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How much faster are disc wheels?
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 2007-03-05 3:38 PM |
Extreme Veteran 400 |  Subject: How much faster are disc wheels? Does anyone know this? All I can find are efficiency/drag comparisons, but not much on how that translates into speed. Thanks. |
| 2007-03-05 3:40 PM in reply to: #712260 |
Resident Curmudgeon 25290   The Road Back Gold member | Subject: RE: How much faster are disc wheels? LOTS. |
 2007-03-05 3:44 PM in reply to: #712260 |
| Subject: ... This user's post has been ignored. |
| 2007-03-05 3:53 PM in reply to: #712260 |
Champion 6627  Rochester Hills, Michigan Gold member | Subject: RE: How much faster are disc wheels? Q. How much time could I save in a 25 mile time trial by switching to aero rims? A. It depends on the wheels. Using our 150 lb test rider in an aero tuck as a model, switching to aero wheels will typically save between 1 minute 30 seconds and 2 minutes over a flat 25 mile course. Using a Deep front and Disc rear, two minutes is a realistic figure Source: Hed Website, http://www.hedcycling.com/technical/faq.php Given a power output of 300 Watts, a wind angle of 15 degrees of yaw, the Zipp 404 will require 4 Watts less power than a Mavic Ksyrium to spin. This is added to the drag saving of 16 Watts (0.26lbs of drag) for a 20 Watt saving, or roughly 82 seconds over 40 km in these (unrealistically) static conditions. When comparing to a GL330 (round spoked, box section wheel), a Zipp 404 will save you about an extra 15 Watts on top of a Ksyrium, which will end up as approximately 140 seconds over 40 km. Note: the data listed above is for a 404, not a disc. Disc will yield slighly better time savings. This is pretty consistent with data generated by 2 other frequently-cited sources: 1) MIT wind tunnel testing, 2) Texas A&M wind tunnel testing. |
| 2007-03-05 4:00 PM in reply to: #712260 |
| Extreme Veteran 474 Mountains of Colorado! | Subject: RE: How much faster are disc wheels? the cool factor takes off at least 1 min... |
| 2007-03-05 4:03 PM in reply to: #712260 |
| Expert 1103 Plano, TX | Subject: RE: How much faster are disc wheels? You forgot to factor in the aero advantage of a thinner wallet. That's at least another 30". Get a disk cover. (spoken by someone who doesn't have a disc wheel) |
| 2007-03-05 4:03 PM in reply to: #712311 |
Pro 4481 Reston | Subject: RE: How much faster are disc wheels? ellasdad - 2007-03-05 5:00 PM the cool factor takes off at least 1 min... I believe it is also proportional to the color of your bike. |
| 2007-03-05 4:19 PM in reply to: #712260 |
| Extreme Veteran 400 | Subject: RE: How much faster are disc wheels? Have any figures on a red disc? |
| 2007-03-05 4:20 PM in reply to: #712260 |
| Expert 1113 Las Vegas | Subject: RE: How much faster are disc wheels? Doesnt seem reasonable to me to spend that kind of coin, just to make my wallet thinner for less drag (sarcasm intended), and to save 2:30 to 3:00 min over 25 miles. Seems like mechanics and persistance would cut more for me at this point. I could see the advantage if I already had perfect form, and perfect stamina and endurance, then maybe the only place I could shave more time is in the wheels. I will grant one thing, they do look cool. |
| 2007-03-05 4:30 PM in reply to: #712260 |
| Extreme Veteran 400 | Subject: RE: How much faster are disc wheels? I finally found an article. It puts the total time gain from regular 32 spoke wheels to a disc at about 60 - 90 seconds over 40km. I think this would have to increase for faster riders, though. http://www.insidetri.com/portal/news/news.asp?item=103266 |
| 2007-03-05 4:54 PM in reply to: #712368 |
| Not a Coach 11473 Media, PA | Subject: RE: How much faster are disc wheels? HankJKy - 2007-03-05 4:30 PM I finally found an article. It puts the total time gain from regular 32 spoke wheels to a disc at about 60 - 90 seconds over 40km. I think this would have to increase for faster riders, though. http://www.insidetri.com/portal/news/news.asp?item=103266"href="http://www.insidetri.com/portal/news/news.asp?item=103266">http://www.insidetri.com/portal/news/news.asp?item=103266 Time savings are greater for SLOWER riders (but it's a bigger percentage savings for a faster rider). |
| 2007-03-05 8:32 PM in reply to: #712344 |
| Champion 9430 No excuses! | Subject: RE: How much faster are disc wheels? HankJKy - 2007-03-05 5:19 PM Have any figures on a red disc? Yep slower than a "black disc"  |
| 2007-03-05 8:43 PM in reply to: #712347 |
| Champion 6627 Rochester Hills, Michigan Gold member | Subject: RE: How much faster are disc wheels? ryanlc - 2007-03-05 5:20 PM Doesnt seem reasonable to me to spend that kind of coin, just to make my wallet thinner for less drag (sarcasm intended), and to save 2:30 to 3:00 min over 25 miles. Seems like mechanics and persistance would cut more for me at this point. I could see the advantage if I already had perfect form, and perfect stamina and endurance, then maybe the only place I could shave more time is in the wheels. I will grant one thing, they do look cool. Ding. We have a winner. Work on yourself first, your position second, and everything else third. |
| 2007-03-05 11:05 PM in reply to: #712344 |
| Expert 1240 Columbia, MO | Subject: RE: How much faster are disc wheels? HankJKy - 2007-03-05 4:19 PM Have any figures on a red disc? Lightspeed +1 |
| 2007-03-06 4:05 AM in reply to: #712260 |
| Extreme Veteran 579 | Subject: RE: How much faster are disc wheels? Fast wheels are faster of course, but you have to think of this in a total package deal. You and all the componets that make up your bike. 70% of wind resistance is you and how well you slice thru the wind, a elbow tuck here, the knees kept inward on the down stroke instead of rotating outward, head kept down(but looking ahead), all this is tough to do without the use of a windtunnel and for us mere mortals it is a trial and error type of thing. But if you study fast guys/girls and try to copy I suspect that is a good start. Pick someone that has a similar build to yours and try to make yourself look like them on the bike. Also, as I have mentioned on another post a powermeter gives you real time ability to judge minor changes in your position and how much more or less wattage that change requires to maintain a set speed. Not exactly a windtunnel but probably a really good start. Edited by Special K 2007-03-06 4:06 AM |
| 2007-03-06 8:11 AM in reply to: #712260 |
| Member 182 | Subject: RE: How much faster are disc wheels? I have heard that true disc wheels have a lot of cross drag depending on wind direction. Hence why like the zipp 808s are so popular. Zipp 808s are well...very, very sexy. Seriously though somone (I think slow twitch maybe?) did a disc wheel count at Kona, and there was like 1 or 2. If those guys aren't using them, there's probably a reason. Edited by joelkratzer 2007-03-06 8:20 AM |
| 2007-03-06 8:23 AM in reply to: #712643 |
| Pro 3673 MAC-opolis | Subject: RE: How much faster are disc wheels? rkreuser - 2007-03-05 9:43 PM ryanlc - 2007-03-05 5:20 PM Doesnt seem reasonable to me to spend that kind of coin, just to make my wallet thinner for less drag (sarcasm intended), and to save 2:30 to 3:00 min over 25 miles. Seems like mechanics and persistance would cut more for me at this point. I could see the advantage if I already had perfect form, and perfect stamina and endurance, then maybe the only place I could shave more time is in the wheels. I will grant one thing, they do look cool. Ding. We have a winner. Work on yourself first, your position second, and everything else third. X2
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| 2007-03-06 8:29 AM in reply to: #712913 |
| Champion 8936 | Subject: RE: How much faster are disc wheels? They're not using them because you're not allowed to. That's a good reason. joelkratzer - 2007-03-06 8:11 AM Seriously though somone (I think slow twitch maybe?) did a disc wheel count at Kona, and there was like 1 or 2. If those guys aren't using them, there's probably a reason. |
| 2007-03-06 9:03 AM in reply to: #712913 |
| Subject: ... This user's post has been ignored. |
| 2007-03-06 9:15 AM in reply to: #713018 |
| Master 1831 Keller Tx | Subject: RE: How much faster are disc wheels? JeepFleeb - 2007-03-06 9:03 AM joelkratzer - 2007-03-06 8:11 AM I have heard that true disc wheels have a lot of cross drag depending on wind direction. With a disc the wind drag will decrease as the angle of the wind increases. Discs and deep rimmed wheels are very similar in a headwind, but discs are much more aero in a crosswind. I've heard and read this before, and each time I see it, it seems counter-intuitive. That said, the data that you read on it supports this 100% |
| 2007-03-06 9:57 AM in reply to: #712948 |
| Member 182 | Subject: RE: How much faster are disc wheels? DerekL - 2007-03-06 8:29 AM They're not using them because you're not allowed to. That's a good reason. joelkratzer - 2007-03-06 8:11 AM Seriously though somone (I think slow twitch maybe?) did a disc wheel count at Kona, and there was like 1 or 2. If those guys aren't using them, there's probably a reason. I don't know if I would call that a "good" reason. Maybe a "fair", to "pretty fair." Maybe even call it "reasonable". |
| 2007-03-06 5:00 PM in reply to: #713035 |
| Master 1597 Colorado | Subject: RE: How much faster are disc wheels? Doughboy - 2007-03-06 10:15 AM JeepFleeb - 2007-03-06 9:03 AM joelkratzer - 2007-03-06 8:11 AM I have heard that true disc wheels have a lot of cross drag depending on wind direction. With a disc the wind drag will decrease as the angle of the wind increases. Discs and deep rimmed wheels are very similar in a headwind, but discs are much more aero in a crosswind. I've heard and read this before, and each time I see it, it seems counter-intuitive. That said, the data that you read on it supports this 100% It's called the "sail" effect for a reason. With a crosswind, a disk acts just like a sail. |
| 2007-03-06 6:32 PM in reply to: #712260 |
| Extreme Veteran 437 | Subject: RE: How much faster are disc wheels? I would opt for an aero helmet. Just about as much of a speed increaser and a lot less money. |
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