|
rbent Forum
https://rbentonline.org/YaBB.pl General Category >> Technical >> Fastest Recumbent https://rbentonline.org/YaBB.pl?num=1312241925 Message started by jayg on Aug 1st, 2011, 6:38pm |
|
Title: Fastest Recumbent Post by jayg on Aug 1st, 2011, 6:38pm Since I have a lot of free time on my hands, I decided to run some coast-down tests on the five high-performance recumbents I own to determine which is the fastest. The fastest should be the one with the lowest combination of air and rolling resistance. Hope the following report will be of interest to at least some of the members who are into high performance recumbents. I spent parts of the past two days making a total of 22 runs down the steep concrete path that parallels the spillway at WRL. All the recumbents are equipped with high-performance, smooth-tread tires. I pressured the front tires to 110 psi and the rears to 115 psi. I crossed the starting point at approximately 15 mph and coasted until each recumbent reached its maximum speed. All of the runs were made under no-wind conditions at 100 degrees, plus. I made a minimum of three runs per recumbent and averaged the results. Average maximum speeds were as follows: a. 2010 Optima Baron – 26.8 mph b. 2011 Catbike Musashi – 26.7 mph c. 2009 Carbent Raven – 26.1 mph d. 2007 Catrike Speed w/26” rear wheel conversion kit – 25.8 mph e. 2009 RANS X-Stream – 25.2 mph The above results can’t be used to judge relative cranking effort, because from my experience the Musashi requires less cranking effort than the Baron, and the X-Stream requires less cranking effort than the Speed at elevated speeds on the flats. My subjective opinion of cranking effort required to maintain a 21 mph cruising speed on the flats from least to maximum by recumbent is as follows: a. Musashi b. Baron c. Carbent d. X-Stream e. Speed |
|
Title: Re: Fastest Recumbent Post by Ric_Clark on Aug 1st, 2011, 7:45pm Thanks Jay [smiley=notworthy.gif] [smiley=notworthy.gif] [smiley=notworthy.gif] |
|
Title: Re: Fastest Recumbent Post by johnnybent on Aug 1st, 2011, 8:15pm Heat's really getting to you is'nt it. |
|
Title: Re: Fastest Recumbent Post by power_bent on Aug 1st, 2011, 8:17pm That good info jay, If i remember correctly on my trike when i do about 10 or 11 mph on the crest and i get right at 27 mph at the bottom.. Pretty close to ya.. |
|
Title: Re: Fastest Recumbent Post by jayg on Aug 1st, 2011, 8:28pm johnnybent wrote:
You're just saying that because you're riding one of those slow X-Streams. ;D |
|
Title: Re: Fastest Recumbent Post by johnnybent on Aug 1st, 2011, 8:31pm You callin' me slow? Well...I'll just have to put one of them sun shades on it then. |
|
Title: Re: Fastest Recumbent Post by jayg on Aug 1st, 2011, 8:45pm johnnybent wrote:
You need to get with Kenny. He has the plans and material list. :) |
|
Title: Re: Fastest Recumbent Post by FlyingLaZBoy on Aug 1st, 2011, 10:08pm jayg wrote:
"Smoke 'em if you got 'em!!!" [smiley=cheesy.gif] Pretty cool little test there, Jay... I'm not too surprised, since the XStream is probably the least "laid back" of them all. |
|
Title: Re: Fastest Recumbent Post by aikigreg on Aug 1st, 2011, 11:21pm Coast down figures are fairly irrelevant, but a good power meter can eliminate all that guesswork! |
|
Title: Re: Fastest Recumbent Post by power_bent on Aug 2nd, 2011, 2:59pm aikigreg wrote:
I agree |
|
Title: Re: Fastest Recumbent Post by Opus the Poet on Aug 2nd, 2011, 4:29pm aikigreg wrote:
Not entirely irrelevant, coastdown will give a comparison at the initial speed or for the same hill. While it won't give hard numbers it will still give relative strengths. |
|
Title: Re: Fastest Recumbent Post by Bud_Bent on Aug 2nd, 2011, 4:51pm Coast down is too affected by gravity. If you load the bikes enough to make them weigh the same, you get a better test. |
|
Title: Re: Fastest Recumbent Post by jayg on Aug 2nd, 2011, 7:07pm Bud_Bent wrote:
I've seen a similar statement (weight as a variable) made in some coast-down testing literature, but no explanation was given. Weight affects rolling resistance, so maybe that was the reason for the statement. Bob M. reminded me the other day that we learned in our physics courses that in a vacuum all free falling objects accelerate at the same rate, independent of mass. Aerodynamics accounts for the difference in terminal velocities of two free falling objects in the atmosphere, not their weights. This (along with other minor variables, such as rolling resistance) sounded reasonable to me to explain the differences in various recumbents' terminal velocities attained during roll-down tests on inclines. I think the variables that introduced the biggest errors in my test results were the varying running start speeds (I was shooting for 15 mph), computer inaccuracies, and the winding concrete path. According to literature, I should have selected a 1/4 mile long straight slope of at least 5%, and should have utilized standing starts. |
|
Title: Re: Fastest Recumbent Post by power_bent on Aug 2nd, 2011, 7:35pm Sounds good Jay...I said what i said becuase of to many varables as grease in wheels and rear freewheel drag and to tires differences and weight . But what you did is close enough for what your doing.I was thinking the baron should have won but it didn't. Later |
|
Title: Re: Fastest Recumbent Post by jayg on Aug 2nd, 2011, 8:16pm aikigreg wrote:
Don't agree that coast-down test results are irrelevent, if the tests are properly conducted, but a power meter would definitely be a much better way to go. If I was Mark Cuban, I would have some Power Tap wheels built up for my bikes, and run some more tests. :) |
|
Title: Re: Fastest Recumbent Post by jayg on Aug 2nd, 2011, 8:24pm power_bent wrote:
I cruised at 23 mph on the Musashi this morning on West Lawther. Don't think I can sustain 23 mph on the Baron. I'm going to convert the rear gearing to close-ratio 10-speed, like the Musashi's. After I do it, I'll take it out and see if I can match the above cruising speed. |
|
Title: Re: Fastest Recumbent Post by aikigreg on Aug 2nd, 2011, 9:43pm All a coast down test does, Jay, is show which bike is lower to the ground and weighs more. Looks at your results and it becomes obvious. Most B riders I ride with ride much more reclined but they rarely beat me down the hills unless they crank. My fat butt overcomes a lot! But all that mass has to go right back uphill, and now we're talking about weight again, in reverse. I bet if you did a lot of hill CLIMBS your results would be based purely on weight. However, a mile of cruising on flat ground at the same wattage will tell you a lot more about true power to the pedals. Powertaps can be had relatively cheaply compared to the cost of the bikes in your stable ;D. You'd only need 1 in 650 and 1 in 700. Dana had a special for the hub at 699. Mount them both to the same cheap wheel. |
|
Title: Re: Fastest Recumbent Post by rmillay on Aug 2nd, 2011, 10:03pm It's not your weight, Greg, but its distribution! ;D The real loser was the trike, which has more frictional drag problems, not to mention the curves on the test course. BTW, I hit 26.1 mph with my Cat 700 under similar circumstances this morning. |
|
Title: Re: Fastest Recumbent Post by jayg on Aug 3rd, 2011, 11:06am aikigreg wrote:
Greg, from what I understand drag starts to become the most significant factor in resisting forward movement at 15 mph and over (that's why I did running starts at about 15 mph in my test runs). If conducted properly, coast down tests should reveal the most aero recumbent to the least in order. The most aero should require the least cranking effort at say 23 mph on the flats. In my case (My Carbent and I weigh a total of about 168 lbs) I pass heavier, tucked roadies, in high-speed coasting down steep hills. This can only be attributed to superior aerodynamics. I'm an older rider - new bikes, not expensive power meters and associated computers, are on my bucket list. :) |
|
Title: Re: Fastest Recumbent Post by Bud_Bent on Aug 3rd, 2011, 1:30pm Again, it's not just aerodynamics. Gravity has its say; more weight makes you go downhill faster. jayg wrote:
If you're going downhill, it's not just forward movement, is it? It's also downward movement. |
|
Title: Re: Fastest Recumbent Post by rmillay on Aug 3rd, 2011, 1:54pm Again I will remind you, Bud, the weight (or mass) of a falling object does not appear in the equation for acceleration due to gravity. Thanks to that meddling Italian, Galileo, we have to face it, that gravity only works against us, not for us. [smiley=shrug.gif] |
|
Title: Re: Fastest Recumbent Post by power_bent on Aug 3rd, 2011, 3:15pm power_bent wrote:
Hint what I said about the crest and what it is at bottom???? |
|
Title: Re: Fastest Recumbent Post by power_bent on Aug 3rd, 2011, 3:21pm Hey jay, here something you can do and only you because of your unique setup and tested. Take your fastest bike duplicate the same test but add weight like 50 lbs without restricting the airflow or aero of the bike and see what up.. |
|
Title: Re: Fastest Recumbent Post by johnnybent on Aug 3rd, 2011, 3:36pm ya'll just got it all wrong....it ain't got nuthin ta do with weight, aerodamictics or whatever....It's gotta be RED! Ya know like them Italian sports cars. |
|
Title: Re: Fastest Recumbent Post by TonyWard on Aug 3rd, 2011, 5:11pm johnnybent wrote:
Best answer all thread!!!! Jay you gotta quit buying those black bikes - that is why i'm kicking your butt on the actionbent! ;) |
|
Title: Re: Fastest Recumbent Post by power_bent on Aug 3rd, 2011, 5:47pm TonyWard wrote:
Best answer all thread!!!! Jay you gotta quit buying those black bikes - that is why i'm kicking your butt on the actionbent! ;)[/quote] LMAO... |
|
Title: Re: Fastest Recumbent Post by jayg on Aug 3rd, 2011, 6:12pm johnnybent wrote:
You have two fast red bikes, but I never see you on them. Still think you have them hung from the ceiling of your apartment as mobiles. :) |
|
Title: Re: Fastest Recumbent Post by power_bent on Aug 3rd, 2011, 6:49pm jayg wrote:
You have two fast red bikes, but I never see you on them. Still think you have them hung from the ceiling of your apartment as mobiles. :) [/quote] LOL |
|
Title: Re: Fastest Recumbent Post by jayg on Aug 3rd, 2011, 7:02pm Bud_Bent wrote:
If you're going downhill, it's not just forward movement, is it? It's also downward movement.[/quote] Bob M, I think I'm going to have to part way with the Galileo argument and agree with Bud. Spent the whole day researching this question (I've said before that I have a lot of free time :)) until my head was about to explode. This question about weight affecting downhill speed has been discussed in many articles and forums with many people taking opposing positions. I refreshed my memory of inclined plane dynamics and found that acceleration of a rider down a uniform slope is equal to the force component parallel to the slope (This force component includes a portion of the rider's weight, minus rolling resistance, minus an increasing drag force) divided by the rider's mass. So, weight of the rider plus the bike does make a difference. Here is an excerpt from one of articles I found: "Thus, the terminal velocity is roughly proportional to the square root of the ratio of M/A. Scaling reveals that larger cyclists have a greater ratio of mass to frontal area. They therefore descend hills faster as a consequence of purely physical, not physiological, laws. Since the larger cyclist has a greater mass, gravity acts on him or her with a greater force than it does on a smaller cyclist. (Note: A common misconception is to note the equal acceleration of two different sized objects in free fall in a vacuum, and assume that the force of gravity on both is equal. The force on the more massive object is greater, being exactly proportional to mass, which is why the more massive object is accelerated at the same rate as the less massive one.) While the larger cyclist also has a greater absolute frontal area than the smaller cyclist, the difference is not as great as that for their masses. Thus, the larger cyclist will attain a greater s3 before a balance of forces results in terminal velocity." Regarding the question of whether or not my lighter bikes should have been ballasted, so all of them would have been of equal weight - The weight difference between the lightest and heaviest is 13 pounds. Might have been a good idea to do that. Hope this puts an end to the discussion. My head hurts. [smiley=injured.gif] |
|
Title: Re: Fastest Recumbent Post by jayg on Aug 3rd, 2011, 7:11pm TonyWard wrote:
Best answer all thread!!!! Jay you gotta quit buying those black bikes - that is why i'm kicking your butt on the actionbent! ;)[/quote] It's not nice to pick on your elders. I'd like to see you and Johnnybent race your red ActionBents for pink slips. That way one of you could increase your stable of red bikes at no cost. :) |
|
Title: Re: Fastest Recumbent Post by Bud_Bent on Aug 3rd, 2011, 8:42pm rmillay wrote:
That's just not true at all. Step off that second floor balcony and tell me that gravity doesn't take you down. This isn't rocket science, folks. Get past the half-baked coast down tests and find the ones where people took it seriously. Weight is a factor in downhill speed. Period. (Just as it's a factor in uphill speed.) Another x-factor thrown into all the test riding is the fact that weight has so little effect when riding on flats. At speed, aerodynamics and comfort are the biggest factors there. (Never underestimate the comfort factor.) But it's always been amazing to me how few people seem to know how weight really affects the speed of a bicycle. It doesn't take that much research to find out. And it's always struck me strange that the lightest riders, who will be the ones slowed down the most by a heavier bike, seem to never pay attention to bike weight when they buy, while the heavy riders, who will be affected very little by bike weight, turn into bike weight weenies. Go figure. [smiley=shrug.gif] |
|
Title: Re: Fastest Recumbent Post by TonyWard on Aug 3rd, 2011, 8:43pm jayg wrote:
Best answer all thread!!!! Jay you gotta quit buying those black bikes - that is why i'm kicking your butt on the actionbent! ;)[/quote] It's not nice to pick on your elders. I'd like to see you and Johnnybent race your red ActionBents for pink slips. That way one of you could increase your stable of red bikes at no cost. :) [/quote] no way - i'm afraid i'd loose...... i am still licking my wounds from last summer where he popped me off on a hill on W. Lawther. Plus all those 100+ mile rides he keeps posting scare me. |
|
Title: Re: Fastest Recumbent Post by jayg on Aug 3rd, 2011, 9:01pm TonyWard wrote:
Best answer all thread!!!! Jay you gotta quit buying those black bikes - that is why i'm kicking your butt on the actionbent! ;)[/quote] It's not nice to pick on your elders. I'd like to see you and Johnnybent race your red ActionBents for pink slips. That way one of you could increase your stable of red bikes at no cost. :) [/quote] no way - i'm afraid i'd loose...... i am still licking my wounds from last summer where he popped me off on a hill on W. Lawther. Plus all those 100+ mile rides he keeps posting scare me.[/quote] I think the heat is getting to him. He doesn't know when to quit riding. |
|
Title: Re: Fastest Recumbent Post by Opus the Poet on Aug 3rd, 2011, 11:37pm rmillay wrote:
But the force to overcome aerodynamic drag does. Your potential energy is a factor of both altitude and mass, and is expressed as the mass times the distance times the force of gravity expressed as an acceleration. |
|
Title: Re: Fastest Recumbent Post by power_bent on Aug 4th, 2011, 10:48am Bud wrote: But it's always been amazing to me how few people seem to know how weight really affects the speed of a bicycle. It doesn't take that much research to find out. And it's always struck me strange that the lightest riders, who will be the ones slowed down the most by a heavier bike, seem to never pay attention to bike weight when they buy, while the heavy riders, who will be affected very little by bike weight, turn into bike weight weenies. Go figure. [smiley=shrug.gif][/quote] Hey Bud I can relate to what you said. That being said, my lightest bike that i owned was the Thunderbolt bike and it was the fasted that i've riden on the flats and climbimg.My others bikes beside my trike has been close to that. My homebuilt heavy bike on flats is ok but when i come to the hills it get me real bad.. |
|
Title: Re: Fastest Recumbent Post by Bud_Bent on Aug 4th, 2011, 11:30am power_bent wrote:
Yeah, in a sport where we refer to everyone over 200 pounds as Cyldesdales, someone your size doesn't have a lot to pick from, when it comes to bikes and even parts for them. My hat's off to you for sticking with it, even after your injury. |
|
Title: Re: Fastest Recumbent Post by power_bent on Aug 4th, 2011, 11:46am Hey I'm trying, It going to click someday. lol I'm just glad there suck a thing as recumbent , otherwise i wouldn't be riding.. |
|
Title: Re: Fastest Recumbent Post by FlyingLaZBoy on Aug 4th, 2011, 12:06pm It's the Pinewood Derby factor -- heaviest car wins... the mass inertia helps overcome wind resistance. |
|
Title: Re: Fastest Recumbent Post by power_bent on Aug 4th, 2011, 12:31pm :) [smiley=laugh.gif] ;D [smiley=lolk.gif] [smiley=vrolijk_26.gif] |
|
Title: Re: Fastest Recumbent Post by jdviz on Aug 4th, 2011, 4:54pm Elizabeth and I both have the same bike. Uphill, she drops me regularly. Down hill, I'll coast past her, even if she's still pedaling furiously. I weigh 225, she weighs 120. (Shhhh, don't tell I told). Bikes weigh 40+... |
|
Title: Re: Fastest Recumbent Post by power_bent on Aug 4th, 2011, 7:24pm Thanks JD |
|
rbent Forum » Powered by YaBB 2.1! YaBB © 2000-2005. All Rights Reserved. |