Why do some forks and frames have brake rotor size limits?
On Fri, 27 Oct 2017 12:43:07 -0400, Frank Krygowski
wrote: On 10/27/2017 4:34 AM, John B. wrote: On Wed, 25 Oct 2017 08:59:46 -0700 (PDT), wrote: I see no reason whatsoever for disk brakes and their complications even on most MTB's since a good V-Brake is longer lasting, just as effective, cheaper and doesn't require special wheels and frame and fork changes. Well, "cause I want 'em" is, I guess, a valid reason. But not necessarily proof of superiority :-) "I want 'em" is the ultimate decision point for lots and lots of consumer goods. Of course, people learn to "want them" after consuming tons of advertising bull****. I guess it keeps our economy going. In a more sober basis, of course it does. -- Cheers, John B. |
Why do some forks and frames have brake rotor size limits?
On Fri, 27 Oct 2017 10:42:48 -0700, Jeff Liebermann
wrote: On Fri, 27 Oct 2017 15:53:31 +0700, John B. wrote: At the copper mine, in Irian Jaya, the trucks and busses that ran from the base camp up to the tramway, that made the final jump up the mine, were all equipped with "Jacobs Brakes" which used the engine compression to reduce speed. https://en.wikipedia.org/wiki/Compression_release_engine_brake Ugh, don't remind me. I was going to college at Cal Poly, Pomona and living in a dormitory located at the base of Kellogg Hill. Going over the top of the hill was the San Bernardino Freeway. The slope was steep enough that trucks had to use secondary braking to slow down. At any hour of the day, a series of small explosions would be heard as the trucks descended down Kellogg Hill: https://archive.is/20130127022926/http://jake-brakes.com/about-us/noise-concerns.php https://www.youtube.com/watch?v=a8PDO6tbVtw (first few seconds as he slows the truck down). Riding in one of the crew busses at the mine I don't remember the jake brake being excessively loud, and as the alternate on most of that road was "straight down a thousand feet" probably wouldn't have minded anyway. -- Cheers, John B. |
Why do some forks and frames have brake rotor size limits?
On 10/27/2017 8:42 PM, John B. wrote:
On Fri, 27 Oct 2017 08:06:33 -0700 (PDT), wrote: On Friday, October 27, 2017 at 1:24:49 AM UTC-7, John B. wrote: On Thu, 26 Oct 2017 13:37:00 -0400, Radey Shouman wrote: Joerg writes: On 2017-10-24 17:21, John B. wrote: On Tue, 24 Oct 2017 11:47:12 -0700, Joerg wrote: [ ... ] 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. I don't understand the difference myself. When it's really raining, meaning there's a continuous film of water on the road and a rooster tail shooting forward off the front tire, I ride like a little old lady, because of the delay in braking. Especially when it's dark, and leaves and other blown down crap cover the road. I suspect that may be the secret. I've never been "doored", perhaps because if I have to ride past a line of parked cars where a door might be opened I either slow down or ride further enough away that a door wouldn't hit me. Here the bike lane can be so narrow that the car door on a two-door totally covers the lane and there's no place to dodge because passing cars will spot that and not let you out. If the choice is to run into a car door or be run over by a car then I think I'd get off and walk. In practice, at least in my experience, the actual choice is between the _risk_ of getting hit by an opening door, and the _risk_ of a motorist deliberately running me over from behind. In my experience, the latter risk is almost zero. Consider, we're almost certainly talking about a place where there are witnesses, because the situation requires people parking, getting out of their cars, opposing traffic that would prevent the guy behind from changing lanes, etc. There just aren't that many psychopaths who would risk prison terms by deliberately running you over, especially because it would slow them down. On the other hand, the person doing the dooring doesn't have to be a psychopath. He just has to be inattentive. There are lots and lots of those people. Now, for corroboration: I have definitely had situations where a door popped open, and I would have been doored if I had been riding within reach. But while I've occasionally (but rarely) had motorists honk or yell when I claim a lane, I've never had one run me over. And let's remember that dooring can be fatal. If the door snags your right handlebar, the bike whips to the right and you are instantaneously thrown to the left, directly into the path of the cars you were so worried about. -- - Frank Krygowski |
Why do some forks and frames have brake rotor size limits?
John B. wrote:
On Fri, 27 Oct 2017 09:32:04 -0700, Joerg wrote: On 2017-10-27 09:25, Frank Krygowski wrote: On 10/27/2017 9:58 AM, Joerg wrote: 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? sigh There are advantages and disadvantages to this equipment choice, just as with other equipment choices. The disadvantages of discs have been discussed. If they don't matter or apply to you, fine; but they matter to others. Many others just don't know any better. I have witnessed several people riding a bike with hydraulic disc brakes for the first time and the reaction was usually "WHOA!". Same with me, it almost sent me over the bar. But I'll note that you're currently in a project to increase your disc's diameter from something like 160mm or 180mm up to 200mm or more. You seem to feel bigger diameter is better. Because bigger is better here. Well, even "better," why not go up to roughly 622mm? That's what lots of us prefer, with cable actuation. The disadvantages have been discussed ad nauseam. A rim brake is not a disc brake. Not even close. Care to explain the mechanical difference? I mean a rotating surface and two friction pads that are tightened against it.... -- Cheers, John B. As far as I can tell, the differences between a rim brake and a 622 mm disk a 1) The disk doesn't have to provide tire clearance, so the pads can sit closer, facilitating higher mechanical advantage. 2) The disk is not connected to the rim, so it doesn't bend and warp when you hit a pothole. Again, the pads can sit closer and have higher MA. 3) The disk doesn't thermally couple to the tire, so no blowouts on long descents. 4) The disk is solid, so there's less flexing when you squeeze it with the pads. |
Why do some forks and frames have brake rotor size limits?
Ralph Barone wrote:
John B. wrote: On Fri, 27 Oct 2017 09:32:04 -0700, Joerg wrote: On 2017-10-27 09:25, Frank Krygowski wrote: On 10/27/2017 9:58 AM, Joerg wrote: 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? sigh There are advantages and disadvantages to this equipment choice, just as with other equipment choices. The disadvantages of discs have been discussed. If they don't matter or apply to you, fine; but they matter to others. Many others just don't know any better. I have witnessed several people riding a bike with hydraulic disc brakes for the first time and the reaction was usually "WHOA!". Same with me, it almost sent me over the bar. But I'll note that you're currently in a project to increase your disc's diameter from something like 160mm or 180mm up to 200mm or more. You seem to feel bigger diameter is better. Because bigger is better here. Well, even "better," why not go up to roughly 622mm? That's what lots of us prefer, with cable actuation. The disadvantages have been discussed ad nauseam. A rim brake is not a disc brake. Not even close. Care to explain the mechanical difference? I mean a rotating surface and two friction pads that are tightened against it.... -- Cheers, John B. As far as I can tell, the differences between a rim brake and a 622 mm disk a 1) The disk doesn't have to provide tire clearance, so the pads can sit closer, facilitating higher mechanical advantage. 2) The disk is not connected to the rim, so it doesn't bend and warp when you hit a pothole. Again, the pads can sit closer and have higher MA. 3) The disk doesn't thermally couple to the tire, so no blowouts on long descents. 4) The disk is solid, so there's less flexing when you squeeze it with the pads. Oops. Missed one. 5) The pads on the disk brake can be harder (because they're riding on a harder material) and we care less about disk wear than rim wear. This reduces slop in the system, which again allows tighter tolerances, which begets higher MA. Now the funny thing is that a 622 mm disk might end up having less effective wet braking than a smaller disk because the increased lever arm of the disk on the wheel would mean that the MA of the drive system would have to be reduced in order to prevent you doing an endo on every stop. Because of the lower pad pressure, water would not be displaced from the disk as quickly and wet braking would then suffer. |
Why do some forks and frames have brake rotor size limits?
On Sat, 28 Oct 2017 01:13:54 +0000 (UTC), Ralph Barone
wrote: John B. wrote: On Fri, 27 Oct 2017 09:32:04 -0700, Joerg wrote: On 2017-10-27 09:25, Frank Krygowski wrote: On 10/27/2017 9:58 AM, Joerg wrote: 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? sigh There are advantages and disadvantages to this equipment choice, just as with other equipment choices. The disadvantages of discs have been discussed. If they don't matter or apply to you, fine; but they matter to others. Many others just don't know any better. I have witnessed several people riding a bike with hydraulic disc brakes for the first time and the reaction was usually "WHOA!". Same with me, it almost sent me over the bar. But I'll note that you're currently in a project to increase your disc's diameter from something like 160mm or 180mm up to 200mm or more. You seem to feel bigger diameter is better. Because bigger is better here. Well, even "better," why not go up to roughly 622mm? That's what lots of us prefer, with cable actuation. The disadvantages have been discussed ad nauseam. A rim brake is not a disc brake. Not even close. Care to explain the mechanical difference? I mean a rotating surface and two friction pads that are tightened against it.... -- Cheers, John B. As far as I can tell, the differences between a rim brake and a 622 mm disk a 1) The disk doesn't have to provide tire clearance, so the pads can sit closer, facilitating higher mechanical advantage. I'm not sure that is correct. After all some old Greek guy was supposed to have said, "Give me a lever and a place to stand and I will move the earth". Nothing about being close. 2) The disk is not connected to the rim, so it doesn't bend and warp when you hit a pothole. Again, the pads can sit closer and have higher MA. 3) The disk doesn't thermally couple to the tire, so no blowouts on long descents. 4) The disk is solid, so there's less flexing when you squeeze it with the pads. -- Cheers, John B. |
Why do some forks and frames have brake rotor size limits?
On Sat, 28 Oct 2017 01:20:37 +0000 (UTC), Ralph Barone
wrote: Ralph Barone wrote: John B. wrote: On Fri, 27 Oct 2017 09:32:04 -0700, Joerg wrote: On 2017-10-27 09:25, Frank Krygowski wrote: On 10/27/2017 9:58 AM, Joerg wrote: 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? sigh There are advantages and disadvantages to this equipment choice, just as with other equipment choices. The disadvantages of discs have been discussed. If they don't matter or apply to you, fine; but they matter to others. Many others just don't know any better. I have witnessed several people riding a bike with hydraulic disc brakes for the first time and the reaction was usually "WHOA!". Same with me, it almost sent me over the bar. But I'll note that you're currently in a project to increase your disc's diameter from something like 160mm or 180mm up to 200mm or more. You seem to feel bigger diameter is better. Because bigger is better here. Well, even "better," why not go up to roughly 622mm? That's what lots of us prefer, with cable actuation. The disadvantages have been discussed ad nauseam. A rim brake is not a disc brake. Not even close. Care to explain the mechanical difference? I mean a rotating surface and two friction pads that are tightened against it.... -- Cheers, John B. As far as I can tell, the differences between a rim brake and a 622 mm disk a 1) The disk doesn't have to provide tire clearance, so the pads can sit closer, facilitating higher mechanical advantage. 2) The disk is not connected to the rim, so it doesn't bend and warp when you hit a pothole. Again, the pads can sit closer and have higher MA. 3) The disk doesn't thermally couple to the tire, so no blowouts on long descents. 4) The disk is solid, so there's less flexing when you squeeze it with the pads. Oops. Missed one. 5) The pads on the disk brake can be harder (because they're riding on a harder material) and we care less about disk wear than rim wear. This reduces slop in the system, which again allows tighter tolerances, which begets higher MA. Ahem, but aluminum rims are a relatively recent innovation. Before that rims were steel. Now the funny thing is that a 622 mm disk might end up having less effective wet braking than a smaller disk because the increased lever arm of the disk on the wheel would mean that the MA of the drive system would have to be reduced in order to prevent you doing an endo on every stop. Because of the lower pad pressure, water would not be displaced from the disk as quickly and wet braking would then suffer. As I've written in the past. My utility bike with conventional Vee brakes has sufficient braking force to lock the front wheel on either wet or dry blacktop pavement. Can a disc brake provide more braking force? -- Cheers, John B. |
Why do some forks and frames have brake rotor size limits?
On Fri, 27 Oct 2017 06:59:56 -0700, Joerg
wrote: Oh yeah, now we have to wash out bikes after each rain ride. Standing out there in the rain with sponge and shampoo. Great. You don't have a garden hose? Back when I could ride after the outside faucets had been turned off for the winter, I used to hose salt and ice off my bike by filling my water bottles with hot tap water, reserving the first squirt from each bottle to get under the fenders. I don't think I ever had to make more than two trips into the house for more water. Come to think of it, I don't think I ever hosed it in the summer (except when cleaning the braking surfaces, of course), because I rode only on pavement. There was one mile of gravel road in an adjacent county, but the grader wore out and it was cheaper to pave the road than to buy a new grader. -- Joy Beeson joy beeson at comcast dot net http://wlweather.net/PAGEJOY/ |
Why do some forks and frames have brake rotor size limits?
John B. wrote:
On Sat, 28 Oct 2017 01:20:37 +0000 (UTC), Ralph Barone wrote: Ralph Barone wrote: John B. wrote: On Fri, 27 Oct 2017 09:32:04 -0700, Joerg wrote: On 2017-10-27 09:25, Frank Krygowski wrote: On 10/27/2017 9:58 AM, Joerg wrote: 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? sigh There are advantages and disadvantages to this equipment choice, just as with other equipment choices. The disadvantages of discs have been discussed. If they don't matter or apply to you, fine; but they matter to others. Many others just don't know any better. I have witnessed several people riding a bike with hydraulic disc brakes for the first time and the reaction was usually "WHOA!". Same with me, it almost sent me over the bar. But I'll note that you're currently in a project to increase your disc's diameter from something like 160mm or 180mm up to 200mm or more. You seem to feel bigger diameter is better. Because bigger is better here. Well, even "better," why not go up to roughly 622mm? That's what lots of us prefer, with cable actuation. The disadvantages have been discussed ad nauseam. A rim brake is not a disc brake. Not even close. Care to explain the mechanical difference? I mean a rotating surface and two friction pads that are tightened against it.... -- Cheers, John B. As far as I can tell, the differences between a rim brake and a 622 mm disk a 1) The disk doesn't have to provide tire clearance, so the pads can sit closer, facilitating higher mechanical advantage. 2) The disk is not connected to the rim, so it doesn't bend and warp when you hit a pothole. Again, the pads can sit closer and have higher MA. 3) The disk doesn't thermally couple to the tire, so no blowouts on long descents. 4) The disk is solid, so there's less flexing when you squeeze it with the pads. Oops. Missed one. 5) The pads on the disk brake can be harder (because they're riding on a harder material) and we care less about disk wear than rim wear. This reduces slop in the system, which again allows tighter tolerances, which begets higher MA. Ahem, but aluminum rims are a relatively recent innovation. Before that rims were steel. True, but I also mentioned rim wear. Even back in the steel rim days, brake pads were pretty soft, and until ceramic coated rims came out, there was nothing nearing the hardness of disk brake pads. Now the funny thing is that a 622 mm disk might end up having less effective wet braking than a smaller disk because the increased lever arm of the disk on the wheel would mean that the MA of the drive system would have to be reduced in order to prevent you doing an endo on every stop. Because of the lower pad pressure, water would not be displaced from the disk as quickly and wet braking would then suffer. As I've written in the past. My utility bike with conventional Vee brakes has sufficient braking force to lock the front wheel on either wet or dry blacktop pavement. Can a disc brake provide more braking force? -- Cheers, John B. |
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