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#141
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Bicycle Stopping Distances
RicodJour wrote: On Nov 7, 11:48*pm, birdbrain wrote: On Nov 7, 7:01*pm, RicodJour wrote: On Nov 7, 9:42*pm, MagillaGorilla wrote: But the front brake...it is essential that it is mounted to the front of the fork. http://www.bikeradar.com/gallery/art...-evans-silence... Maybe you should save the Cervelo engineers a lot of embarrassment and give them a call to straighten them out. Just keep digging, Sponge Bob. Dumbass, that's a time trial bike. Excellent. Your eyes are functioning. Your point being...what? That the brakes aren't applied as often? True. That it's unlikely that someone will be screaming downhill at 100 KPH on it? Also true. How does that change things? It changes the only 2 things that really matter, dumbass. Any braking force beyond locking up the wheel is pointless. Do you doubt that the brake mounted in that position would lock up the front wheel? On a 55 mph descent with maximum braking, with a 250 pound rider the Cervelo design would fail in a mean time that is 3x faster than if it were mounted on the front. Also, you would probably get into problems with the brake pads migrating up towards the tire under heavy loads whereas if it was mounted on the front it wouldn't do that. Also, if you mount it on the front of the FORK, your front wheel will lock up earlier and with less braking force than if you use the Cervelo design.. So the QUALITY of braking is better (faster and easier) if you put the calipers on the front when braking under HIGH LOADS. Engineers talk about quality, stability, and longevity of a design, not just YES/NO in terms of functionality. Mounting the calipers on the front of the fork is a much better design in terms of those qualities. Massengill stated an absolute, and he's absolutely full of ****. I am performing my civic duty by pointing this out. You're welcome. R Stop acting like an asshole in here. Magilla |
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#142
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Bicycle Stopping Distances
birdbrain wrote:
On Nov 7, 9:26*pm, RicodJour wrote: On Nov 7, 11:48*pm, birdbrain wrote: On Nov 7, 7:01*pm, RicodJour wrote: On Nov 7, 9:42*pm, MagillaGorilla wrote: But the front brake...it is essential that it is mounted to the front of the fork. http://www.bikeradar.com/gallery/art...-evans-silence... Maybe you should save the Cervelo engineers a lot of embarrassment and give them a call to straighten them out. Just keep digging, Sponge Bob. Dumbass, that's a time trial bike. Excellent. *Your eyes are functioning. Your point being...what? That the brakes aren't applied as often? *True. That it's unlikely that someone will be screaming downhill at 100 KPH on it? *Also true. So you're admitting that front mounted front brakes are superior? Proof of this is that Cervelo mounts the brakes on the FRONT of the fork on its road bikes.... http://bicyclebananas.com/mm5/mercha...ervelo_09_R 3 How do you like them bananas, Magilla |
#143
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Bicycle Stopping Distances
MagillaGorilla wrote:
RicodJour wrote: On Nov 7, 4:28 pm, " wrote: On Nov 7, 6:44 am, MagillaGorilla wrote: Correct, but when it's pulling away from the stays, the only thing keeping it there is the mounting bolt. All the stress of the braking is transfered through the mounting bolt and nut. The bolt itself bends and is not inelastic. And the hold that the bolt goes through is not perfectly flush with the bolt. But on the front brake, the entire brake caliper assembly is being forced into the frame which is for the most part immovable and thus gives better stability. I get a ****ing headache every time I read that. I don't have my stupid-to-English translator engaged, so tell me this, Batbuoy, are you arguing that a loose brake bolt is what makes the difference? If not, and the braking force is the same, as it must be, and all braking force is transmitted to the frame, as it must be, where does this extra braking force come from? The bolt, submitted to the same force in either mounting position, will deflect the same amount as the difference in geometry is negligible. Much like your argument. No no no no. The front brake transfers most of the force through the mating surface of the caliper to the FORK. The front bolt transfers probably 30% of the force. On the rear brake, the bolt transfers nearly 100% of the force. It is true that all the force is ultimately absorbed by the frame. But the design of the front bake via its placement on the front of the FORK makes it a more stable design under high loads and high speeds. Ask any frame builder/engineer. Harry Havnoonian is a frame builder AND mechanical engineer (degree from Drexel). He mounts the rear brake in front of the seat stays for this very reason and has been doing it for over 20 years. Give him a call and he'll tell you why: http://www.hhracinggroup.com/page6.html Talk to any frame builder or any engineer at Shimano or Campy or SRAM and they will all tell you this. Most good mechanics know this too. Here's the deal, you work up a free body force diagram and post it, and I'll get on the horn and talk to Campy. I'll spare your other little Mr. Softy - you don't even have to plug in numbers, just show the arrows for the force vectors. Why can't you just envision it - this is not a hard test.....Call Harry and ask him: http://www.hhracinggroup.com/page6.html The mounting bolt will bent toward the wheel when it's mounted on the rear of the stay and bend away from the tire when it's mounted on the front of the stay. Again with the loose terminology - it's deflecting, and the amount is truly miniscule. Correct, except in your front brake, most of the force is transfered into the frame which is for the most part an immovable object. On the rear brake, the brake caliper is being pulled into the air away from the frame. That doesn't matter as long as it doesn't get pulled off the frame. It's still transferring the force to the frame. Correct. But remember what we're arguing here....I'm only saying the front brake is a more STABLE design and can take higher loads before it fails. The rear brake is a less stable design (due to where it's mounted) and will fail earlier and offer less stability under maximum load. Your rear brake will not feel as tight as your front brake if you do a max brake effort from 55 mph going downhill. It matters more in tandems where the brakes must take double the normal load over along period of time. And it's also more important for heavy riders, especially if they go down major descents and need to stop fast. Another Liz Hatch slam? Brake bolts are sufficiently large diameter (M6) that they don't bend significantly in normal use. This is good, because if your brake bolt bends repeatedly when you apply the brakes normally, it will eventually fail from metal fatigue, and then you will be up monkey **** creek. Bent brake bolts happen, but mostly from poor maintenance, like beater bikes that people ride around with the bolt loose and sticking out so there's a bigger lever arm on it. Fortunately people who ride these bikes (undergrads, DUI guys etc) rarely go fast enough to do full on panic stops and snap the bolt. (snip MG drivel) If you have a problem with braking like this, that isn't going to help, because if you brake enough to plastically bend the bolt, let alone pull it away from the frame, you're in trouble. What you need in those circumstances, and what some tandem riders use, is a third brake (rear drum). Only a faggot would ride a bike with a drum brake on it. Magilla |
#144
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Bicycle Stopping Distances
thirty-six wrote:
On 8 Nov, 02:42, MagillaGorilla wrote: " wrote: On Nov 7, 6:44*am, MagillaGorilla wrote: Correct, but when it's pulling away from the stays, the only thing keeping it there is the mounting bolt. * All the stress of the braking is transfered through the mounting bolt and nut. The bolt itself bends and is not inelastic. And the hold that the bolt goes through is not perfectly flush with the bolt. *But on the front brake, the entire brake caliper assembly is being forced into the frame which is for the most part immovable and thus gives better stability. Talk to any frame builder or any engineer at Shimano or Campy or SRAM and they will all tell you this. * Most good mechanics know this too. The mounting bolt will bent toward the wheel when it's mounted on the rear of the stay and bend away from the tire when it's mounted on the front of the stay. Correct, except in your front brake, most of the force is transfered into the frame which is for the most part an immovable object. *On the rear brake, the brake caliper is being pulled into the air away from the frame. That doesn't matter as long as it doesn't get pulled off the frame. *It's still transferring the force to the frame. No, it does matter. *The front brake transfer most of its force to the face of the FORK that mates with the calipers. *The rear brake, the forces are transferred only to the nut threads and the end of the bolt that holds the brake calipers. *The front brake has more lateral stability because the brake caliper is being pressed super-hard against the frame whereas the rear brake is being pulled away from the frame and held onto the bike only by the threads on the nut. *The caliper moves less on the front brake under maximum load. *The rear brake design can't away with it because the loads are less than on the front brake by a factor of 3 and the rear brake design - even with the mounting deficiency - is still sufficient to lock up the wheel. *But the front brake...it is essential that it is mounted to the front of the fork. If you could somehow mount your front brake to the rear of your fork, and then did maximum braking on a 55 mph descent, you would eventually see some catastrophic front brake failures in the peloton over the course f a few years unless gruppos companies beefed up the mounting bolts. Brake bolts are sufficiently large diameter (M6) that they don't bend significantly in normal use. *This is good, because if *your brake bolt bends repeatedly when you apply the brakes normally, it will eventually fail from metal fatigue, and then you will be up monkey **** creek. The rear bolt is under 3x less load than the front bolt during a maximum braking effort at high speed. *So this is why the M6 can take the beating and keep on ticking. *However, if you put that same load on the front brake which is subject to 3x the load of the rear brake, you would eventually see bolt failures. *But because most of the load on the front brake is transferred to the FORK, the bolt is spared the beating it would get had the front brake been mounted to the rear of the fork as the rear brake is mounted to the seat stays. Bent brake bolts happen, but mostly from poor maintenance, like beater bikes that people ride around with the bolt loose and sticking out so there's a bigger lever arm on it. *Fortunately people who ride these bikes (undergrads, DUI guys etc) rarely go fast enough to do full on panic stops and snap the bolt. If you are a 250 pound rider (or a tandem bike) and routeinly go down 55 mph descents and need to stop, you would want your rear brake mounted opposite of where it normally is. If you have a problem with braking like this, that isn't going to help, because if you brake enough to plastically bend the bolt, let alone pull it away from the frame, you're in trouble. What you need in those circumstances, and what some tandem riders use, is a third brake (rear drum). Ben Always use a superior design and technique. *Never accept less than the best. Magilla You are wrong. Bending of sidepull mounting bolt is due to torque upon the caliper arms caused from the drag of the brake pads upon the rotating rim. If the bolt is made tight enough, this bending strain does not take place. Envision it this way....if you mounted the front brake on the rear side of the fork (like the Cervelo TT bike)...under maximum load (say 250 lb rider, 55 mph descent, maximum braking effort to avoid a guardrail)..the brake would be pulled away from the frame by a fraction of an inch, creating lateral instability. If mounted on the front of the FORK, the calipers would not move at all because a large surface area would be pressing against the fork , which is basically immovable. Over a long period of time, the Cervelo TT design is putting more stress on your parts than the front-of-fork design. Since bike parts are made to trade best design for weight, you can use lighter weight bolt with the front design and still have it be more stable than a heavier bolt in a rear-mount. If you are telling me the bolt can take 3x the load when mounted on the rear of the fork, then you are also admitting that you pushing the envelope of failure EARLIER. Any design that puts less load on the parts is considered a better design. And you can in fact design a bolt that is lighter and offers more of a safety envelope simply by mounting the calipers of front brake on the FRONT of the fork. Engineers take things like durability, mean time to failure, and fail-safe loads into consideration. Your mistake is you are claiming simply because the brake "will work" regardless of where it's mounted it is mounted (you are correct) is an equally good design (you are wrong). You are wrong because any engineer will tell you that you are not looking at all the variables that must be assessed in component designs: - mean time to failure would increase if mounted on the rear of FORK, thus a heavier bolt must be used than if mounted on the front - less lateral stability if mounted on rear of fork under high loads - in rear fork mounted brakes, bolt would have to be made heavier to endure the same loads that a bolt would be subjected to if the calipers were mounted on the front of the fork, thus the part is heavier and not safer. A rear mounted brake on the fork would fare poorer in those 3 above categories (weight, stability, and mean time to failure) than those same calipers had they been mounted on the front of the fork. See what I'm saying? And as a result of that, you can make the bolt of a front mounted brake LIGHTER while still having an even greater safety envelope (and longer mean time to failure) than if you used a heavier bolt and mounted the calipers on the rear. Your design concept fails to take into consideration the things that are very important to engineers who make high end gruppos and are always trying to push the envelope with weight vs. safety/durability. Magilla Magilla |
#145
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Bicycle Stopping Distances
RicodJour wrote: On Nov 7, 10:02*pm, thirty-six wrote: Bending of sidepull mounting bolt is due to torque upon the caliper arms caused from the drag of the brake pads upon the rotating rim. *If the bolt is made tight enough, this bending strain does not take place. That is not strictly true. If you model the break bolt as a cantilevered beam, the bolt tightness is analogous to post tensioning...partial post tensioning. The tightness of the bolt will affect the deflection, and the bolt between the mounting contact points will deflect. The deflection with a properly tightened bolt is totally negligible and could never be a factor by the time you lock up the wheel. More to the point Maxipadilla has no idea what he is talking about, and, if he in fact has had conversations with bike engineers on the topic, he had no idea what they were talking about. That much is clear. R Dude, It's you who don't know what you are talking about. Magilla |
#146
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Bicycle Stopping Distances
" wrote: On Nov 7, 7:42*pm, MagillaGorilla wrote: No, it does matter. *The front brake transfer most of its force to the face of the FORK that mates with the calipers. *The rear brake, the forces are transferred only to the nut threads and the end of the bolt that holds the brake calipers. *The front brake has more lateral stability because the brake caliper is being pressed super-hard against the frame whereas the rear brake is being pulled away from the frame and held onto the bike only by the threads on the nut. *The caliper moves less on the front brake under maximum load. *The rear brake design can't away with it because the loads are less than on the front brake by a factor of 3 and the rear brake design - even with the mounting deficiency - is still sufficient to lock up the wheel. *But the front brake...it is essential that it is mounted to the front of the fork. ENGLISH PLEASE. Where does the force go after it's transferred to the rear brake bolt and nut? It doesn't magically leak out into the air before being transferred to the seat stay brake bridge. The nut is plenty strong enough. If those nuts weren't strong enough, front brakes would come flying off of forks all the time. In fact, this reminds me that you have it backwards. The front brake bolt is under tension and is held on by the nut, while the rear brake is compressed against the seat stays. You can argue all you want about whether bolts and nuts are stronger in compression or tension, I don't care, as both are clearly strong enough in use. I don't even remember why you started this pointless argument about brakes, and you don't remember enough to be consistent in the arguments you're making. Ben Shut up you idiot. Magilla |
#147
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Bicycle Stopping Distances
RicodJour wrote:
On Nov 8, 4:12*am, " wrote: On Nov 7, 7:42*pm, MagillaGorilla wrote: No, it does matter. *The front brake transfer most of its force to the face of the FORK that mates with the calipers. *The rear brake, the forces are transferred only to the nut threads and the end of the bolt that holds the brake calipers. *The front brake has more lateral stability because the brake caliper is being pressed super-hard against the frame whereas the rear brake is being pulled away from the frame and held onto the bike only by the threads on the nut. *The caliper moves less on the front brake under maximum load. *The rear brake design can't away with it because the loads are less than on the front brake by a factor of 3 and the rear brake design - even with the mounting deficiency - is still sufficient to lock up the wheel. *But the front brake...it is essential that it is mounted to the front of the fork. ENGLISH PLEASE. Where does the force go after it's transferred to the rear brake bolt and nut? *It doesn't magically leak out into the air before being transferred to the seat stay brake bridge. The nut is plenty strong enough. *If those nuts weren't strong enough, front brakes would come flying off of forks all the time. *In fact, this reminds me that you have it backwards. *The front brake bolt is under tension and is held on by the nut, while the rear brake is compressed against the seat stays. You can argue all you want about whether bolts and nuts are stronger in compression or tension, I don't care, as both are clearly strong enough in use. I don't even remember why you started this pointless argument about brakes, and you don't remember enough to be consistent in the arguments you're making. I'm suprised Myra didn't convince you with "The front brake has more lateral stability because the brake caliper is being pressed super- hard against the frame". Can't you read?! SUPER-hard!* R * The ball is lobbed high in the air, and... You need to wash out your Fleshlight, pal. Tom Kunich |
#148
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Bicycle Stopping Distances
On 9 Nov, 21:50, MagillaGorilla wrote:
thirty-six wrote: On 8 Nov, 02:25, MagillaGorilla wrote: Use Phil grease, not oil. I use a combination of cacium grease which is loaded when the need arises with cycle oil. *Works well. *Saves having to dissasemble each year. *I think its ten years(at least) since taking apart my bottom bracket. *Still running sweet. Don't make mistakes. *That what Lance tells his mechanic. *You need to treat yourself like Lance's treats his mechnic and you'll be fine. *Don't be a pussy. The quicker I can perform a service item the more reliable it's going to be. *I'm always looking for shortcuts. *Fewer steps reduce the likelyhood of tripping up. You sound like a mechanic who works for Alaska Airlines in 2000. *Let me give some advice...if the directions that came with the part tells you to lube the jackscrew every 2,000 hours, lube the ****ing jackscrew. *Don't give me any of this jazz about how many steps there are. *Just do it. Never seen any manufacturers brake servicing instructions. I have enough experience to know how long the lubricants I install remain effective. The checks I make, guarantee that aghh bollox |
#149
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Bicycle Stopping Distances
z wrote:
MagillaGorilla wrote: RicodJour wrote: On Nov 7, 4:28 pm, " wrote: On Nov 7, 6:44 am, MagillaGorilla wrote: Correct, but when it's pulling away from the stays, the only thing keeping it there is the mounting bolt. All the stress of the braking is transfered through the mounting bolt and nut. The bolt itself bends and is not inelastic. And the hold that the bolt goes through is not perfectly flush with the bolt. But on the front brake, the entire brake caliper assembly is being forced into the frame which is for the most part immovable and thus gives better stability. I get a ****ing headache every time I read that. I don't have my stupid-to-English translator engaged, so tell me this, Batbuoy, are you arguing that a loose brake bolt is what makes the difference? If not, and the braking force is the same, as it must be, and all braking force is transmitted to the frame, as it must be, where does this extra braking force come from? The bolt, submitted to the same force in either mounting position, will deflect the same amount as the difference in geometry is negligible. Much like your argument. No no no no. The front brake transfers most of the force through the mating surface of the caliper to the FORK. The front bolt transfers probably 30% of the force. On the rear brake, the bolt transfers nearly 100% of the force. It is true that all the force is ultimately absorbed by the frame. But the design of the front bake via its placement on the front of the FORK makes it a more stable design under high loads and high speeds. Ask any frame builder/engineer. Harry Havnoonian is a frame builder AND mechanical engineer (degree from Drexel). He mounts the rear brake in front of the seat stays for this very reason and has been doing it for over 20 years. Give him a call and he'll tell you why: http://www.hhracinggroup.com/page6.html Talk to any frame builder or any engineer at Shimano or Campy or SRAM and they will all tell you this. Most good mechanics know this too. Here's the deal, you work up a free body force diagram and post it, and I'll get on the horn and talk to Campy. I'll spare your other little Mr. Softy - you don't even have to plug in numbers, just show the arrows for the force vectors. Why can't you just envision it - this is not a hard test.....Call Harry and ask him: http://www.hhracinggroup.com/page6.html The mounting bolt will bent toward the wheel when it's mounted on the rear of the stay and bend away from the tire when it's mounted on the front of the stay. Again with the loose terminology - it's deflecting, and the amount is truly miniscule. Correct, except in your front brake, most of the force is transfered into the frame which is for the most part an immovable object. On the rear brake, the brake caliper is being pulled into the air away from the frame. That doesn't matter as long as it doesn't get pulled off the frame. It's still transferring the force to the frame. Correct. But remember what we're arguing here....I'm only saying the front brake is a more STABLE design and can take higher loads before it fails. The rear brake is a less stable design (due to where it's mounted) and will fail earlier and offer less stability under maximum load. Your rear brake will not feel as tight as your front brake if you do a max brake effort from 55 mph going downhill. It matters more in tandems where the brakes must take double the normal load over along period of time. And it's also more important for heavy riders, especially if they go down major descents and need to stop fast. Another Liz Hatch slam? Nice. Take that, Lizard. Magilla |
#150
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Bicycle Stopping Distances
On Nov 9, 3:18*pm, MagillaGorilla wrote:
RicodJour wrote: On Nov 7, 4:28*pm, " wrote: On Nov 7, 6:44*am, MagillaGorilla wrote: Correct, but when it's pulling away from the stays, the only thing keeping it there is the mounting bolt. * All the stress of the braking is transfered through the mounting bolt and nut. The bolt itself bends and is not inelastic. And the hold that the bolt goes through is not perfectly flush with the bolt. *But on the front brake, the entire brake caliper assembly is being forced into the frame which is for the most part immovable and thus gives better stability. I get a ****ing headache every time I read that. *I don't have my stupid-to-English translator engaged, so tell me this, Batbuoy, are you arguing that a loose brake bolt is what makes the difference? If not, and the braking force is the same, as it must be, and all braking force is transmitted to the frame, as it must be, where does this extra braking force come from? *The bolt, submitted to the same force in either mounting position, will deflect the same amount as the difference in geometry is negligible. *Much like your argument. No no no no. *The front brake transfers most of the force through the mating surface of the caliper to the FORK. *The front bolt transfers probably 30% of the force. *On the rear brake, the bolt transfers nearly 100% of the force. *It is true that all the force is ultimately absorbed by the frame. *But the design of the front bake via its placement on the front of the FORK makes it a more stable design under high loads and high speeds. *Ask any frame builder/engineer. Harry Havnoonian is a frame builder AND mechanical engineer (degree from Drexel). *He mounts the rear brake in front of the seat stays for this very reason and has been doing it for over 20 years. *Give him a call and he'll tell you why: http://www.hhracinggroup.com/page6.html Jesus Christballs. When a bike moves FORWARD the top of the rim is moving FORWARD and when you brake, the frictional force of the rim on the brake tries to pull the brake FORWARD. You appear to be pedaling your monkey-bike BACKWARD. Are you a fixed gear hipster, or worse yet, a trackie? What do trackies know about brakes anyway? The front brake is pulling on the bolt - the entire force is on the bolt. The rear brake when conventionally mounted is pushed against the seatstay by the braking force. I could see making some kind of argument that turning the brake around would load the structure of the brake in tension and reduce brake squeal, but with modern road brake arms that don't flex much (not skinny old inferior Campy competitors from the 60s) and proper brake pad toe-in, this is not an issue. Ben |
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