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#111
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Tips on carbon fiber WSD bikes?
On 1/4/2011 6:48 PM, Peter Cole wrote:
On 1/4/2011 4:34 PM, Duane Hébert wrote: On 1/4/2011 4:25 PM, Michael Press wrote: In , wrote: Michael Press wrote: In , Duane wrote: On 1/3/2011 3:45 PM, Chalo wrote: Duane Hébert wrote: Jay Beattie wrote: In contrast, I can buy a box of 525 tubing and braze it up in adult ed metal shop -- and since I am not like you and do not work in a shop, that is where I go to fix my steel frames. Jay, are you replying to me or to Chalo? I suspect that he works in a shop but I'm certain that I don'tg Hey, maybe you should consider it! "Vélocipèdes Artisanales par Maître Douain Hébert." Sounds expensive. LOL. But I'm afraid that if it doesn't start with int main() { I'm going to be lost. I am positive you meant to write int main(void) { If std C, more likely int main(int argc, char **argv) Note that the opening '{' is on the next line. But if C++? Well, why bother. C is the one true programming language. Use assembly only in extreme cases. Yes, in fact, I put the opening brace on the next line; but that is another kettle of worms. Yep. We have 5 SEs in my group and we had problems arriving at a consensus. It's not just whether it's on the next line but how many spaces to indent. Seems like we should have better things to waste our time on. Ugh. I went to interpreted, dynamically typed languages decades ago and never looked back. What type of applications do you develop for? |
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#112
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Tips on carbon fiber WSD bikes?
On 1/4/2011 6:43 PM, Peter Cole wrote:
On 1/4/2011 3:46 PM, Duane Hébert wrote: On 1/4/2011 3:30 PM, landotter wrote: On Jan 4, 2:21 pm, Duane wrote: On 1/4/2011 3:09 PM, Chalo wrote: Those frames seem a lot less flimsy and flexible when they are equipped with stiff wheels, stems, and cranks. I like the steel frames precisely because of the thin tubes. Cannondale is probably one of the reasons that I don't like aluminum. I had one around 20 years ago with the fat tubes. I was coming down a mountain side in New Hampshire and I hit a pebble or something. The frame started doing this harmonic hum that went through the fillings in my teeth. Pretty scary at 60k/h. I don't really care what sound pebbles make when they hit my down tube. Thak, pinnnnng, or ponk. Whatever. No, it wasn't the pebble hitting the frame that bothered me. It's the frame that started "humming" - high frequency vibration. I have a couple of lugged steel, a couple of welded steel, and a couple Cannondales. The Cannondales seem much more stable at high speeds. I'll ride no hands at 60 kph. The Cannondale wasn't unstable although it was a bit jarring of a ride. |
#113
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Stiff Wheels
On Jan 4, 11:56*pm, Chalo wrote:
Jay Beattie wrote: James wrote: When I made the swap from Ultegra Hubs, 28 spoke front and rear CXP30s to 32 spoke OpenPro on Mavic hubs, same tyres, same pressure (as near as my floor pump can be used), the OpenPro wheels _felt_ like they rode bumps around corners with less jitter across the road. You must have Princess and the Pea sensibilities. *I switch between Open Pros and Aeroheads and old MA2s and Open 4CDs and can't tell the difference when using the same tire. * He did specify that the difference was noticeable when cornering on bumps, which is a time when the wheels are loaded out of plane and thus a time when a less-stiff wheel would flex more. *Whether this effect could be noticeable in the context of other flex in the system (and particularly in the context deflection in the tires) is outside my experience, but it isn't completely out of the question. *Road bike wheels are pretty wimpy. Yah, and I'm not saying it can't be felt, and maybe if I dabbled in the pre-fab wheel market, I could feel the difference, too. As it stands now, I have a basement full of post-fab wheels that will have to wear out or break before I start dropping money on new technology. -- Jay Beattie. |
#114
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Stiff Wheels
On Jan 4, 8:52*pm, wrote:
It doesn't need to be exceptionally low because the rim distributed spoke stiffness circumferentially if it isn't terminally radially flexible, and fails to transfer the stiffness of spokes around the rim. Really? "Exceptionally low?" Are you sure it wasn't "exceptionally exceptionally low?" Please leave the fluff out of your writing. People who use such modifiers are generally trying to use bluff and bluster to cover their lack of understanding. At least that's what a "friend of mine" once told me. |
#115
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Tips on carbon fiber WSD bikes?
SMS wrote:
Apparently a lot of people make the same mistake regarding rolling resistance. Sheldon goes into it on his web site. The key thing to remember is that you must look at rolling resistance at the pressure appropriate for each tire, and the narrower tires are intended to be inflated to a higher pressure. There's no free lunch here. As you point out, if you under-inflate the narrower tire buy inflating it to the same pressure as the wider tire then the narrower tire will ride less harshly than the wider tire. Yeah, a 700x47c tire inflated to its maximum pressure of 58 psi will have less rolling resistance than an 145 psi 700x23c tire inflated to 58 psi. Actually the 700x23c tire may just fall off the rim, while cornering, at 58 psi, which would be _really_ uncomfortable! In turn, you are ignoring two things: 1) the nice soft ride of an underinflated narrow tire can't be exploited on normal riding surfaces, because the available travel is so short that the rim would get damaged if you tried to ride it that way; and 2) The only rolling resistance you are considering is rubber losses (the resistance you can measure with a smooth drum). There is also rolling resistance incurred when transmitting bumps and vibration to the bike and rider because the tire's suspension was inadequate to absorb and restore them. That can amount to much greater energy loss, and it's the kind of rolling resistance that made pneumatic tire bikes instant race winners from the moment the first crude pneumatics hit the market. Just like Euro racers win races with fatter tires when the racecourse includes stretches of cobbles, those of us who ride on normal non- groomed streets are faster on tires that are fatter than currently fashionable for road bikes. It's not even clear what that size might be, because most current go-fast bikes can't accommodate a tire larger than 28mm, and thus tires of thinnest low-loss construction top out at that size. Chalo |
#116
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Tips on carbon fiber WSD bikes?
On 1/5/2011 8:56 AM, Chalo wrote:
Just like Euro racers win races with fatter tires when the racecourse includes stretches of cobbles, those of us who ride on normal non- groomed streets are faster on tires that are fatter than currently fashionable for road bikes. It's not even clear what that size might be, because most current go-fast bikes can't accommodate a tire larger than 28mm, and thus tires of thinnest low-loss construction top out at that size. There's no debate that a wider, lower pressure, tire often ends up resulting in being able to be faster overall. But it's a mistake to say that a wider tire has less rolling resistance than a narrower tire when both are inflated to the proper pressure. If rolling resistance went down as width went up, we could all get those Surly Large Marge wheels with 3.7" Endomorph tires pumped up to 28 psi, and have our rolling resistance approaching zero If you're trying to persuade someone that a narrower tire is not necessarily a better choice for them, it's probably best to deal with facts, and explain the real reasons that they would be happier with a 700x28 or 700x32 tire than a 700x23. Alas so few bicycle buyers look at the big picture when they choose a bicycle, I don't know how much success any of us would have in convincing someone that ensuring that the frame and brakes can accommodate 32mm tires is an important consideration. As Grant Peterson writes on this subject, "Logic always loses arguments with emotion!" http://www.rivbike.com/article/bicycle_making/the_big_picture. If people used logic when choosing a bicycle, we'd have no compact frames, handlebar heights would be higher, and we'd have no carbon fiber frames, which would be devastating to the entire industry. |
#117
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Stiff Wheels
Jim Rogers wrote:
On Jan 4, 8:52 pm, wrote: It doesn't need to be exceptionally low because the rim distributed spoke stiffness circumferentially if it isn't terminally radially flexible, and fails to transfer the stiffness of spokes around the rim. Really? "Exceptionally low?" Are you sure it wasn't "exceptionally exceptionally low?" Please leave the fluff out of your writing. People who use such modifiers are generally trying to use bluff and bluster to cover their lack of understanding. At least that's what a "friend of mine" once told me. LOL. JS. |
#118
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Tips on carbon fiber WSD bikes?
On Jan 5, 5:35*am, Tºm Shermªn™ °_° ""twshermanREMOVE\"@THI
$southslope.net" wrote: On 1/4/2011 8:49 AM, SMS aka Steven M. Scharf wrote: [...] Understandably, the whole marketing push for carbon fiber bicycles carefully avoids calling the tubing material by its real name, or acronym, carbon fiber reinforced plastic, or CFRP. No one wants to use the P word. Scharf should know that CFRP stands for Carbon Fiber Reinforced Polymer. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *^^^^^^^ "Plastic" refers to unrecoverable deformation. Yeah, like shatters. -- T m Sherm n - 42.435731,-83.985007 I am a vehicular cyclist. |
#119
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Stiff Wheels
On Jan 5, 5:46*am, Tºm Shermªn™ °_° ""twshermanREMOVE\"@THI
$southslope.net" wrote: On 1/4/2011 4:04 PM, Jay Beattie wrote: * [...] The first link is lateral stiffness. *The second link does talk about frontal/radial stiffness and makes me wonder why anyone would buy a wheel with spoke tension so low that it would allow rim deformation under normal load[...] Uh, because they live on Planet Trevor? -- T m Sherm n - 42.435731,-83.985007 I am a vehicular cyclist. Very true, where as you can use disc wheels, so comfy eh? |
#120
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Tips on carbon fiber WSD bikes?
Lou Holtman wrote:
I wouldn't demand that a road bike fit 32s, like mine does, but if it fits 28s or 25s with fenders, it gives you options for free. Why not? There are times of the year when 32s are really nice to be able to install, and times when the lower rolling resistance of the narrower 23s is desirable. 23-32 is not an unreasonable range to insist upon for a road bike. Scharf should realize that for a given casing construction, tread, and inflation pressure, a wider tire has *less* rolling resistance. and you should know that in that case the narrower tire is more comfortable. I think you might review what keeps the tire from bottoming when inflated. I think that is often overlooked in such discussions. FAQ item: Subject: 8b.25 What holds the rim off the ground? From: Jobst Brandt # What forces keep the rim of a wheel with pneumatic tires off the # ground. It obviously can't be the air pressure because that's acting # from top as well as from below. # As has been pointed out, the casing walls pull on the rim (or its # equivalent) and thereby support the load. The casing leaves the rim # at about a 45 degree angle, and being essentially a circular cross # section, it is in contact with the rim over its inner quarter # circle. At least this is a good representative model. The # visualization may be simpler if a tubular tire is considered. It # makes no difference whether the tire is held on by glue or is # otherwise attaches to the rim such as a clincher is. Either way the # tire is attached to the rim, a relatively rigid structure. -- Jobst Brandt |
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