal bike path purely for exercise. It's otherwise a boring ride but ... no speed limit ... woohoo! The path sometimes tunnels underneath roads and such but for some obstacles it runs above, steep sections. With enough leg muscle you don't have to shift, just leave it in high gear, put on the coals so you reach 25mph or more at the bottom, keep the torque on until it crests and then let it coast back down. I didn't shift at all until I reached the Cosumnes River where I had my snack break. Four years ago I couldn't have done that. I have to differ with you there. Climbing is only half of it. Descending is the other half and a heavy bike under any conditions is a dangerous downhill bike if you do not know the trail intimately. |
#214
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Why do some forks and frames have brake rotor size limits?
On Monday, October 30, 2017 at 9:51:06 AM UTC-7, Joerg wrote:
I worked in med-tech for a long time and so far all docs are of opposite opinion. Yes, some benefits of helmets will be offset by increase sisk taking. Also, there were no Kawasaki Ninjas and such before the helmet law. I know and that is why it is dangerous to listen to doctors. http://www.vehicularcyclist.com/kunich.html There is no change since 2002 because the only way of improving a helmet is via increasing the size. And helmets are already of bothersome size to people. Remember that I was the safety director of the American Federation of Motorcyclists after I gave up racing. I was also a professional mechanic with the American Motorcycle Association. So when I speak about helmets it is from a position of study as well as painful experience. |
#215
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Why do some forks and frames have brake rotor size limits?
On Saturday, October 28, 2017 at 8:13:26 PM UTC-7, Frank Krygowski wrote:
On 10/28/2017 9:11 PM, John B. wrote: On Sat, 28 Oct 2017 16:59:47 -0700 (PDT), jbeattie wrote: On Saturday, October 28, 2017 at 3:40:36 PM UTC-7, AMuzi wrote: On 10/28/2017 4:27 PM, jbeattie wrote: On Saturday, October 28, 2017 at 12:08:44 PM UTC-7, Sir Ridesalot wrote: On Saturday, October 28, 2017 at 11:09:18 AM UTC-4, Joerg wrote: On 2017-10-27 17:11, John B. wrote: On Fri, 27 Oct 2017 06:58:27 -0700, Joerg wrote: On 2017-10-27 01:11, John B. wrote: On Wed, 25 Oct 2017 07:53:11 -0700, Joerg wrote: On 2017-10-24 17:21, John B. wrote: On Tue, 24 Oct 2017 11:47:12 -0700, Joerg wrote: On 2017-10-24 07:27, wrote: On Tuesday, October 24, 2017 at 2:19:48 AM UTC-7, John B. wrote: On Mon, 23 Oct 2017 10:09:20 -0700, Jeff Liebermann wrote: On Mon, 23 Oct 2017 12:48:29 +0700, John B. wrote: On Sun, 22 Oct 2017 20:51:15 -0700, Jeff Liebermann wrote: On Mon, 23 Oct 2017 07:02:08 +0700, John B. wrote: But re disc brake cooling F1 car brakes appear to work with the discs red hot. In the 1,000 degree (F) range. And they use Carbon Fiber discs too :-) And everyone knows that CF is better. "Thermal Conductivity of Carbon Fiber, and other Carbon Based Materials" http://www.christinedemerchant.com/carbon_characteristics_heat_conductivity.html "So...Is Carbon Fiber a good heat conductor? As usual the answer is "it depends." The short answer is NO not when regular carbon fiber is made up in regular epoxy and expected to conduct heat across the thickness. IF a highly carbonized pan fiber with graphite or diamond added, is measured for heat transmission in the length of the fiber it is very good and can rival and exceed copper." On the other hand, they seem to work pretty well :-) See https://www.youtube.com/watch?v=h5JcHAEmIYM for a visual indication of heat dissipation. :-) Impressive. I'll assume it's a carbon-carbon rotor, since all F1 cars seem to using them. Undoubtedly so. But if the advantage of "carbon" bikes can be extolled that a carbon-carbon frame must have twice the bragging rights :-) http://www.racecar-engineering.com/technology-explained/f1-2014-explained-brake-systems/ (4 pages) "A typical road car uses a cast iron brake disc with an organic brake pad. In an F1 car, though, the same material is used for both disc and pad, and this material is known as carbon-carbon - a significantly different material to the carbon-fibre composites used in the rest of the car" In other words, the F1 brakes are NOT made from CF. Some detail on Formula 1 brakes: https://www.youtube.com/watch?v=ev6XTdlKElw Fun destroying brakes: https://www.youtube.com/watch?v=KslGsXMgmqg The brake starting at 4:45 sure looks like CF but I'm not sure. Maybe twin disk brakes would be easier? http://nuovafaor.it//public/prodotto/75/nccrop/DOPPIO_FRENO_CROSS_ENDURO.jpg https://i.ytimg.com/vi/Pvwj-WWlKkg/maxresdefault.jpg https://gzmyu4ma9b-flywheel.netdna-ssl.com/wp-content/uploads/2011/09/Gatorbrake-dual-hydraulic-front-disc-brakes-carbon-rotors01.jpg https://lh4.googleusercontent.com/-cDfAFWrGR6Q/VHKPsm-f6YI/AAAAAAAAX10/2FCyj87xs0g/s640/14%2520-%25201.jpg https://www.minibikecraze.co.uk/wp-content/uploads/bs0978.jpg https://endless-sphere.com/forums/viewtopic.php?f=28&t=56268 Given the coefficient of friction between a 1.25" wide rubber tire (32mm) and a wet road probably dragging the feet will work.. :-) Joerg's experience is with full suspension MTB's. These things are incredibly heavy and long wheelbased. He has his judgement of disks and it is no doubt quite accurate for his experience and riding. I have disks on a much lighter and shorter wheelbased bike. I know the failings up close and personal. I simply cannot imagine WHY a person would want a more complicated system than that offered by the Campy Skeleton brakes. The reason can be summed up in one word: Rain :-) But last Sunday I started out my "weekend" ride in the rain. It had been raining nearly all night and the roads had a lot of water on them - note we have been having floods here in Bangkok lately - but it appeared that the rain was ending so off I went. Unfortunately my weather forecasting facility wasn't working very well and I rode 20 Km of a 30 Km ride in light rain and flooded roads in many places. I was splashing through water in some places and cars were splashing through (and splashing me) in others. Of course, Sunday is much lighter traffic then on work days but still, Bangkok is rated as one of the cities with the most chaotic traffic in the world, and I did have to stop suddenly several time, on flooded roads with wet wheels and brakes. My brakes worked just as they do in the dry. Back brake stops me somewhat slowly and front brake stops rather suddenly, both brakes together provides best stopping. No long wait after grabbing a brake lever although I did think of you with your stopping problems and I have the feeling that the brake lever pressure might be a tiny bit more to stop in the rain but if it was it was so little that it couldn't be quantified. But of course I am using quality brake pads. Why it costs me US$12.12 a wheel just for pads alone.... but they do last a year or more. It seems Californian rain and Thai rain aren't the same. When it rains heavily and I have to do a surprise emergency stop after not having used the brakes for a while there is 1-2sec of nada, absolutely nothing. It makes no difference whatsoever whether I use $17 high-falutin Koolstop rain-rated pads or $4 Clarks pads. The experience of other riders around here and in this NG is similar. Which, to be honest, I find a little mystifying as I've had pretty constant success with conventional brakes. Frankly, I can't believe this is solely because I'm somehow so uniquely skilled or that y'all are all in the awkward squad I do see a number of people here and many who are not here who seem to have ridden for years using conventional brakes without complaint and some of the blogs I read don't even talk about brakes. Dave Moulton, for example. An old fellow, used to race bikes, came to the U.S.. in about 1979 and built frames commercially for years, now retired, has one entry in his blog about brakes - "centering side pull brakes". Another blog from the long distance side of the bicycleing world, The Blayleys, who are into Audex's and who apparently each ride in the neighborhood of 10,000 miles annually, mentions Vee brakes in reference to a Tandem while a photo of them on a tandem on their web page shows disc brakes. On the other hand, when she discusses a "good brevet bike she simply says that the "brakes must clear the fenders and probably long reach caliper brakes will suffice". In short, it seems that brakes just don't seem to be a hot subject in much of the cycling fraternity. To a large part that is because most cyclist will not ride in driving rain. Some do and those know exactly how that delay with rim brakes feels. Occasionally it is called "free fall" because that's how it feels like. Well, the Blayleys state that the husband, John, has ridden 10 - 17 thousand miles a year for the past 25 years and the wife, Pamela, has ridden from 10 - 14 thousand miles a year for the past 20 years, or another way to put it might be that together they have ridden from 20 - 30 thousand miles a year for the past 20 years. Somehow I suspect that they may have encountered rain in that period. And grandpa has driven his cars without safety belts yet survived .... For people who do not shy away from unpaved roads or use a lot of singletrack and ride in the rain there is a much more extreme issue: Wet mud. You may have never encountered it but I have many times. You reach in and, after a second or two of nothing, the rim brakes come on but let off an awful grinding noise. You can literally hear the rim being tortured but because of a rapidly approaching curve you can't let go. As I have mentioned before the rims on my old MTB are only 1000mi old but the front rim is almost shot from all that. Deep grooves. I stand by my opinion that rim brakes are fair weather brakes. Then they are fine but not when the going gets tough. Like this kind of weather: https://www.youtube.com/watch?v=mX_EKybzK4Y I might comment that I've ridden coaster brakes, drum brakes, rod pull brakes, cantilever brakes, side pull single pivot caliper brakes, double pivot caliper, Vee brakes and for one short ride a cable disc brake. and at the time I rode them I found all the brakes to give acceptable service. Well with one exception, rim brakes and chrome plated steel rims were sometimes a bit iffy :-) Yes, those were the worst. It got a little better with aluminum rims but not a lot. In the world of automotive such a brake "system" would not stand the slightest change of being legal. Finally after many decades the bicycle industry woke up and adopted what the automotive guys had all along, disc brakes. Why should I accept an inferior brake system on a new bike when there is a much better one? Well, when I worked on airplanes I remember that the F-4 had multi plate disc brakes which provided a tremendous amount of stopping power in a very small package. Some tandems have that as well, and of course motorcycles: Two discs up front. But not stacks of discs. One supposes that will be next big improvement in bicycle brakes. Or perhaps a drag chute for those long downhill's to keep the rims from melting? I've thought about it :-) -- Regards, Joerg http://www.analogconsultants.com/ Oh ****! I've ridden many hundreds of miles off road in dry and wet sand, mud, heavy rain, rutted roads/trails and did so on an MTB with cantilever brakes and NEVER had trouble stopping either when I needed to or when I wanted too. I've ridden on ice and in 4 inches+ deep snowand also never had trouble stopping. Perhaps you ride too fast for the conditions/sight lines or you don't keep your brakes adjusted properly. Really? I have trouble standing up on ice. There is a point at which you don't want super-strong brakes. -- Jay Beattie. Yeah me too. Snow is one thing - I'm used to that- but ice is quite another. Depending on the recent weather, a frozen slick patch of ice under snow will dump me right on my ass. We mere humans would have some trouble with Jobst's famous tour down a frozen Swiss river. I live at a whopping 400 feet (about) elevation. The garage in my building is probably 0 feet. That minor elevation change sometimes means the difference between ice and no ice -- so I walk outside in the morning and say f*** this! And then I jump in the car and half-way to work, creeping along in traffic, there is no ice -- and then I regret not riding. So, in order to avoid that regret, I have done some pretty stupid sh** spinning around on ice or hoofing it in my SPDs to get out of my neighborhood and then being freaked out riding over the slick bridges and viaducts into town. I met up with another guy on a bike who was fish-tailing down the road on one of those mornings, and we looked at each other and shook our heads -- "we're a couple of idiots." So, now I'm working on not feeling regret or guilt if I drive. And don't get me going about the dopes who jump into their Malibus with no-season/no-tread tires and crash on the ice and/or snow. I'll slap on the snow tires in November. I really miss studs, but I'm doing penance with studless. -- Jay Beattie. Are studded auto tires legal? I seem to remember that back in the 1960's when I was in Maine that it was illegal to drive studded tires on bare roads. It was a long time ago and memory is always questionable but I'm sure that I remember people getting a ticket for using studded tires under certain conditions. I don't know if they're legal in Oregon now (Jay can tell us) but I've driven out there in the summer and experienced the weirdness of a freeway with two troughs worn in it by thousands of studded tires. Our cars track (i.e. left to right wheel span) didn't quite match the trough widths, and our car had a disturbing tendency to "hunt" back and forth as I drove. Studs are still legal. https://www.tripcheck.com/Pages/Chain-Law# -- Jay Beattie. |
#216
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Why do some forks and frames have brake rotor size limits?
On Monday, October 30, 2017 at 9:39:55 AM UTC-7, Joerg wrote:
On 2017-10-29 12:57, wrote: On Sunday, October 29, 2017 at 10:02:12 AM UTC-7, Joerg wrote: On 2017-10-29 09:45, wrote: On Saturday, October 28, 2017 at 8:09:18 AM UTC-7, Joerg wrote: And grandpa has driven his cars without safety belts yet survived ... For people who do not shy away from unpaved roads or use a lot of singletrack and ride in the rain there is a much more extreme issue: Wet mud. There is NO brake the is proof against wet mud. In fact it is perhaps worse on a disk since the additional pressure of the pads can turn the silicon present in most muds into cutting instruments that on rim brakes cuts into the rubber show rather than the hard and thin disk pad. Actually, no. I've had mud literally dripping from the calipers which had become barely recognizable brownish blobs. The only thing that happens is that they make an awful grinding noise just like muddy rim brakes do. With the two major differences that they still come on full force immediately and that this grinding does not eat up aluminum. Aluminum as one of the braking surfaces plain does not make any sense, certainly not in a muddy environment. A downside of bicycle disc brakes is that in contrast to most motor vehicles the rotors have "vent holes" and weight weenie spiders. This results in rather fast heat-up and in "brake mousse" when you plow through thick vegetation on an overgrown trail. Mashed star-thistle and other weeds get shredded and a sort of pulp develops which cakes up in the holes of the rotor. It doesn't diminish the brake force but lets of a bad stench. One of the reasons why I carry a Swiss Army knife in a pocket. Not in a pannier, so I can whip it out in seconds. This also helps in poking out the giant mud clump that forms behind the BB and can prevent the rear wheel from turning. Joerg - that additional noise is wear. Sure. However, the rotors last thousands of miles, cost around $20 and take only minutes to change. The pads cost $2/pair for ceramic-based material (like motorcycles have) and last around 1000mi depending on turf and weather. That is way more hassle than with a motor vehicle but way less hassle than swapping out a shot rim. I started riding again in fall 2013, using an older model MTB with almost zero miles on it. By the end of 2013 it had around 1000mi on it and the front rim looks horrible. The problem in our area is this: Mud contains granules of decomposed granite. Rubber pads need water diverter grooves and the granules lodge in these grooves. They also pierce the rubber itself and lodge in there. When pulling the lever that lets of a horrid grinding noise. Coming down a hill you have to keep the brake engaged and you can literally hear the rim being tortured all the way to the bottom of the hill. On flat surfaces you have to stop and pry out the granules. On a rainy day that means stopping every few miles. I stand by my opinion that rim brakes are inadequate for any serious MTB riding. That is the reason to use Kool-stop Salmons. The compound will not let granules lodge. |
#217
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Why do some forks and frames have brake rotor size limits?
Well, it certainly doesn't help to be wearing all black in the evening without lights. That was so popular for several years that it's almost unbelievable. A friend in Oregon had a nasty crash with injuries when he rear-ended a black cow with no taillights standing in the middle of the road |
#218
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Why do some forks and frames have brake rotor size limits?
On 2017-10-30 12:38, wrote:
On Monday, October 30, 2017 at 9:48:34 AM UTC-7, Joerg wrote: On 2017-10-30 08:33, wrote: Joerg, heroics can also be described as riding a really heavy bike such as yours at any pace above mild. That's not heroic because it doesn't come with additional risk. Over time you just build up a lot of leg muscle. This also helps for rides with the road bike like yesterday. I rode along a canal bike path purely for exercise. It's otherwise a boring ride but ... no speed limit ... woohoo! The path sometimes tunnels underneath roads and such but for some obstacles it runs above, steep sections. With enough leg muscle you don't have to shift, just leave it in high gear, put on the coals so you reach 25mph or more at the bottom, keep the torque on until it crests and then let it coast back down. I didn't shift at all until I reached the Cosumnes River where I had my snack break. Four years ago I couldn't have done that. I have to differ with you there. Climbing is only half of it. Descending is the other half and a heavy bike under any conditions is a dangerous downhill bike if you do not know the trail intimately. It's a canal bike trail, long straight shot, very wide. Almost like a midwest freeway. You could go 50mph and be totally safe. https://cdn-assets.alltrails.com/upl...31324781d8.jpg The only real danger there is falling asleep and veering off the side. Probably happens, sometimes a soft curve like this comes and you see screech marks: https://cloudfront.traillink.com/pho...l_27481_lb.jpg At 29:15min you can see a small hump, the ones on the sides are a bit higher: https://www.youtube.com/watch?v=A-3gnLIUum0 -- Regards, Joerg http://www.analogconsultants.com/ |
#219
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Why do some forks and frames have brake rotor size limits?
On 2017-10-30 12:44, wrote:
On Monday, October 30, 2017 at 9:51:06 AM UTC-7, Joerg wrote: I worked in med-tech for a long time and so far all docs are of opposite opinion. Yes, some benefits of helmets will be offset by increase sisk taking. Also, there were no Kawasaki Ninjas and such before the helmet law. I know and that is why it is dangerous to listen to doctors. http://www.vehicularcyclist.com/kunich.html With all due respect, quote "... that no area receives more than a single blow. While it is plain why this is done, it most assuredly does not mimic the real world where a person falling off a bicycle may have his head bounce down the road several times before stopping ..." doesn't apply to many serious accidents. Most that I know of were one big smack into something hard. A tree, a rock, a car. You might roll off and hit something else or the pavement but not at full brunt anymore. Others have had such crashes where they came away alright but the styrofoam inside the helmet had clearly absorbed a lot of the impact energy and was crushed. That's when the helmet must be replaced. This is why you find styrofoam in or behind the bumber of many cars. There is no change since 2002 because the only way of improving a helmet is via increasing the size. And helmets are already of bothersome size to people. Remember that I was the safety director of the American Federation of Motorcyclists after I gave up racing. I was also a professional mechanic with the American Motorcycle Association. So when I speak about helmets it is from a position of study as well as painful experience. Ok, everybody has their opinion. The docs I spoke to were very much convinced of the benefits of helmets. Some accidents remained the same in terms of force despite advances in motorcycle engines. For example in cities where traffic is slow it doesn't matter much whether you ride a Ninja or a 250. That's one area where they saw a noticable drop in the severity of head injuries. -- Regards, Joerg http://www.analogconsultants.com/ |
#220
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Why do some forks and frames have brake rotor size limits?
On 2017-10-30 12:35, wrote:
On Monday, October 30, 2017 at 9:39:55 AM UTC-7, Joerg wrote: On 2017-10-29 12:57, wrote: On Sunday, October 29, 2017 at 10:02:12 AM UTC-7, Joerg wrote: On 2017-10-29 09:45, wrote: On Saturday, October 28, 2017 at 8:09:18 AM UTC-7, Joerg wrote: And grandpa has driven his cars without safety belts yet survived ... For people who do not shy away from unpaved roads or use a lot of singletrack and ride in the rain there is a much more extreme issue: Wet mud. There is NO brake the is proof against wet mud. In fact it is perhaps worse on a disk since the additional pressure of the pads can turn the silicon present in most muds into cutting instruments that on rim brakes cuts into the rubber show rather than the hard and thin disk pad. Actually, no. I've had mud literally dripping from the calipers which had become barely recognizable brownish blobs. The only thing that happens is that they make an awful grinding noise just like muddy rim brakes do. With the two major differences that they still come on full force immediately and that this grinding does not eat up aluminum. Aluminum as one of the braking surfaces plain does not make any sense, certainly not in a muddy environment. A downside of bicycle disc brakes is that in contrast to most motor vehicles the rotors have "vent holes" and weight weenie spiders. This results in rather fast heat-up and in "brake mousse" when you plow through thick vegetation on an overgrown trail. Mashed star-thistle and other weeds get shredded and a sort of pulp develops which cakes up in the holes of the rotor. It doesn't diminish the brake force but lets of a bad stench. One of the reasons why I carry a Swiss Army knife in a pocket. Not in a pannier, so I can whip it out in seconds. This also helps in poking out the giant mud clump that forms behind the BB and can prevent the rear wheel from turning. Joerg - that additional noise is wear. Sure. However, the rotors last thousands of miles, cost around $20 and take only minutes to change. The pads cost $2/pair for ceramic-based material (like motorcycles have) and last around 1000mi depending on turf and weather. That is way more hassle than with a motor vehicle but way less hassle than swapping out a shot rim. I started riding again in fall 2013, using an older model MTB with almost zero miles on it. By the end of 2013 it had around 1000mi on it and the front rim looks horrible. The problem in our area is this: Mud contains granules of decomposed granite. Rubber pads need water diverter grooves and the granules lodge in these grooves. They also pierce the rubber itself and lodge in there. When pulling the lever that lets of a horrid grinding noise. Coming down a hill you have to keep the brake engaged and you can literally hear the rim being tortured all the way to the bottom of the hill. On flat surfaces you have to stop and pry out the granules. On a rainy day that means stopping every few miles. I stand by my opinion that rim brakes are inadequate for any serious MTB riding. Well, perhaps it was from older parts but I saw a significant number of MTB riders walking their bikes back off of hills. Those were the older cable pull brakes so that might have been when they were still developing the proper compounds. https://www.youtube.com/watch?v=Wdb7KEc7xJI Wow, 2x the stopping distance for the rim brakes. I wouldn't have imagined it could be that much worse. This is comparing an 11 speed Ghost with an aluminum el-cheapo Raleigh. This was a highly unfair test to begin with: On the climbing test the Raleigh had an eight speed compact that simply didn't have the correct gearing. And the bicycle size and set-up was entirely wrong. On the braking test it was hydraulic disks against what appeared to the the old-fashioned long throw brakes. There was so much bend in the brakes that you could bottom out the lever. I don't think he bottomed out the levers. On the TT again the problem was that there simply wasn't the proper gearing. And since the Raleigh wasn't sized correctly it was nearly impossible to get into an aero position. Personally in the brake test I believe my Skeleton brakes would have finished not exactly with the disks but really close. There is no flex to speak of in my brakes and while I think I could lock the front wheel and allow the rear wheel to rise off of the ground there is absolutely no day I would do such a thing. My bikes are set up similar seating position to the Raleigh. But I could merely change the stem to gain a position such as the Ghost. I personally don't give much credit to the aerodynamics of a frame. Gearing and such are a different matter but brakes are safety-relevant. I wouldn't want to compromise there. -- Regards, Joerg http://www.analogconsultants.com/ |
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