|Light wheels vs. Aero wheels||fzrrider|
Nov 21, 2002 2:13 PM
|At what point does aerodynamics replace light weight? I've been looking at the $500 1300g american classic 350 wheels then I read that the aerodynamics of zipp/ksyrium type wheels more than makes up for the 200-400g difference in weight.|
|re: sustained speeds above 23 MPH...||Akirasho|
Nov 21, 2002 2:22 PM
|... there is evidence of aero advantages for speeds as low as 18 MPH, but you'd not see any real advantage unless you were goning to be able to sustain those speeds over time and distance (aero wheels on a mountain TT would yield to lightweight if speeds were gonna be in the 18 to 20 MPH range).
Remain In Light.
Be the bike.
|Not much difference for most of us||Kerry|
Nov 21, 2002 5:47 PM
|Aero wheels are always faster on the flats, full stop. When climbing, weight is weight, so the 300 gm penalty for areo vs. AC 350 is the same as 300 ml of water, or a spare tubular plus a CO2 cartridge, etc. Wheel weight is different than other weight ONLY when you are constantly braking and accelerating, like in a crit. And even then, it is a tiny effect. BTW, only MAVIC and a few patriots would claim that Ks are aero compared to Zipps. Aero wheels will save you 3-4 min in a 5 hour century - huge if you are racing and meaningless otherwise. Saving 300 gm will give you some minor yardage on a long climb - huge if you are racing and meaningless otherwise. Make your choice on things like cost, durability, flash, or whatever other criteria you have. For me, I'd go w/Record & Velocity Aerohead - $200 cheaper than the ACs, much more durable, and about 130 gm heavier (weighs about the same as 4 swallows of water).|
|Good point, "if your racing" is the deciding factor||JS|
Nov 21, 2002 7:15 PM
|in my book. In fact that's a big factor in most "rational" bike purchases. I would never put up with the hassles of My ZIPP tubulars if they weren't my race wheels. I've kinda gone full circle, First road bike had standard wheels(Ultegra, 32 3x) then went high end boutique hubs with weird lacing patterns(Hey, had to mess with new build techniques)with the appropriate pain in the ass problems and now my next set of training/all day wheels are gonna be Dura-Ace 3x 32, live and learn. If I was a Campy guy I wouldn't use anything other than Record hubs, they are sooo nice, as light as any high dollar aftermarket hub and 10 times more durable.|
|Go to Bike.com||jhr|
Nov 22, 2002 5:51 AM
|And search there tech archives. There is a two part series on wheels. One of the article strongly suggest that aerodynamics is more significant than any weight penalty except on the steepest grades (ie speeds less than 12 or 14 mph). Not surprisingly they ultimately conclude light and aero is best.
I think if you objectively analyze the available information from the bike.com web cite and other cites you would conclude a set of cosmic elites (@ about 2000 grames a pair) should be faster than a set of am. clasic 350's, not to mention more durable. Frankly this subject is a pet peave of mine, it drives me crazy when people claim they can feel their ultralight wheels accelerating faster (don't even get me started on perceived wheel stiffness claims). Objectively, there is no basis for such claims.
Fyi Ksyriums are both non aero and heavy.
People will disagree with this post, so don't take my word for it, or theirs, check out the bike.com tech archives and decide for yourself.
|Go to Bike.com||altidude|
Nov 22, 2002 8:07 AM
|I agree with your post completely, especially the comment on Ksyriums, an amazing $650 wheel that is neither light, nor aero nor handles well in windy conditions. I'm also not so sure an aero wheel would lower your time by 3-4 minutes on a 100 mile century unless you were a solo breakaway. Riding in a pack, those aero wheels will not help but a bit for the short periods of time you are taking your turn pulling, but they certainly are not going to give you the extra speed to open up a breakaway on a group determined to keep in touch with you. A few minutes or even seconds is important to a peleton pro. To your weekend warrior type I think it's more about how cool looking of a bike can I offload off my car at the grouprace than it is anything else. I laugh at guys who claim they can drop people because they are riding different wheels or tires, true comics indeed.|
|I'll disagree with part of it||Ray Sachs|
Nov 22, 2002 10:51 AM
|Aero wheels clearly make more of a speed difference except on the steeper climbs and, as an earlier poster said, none of it makes enough difference to worry about unless you're racing (at a pretty high level too, I'd say). But having ridden many different wheels over the years, I'd say you CAN feel the difference with a light set of wheels compared to a heavy set. Light wheels may not BE faster, but they can sure feel quicker, easier to accellerate, etc. I'm not claiming I can feel the difference with 50 grams here or there. But the difference between a heavy touring wheel and a light racing wheel (even with comparable tires) is very obvious. If I was fast enough to worry about actual speed, I'd go with aero. But since I ride for the enjoyment of the feel of the bike, I tend to go with lighter wheels for the perceived speed instead. Not crazy light, just something reasonably light like Dura Ace hubs, Open Pro rims, 32 spokes.
|How do you reconcile this claim with the published data||jhr|
Nov 22, 2002 12:26 PM
|I will be the first to admit some wheels "feel" faster than others, but if you review the data I think you have to concede this is most likely psychological (placebo effect).
The bike.com archive article (August 1, 2001) states as follows:
"So, what do all these numbers mean? It means that when evaluating wheel performance, wheel aerodynamics are the most important, distantly followed by wheel mass. Wheel inertia effects in all cases are so small that they are arguably insignificant.
How can it be that wheel inertial forces are nearly insignificant, when the advertisements say that inertia is so important? Quite simply, inertial forces are a function of acceleration. In bike racing this peak acceleration is about .1 to .2 g’s and is generally only seen when beginning from an initial velocity of 0 (see criterium race data in Appendix D ). Furthermore, the 0.3kg/0.66lb difference in wheels, even if this mass is out at the rim, is so small compared to your body mass that the differences in wheel inertia will be unperceivable. Any difference in acceleration due to bicycle wheels that is claimed by your riding buddies is primarily due to cognitive dissonance, or the placebo effect (they paid a lot of money for the wheels so there must be some perceivable gain)."
As I review/understand the charts accompanying the article a 50% decrease in wheel inertia (e.g. 1000 gram rear wheel to 500 gram) results in at best a .022% (thats 22/1000's of a percent)decrease in drag. FYI a reduction of 500grams for a 150lb rider (68,100 grams) and 15lb bike (6810 grams) represents a total reduction on the order of .667% (2/3rds of 1 percent).
I don't dispute for one second what you think you feel, I sometimes think I feel the same, but its all in your head. I once built up a set of tubulars with a 30mm section rim. Because they were tubulars I felt like they had to be lighter than the clinchers they replaced. Indeed they seemed to accelerate faster than the old clinchers. Much to my chagrin when I finally weighed the bike with the new tubulars it weighed about 4 oz.'s more than before! My new tubulars were heavier not lighter.
|you hit the nail square on the proverbial head||scorpionking|
Nov 22, 2002 5:25 PM
|Pure placebo affect, lots of owner ego and BS to support their $5000 bicycle, little common sense and almost all pure hype. Most biomechanical studies have shown that minor weight changes in components whether they be wheels or frame or whatever have tiny, tiny, tiny affects on a riders true performance in real road riding conditions.
A few years ago, Antonio Mondonico was commissioned to build a series of steel bicycles from various price level steel tubesets from Columbus. They bikes were all painted the same and only Antonio knew which were which. The testriders of the bikes picked the biked built with his cheapest entry level chromo steel 4000 series tubeset as the best riding. Take a guess if that would have happened had the bikes been painted so that the testriders actually knew which frame they were on?
When is the last time you heard even a single owner of a $3500 Serotta steel bike for example not concede that his new super expensive steed rides no better than the Lemond Zurich he just replaced it with? Lots of owner ego hype and BS, gee I spent lots more cash on my new bike it has to be worlds better right? I'd be willing to wager serious cash that if you could disguise a $1500 bike as a custom $4000 bike and disguise the custom $4000 bike as an off the shelf $1500 solid performer virtually all if not all testriders of the two bikes would rave about the ride of the $1500 disguised bike while extolling all its virtues over the $4000 bike. Same thing applies to guy who drop huge cash on stuff like Record 10 or expensive wheels, oh they roll so much smoother, they spin up so much faster, now I climb so much better, blah, blah, blah. All placebo and ego extolling imaginary huge performance leaps. I actually saw some idiot last year on a website try to claim his average time on a pair of stationary rollers increased from an average of 22 mph to over 30 mph simply by changing wheels from Open Pro's to Ksyriums, LOL, I almost fell over laughing over that total BS. The bottom line is, most recreational bike buyers have been sold with the endless marketing BS that a tiny bit of weight savings will somehow make you a much faster rider, which any experienced rider will tell you is total nonsense. When I see an out of shape middle aged guy go buy a pair of HED 3's and then start telling everyone how he is now blowing by and dropping riderswho are stronger and in better shape about all you can do is laugh and then yawn. Lots of hype, smoke and mirrors and nonsense filled claims.
|Rollers - I love it!||deHonc|
Nov 28, 2002 9:06 PM
|Farkin funny - increased average speed on a set of rollers - very nice!!!!|
|I obviously can't refute the numbers||Ray Sachs|
Nov 23, 2002 3:39 AM
|but I don't ride for numbers. I only use a computer to track my overall mileage anyway. And I *HAVE* done blind tests with heavier vs. lighter wheels and I haven't been wrong yet when there's a significant difference in weight. Like I said, I don't claim to be able to feel the difference between two rims that are 30-40 grams apart. But comparing a roughly 900 gram rear Open Pro/Dura Ace wheel with a much heavier touring wheel (Phil freewheel hub / Bontrager Fairlane rim - don't know the actual weight), with similarly different wheels on the front, the heavier wheels always feel more sluggish to me.
Again, I'm not claiming the lighter wheels actually make me quantifiably faster over any given distance, just that they feel quicker in the real world. In steady state pedalling, no difference. But on short hill sprints and in the transition between seated and standing when there IS a lot of accelleration, that's where I can feel it. I'm not a weight weenie with my bike at all - I ride a steel rig that usually comes in at around 21-22 pounds and I'm just as fast on that as on an 18 pound ti bike that I also spend some time on. But over the years I've found that light wheels feel like more fun to me.
My story and I'm sticking to it,