tag:blogger.com,1999:blog-6240416284552619444.post5454108396269075809..comments2018-06-13T07:52:42.268+08:00Comments on The Bike Geek: No power meter? Just use your home trainer!The Bike Geekhttp://www.blogger.com/profile/14378607523322893180noreply@blogger.comBlogger22125tag:blogger.com,1999:blog-6240416284552619444.post-31855566607744581942018-03-22T05:08:54.424+08:002018-03-22T05:08:54.424+08:00Amazing article! Does anyone have information abou...Amazing article! Does anyone have information about the power curve for their new cycleops fluid (yellow) trainer?Yauhen Shulitskihttps://www.blogger.com/profile/15037212126832679606noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-65063441384232569892018-01-15T23:52:57.992+08:002018-01-15T23:52:57.992+08:00Thanks for your reply
Am I right in thinking that...Thanks for your reply<br /><br />Am I right in thinking that you're power curve only allows you to figure out power from your speed 'after the event' as it were. I.e. its a post-processing step after you've finished your turbo session?<br /><br />I'm wondering if an app exists that can connect to a speedo (bluetooth?) and import a powercurve such that it could give a live power readout as you are training? <br /><br />Does that exist?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-65855231924500494352018-01-12T20:26:55.768+08:002018-01-12T20:26:55.768+08:00Correct, the curve is nothing like what I would ge...Correct, the curve is nothing like what I would get from plotting the data from a proper powermeter versus wheel speed. Makes you wonder how variable the curves are from trainer to trainer, and how accurate the "virtual power" numbers are in say Zwift or Trainer RoadThe Bike Geekhttps://www.blogger.com/profile/14378607523322893180noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-766113133044877802018-01-12T20:24:50.406+08:002018-01-12T20:24:50.406+08:00No reason in particular! You could go as high as ...No reason in particular! You could go as high as you wanted in terms of the order of the equation to get a more accurate fit.The Bike Geekhttps://www.blogger.com/profile/14378607523322893180noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-59892314523169862662018-01-12T20:21:27.425+08:002018-01-12T20:21:27.425+08:00I would say that once the fluid has warmed up a bi...I would say that once the fluid has warmed up a bit, no. The new virtual training apps (Zwift, Trainer Road) do not take into account ambient temp at all for their "virtual power." There's a related discussion here: http://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Does_temperature_have_a_big_impact_on_fluid_trainer_resistance%3F_P4893016/The Bike Geekhttps://www.blogger.com/profile/14378607523322893180noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-16339001576255308762018-01-12T18:09:26.898+08:002018-01-12T18:09:26.898+08:00does the ambient temp have a sig effect on the pow...does the ambient temp have a sig effect on the power curve?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-88344601230523024812017-05-02T16:44:23.634+08:002017-05-02T16:44:23.634+08:00I haven't seen any. The best option would be ...I haven't seen any. The best option would be to make a curve using a borrowed powermeter. Obviously the good folks at Zwift and Trainer Road have gone through the trouble. And have a look at this: http://www.powercurvesensor.com/bikestudio/The Bike Geekhttps://www.blogger.com/profile/14378607523322893180noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-34720569170281124862017-04-16T05:51:29.971+08:002017-04-16T05:51:29.971+08:00Does anyone know if there is a place one could obt...Does anyone know if there is a place one could obtain up to date power curves for a wide variety of trainers?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-9376291346409988882016-12-09T22:03:51.437+08:002016-12-09T22:03:51.437+08:00You can probably figure it out from here: https://...You can probably figure it out from here: https://www.cycleops.com/post/blog-15-cycleops-science-resistance-curvesThe Bike Geekhttps://www.blogger.com/profile/14378607523322893180noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-8338542762749263952016-12-09T22:02:12.423+08:002016-12-09T22:02:12.423+08:00Actually not quite right for a fluid trainer. In ...Actually not quite right for a fluid trainer. In a fluid trainer the power varies with wheel speed in accordance to a curve determined by the design of the trainer. CycleOps has a great article on the different characteristics of different types of trainers. https://www.cycleops.com/post/blog-15-cycleops-science-resistance-curvesThe Bike Geekhttps://www.blogger.com/profile/14378607523322893180noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-71127674304107214212016-12-09T10:59:14.542+08:002016-12-09T10:59:14.542+08:00As long as the resistance in the trainer is held c...As long as the resistance in the trainer is held constant, the power will vary directly with the speed. SO, for example at 5 mph the power will be exactly half of that at 10 mph.This assumes the resistance<br />does not vary with time or speed.( eg no road wind considerations)IN THE ABOVE example therefore, 163/28= x/31<br />or x=163x31/28 =182. Therefore in that case the resistance had to go up with increasing speed.It would be best to avoid<br />trainers with this characteristic as it makes<br />the power calculation dicey and likely less<br />reproducible. With constant resistance trainers you can use speed as a reliable<br />measure of RELATIVE power due to the considerations above.<br />William Reicherthttps://www.blogger.com/profile/10062067819184876941noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-63196669061412789012016-11-24T03:44:47.795+08:002016-11-24T03:44:47.795+08:00This comment has been removed by a blog administrator.Unknownhttps://www.blogger.com/profile/00761446879353968450noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-73121461718084463842016-11-12T12:07:41.096+08:002016-11-12T12:07:41.096+08:00I just came across this article. The last couple o...I just came across this article. The last couple of weeks I worked on a fluid2 with my son's power meter data. I basically find the same formula as described above although a X2 equations has the same accuracy.<br />What I found counter intuitive is to see lower power level for a given speed when the trainer is cold (thicker oil). You need to run the trainer a good 15mn before having stable data.<br />The real challenge with the accuracy is when you reach speeds of about 30km/h. The curve is very steep and a small variation in speed has a big variation in power. 52x19 at 80rpm is 28km/h or about 165W. At 90rpm the speed is 31km/h or about 220W.<br />Any small variation in the equation parameters has a big impact on the resulting power. Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-7281627180668355332015-12-18T05:16:49.478+08:002015-12-18T05:16:49.478+08:00any one known the formula for MAG/MAG+any one known the formula for MAG/MAG+Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-65888789299321624862015-09-30T20:56:02.800+08:002015-09-30T20:56:02.800+08:00There is lot of articles on the web about this. Bu...There is lot of articles on the web about this. But I like yours more, although i found one thatâ€™s more descriptive.<br /><a href="http://www.carbonspeedcycle.com/" rel="nofollow">carbon wheels</a>Amy Cooperhttps://www.blogger.com/profile/08746926848664365445noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-23592302608761704232015-01-07T08:57:26.127+08:002015-01-07T08:57:26.127+08:00Why do you use a cube rather than a simple square ...Why do you use a cube rather than a simple square to model this power curve? Say:<br />y = 0.4 x^2 + 6x <br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-13532204211462800112012-01-23T17:57:02.718+08:002012-01-23T17:57:02.718+08:00Came across your post when trying to follow my Pow...Came across your post when trying to follow my Power-training program, without a power meter! I had done the same thing as you, pulled a number of points of the Cyclops power curve, just to realize that it was complete bullshit, unless I had become excessively weak from my last power test.<br /><br />I used a SRAM crank powertap. The result for my Cyclops Fluid 2 trainer (from Aug. 2011) Power = 1.5981 x + 0.006942 x^3, where x is tire speed in km/hour. 100psi in the tires. This curve is rather steeper than the one from the Cyclops, but not quite as steep as the one from Kurt Kinetics.<br /><br />Whether people can use this curve for their own Fluid 2 is not certain, since Cyclops may change their oil sligtly, or even design between models.Armannnoreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-22044073894013787362011-08-15T19:10:57.567+08:002011-08-15T19:10:57.567+08:00Yes, it is only speed related. If you change to a...Yes, it is only speed related. If you change to a higher gear and keep the same cadence, the speed goes up, as does the power, in accordance with the curve above.The Bike Geekhttps://www.blogger.com/profile/14378607523322893180noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-49640963106173327612011-08-15T18:37:14.679+08:002011-08-15T18:37:14.679+08:00Nice post. TFS. I have one, maybe stupid question....Nice post. TFS. I have one, maybe stupid question. Is this related only to speed? What happens if I change gears on the bike while riding? Obviously to keep up the same speed in a difficult gear will mean more power output.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-22719782763881350172010-11-30T11:03:02.243+08:002010-11-30T11:03:02.243+08:00It shouldn't make a significant difference as ...It shouldn't make a significant difference as long as the roller is not so tight that you are deforming the wheel or hub. If properly adjusted, the friction between the roller and wheel will be negligible compared with the energy required to run the trainer. <br /><br />Here's a good article on how to properly adjust the tension: http://jimlangley.blogspot.com/2009/03/q-indoor-trainers-cliff-house-tandem.htmlThe Bike Geekhttps://www.blogger.com/profile/14378607523322893180noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-22686317610845880612010-11-21T07:51:41.404+08:002010-11-21T07:51:41.404+08:00Does the torque on the roller against your wheel a...Does the torque on the roller against your wheel affect the curve?K Petersonhttps://www.blogger.com/profile/00586820334967757481noreply@blogger.comtag:blogger.com,1999:blog-6240416284552619444.post-58235723819658399932010-09-21T16:10:13.372+08:002010-09-21T16:10:13.372+08:00That's very helpful! I've got a more detai...That's very helpful! I've got a more detailed breakdown for Kph if you want a bit more granularity (matlab):<br /><br />p = [0.0115 -0.0137 8.9788 0]; % Polynomial<br />kmph = 0:0.1:50; % Kilometers per hour<br />mph = kmph / 1.609; % Convert to MPH<br /><br />y = polyval(p,mph); % Power output y<br /><br />plot(kmph,y);<br /><br />for k = 1:length(kmph)<br /> fprintf('%0.1f,\t %0.1f\n',kmph(k),y(k))<br />endStephen Kavanaghhttps://www.blogger.com/profile/13036215528418043169noreply@blogger.com