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#11
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Fastest speed on a coker?
On Wed, 3 Sep 2003 13:01:15 -0500, Ken Fuchs wrote: To calculate wheel size, one must ride a carefully measured one turn of the wheel or several turns / number of turns. Measuring my wheel without riding resulted in a circumference that was about 2% longer (2839mm) than measuring when riding (2834mm). Riding appears to compress the tire slightly, giving a smaller than expected circumference. Ken, you've probably made a typo in the numbers or misplaced a decimal point. The difference between those two rollouts is actually about 0.18%. There is also unclarity in my mind about the definition of 'speed'. I can think of two definitions for speed. One is the circumference of the wheel multiplied by the cadence, I call that tyre speed. The other is the distance covered per unit of time, I call that road speed. The two are different for (again) two reasons; for both of these, their effect is in the same direction: 1. Wobble. 2. Tyre compression. The first is fundamental, and it is a philosophical question what the 'best' definition of speed would be. The second could be avoided by measuring the rollout while sitting on the uni. I measured the rollout of my wheels when unloaded but when I sit on them the tyre compresses and the effective wheel radius decreases. According to my measurements, the two effects combined cause a difference on the order of 3%. Klaas Bil -- Klaas Bil - Newsgroup Addict ------------------------------------------------------------------------ Klaas Bil's Profile: http://www.unicyclist.com/profile/3442 View this thread: http://www.unicyclist.com/thread/27287 |
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#12
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Fastest speed on a coker?
Klaas Bil wrote: *I can think of two definitions for speed. One is the circumference of the wheel multiplied by the cadence, I call that tyre speed. The other is the distance covered per unit of time, I call that road speed. The first is fundamental, and it is a philosophical question what the 'best' definition of speed would be. * With all due respect.... Philosophy Shmilosophy. If you're racing your Coker against a car, and when you get to your max speed and they're still with you they yell their speedometer reading out the window at you for encouragement, what is the number they're yelling? TB "Putting the "oup" in "newsgroup"..... -- tomblackwood - Registered Nurtz My other brake is my face! ------------------------------------------------------------------------ tomblackwood's Profile: http://www.unicyclist.com/profile/3762 View this thread: http://www.unicyclist.com/thread/27287 |
#13
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Fastest speed on a coker?
tomblackwood wrote: *Philosophy Shmilosophy. If you're racing your Coker against a car, and when you get to your max speed and they're still with you they yell their speedometer reading out the window at you for encouragement, what is the number they're yelling?* Thank you for the example because that refers precisely to my point. A car has no wheel wobble to speak of - or something is terribly wrong. So they are yelling your road speed (in my terms). If you have calibrated your cyclometer on a straight (and loaded) rollout it measures your tyre speed. The difference is (in my experiments) about 3%. Shmilosophy? You may call it that but I wouldn't. Klaas Bil -- Klaas Bil - Newsgroup Addict ------------------------------------------------------------------------ Klaas Bil's Profile: http://www.unicyclist.com/profile/3442 View this thread: http://www.unicyclist.com/thread/27287 |
#15
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Fastest speed on a coker?
Klaas Bil wrote: *Shmilosophy? You may call it that but I wouldn't.* Deal.... -- tomblackwood - Registered Nurtz My other brake is my face! ------------------------------------------------------------------------ tomblackwood's Profile: http://www.unicyclist.com/profile/3762 View this thread: http://www.unicyclist.com/thread/27287 |
#16
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Fastest speed on a coker?
The way speed is usually measured in sports competitions is by timing something over a measured distance. This is how it's done for runners, race cars, and bikes. This gives the rider the freedom to zig zag all they want, or not, as whatever "speed" is contained in those motions it's irrelevant to getting from A to B. Onboard cyclometers are good for training and comparison from one ride to the next, but are not real good for comparing one to another. To do so accurately, calibration must be very accurate on the part of both riders. It would (should) not be used in setting speed records, or racing. All of that said, there are a few "recognized" existing records out there. We race 10k fairly regularly, though I don't know what the record is. That should be researchable, and the fastest time is probably from one of the last three UNICONs. Hopefully their 10k distances were all accurately measured. This can establish for us a 10k speed record. I remember reading a thing from 1888 or so, in which a guy went out and established speed records in one mile increments all the way up to 14.8 or so. This was how far he got in an hour. In 1888! His wheel size is unknown, but was probably in the range of common bike front wheels of the day. The IHPVA (International Human Powered Vehicle Association) keeps speed records for various types of pedal powered vehicles. In 1986 or 7, Floyd Beattie went to their meet in Indianapolis and set a "sprint" record, using their 200 meter speed trap. To establish a record, you must ride the course in both directions, and then the two times are averaged to eliminate wind effects. He was riding on a brand new 45" Tom Miller big wheel, that had just been assembled so he wasn't yet used to it. I don't remember the details, but his times meant a speed of about 23 mph. That's the only such record I know of for top speed over a short distance. Even Floyd knows it wasn't that fast, and I'm sure he could have gone much faster after getting acquainted with the cycle. Floyd Beattie also did an hour record on a velodrome. He was a purist about the whole thing, and only drank the water he carried with him, refusing to pick up any he hadn't brought along. Anyway, he used up all his water pretty quick, got dehydrated, and then had to "retire" in the last few minutes to heave ho. He covered something like 14.89 miles, about the same as the guy in 1888. This is from memory; not sure about the exact numbers other than that it was real close to 15 miles. Of course we know the 100 mile record is 6:44, which is amazingly fast over such a long distance. That one is also supposedly the world record for longest unicycle ride without a dismount (Takayuki Koike, 1987). The Budweiser Rocket Car, making a run at the land speed record in 1982 or so, went up onto its single front wheel for more than 100' when shockwaves formed on the rear part of the car. That's the world's fastest *powered* unicycle. Brett Bymaster has done gliding at speeds over 20mph, which is pretty dang scary. He says he has approached 25, but I don't know if he ever quite got there. That's just dangerous. Someone in Germany, maybe Arne Tilgen (?) has gone over 40 kph gliding, while being towed by a motorcycle. Possibly the fastest glide I ever saw was done by Yuichiro Kato at UNICON IV in 1988, at the world's first-ever Gliding competition. He went flying down that hill at an unknown speed, his pedals a blur, until he lost it and went sliding about 10m on his hands and knees. Fortunately that was also the first year UNICON required everyone to wear kneepads and gloves! He was unharmed. His second run was much more conservative, and he didn't win. The winner of the contest was Fuyuki Tsuchiya, who now works for Miyata and the JUA, and may be one of the hosting persons at UNICON next summer. Coasting? You just don't go fast. I've never seen anyone coast faster than they do in one of our flat-ground coasting competitions. To do it downhill would be spectacular to watch, but very dangerous for the rider. So, I believe what I've heard about Christian Hoverath. He's probably the fastest unicyclist on earth, but it's unofficial. He's got to do some kind of repeatable speed trap record for it to be a "real" record. 30mph? I'm not going that fast... -- johnfoss - Now riding to work John Foss the Uni-Cyclone www.unicycling.com ________________ "Where's my kids?" -- Amy Drummond "Where's my unicycle?" -- Andy Cotter spoken one right after the other, mostly to themselves, at NAUCC 2003 ------------------------------------------------------------------------ johnfoss's Profile: http://www.unicyclist.com/profile/832 View this thread: http://www.unicyclist.com/thread/27287 |
#17
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Fastest speed on a coker?
Good stuff John. According to Brett's (now dead) High Speed Gliding page, he's gone 25.5mph gliding. In case you're not really sure what gliding is, vs coasting, check out these photos of Brett and John: http://www.unicycling.org/unicycling/skills/glide.html John, remember that time at Tahoe when Brett decided to glide down that steep hill by the cabin before we left for Mr Toads? No safety gear, no nothing, in seconds he was FLYING down that hill. I think he said that run felt like under 20mph, so I'd hate to see 25.5. ---Nathan -- nathan - BIG rides: Muni & Coker ------------------------------------------------------------------------ nathan's Profile: http://www.unicyclist.com/profile/251 View this thread: http://www.unicyclist.com/thread/27287 |
#18
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Unicycle computer calibration [was Fastest speed on a Coker?]
On Thu, 4 Sep 2003 12:48:17 -0500, Ken Fuchs
wrote: So to get an accurate wheel circumference, one really should ride a long accurately measured course in the way one expects to ride. One should go about the speed one most often expects to go. The Q factor is a constant for the Coker until the hub is changed. The Wobble mass is a constant for the Coker and rider until the cranks/pedals are changed or the rider bulks up (or loses weight in) his legs. If one gets an accurate wheel rotation count, one can simply divide the distance by the count to get the effective wheel circumference, including both wobble and tire compression effects. Otherwise, one can simply enter one's best guess of the effective wheel circumference. Ride the measured course and compare the real (measured) distance to the computer's distance. Compute the difference as a +/- percentage and adjust the computer's circumference by the same percentage. That is all clear. Of course we have to bear in mind that the difference between the two kinds of speed is only of the order of 1%, as pointed out by Ken. So many people would consider the following argument to be nitpicking; but hey, I like to pick a nit every now and then :-) It is a matter of taste what one should consider as the real speed (or real distance, for that matter). Probably most would agree that road speed is real speed, or 'effective' speed as Ken almost called it. Yet, contradictorily (SP?), most people seem to calibrate their computers on a straight-line rollout, sometimes even unloaded. However, tyre speed (and distance) are equally real in their own right. For one thing, tyre speed is the real physical speed with which the tyre contact point travels. Also, tyre distance (as opposed to road distance) determines tyre wear (combined with a lot of other factors, including funnily enough wheel wobble in itself). And when you race between a start line and a finish line 100 metres apart, the wheel will actually have travelled (say) 101 metres, in a wobbly line indeed. Not being able to make a single choice in this matter, the spreadsheet in which I record my road rides calculates both tyre speed and road speed. Klaas Bil - Newsgroup Addict -- I go a sort of ok speed on my Coker... - Roger Davies |
#19
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Fastest speed on a coker?
The high speed gliding page lives! http://www.unicycling.com/brett/hsg.shtml Brett hasn't maintained his content in a long time. He basically turned it over to me, so it's waiting in line, behind my own site, to be brought together and updated. That includes the "Official MUni FAQ," circa 1998 or so... -- johnfoss - Now riding to work John Foss the Uni-Cyclone www.unicycling.com ________________ "Where's my kids?" -- Amy Drummond "Where's my unicycle?" -- Andy Cotter spoken one right after the other, mostly to themselves, at NAUCC 2003 ------------------------------------------------------------------------ johnfoss's Profile: http://www.unicyclist.com/profile/832 View this thread: http://www.unicyclist.com/thread/27287 |
#20
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Fastest speed on a coker?
On Thu, 4 Sep 2003 12:48:17 -0500, Ken Fuchs wrote: So to get an accurate wheel circumference, one really should ride a long accurately measured course in the way one expects to ride. One should go about the speed one most often expects to go. The Q factor is a constant for the Coker until the hub is changed. The Wobble mass is a constant for the Coker and rider until the cranks/pedals are changed or the rider bulks up (or loses weight in) his legs. If one gets an accurate wheel rotation count, one can simply divide the distance by the count to get the effective wheel circumference, including both wobble and tire compression effects. Otherwise, one can simply enter one's best guess of the effective wheel circumference. Ride the measured course and compare the real (measured) distance to the computer's distance. Compute the difference as a +/- percentage and adjust the computer's circumference by the same percentage. That is all clear. Of course we have to bear in mind that the difference between the two kinds of speed is only of the order of 1%, as pointed out by Ken. So many people would consider the following argument to be nitpicking; but hey, I like to pick a nit every now and then :-) It is a matter of taste what one should consider as the real speed (or real distance, for that matter). Probably most would agree that road speed is real speed, or 'effective' speed as Ken almost called it. Yet, contradictorily (SP?), most people seem to calibrate their computers on a straight-line rollout, sometimes even unloaded. However, tyre speed (and distance) are equally real in their own right. For one thing, tyre speed is the real physical speed with which the tyre contact point travels. Also, tyre distance (as opposed to road distance) determines tyre wear (combined with a lot of other factors, including funnily enough wheel wobble in itself). And when you race between a start line and a finish line 100 metres apart, the wheel will actually have travelled (say) 101 metres, in a wobbly line indeed. Not being able to make a single choice in this matter, the spreadsheet in which I record my road rides calculates both tyre speed and road speed. Klaas Bil -- Klaas Bil - Newsgroup Addict ------------------------------------------------------------------------ Klaas Bil's Profile: http://www.unicyclist.com/profile/3442 View this thread: http://www.unicyclist.com/thread/27287 |
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