Kiwi

At 40km/h 90% of a rider?s energy is used up by aero drag. Aero drag is very relevant to every cyclist.Kiwi2008-12-04 08:47:34

If you want 29ers, we have them! http://www.planet-x-bikes.co.za/Category.aspx?CategoryID=50 Hub Thread: https://www.bikehub.co.za/forum_posts.asp?TID=32319&PN=1 Look under the Special Offers section and we also have a Rolling Chassis offer to allow you to swap over your 26er to a 29er and save R900.00 as well! Pics should be on the website tonight, Hub Banner to follow... How good are they? Just Google On One Scandal 29er and check the reviews around the world.

So that acceleration was done using 18w less. OK, most accelerations wont be as strong as that but over a 100km race think about how many accelerations a rider does, over the tops of hills, closing gaps, matching the pace of the riders around them etc. <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" /> How many watts or kilojoules less would the rider on the lighter wheels expend? If you have a power meter it would make some interesting data. If you look at the races where you haven't made it across the crucial gap or you just couldn't quite come around a rider in the sprint to get that podium placing etc. and you think about what if you had those extra joules of energy still in your legs? I'm saying that?s where something like lighter rims could seal the deal.

I think we have lost track of what the original question was: <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" /> And I was say it is because they are more complicated to make and weigh less. I'm saying the 100 grams saved on each wheel at the rim (carbon rim with alloy braking surface vs. full carbon rim and braking surface) is significant and will make a difference to your ride. I totally agree that the weight savings of lighter or fewer nipples or nipples moved to the hub end of the spoke is negligible. Kiwi2008-11-28 12:20:36

Yes, exactly. That's what I am saying!

Edmund R. Burke Ph.D Much like his mentors and associates, Dr. Burke gained worldwide renown. Professionals in the fields of exercise physiology, nutrition and medicine are familiar with his exceptional work ethic and reputation as an author, scientist and educator. His 39 page curriculum vitae speaks for itself as it reveals some of his outstanding career accomplishments, including over 1,000 articles and many book chapters and books that he wrote and published in the areas of health, sport science and applied physiology. He served as Coordinator of Sports Sciences for the U. S. Cycling Team leading up to the Olympic Games in 1996 and was a staff member for the 1980 and 1984 Olympic Cycling Teams. Some of his books: http://www.pickabook.co.uk/typesearch.aspx?Type=authorisbn&Code=9781583331460&Key=Edmund%20R.%20Burke Also: "Kiwi, you posted the full force equation. If you substiture values into this equation for wheels of different Ir (rotational inertia) but the same mass, and calculate acceleration, it will show that Ir has a very very small effect on everything. " Different wheels with different Ir are different because their mass is different. Looking at the table I posted you can see a lighter wheel has a lower Ir and a heavier wheel such as the mountain bike wheel at the other end of the table has a higher Ir. Rotational Inertia and Mass for Various Wheels Wheel Details Ic (kg m^2) Mass (gm)Wire SpokeRear, Std Rim, 700, track, 36 spokes, w/o tire, w/ axle, nuts 0.0528 1177Wire SpokeFront, Std Rim, 700, 32 spokes, w/ tire, tube, rim strip, axle, skewer 0.0885 1264Wire SpokeRear, Std Rim, 700, 32 spokes, w/12-21 cassette, tire, tube, rim strip, axle, skewer 0.0967 1804Specialized tri-spokeFront, 700, w/ tire, tube, axle, skewer 0.0904 1346Specialized tri-spokeRear, 700, w/ 12-21 cassette, tire, tube, axle, skewer 0.1032 1771Specialized tri-spokeFront, 650, w/ tire, tube, axle, skewer 0.0683 1207MavicFront, Std Rim, 650, 28 Bladed Spokes, w/ tire, tube, rim strip, axle, skewer 0.0632 1179MTBFront, 32 Spokes, w/ tire, tube, rim strip, axle, skewer 0.1504 1847 I'm not suggesting anyone should believe me, this is something very easy to find out for yourself. Strap on some wheels in the 1800 gram range, do a race, then strap on something in the 1400 gram range and do a race and you can feel the difference. As I suggested do the above with a power meter and you can measure the difference.

He we go, I cut the relevant bit out for you: Wheel Rotational Inertia It's easy to calculate a wheel's rotational inertia using a kitchen scale, a stopwatch, and a tape measure. The general approach is to measure the time period for a wheel swinging at the end of a pendulum. See Figure 1. From the time period of a swing, one can calculate the rotational inertia of the wheel about the point of rotation of the pendulum. The rotational inertia about the point of rotation of the pendulum can be transformed into the rotational inertia about the center of gravity of the wheel. http://www.analyticcycling.com/WheelsConcept_WheelFor2Blue.gif http://www.analyticcycling.com/Figure1.gif Most of the error of the method comes from measuring the period. Timing 100 swings and dividing by 100 gives a good estimate. This minimizes the error of starting and stopping the stopwatch by hand. A pendulum has the property that its period is constant as it slows down. Take care that the wheel swings in the same plane at all times. The method will be invalid if it does not. Go to Calculation of Inertia to calculate rotational inertial for your own wheels. Data on some wheels is shown in the following table. Wheels were complete, meaning they had tires, tubes, rim strips, rims, spokes, hub, skewers, free wheels, just like they would be ridden. As individual components, rims lend themselves to calculation of rotational inertias; tires and tubes don't. There is a large variation between advertised weights and actual weights as manufactured. More real-world, meaningful results come, in my opinion, from measuring wheels in an "as ridden" state. Hence the values here are for fully rideable wheels, just like the ones handed to you from your support vehicle. Rotational Inertia and Mass for Various Wheels Wheel Details Ic (kg m^2) Mass (gm)Wire SpokeRear, Std Rim, 700, track, 36 spokes, w/o tire, w/ axle, nuts 0.0528 1177Wire SpokeFront, Std Rim, 700, 32 spokes, w/ tire, tube, rim strip, axle, skewer 0.0885 1264Wire SpokeRear, Std Rim, 700, 32 spokes, w/12-21 cassette, tire, tube, rim strip, axle, skewer 0.0967 1804Specialized tri-spokeFront, 700, w/ tire, tube, axle, skewer 0.0904 1346Specialized tri-spokeRear, 700, w/ 12-21 cassette, tire, tube, axle, skewer 0.1032 1771Specialized tri-spokeFront, 650, w/ tire, tube, axle, skewer 0.0683 1207MavicFront, Std Rim, 650, 28 Bladed Spokes, w/ tire, tube, rim strip, axle, skewer 0.0632 1179MTBFront, 32 Spokes, w/ tire, tube, rim strip, axle, skewer 0.1504 1847 Equations of Motion Wheel weight and wheel rotational inertia matter when a rider and bike are accelerating. Drag matters whenever a rider and bike are moving. It is not enough to estimate rider and bike performance under constant conditions. Differential equations are used to describe motion under transient conditions. Such equations let us evaluate the combined effect of wheel weight, rotational inertia, and drag. The following differential equation, with an appropriate starting point and initial speed, describes the position, speed, and acceleration of a rider over time. Using this equation, a comparison can be made between a "Standard Rider" and a "Test Rider" to see the effect of various alternatives. This is the equations that is evaluated in each of the case studies presented here. http://www.analyticcycling.com/WheelsConcept_DiffEqMotionBlue.gif The best answer is to ride the two types of wheels of the same profile (full carbon clincher and alloy/carbon clincher) back to back so that you have just the rim weight to compare as that was what the original question was. I have the full carbon clincher and can get the same with alloy rim to compare (I also have the same wheel with the tubbie version of the rim if someone wants to compare that) then you just need a bike with a power meter and go and do a race and see for your self. I am sure when teams like CSC, Rabobank and Astana are looking at equipment that is what they do and also why they dont ride heavy wheels.Kiwi2008-11-28 07:47:39

http://www.analyticcycling.com http://www.analyticcycling.com/AnalyticCyclingLogo.gif http://www.analyticcycling.com/WheelsConcept_Heading.gif How much does a wheel's weight, rotating inertia, and drag affect performance? Topics on this page: Magnitudes of the Forces and Measurements Wheel Aerodynamics Table of Coefficients of Wheel Drag Wheel Rotational Inertia Table of Wheel Inertia and Mass Equations of Motion Forces on Rider Wheels are a small portion of the forces on a bike and rider. The differences between wheels are small. Ordinarily power can be measured to what is normally a small tolerance, say plus or minus 3%, maybe plus or minus 1% under ideal conditions. As the table below shows, a typical difference between wheels may be 1% or less. Clearly, another approach, other than direct power measurement, is needed. The table below gives typical values for the forces on two riders. The Standard Rider is on 32 hole standard wheels and the Test Rider is on Specialized tri-spokes. Forces are in grams of force since such forces are often quoted that way. Standard Rider Test Rider Force (gmf) % Force (gmf) % Speed (m/s) 10.76 10.76 Total Force on Rider 2337 100 2287 100Wind Resistance 1811 77.5 1811 79.2Rolling Resistance 304 13.0 304 13.3Gravity Force 0 0 0 0Drag on Front Wheel 127 5.4 98 4.3Drag on Rear Wheel 95 4.1 74 3.2 Wheel Aerodynamics A paper by D. I. Greenwell, et. al., entitled "Aerodynamic Characteristics of Low-Drag Bicycle Wheels", Aeronautical J., Vol. 99, No. 983, Mar. 1995, pp.109-120, has a good discussion of the aerodynamics of bicycle wheels. Conclusions by Greenwell et al: The total drag of the wheels is in the range of 10% to 15% of the total drag on a bike. Drag improvements between wheels can reduce this by 25%, or 2% to 3% of the total drag. Axial drag forces are difficult to measure precisely. Most single valued measurements should be suspect. Deep section aero wheels are better than a conventional 36 spoke wheel and are all about the same within the limits of measurement. Disk wheels are better yet. (Don't run a disk in front if there is any chance of wind.) The rotational drag on a wheel does not change as speed changes or with different wheels. The drag on the rear wheel is reduced by 25% due to the seat tube. The forgoing applies to zero yaw angle. Read the paper if you want to know the results for non-zero yaw angles. http://www.analyticcycling.com/WheelsConcept_WheelFor1Blue.gif Coefficients of Drag Reported for Various Wheels (1) Wheel CxoConventional 36-spoke 0.0491Campagnolo Shamal 16-spoke 0.0377HED CX 24-spoke 0.0379Specialized tri-spoke 0.0379FIR tri-spoke 0.0382HED disk (lenticular) 0.0361ZIPP 950 disk (flat sided) 0.0364 Please note that for the coefficients given in the above table, the conventional wheel is significantly different from the deep-section wheels, and deep-section wheels are significantly different from the disk wheels. However, there is no significant difference between the deep-section wheels or between the disk wheels. Wheel Rotational Inertia It's easy to calculate a wheel's rotational inertia using a kitchen scale, a stopwatch, and a tape measure. The general approach is to measure the time period for a wheel swinging at the end of a pendulum. See Figure 1. From the time period of a swing, one can calculate the rotational inertia of the wheel about the point of rotation of the pendulum. The rotational inertia about the point of rotation of the pendulum can be transformed into the rotational inertia about the center of gravity of the wheel. http://www.analyticcycling.com/WheelsConcept_WheelFor2Blue.gif http://www.analyticcycling.com/Figure1.gif Most of the error of the method comes from measuring the period. Timing 100 swings and dividing by 100 gives a good estimate. This minimizes the error of starting and stopping the stopwatch by hand. A pendulum has the property that its period is constant as it slows down. Take care that the wheel swings in the same plane at all times. The method will be invalid if it does not. Go to Calculation of Inertia to calculate rotational inertial for your own wheels. Data on some wheels is shown in the following table. Wheels were complete, meaning they had tires, tubes, rim strips, rims, spokes, hub, skewers, free wheels, just like they would be ridden. As individual components, rims lend themselves to calculation of rotational inertias; tires and tubes don't. There is a large variation between advertised weights and actual weights as manufactured. More real-world, meaningful results come, in my opinion, from measuring wheels in an "as ridden" state. Hence the values here are for fully rideable wheels, just like the ones handed to you from your support vehicle. Rotational Inertia and Mass for Various Wheels Wheel Details Ic (kg m^2) Mass (gm)Wire SpokeRear, Std Rim, 700, track, 36 spokes, w/o tire, w/ axle, nuts 0.0528 1177Wire SpokeFront, Std Rim, 700, 32 spokes, w/ tire, tube, rim strip, axle, skewer 0.0885 1264Wire SpokeRear, Std Rim, 700, 32 spokes, w/12-21 cassette, tire, tube, rim strip, axle, skewer 0.0967 1804Specialized tri-spokeFront, 700, w/ tire, tube, axle, skewer 0.0904 1346Specialized tri-spokeRear, 700, w/ 12-21 cassette, tire, tube, axle, skewer 0.1032 1771Specialized tri-spokeFront, 650, w/ tire, tube, axle, skewer 0.0683 1207MavicFront, Std Rim, 650, 28 Bladed Spokes, w/ tire, tube, rim strip, axle, skewer 0.0632 1179MTBFront, 32 Spokes, w/ tire, tube, rim strip, axle, skewer 0.1504 1847 Equations of Motion Wheel weight and wheel rotational inertia matter when a rider and bike are accelerating. Drag matters whenever a rider and bike are moving. It is not enough to estimate rider and bike performance under constant conditions. Differential equations are used to describe motion under transient conditions. Such equations let us evaluate the combined effect of wheel weight, rotational inertia, and drag. The following differential equation, with an appropriate starting point and initial speed, describes the position, speed, and acceleration of a rider over time. Using this equation, a comparison can be made between a "Standard Rider" and a "Test Rider" to see the effect of various alternatives. This is the equations that is evaluated in each of the case studies presented here. http://www.analyticcycling.com/WheelsConcept_DiffEqMotionBlue.gif

Once you accelerate a wheel up to speed the energy to maintain that speed on a light or heavy wheel should be the same if the are both aerodynamically similar. <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" /> That's why wheel weight isn't such an issue when you are doing a TT or non drafting Tri. The moment you need to speed up or slow down weight become the biggest factor. When was the last time you did a road race and held the same speed through out?

Edmund R. Burke, Ph.D. "Lastly, low weight in rotating components is even more important. To accelerate a wheel or pedal and shoe system, kinetic energy of rotation must be supplied, in addition to the kinetic energy of linear motion. For example, with a wheel, if the weight is mostly concentrated in the rim and tire it would take nearly double the energy needed to accelerate it than an equal nonrotating weight. In other words, one pound added to a wheel or shoe/pedal system is equivalent to nearly two pounds on the bicycle frame." http://www.active.com/cycling/Articles/The_effect_of_weight_on_speed.htm

Rim Weight Specifically, Wikipedia. _lots of stuff here about what makes a bicycle go faster: Kinetic energy Consider the kinetic energy and "rotating mass" of a bicycle in order to examine the energy impacts of rotating versus non-rotating mass. The translational kinetic energy of an object in motion is:[8] http://upload.wikimedia.org/math/b/0/0/b00285433cb3b36e23433488fff606d7.png, Where E is energy in joules, m is mass in kg, and v is velocity in meters per second. For a rotating mass (such as a wheel), the rotational kinetic energy is given by http://upload.wikimedia.org/math/c/a/f/caf45c982f47131b7a9ca1f4cd83a8f8.png, where I is the moment of inertia, ω is the angular velocity in radians per second. For a wheel with all its mass at the outer edge (a fair approximation for a bicycle wheel), the moment of inertia is I = mr2. Where r is the radius in meters The angular velocity is related to the translational velocity and the radius of the tire. As long as there is no slipping, http://upload.wikimedia.org/math/5/7/d/57dfe9909c4f90a93032f39a6155150d.png. When a rotating mass is moving down the road, its total kinetic energy is the sum of its translational kinetic energy and its rotational kinetic energy: http://upload.wikimedia.org/math/a/a/b/aab3ae9a2733fd83162f82c2f8054762.png Substituting for I and ω, we get http://upload.wikimedia.org/math/1/5/9/15909f0a24a703c95014ed6c27dc1d82.png The r2 terms cancel, and we finally get http://upload.wikimedia.org/math/4/4/b/44b416d99429ab5dfe0ebb8715003d60.png. In other words, a mass on the tire has twice the kinetic energy of a non-rotating mass on the bike. There is a kernel of truth in the old saying that "A pound off the wheels = 2 pounds off the frame."[9] This all depends, of course, on how well a thin hoop approximates the bicycle wheel. In reality, all the mass cannot be at the radius. For comparison, the opposite extreme might be a disk wheel where the mass is distributed evenly throughout the interior. In this case http://upload.wikimedia.org/math/a/d/4/ad4dc0c24a3759e70f5c385d981b9986.png and so the resulting total kinetic energy becomes http://upload.wikimedia.org/math/4/2/e/42eb5eba1f7282e44cf46b09907f6561.png. A pound off the disk wheels = only 1.5 pounds off the frame. Most real bicycle wheels will be somewhere between these two extremes. One other interesting point from this equation is that for a bicycle wheel that is not slipping, the kinetic energy is independent of wheel radius. In other words, the advantage of 650C or other smaller wheels is due to their lower weight (less material in a smaller circumference) rather than their smaller diameter, as is often stated. The KE for other rotating masses on the bike is tiny compared to that of the wheels. For example, pedals turn at about http://upload.wikimedia.org/math/5/4/b/54bbd68cb89bf41f5bf194531c037bc0.png the speed of wheels, so their KE is about http://upload.wikimedia.org/math/8/1/9/81949794e9c5db48fcc9083f236eaf7b.png (per unit weight) that of a spinning wheel.

Cane Creek: Physicists use the term Moment of Inertia (MOI) to describe the effects of mass during rotation. And MOI is one of the forces working against you every time you accelerate. More than 95% of the MOI associated with propelling a bicycle is attributable to the wheels. This means that gram for gram, your wheels are your bike?s most critical components. One of the ways our engineers minimize MOI is by locating Cane Creek spoke nipples at the hub. To understand how dramatically this affects acceleration, imagine if we moved the nipples to the traditional location at the rim: Given a nipple weight of 0.27 grams, the effect on the wheel?s MOI would be the same as if we?d replaced them with nipples weighing 48.55 grams. Wikipedia: http://en.wikipedia.org/wiki/Moment_of_inertia The easiest way to see the difference is to ride an alloy rim carbon clincher back to back against a full carbon one and see for your self. You are welcome to take our demo Planet X Full Carbon Clinchers out to see for your self.<?: prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Making the hook bead in full carbon is really tricky to do. There is a huge amount of side wall pressure from the tube that a tubular doesn't have to contend with because the tubular casing looks after that. Then there is heat build up which has to be dissipated to prevent a possible blow-out under heavy braking. <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" /><?: PREFIX = O /> That's why a lot of manufacturers chicken out and bond on an alloy rim. The pay-off of an all carbon clincher is that you are looking at 100grams per rim lighter than the equivalent alloy rim. A point to remember is that weight on the edge of the wheel, eg the rim and tire, increases at the square of the speed. So a 100 grams saved at the rim will have a much bigger effect than a lighter frame for instance. As long as you use carbon compatible brake pads the rim will last as long as any high performance alloy rim.Kiwi2008-11-28 02:45:12

That's the the one MintSauce! http://www.ibiscycles.com/road/hakkalugi/ http://ibiscycles.com/store/old_parts/ http://ibiscycles.com/images/lugi_hj.gifKiwi2008-11-26 04:53:00

Things the Police never mention after another one of us gets whacked on the roads: "The research showed that nationally motorists tested positive for alcohol in 28 percent of the 269 cases tested, whereas positive drug results were obtained in 14 percent," the report said. "After alcohol, amphetamines, methamphetamine and cocaine were the most common drugs of impairment. "There were 14 cases where drivers tested positive for alcohol and drugs, but there were many more where the drivers tested positive only for drugs. Previously their impairment would have gone undetected." A Cape traffic official was among four people arrested in Veldrift on Wednesday for the alleged illegal issuing of learner's and driver's licenses, said West Coast police. http://www.iol.co.za/index.php?set_id=1&click_id=181&art_id=vn20081126060319760C235514 http://www.iol.co.za/index.php?set_id=1&click_id=13&art_id=nw20081126095746885C991269

I made this table a little while ago, I'm pretty sure it's accurate (as long as you believe the manufacturers weights) SRAM 2008Shimano 2008Token 2008Campagnolo 2009 RivalForceRed Dura AceUltegra SL105 AXCX Super Record 11Record 11Chorus 11Shifters320303280 420447500 398398 331338339Front Mech Braze-On888858 748995 99102 727576Rear Mech188178153 180219221 190195 172179192Freewheel 11-23220210160 173217219 9696 177201236Chain265257257 280280280 240240 212212224Brake Calipers287280265 314320359 288211 275282318Cranks (Std) + BB854791760 740788836 820755 689699739Groupset22222107193321812360251021311997192819862124

Damn Pump Fixing Ferries! ? & ? <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" />

HR that bike is something else. The hangers on there, nice!

Thanks Calabash! Best pic so far there for me: http://p1.pinkbike.com/photo/2705/pbpic2705311.jpg

That pic with the cable hangers is my desktop now, just looking at it makes me smile! I dont know where they come from (yet!) I'm sure there was something on cyclingnews a while back with something similar. Beyond cool thats for sure...

I think I will have to do the same! Just the pics alone are so cool.

Probably old news, but for those who haven't checked it out: http://bikemag.com http://bikemag.com/features/onlineexclusive/DiabloFreeridePark.jpg http://bikemag.com/features/onlineexclusive/HandJob_web.jpg

Making the hook bead in full carbon is really tricky to do. There is a huge amount of side wall pressure from the tube that a tubular doesn't have to contend with because the tubular casing looks after that. Then there is heat build up which has to be dissipated to prevent a possible blow-out under heavy braking. <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" /> That's why a lot of manufacturers chicken out and bond on an alloy rim. The pay-off of an all carbon clincher is that you are looking at 100grams per rim lighter than the equivalent alloy rim.