|Zipp 404's and acceleration||lithiapark|
Nov 26, 2003 10:38 PM
|The discussion of acceleration differences between common sturdy box section wheels and lightweight aerodynamic wheels is to me quite interesting. I thought I would start a new thread and see if anyone else was interested. My apologies for any and all offensive and irrelevant to bicycling content from my recent posts. Can we start over?
From John Cobbs Bicycle Sports website he states:
"for group#1(std rims:-Heliums-Arrowheads-Box type rims) its aabout 35 watts to spin the front wheel down the road at 25 mph of apparent wind"
"Group #3 (Carbon V rims:-Zipps-Hed Jet/Aero/J2/Stingers-Corima-Hed3-Nimble-Mavic Carbone-etc)it is about 15 watts"
The difference of 20 watts for the front wheel alone is not an insignificant amount for a non-racer like me. If I were lucky I could maybe manage 400 watts for a few seconds after I'm an hour into a ride. The 20 watts could be calculated into a force at a given speed, and that would be 5% more force available for acceleration rather than just maintaining speed. Some of my friends might suggest I'm only capable of a 200 watt sprint, and in that case the 20 watts would be 10% of maximal power I could produce. Now suppose I was riding with my friends with my box rim wheels at my maximum 200 watts. If, by magic, I suddenly had on my Zipps, I would only need 180 watts to maintain the speed I had achieved. I would have 20 watts in hand to counter their viscious attacks. Now you can play around with the numbers a lot and possibly conclude that at the most you could save 5% of your power by using aerodynamic wheels. Another fellow, Jim Martin, writing on the Cervelo website, states that "aero wheels can reduce drag by about 0.4lb." Since total drag at 30mph (yeah I know, only in my dreams) is 5-7 lb. he is suggesting a 6-8% savings in power needed to overcome bike/rider aerodynamic drag as well, just by using aero rims.
For this discussion I have ignored the differences in the tire/rim weight between the wheels or the overall weight of the wheels, but, although these benefits to acceleration are small, the effect is in favor of the more aero/lighter wheels.
At question seemed to be whether or not a person could actually percieve the difference in wheels when riding in different situations. I would state that it is perceptable. The human body is pretty good at detecting differences, but admittedly poor at judging absolutes. Has anyone ever been riding along on a road that looked flat and "felt" the very slight incline you couldn't see, or the effort needed to overcome a very slightly different angle of gentle wind as you round a corner? Do these humanly detectable differences fall within the technically measurable difference of aerodynamic drag offered by wheels like the Zipp 404's/Hed Alps/Hed3's? I believe they easily do, based on personal observation and studies of what the human body is capable of detecting.
Anyway, I believe you need to look at much more than tire/rim weight of wheels to predict or explain how they are going to feel on the road. Overall weight and aerodynamic drag are important, particularly to the less powerful among us. To those of you who can generate 1500 watts in a sprint or more, it is less important. But I would choose your legs over aero wheels if I could.
I'd like to learn what others think about this topic. You all know I'm not an engineer or a physicist, so be gentle in your critic of my analysis if you can.
|re: Zipp 404's and acceleration||altidude|
Nov 27, 2003 4:16 AM
|When you start averaging 25-30mph in your speed on your group rides then you can talk to me about John Cobb and your Zipp 404's. If you honestly think for one minute you're deriving some meaningful benefit riding Zipp 404's in a non all out TT situation as a non-racing recreational rider (what's your typical average speed on a usual group ride 18-20 mph's maybe??) you keep believing that fantasy. The truth is you are not riding anywhere within lightyears of being fast enough to be deriving big wattage benefits from aero wheels other than perhaps a very flat , all out TT type situation, and even then you better be moving pretyy fast for those wheels to makje any real difference in your speed. At the speed I'm guessing your typically riding at on your grpoup rides, your kidding yourself if you think you're somehow anywhere near 5-8% faster or you're getting some big wattage benefit or whatever those silly numbers were you quoted because of Zipp 404's. You've had a serious overdose of placebo affect of the mind.
Cobbs basic numbers you quoted are flawed first of all in the context you presented them in because they ignore the affects of crosswinds, especially as they pertain to deep dish aero type wheels. Sure in a wind tunnel with perfect aeroflow you can generate some numbers, but that hardly equates to real world cycling unless you know of some route to ride on in Oregon where the wind is always hitting you at zero yaw angle. How many watts are lost with deep dish aero wheels by reacreational riders when you are not riding fast enough to take advantage of lift affects, but your deep dish wheel is getting hit by crosswinds and now you're struggling to maintain a straight course? And please tell me all of these recrational riders you know who are consistently riding at 25-30 mph speeds on group rides a good deal of the time? If they are consistently riding at those speeds on group rides I should be able to turn on OLN and see every one of them on TV racing in Europe in the peleton. But I'll bet I don't see even one of them and guess why? BECAUSE THEY ARE NOT RIDING THAT FAST ON AVERAGE!
As far as weight savings is concerned if you seriously think cutting a half a pound or so off your wheels is making you SOMEHOW climb hills loads faster, making your cadence go up for a given gearing, MAKING IT SUBSTANTIALLY EASIER TO ASCEND A HILL , whatever, I sugGest you open up a Websters dictionary and stare at the word PLACEBO and memorize it like all the other 18-20 mph riding fools in here who bellow on and on about how their aero wheels make them so much faster. You guys are so disjointed from reality with your obsessive equipment purchases I seriously think after a while you actually believe your own drivel and really do think your somehow meaningfully faster because you just dropped $1300 on a wheelset your not even truly able to ride fast enough to to benefit meaningfully from. BUT I JUST DROPPED $1300 ON WHEELS, I HAVE TO BE FASTER DON'T I?
Perhaps another 16 years of post HS education on the subject will help. I'm sure mommy and daddy will be happy to foot the bill. Have a nice Thanksgiving. Maybe the turkey and gravy will make your cadence increase going uphill too in a given gearing. LOL
|re: Zipp 404's and acceleration||asgelle|
Nov 27, 2003 6:13 AM
|That's a lot of attitude for someone who is wrong on almost every point. Most significantly, the slower the speed, the greater the impact of reducing aerodynamic drag. This can easily be calculated at www.analyticcycling.com but in brief, except for steep climbs most rider power goes into overcoming aero drag. At whatever speed the rider is maintaining, reducing drag will increase speed at the same power and since the slower rider has to ride longer, the effect of reduced drag comes over a longer period. Also, there is no magic speed at which the drag reduction takes place, aero wheels reduce drag at all speeds. Regarding crosswinds, deep dish wheels provide a greater reduction in drag as the yaw angle increases, again, at all speeds.
Why do you assert that there is no measurable reduction in drag in the 18-20 mph range when numerous studies, numerical and empirical have shown just the opposite to be true?
Read Kraig Willett, use analyticcyling.com, wisdom will come.
|Please explain your comment||Kerry Irons|
Nov 27, 2003 3:18 PM
|You say that "the slower the speed, the greater the impact of reducing aerodynamic drag." I think you mean that the slower the speed the harder it is to get a comparable reduction in drag. At 10 mph, aero drag consumes roughly 50% of your total power, so a 20% reduction in aero drag would give a 10% reduction in total power. At 30 mph, aero drag consumes 90% of your power, so a 20% reduction in aero drag gives an 18% reduction in total power. Add in the fact that at 10 mph, power reduction is only about 3 watts, whereas the 18% reduction at 30 mph is around 90 watts, I don't understand your statement.|
|I was considering time saved||asgelle|
Nov 28, 2003 8:02 AM
|I was referring to the time saved by reducing drag at constant power. To use your example and the default settings at analyticcycling.com, a rider moving at 10 mph on level ground requires 26.8W, the same rider going 30 mph needs 409W. Changing to an aero wheel reduces total drag by 2-3% (I used 2%). For the slower rider, if he keeps his power the same, his speed will increase to 10.045 mph, or keeping the 10 mph, the power drops to 26.6W. For the faster rider, base power is 409W, dropping to 401.6W or speed increasing to 30.20. So you are right that the magnitudes of the changes are greater for the faster rider changing to the aero wheel.
However, if we look at the time saved covering a fixed distance (say 10 mi) at constant power (rider needs to beat a thunderstorm home) the slower rider saves more time. In the base case, he needs an hour to cover 10 miles, reducing drag increases his speed to 10.045 mph and he gets home in 59.7366 min. saving 0.263 min or 16 sec. The faster rider increases his speed to 30.20 mph and drops his time from 20 min to 19.868 min saving .132 min or 8 sec. Of course, this is due to the fact that the slower rider is out there 3 times as long.
These numbers are small and wouldn't matter much to the rider trying to outrun the storm. For a racer, they may make the difference between winning and not making the podium. For a recreational rider or someone in a group ride, the difference is there though small. How important it is is up to the individual to decide.
|I was considering time saved||al0|
Nov 28, 2003 3:38 PM
|The slowest rider is a rider that rides at 0mph. How many time would he save on 10mi distance with aerowheels?
|NON-FREAK answer here:||Spunout|
Nov 27, 2003 4:30 AM
|Well, pushing 300 watts at 30mph is a good guess for me, and I would gladly save a few percent over a three hour race. I do not have scientific data to support this. Nor do I have strong bias against people with the desire to go this route like the previous poster.
What I do have, is a bit of experience punching a hole in the air at 30 mph dragging 100 wheelsuckers in order to reel in a break in a 100km road race. I attach picture as proof.
|NON-FREAK answer here:||altidude|
Nov 27, 2003 4:42 AM
|Oh boy a self professed non freak. Another internet holier than though idiot.
By the way genius, in his original post on another thread, he discussed how Zipp 404's helped him on group rides with friends. I'll say it again, if you had trouble comprehending that, group rides with friends! Not chasing breaks in a race at 30 mph! But you already knew that because you can read and didn't ASSUME, correct? How many guys do you know who are chasing breaks at 30 mph on group rides? LOL
|If only you had....||divve|
Nov 27, 2003 5:02 AM
|...carbon Ergopowers and Cosmic Carbone wheels you'd be in the break instead of having to real it in. Think about it....|
|re: Zipp 404's and acceleration||Troy16|
Nov 27, 2003 5:19 AM
|Most breaks are jumped over short stretches of time and distance. In these short chases, aero wheels are not important on being successful. Unless it is taking you 10-20 km's or more to bridge a gap the difference between aero wheels and conventional wheels is so small over short distances at all speeds it has no significance. You'll either be strong enough to bridge the gap or you won't, wheel choice is irrelevant over gap filling short distances.|
|that's a silly blanket statement, and not always true.||russw19|
Nov 27, 2003 9:54 PM
|No offence, but that may hold true in Cat 4 and 5 races, but I have tried to bridge a gap for over 6 miles in a race before. I finally managed to do it 28 miles into a 113 mile race. I was in the winning break as we put over 6 minutes on the field. If I hadn't chased that long, I would have been sprinting for 14th instead of 1st. I finished 5th in that race behind race winner Davis Phinney and runner up Roberto Gaggioli. Of course we all raced on standard wheels then, but my issue is with the "most breaks are over a short distance" statement.
|that's a silly blanket statement, and not always true.||altidude|
Nov 28, 2003 7:24 AM
|you actually don't think this entire thread is silly?
You got a recreational rider who seems to believe that somehow by dropping a 1/2 pound or 3/4's of a pound of his wheels, that somehow this will make him ascend climbs faster or with meaningful more ease? Or that a deep dish wheel is gonna make it meaningfully easier for him to pedal his bike faster on a group ride? If you believe either of those two things I just stated above you are as cookoo as he is. There is not even a single recreational rider on this board who is going to experience a meaningful change in either their bike speed, or pedalling ease in a given gearing by riding deep dish aero wheels in a group ride, srtage race situation. These wheels are timtrial and triathete tools and over extremely long distances they result in differences in time typically in seconds, not loads of minutes. Any guy that thinks he's gonna climb a hill with meaningfull more ease because he's just dropped $1300 on Zipp 404's needs his head seriously examined brain surgeaon or not, and the bike shop dealer pushing the product on him trying to convince him that it is somehow gonna make his rides meaningfully faster or easier is little more than a snake oil salesman pushing a high margin product on a fool which in the reality of road riding it means little to nothing to. LOL
|the only statement that is silly and moronic is yours!.||altidude|
Nov 28, 2003 7:39 AM
|Deep[ dish wheel do not make you ride open MPH faster and the mopst certainly do not make you ride anything near open MPH faster in a stage race with non aero handlebars in use. If you actually think an aero wheel is gonna be the difference between a rider bridging a short gap in a field you're a moron and I'd tell you that to your face if I saw you. Total and complete snake oil selling moron! you probably run some stupid bike shop and try to push this crap on your customers convincing them this stuff will actually somehow make their riding meaningfully faster or easier. What are you going to do next, go sell used lemon cars and tell them how they'll get 200K more miles out of the lemon.
An areo wheel is gonna make a difference in a riding bridging a short gap - ROTFLMAO, now I have heard it all. What a buch of mindless chimps. If any of you could ride even 1/10th as well as the bull sheit you spout and profess Armstrong would have no chance at #6 going up against you. As it is, you keep believeing that your 404's and other wheels make you so much faster. I'll just keep laughing watching most of the recreational fools riding thses wheels get dropped on ride after ride after race.............
|You really should read the posts before you rant about them||russw19|
Nov 28, 2003 1:30 PM
|This is the quote from the last line of my post that you seem to take issue with...
"[. . . ]my issue is with the 'most breaks are over a short distance' statement."
You seem to have some real jealousy issues that are pervasive in your posts. Are you 15 and just can't handle that some people have a better bike than you? That was my first impression from the first little tirade you went on about the guy and his Zipps. Zipps don't make you faster if you are a rec rider, but they may make you perceive you are faster. That may seem like an unimportant differentiation, but it's not. If you percieve you are faster because of your wheels, then you will be faster. It's the same reason that people on placebo drugs can get well when they are sick. If you percieve you are faster, then you will ride just a little harder to actually BE faster. That's where Zipp wheels have a place in this world. But for Joe Average to be riding them, I agree, I think it's silly, but I won't try to have a childish little 3rd grade tirade about some guy who has the money actually going out and buying them.
If you have something to prove to that guy, go ride with him and let your legs do the talking.
As for your little tirade in response to my post, what is your issue with it. I chased a break in a Pro 1-2 road race in Vero Beach for over 6 miles. My reason for telling that story wasn't to brag about how fast I am or was, I have the trophies to prove it. My reason for saying that was that someone mistakenly made a very simple statement that most breaks are only bridged if the distance is short. I have chased a break for 6 miles, and I am sure someone else has chased even longer than that. I did it on non-aero wheels, but that's not important because the point that I was making was that some gaps that are bridged are not short. If I had been alone in the wind for that long with aero wheels, would I have had more energy to try for a higher finish when the sprint came along... no. But that's only because the break happened early in the race. I had plenty of time to recover once I bridged the gap.
Now as for your reply to my post, what is your issue with it exactly? Is it because I am a former Cat 2 who happened to be in a position to challenge Davis Phinney for a sprint finish? He kicked my ass in the sprint and I didn't have any delusions of winning, but knew if I made that break it was staying ahead due to who was in it and I could sit in for a top 13 place in a $10,000 race. I paid my entire year's hotel fees for that season by chasing that 6 miles and I knew that's what was happening as I was chasing. They were the hardest 6 miles of my life, but I got paid a ton of money for those 6 hard miles.
And to answer your question, yes, I do think this entire thread is silly. It's silly that you have so much pent up anger for someone you have never met. Some guy who makes a ton of money and wants to spend it riding his bike goes out and gets a pair of Zipp wheels and you have to resort to acting like a spoiled little brat who didn't get the best christmas present on the block this year. If Paul (lithiapark) want's to spend his hard earned salary on a pair of Zipp wheels, who the hell are you to insult him like you are? You could tell him that any speed increase he achieves is most likely due to the placebo effect of those wheels, but you are way out of line with your spoiled child behavior. You really should change your screen name to Attitude as yours is really bad.
This is about cycling... the sport we all love, and the reason we are all here... not about who's johnson is bigger, but it seems that's what you want to make it about.
|Aerodynamic wheels in general||velonomad|
Nov 27, 2003 7:50 AM
|Aerodynamic wheels don't provide important benefits for group riders in a typical road bike riding position and especially don't for casual riders.
The differences in aerodynamics between wheels is very small compared to the aerodynamic forces created by a riders body position. As a riders body creates more drag forces, the very small differences in wheels becomes less and less important on a relative basis. Riding on a typical road setup, even when in the drops is much more anti aerodynamic than riding with aerobars during a timetrial for example. In this typical road bike position, your upper body is creating such great wind resistance forces, that these forces simply overwhelm the importance of tiny differences in the aerodynamics of wheels.
A good analogy would be an 18 wheel truck with a set of dropouts attached to its front bumper. Drive the truck down the road with a Lew wheel in the dropouts at a given horsepower and then drive the truck down the road with a 36 spoke Open pro wheel and you will see no meaningful difference in speeds between the trucks at a given horsepower output from the engine. This is because the forces of the truck overwhelm the very small differences of the wheels. The tiny differences of the wheels have become less relevant to the big picture.
The same thing happens when looking at aero wheels versus regular wheels when comparing a timetrialist versus a person riding a conventional road setup. The guy in the conventional road setup, even when he's in the drops is creating so much more air drag forces that the tiny benefits of aero wheels basically become inconsequential to his overall performance. Take into account additional factors like riding in a paceline, dirty air and the differences of aerodynamic wheels on a standard road bike setup or ride becomes even less important.
Most casual riders don't get even a moderate benefit to their performance from aerodynamic class wheels when riding on a conventiuonal road setup. The same applies to component weights and frame weights. Most casual riders simply are not climbing long enough hills for long enough period of time for small differences in weight to add up to anything of consequence.
I guess you could ride Zipp 404's if you want, but I don't see it allowing you to drop anyone you could not drop on a pair of Open Pro's. And I don't see it preventing a better rider from dropping you if they could drop you while you were riding a standard wheel.
I think the bike component manufacturers have done a wonderful job selling consumers on the false notion of performance advantages of aerodynamic wheels and losing component weight. In reality, these two variables have a tiny impact on performance in most road situations and are only of real consequence to extremely elite pro riders over very long races where the riders are separated by very small amounts. No components or wheel is gonna take someones riding to another level. That's just a marketing ploy to sell products to people who gain no important benefit from them.
Good topic, my answer would be very light performance and aero wheels are highly overated as to their performance benefits to 99.99% of the riders out there. Marketing is a wonderful thing.
|Aerodynamic wheels in general||altidude|
Nov 28, 2003 7:30 AM
|Amen brother. Someone who actually understands the realities of these products, not the bull sheit spoon fed to customers by crooked bike shops and manufacturers looking to push products upon idiots with the notion they will somehow make them ride loads faster or easier up a hill or flats with these wheels.|
|Aerodynamic wheels in general||ngl|
Nov 28, 2003 9:00 AM
|should change your name from altidude to attitude|
|Aerodynamic wheels in general||MShaw|
Dec 1, 2003 11:12 AM
|Have any of y'all that are pooh-poohing aero wheels ever ridden them? I mean RIDDEN them, not just around the parking lot!
I have a pair of 404s that I race at the track, and a pair of first gen Cosmics that I race on the road.
The thing that I've noticed over the years is that the faster you go, the more difference the wheels make. I can consistently ride one gear harder for the same effort on the aero wheels vs. my Reflex wheels. At 35+mph, it may mean the difference between staying in the pack (every Thurs at Fiesta Is. if you're wondering where I go 35+) and not.
Aero wheels aren't a magic bullet that will let you win races, it takes legs and brains for that. They may help you be a little fresher at the end of the race. Go check out www.anaylyticcycling.com to see the difference at the end of a straight between OP wheels and aero wheels. That few feet may make the difference between a podium and not on the right (wrong?) day.
That said, IMO, aero wheels are pretty well useless below 20mph or so. If you aren't riding above 20mph consistently, go buy something else with that $1000. A good coach is the first thing that comes to mind.
|re: Zipp 404's and acceleration||lithiapark|
Nov 27, 2003 8:53 AM
|I would agree that the performance benefits of more expensive bicycle components are not large and are of little importance in the grand scheme of the cosmos unless you plan on making money riding a bicycle, the value of which in a cosmic sense is also irrelevant. Whether or not I come last in a group ride or first is certainly irrelevant to me. If I'm riding by myself and it takes 3 hours or 5 hours for my favorite 50 mile ride is also irrevant to me. In both of these situations I've enjoyed myself. For that I am thankful.
The question for a recreational rider like me is whether or not I can feel a difference between wheels and if so is the extra cost worth it. Can I feel a difference in my performance if I reduce my aerodynamic drag by .4lb out of a total of 7lb, which is what the data available on the net suggest may be the benefit of aero wheels? I believe I can, particularly if I'm going up a good grade into a headwind. Is it important to anyone? Probably not. Is it worth the money? Only to me if I can afford it without sacrificing something that obviously is important. I refuse to by a suit that costs more than $200-300, because the $1000 suits don't feel any better and don't seem worth the extra money. I'd rather buy bicicyle parts:) Does anyone out there drive a car that cost more than $10,000 new? Sure. But they don't get to and from the grocery store with any greater certainty. Is it appropriate to buy a BMW if it means your kids can't go to college without having to work? Lots of possible correct answers here I think. While I'm riding my bike, very slowly at times, I have lots of opportunities to think about a lot of stuff which is unimportant but helps clear my head and keep me sane(I think).
Whatever floats your boat.
My family wants to go for a run so I'll talk to you all later.
|re: Zipp 404's and acceleration||altidude|
Nov 27, 2003 10:25 AM
|Please refrain from discussing the true realities of how little impact bike equipment has on rider performance. Most of the delusional wannabee pretenders in here have a difficult time dealing with both reality and their overpriced cycling components at the same time. You could base a great Psychology thesis upon all the delusions of compnent related riding enhancements discussed in here on a daily basis. If you don't get enough fill here, try hydromedia.com at the Serotta owners board. There you can listen to even more bs artists like bigmac, dman, mavic1010 and a slew of others babble on and on each day about how "their Otrott is so much stiffer thgan their Legend ti, it just explodes!" or " oh my Legend Ti is stiffer than a Cannondale, but it's soooo comfortable too."
Actually reading all the stuff is pretty comical, all these fantasies would probably make great material for an SNL skit.
Rember folks, if yuor engine can't get youy up that hill quickly or comfortably, go out and buy some Zipp 404's, you'll be transformed into Lance instantly riding at a different cadence, at a different speed, yada, yada, yada. LOL
|re: Zipp 404's and acceleration||rogue_CT1|
Nov 27, 2003 11:25 AM
|I can't tell any difference between my Ksyrium SL's and my Zipp 404's in any aspect of riding. There is no percieved difference in acceleration or aerodynamics. The only thing I noticed is that the K's seem stiffer and more durable which makes me more confident when I power out of the saddle. This confidence in the wheelset in turn makes me faster. That's why I am probably going to sell my 404's.
The only wheel that I notice an immediate difference is with the Hed H3. They are slow to spool up but they are require less effort to maintain a cruising speed. Combined with my full TT bike the difference is really noticable.
|re: Zipp 404's and acceleration||ngl|
Nov 27, 2003 12:46 PM
|Then why did you guys buy the 404s in the first place???
There are some real pissheads on this form who really like to pull down the other guy!
|re: Zipp 404's and acceleration||lithiapark|
Nov 27, 2003 1:16 PM
|From commercial websites and what others have posted about wheel weights, these figures are available:
404's: 1283gm, .191# aero drag
Mavic K's: 1570gm, .404# aero drag (actually a number for Heliums since the K's weren't in the test)
H3's: 1700gm, .168# aero drag
The weights are for tubular wheels.
If the same tires were mounted on all three, the H3's should take a little more effort to bring to speed. Some have suggested this is imperceptable. I don't know having never used them. Once at speed, the H3's should be the fastest, all other factors being equal, but there isn't much difference between them and the 404's. The 404's might have an advantage in an uphill time trial for competitive cyclists because they weigh less. It will be interesting to see which wheels the racers choose for the time trial up the Alpe d'Huez (I think I remember this correctly) in the '04 TdF.
What has seemed easily perceptable to me is the difference between going up a modest hill with 1283gm 404's with 195gm tubulars vs 1800gm+/- box rimmed wheels with 300gm tires. The 404/tire combination is about 700 gm lighter and may reduces my total aerodynamic drag 5%. The difference in the way it feels may not be worth $1000 to some and I can certainly understand that. Since I have more money than I need, most of what I spend could be considered silly, or a vice. The difference in the way it feels is worth it to me, otherwise I'd put slicks on my 28# mountain bike and sell my road bike:(
|re: Zipp 404's and acceleration||ngl|
Nov 27, 2003 2:03 PM
|I agree Paul. I've noticed the difference just by losing 300 grams of rotational weight. Some of us love the sport and we always strive to improve or go faster. It may be by purchasing new equipment... through training, or, a combination of both. Others have a hard time accepting this. Its like the Lance theory: they realy don't care who wins as long as Lance loses. A very negative outlook on life.|
|re: Zipp 404's and acceleration||asgelle|
Nov 27, 2003 7:54 PM
|And some strive to improve or go faster based on proven results and theories rather than one rider's perceptions and prejudices. It has been shown repeatedly that the effect of reducing rotational mass is virtually the same as reducing non-rotating mass (effect of rotational inertia O(0.00015). So you are saying you can tell the difference from 300 gm. Even if the combined weight of bike and rider was only 60 kg, this would be 1/2 of 1% in total mass. You are saying you can feel a difference of 0.005. I'm skeptical (to say the least). Perhaps we're seeing a placebo effect here.|
|re: Zipp 404's and acceleration||ngl|
Nov 28, 2003 12:37 PM
|Well Asgelle, next time I beat my long term riding buddy by 10 seconds up that same hill we have been climbing together for years, I'll just think of you ( and how wrong I am) not the 300 grams ROTATIONAL weight I saved the tires and tubes.
Oh, by the way, I've got my wife's permission already to purchase a new seat and seatpost. Do YOU MIND if I pick a light one?
|re: Zipp 404's and acceleration||asgelle|
Nov 28, 2003 1:37 PM
|Hey, you can buy whatever you like. I never said you couldn't. You can also believe whatever you want. But if you come here and try to pass off as facts things that are just not true, I'm going to call you on it.
As for the saddle, you can pick a light one if you want, but my opinion is that there's more benefit to choosing a comfortable saddle over one that saves a few grams. But that's my opinion.
|re: Zipp 404's and acceleration||ngl|
Nov 28, 2003 4:31 PM
|I guess it is only you and attitude who are on the wrong side of the fence.|
Nov 28, 2003 5:02 PM
|Given we have diametrically opposed views, I really don't understand this.
If you review what I've written, I've consistently said that using aero wheels reduces drag and increases speed. I've also indicated how the magnitude of the effect from reducing drag (or weight or rolling resistance) can be estimated. I've also shown estimates of the amount of time or power saved with aero wheels. I've never said whether these savings justified the cost as this is a personal decision for each individual.
|If you only rode more than you think ,it wouldn't matter. .(nm)||davidxy|
Nov 29, 2003 9:59 AM
|re: Zipp 404's and acceleration||satanas|
Dec 3, 2003 10:42 AM
|A number of points:
1. Unthinking gratuitous abuse is not helpful, and reflects poorly on those offering it!
2. Would people *please* stop quoting analyticcycling.com as if it was the first, last and only authority on this stuff? I believe there are problems with their analysis since they don't consider the way that power is applied to the bike...
3. Unless aero wheels are lighter *at the rim* there is a "threshold speed" below which they are a burden rather than an asset.
Don't believe me? Consider the fact that Lance and co have used Mavic Cosmic Carbone wheels on flat Tour stages due to the fact that reduced drag saves energy for later in the day, but switch to (lighter, less aero) Ksyriums for climbing stages. Why? Because they are faster under these conditions.
Many "light" wheels get there by using featherweight hubs and not many spokes, but often the rims are as heavy or heavier than an average rim such as an Open Pro. This is all very well on the flat, BUT things change when climbing.
Gravity acts to slow the bike and is resisted by the force of the "motor" (rider). Unfortunately, unlike a motor vehicle the bike motor rotates only very slowly, is poorly balanced and lacks a (high revving) flywheel to smooth out power delivery. As a result gravity has plenty of time to slow the bike between power pulses, even more so if the rider pedals at low rpms and/or has an inefficient pedal stroke. (This may partially explain why Lance's high rpm climbing style is so effective IMO.)
Every time the bike slows it must be re-accelerated, and this is made harder by heavier (at the periphery) wheels. For any heavy aero wheel, there is a speed above which the aero benefits outweigh (sorry!) the burden placed on accelerating it. Typically this is at about 20-25 km/h.
A number of years ago I did a comparison between Open Pros (with 28/32 DB spokes), Zipp 530s (24 bladed spokes) and Velocity Deep Vs (24 bladed spokes). All wheels used the same tires, tubes and inflation pressures. The Open Pros generally accelerated and climbed better, and were more comfortable than the Deep Vs. The Zipps required noticeably less effort above ~28km/h, but started to draw ahead from about 24km/h; at 20km/h life was more difficult and at 16km/h they were horrible! There did seem to be some damping effect from the carbon rim, so they weren't uncomfortable despite the deep section. The Deep Vs didn't seem to offer any real benefit or have any great drawbacks apart from the slightly harder ride.
I've also used the Specialized Trispoke wheels and these are also good above a certain speed. Provided that there are no steep climbs or gusty crosswinds and that the rider can maintain a certain minimum power output then aero wheels undoubtedly help. Unfortunately this is not always the case!
My conclusion is that deep-section aero wheels are good for not-too-hilly TTs (and breakaways) provided that gusty crosswinds aren't an issue, but a traditional wheel is cheaper, easier to accelerate, repair and maintain, more comfy, and less affected by crosswinds.
What is important is up to the individual...