I have the skewer tight but not overly as they are carbon tips on the fork.It is never a problem just annoying.But now I have a DuraAce front wheel may get ride of the SL.artemidorus wrote:You mean you loctite the preload cap thread and it still loosens? How tight do you have your skewers? They are supposed to lock the cap on the axle.toolonglegs wrote:Mine will get play during a ride.Even if (and I have) pulled the axle out and loctited it it still comes loose.
Wheel Build
- toolonglegs
- Posts: 15463
- Joined: Fri Jun 29, 2007 7:49 pm
- Location: Somewhere with padded walls and really big hills!
Postby toolonglegs » Tue Nov 27, 2007 11:16 am
-
- Posts: 118
- Joined: Fri Feb 23, 2007 11:27 am
- Location: Sydney
Postby artemidorus » Tue Nov 27, 2007 11:27 am
Moment of inertia of a bicycle wheel has been shown to make a vanishingly tiny difference to acceleration. It simply isn't worth worrying about. Reference below.Kid_Carbine wrote: When it comes to weight in wheels, I still ponder what it is that we are actually weighing.
Is it the mass of the whole wheel assembly complete? If so, then why leave out the skewer? [when used]
Is it the rotating mass of the wheel? If so, then why include the axle & cones?
If just bare overall weight of the finished bike is so important, then a laxative before riding would help as would leaving the bidon behind, but we never do these [well I don't] so it's really the rotating mass of the wheel that is really the important component
If we are looking for a 'lively' wheel, then surely we need to reduce the mass of the rim as this is where the greatest inertia is. [flywheel effect] This is the part that sees the greatest linear acceleration rates while the hub mass, being located so much closer to the center, will offer much less rotational inertia, gramme for gramme, so a wheel with a heavier hub & light rim would [theoretically] perform better than an identical weight wheel with light hub & heavier rim.
What I'm saying here is that it's not just the actual weight of the wheel by itself, that affects performance, but where the weight is located.
Your thoughts?
Only the overall weight of a wheel makes a difference, and even that is trivial for everyone except a high-cat racer. Maximum 1-2% difference between the best and worst wheels when climbing, less otherwise. Aerodynamics are a different matter, but also make only up to about 1% difference.
So, it really comes down to whatever tickles your fancy when you buy wheels.
Reference: The following was posted by "McM" on a weight weenies forum:
I can't believe that people keep arguing that rotating mass climbs slower than non-rotating mass under the same power. When you are working against gravity, mass is mass, it doesn't matter if it rotates or not. The idea that micro-accelerations due to pedal force fluctations make a difference in the overall picture is a strawman. During pedal force fluctuations, accelerations are decelerations cancel out. All that really matters is average power output vs. gravity.
Since Ras11 complained that no math has been offered, I decided to set up a model to simulate the accelerations/decelerations due to pedal fluctuations. The equations and variable values were taken from the Analytic Cycling web page.
Pedaling force: The propulsion force (from pedaling) was modeled as a sinusoidal. Since it is assumed average power is constant, the nomimal drive force will vary inversely with velocity. So, the propulsion force is modeled as:
Fp = (P/V)(1+Sine(2RT))
Fp = Propulsion force (pedaling)
P = Average power
V = Velocity
R = Pedaling revolution rate
T = Time
(Note: The angle in the sine term is double the pedal revolution rate, since there are two power strokes per revolution)
The drag forces on the rider are aerodynamic drag, rolling resistance, and gravity. These three terms together are:
Fd = (1/2)CdRhoAV^2 + MgCrrCosine(S) + MgSin(S)
Fd = drag force
Cd = Coefficient of aerodynamic drag
Rho = Density of air
A = Frontal area
M = total mass of bike and rider
Crr= Coefficient of Rolling Resistance
g = Acceleration of gravity
S = Slope of road
The total force is thus:
F = Fp - Fd
From Newton's second law, the equation of motion is:
dV/dt = F/I
I = Inertia
Because there is both rotating and non-rotating mass, total mass and total inertial will not be the same. Because mass at the periphery of the wheel as twice the inertia as non-rotating weight, the total mass and inertia of a bike are:
M = Ms + Mr
I = Ms + 2Mr
Ms = Static mass
Mr = Rotating mass
The complete equation of motion is thus:
dV/dt = {(P/V)(1+sin(2RT)) - [ (1/2)CdRhoAV^2 + (Ms+Mr)gCrrCosine(S) + (Ms+Mr)gSine(S) ] } / (Ms + 2Mr)
This equation is non-linear, so I solved it numerically with a 4th order Runge-Kutta numerical differentiation.
Borrowing the default values in the Analytic Cycling web page for "Speed given Power" page, the values used are:
P = 250 Watts, Cd = 0.5, Rho = 1.226 Kg/m^3, A = 0.5 m^2, Crr = 0.004, g = 9.806 m/s^2, S = 3% (= 1.718 deg.)
For this simulation, the pedal revolution rate was selected as 540 deg/sec. (90 rpm cadence)
To solve this equation, a 4th order Runge-Kutta numerical differentiation was set up using an Excel spread sheet. Step size was selected at 0.01 sec., and the initial Velocity was 1 m/sec. The solution was calculated for 3 cases of equal total mass, but different distributions of static and rotating mass, calculated over a 200 second period, by which time each case had reached steady state. As expected, the velocity oscillated with the pedal strokes. The average, maximum, and minimum velocities during the oscillilations during stead state were:
Case 1:
Ms = 75 kg, Mr = 0 kg (0% rotating mass)
Average Velocity: 7.457831059 m/s
Maximum Velocity: 7.481487113 m/s
Minimum Velocity: 7.434183890 m/s
Speed fluctuation: 0.047303224 m/s
Case 2:
Ms = 70 kg, Mr = 5 kg (5.33% rotating mass)
Average Velocity: 7.457834727 m/s
Maximum Velocity: 7.480016980 m/s
Minimum Velocity: 7.435662980 m/s
Speed fluctuation: 0.044354000 m/s
Case 3:
Ms = 65 kg, Mr = 10 kg (10.67% rotating mass)
Average Velocity: 7.457837584 m/s
Maximum Velocity: 7.478718985 m/s
Minimum Velocity: 7.436967847 m/s
Speed fluctuation: 0.041751139 m/s
These results agree very strongly with the solution on the Analytic Cycling web page, which predicted an average speed with constant power of 7.46 m/s (16.7 mph)
The results show that as expected, the smaller the percentage of rotating mass, the greater the magnitude of the velocity oscillations (which are quite small). But a more interesting result is in the average speed. As the amount of rotating mass decreased, the more the average velocity _decreased_, not increased (at steady stage). This result is actually not unexpected. The drag forces are not constant, but vary with velocity, especially aerodynamic drage (Because aerodynamic drag increases with the square of velocity, power losses are increase out of proportion with speeds - so, for example, aerodynamic losses at 20 mph are 4 times as much as they would be at 10 mph). Because speed fluctuates as the propulsion force oscillations, in the cases of the low rotating mass, the maximum peak speeds reached are higher than for the cases with the high rotating mass. This means that when a lower percentage of rotating mass there will be greater losses during the speed peaks. Because of the total drag losses will be greater over the long run, the greater momentary accelerations with lower rotating mass actually results in a lower average speed.
To see what happens at a steeper slope, which will have a lower speed (and presumably larger speed oscillattions), I ran the model again with a 10% (5.7 deg.) slope. Here are the results:
Case 1:
Ms = 75 kg, Mr = 0 kg (0% rotating mass)
Average Velocity: 3.217606390 m/s
Maximum Velocity: 3.272312291 m/s
Minimum Velocity: 3.162540662 m/s
Speed fluctuation: 0.109771630 m/s
Case 2:
Ms = 70 kg, Mr = 5 kg (5.33% rotating mass)
Average Velocity: 3.217613139 m/s
Maximum Velocity: 3.268918539 m/s
Minimum Velocity: 3.165997726 m/s
Speed fluctuation: 0.102920813 m/s
Case 3:
Ms = 65 kg, Mr = 10 kg (10.67% rotating mass)
Average Velocity: 3.217618914 m/s
Maximum Velocity: 3.265921742 m/s
Minimum Velocity: 3.169047012 m/s
Speed fluctuation: 0.096874730 m/s
This data follows the same pattern as above. The speed oscillations (micro-accelerations) are greater with the lower rotating mass, but the average speed is also slightly lower with lower rotating mass. So next time you want to claim that lower rotating mass allows faster accelerations, remember too that the greater speed fluctuations (due to greater accelerations) will also results in greater energy losses due to drag forces.
But, in reality, the differences in speed fluctions and average speeds are really very small between all these cases. For all practical purposes, when climbing, it is only total mass that matters, not how it is distributed.
I'd be happy to send the Excel spreadsheet to anyone that is interested.
- toolonglegs
- Posts: 15463
- Joined: Fri Jun 29, 2007 7:49 pm
- Location: Somewhere with padded walls and really big hills!
- sogood
- Posts: 17168
- Joined: Thu Aug 31, 2006 7:31 am
- Location: Sydney AU
Postby sogood » Tue Nov 27, 2007 11:42 am
For regular non-competitive cyclists riding into the sunset, those data indeed proved that people were worrying over nothing. But for racing cyclists who need the snap to catch an attacker's rear wheel, when you are already working at 99.99% capacity, I wondered if those tiny variations can become a more relevant issue?
RK wrote:And that is Wikipedia - I can write my own definition.
- sogood
- Posts: 17168
- Joined: Thu Aug 31, 2006 7:31 am
- Location: Sydney AU
- mikesbytes
- Super Mod
- Posts: 22179
- Joined: Thu Dec 01, 2005 11:42 pm
- Location: Tempe, Sydney
- Contact:
Postby mikesbytes » Tue Nov 27, 2007 11:59 am
- mikesbytes
- Super Mod
- Posts: 22179
- Joined: Thu Dec 01, 2005 11:42 pm
- Location: Tempe, Sydney
- Contact:
Postby mikesbytes » Tue Nov 27, 2007 12:01 pm
-
- Posts: 118
- Joined: Fri Feb 23, 2007 11:27 am
- Location: Sydney
Postby artemidorus » Tue Nov 27, 2007 12:04 pm
But who would buy a name brand? OK, silly question, I know many do. But, in fact, as well as it costing up to twice as much as a homebuilt, most of the components of a name brand are much inferior to those that I would use, with mine costing half the price.sogood wrote: The facts of the matter are, 1) Apple is no longer more expensive when compared with name brands.
- Kid_Carbine
- Posts: 1300
- Joined: Tue Aug 14, 2007 11:35 pm
- Location: Southern Tablelands N.S.W.
Postby Kid_Carbine » Tue Nov 27, 2007 12:06 pm
Laymans logic [hey, it's the best I can do] suggests that the lighter rim/tyre rider would probably have something up his metaphoric sleeve. [But the maths tell us he would be too tired to use it]
As for pricing, well I have never purchased a new computer in my life, of either type, so I offer up no argument there.sogood wrote:As can be seen, computer allegiance can be a religion too, just like bikes.
The facts of the matter are, 1) Apple is no longer more expensive when compared with name brands. 2) Enjoy virus threats on PCs.
In my family, we build & upgrade our own computers, so the costs are way down. This way we get the spec's we want at pricing we can afford & it's so easy, all I really need is a Phillips screwdriver.
Virus? Well, so far so good, our constantly updated AV programs have kept us free from problems, so that's not an issue at the moment, thank goodness.
Now that's AUSTRALIAN to the core.
-
- Posts: 118
- Joined: Fri Feb 23, 2007 11:27 am
- Location: Sydney
Postby artemidorus » Tue Nov 27, 2007 12:07 pm
On the flat, none. Up a steep hill, 0.2% difference.mikesbytes wrote:So in plain english, if a 82kg 46year old with extra wide (poor aerodynamic) shoulders is riding at 40kph, how much difference is 100gms of rim (each) going to make?
-
- Posts: 118
- Joined: Fri Feb 23, 2007 11:27 am
- Location: Sydney
Postby artemidorus » Tue Nov 27, 2007 12:10 pm
If the rider with the heavy wheels has shallow rims, then you are correct. If the rider with the heavy wheels has deep rims, and the rider with light wheels does not, then the heavy wheel rider will win, all other things being equal. Aero is more important than light, even in a sprint. Again, this is well established - go to analytic cycling.Kid_Carbine wrote:I tend to go with Sogood here. The maths are undeniable but when it comes to that sprint at the finish, would the rider with the heavier rim/tyre combination [ALL other things being equal] be at a disadvantage or not.
- toolonglegs
- Posts: 15463
- Joined: Fri Jun 29, 2007 7:49 pm
- Location: Somewhere with padded walls and really big hills!
Postby toolonglegs » Tue Nov 27, 2007 12:17 pm
No wonder I flunked it!sogood wrote:Relax. It's all just high school level math.toolonglegs wrote:
- toolonglegs
- Posts: 15463
- Joined: Fri Jun 29, 2007 7:49 pm
- Location: Somewhere with padded walls and really big hills!
Postby toolonglegs » Tue Nov 27, 2007 12:24 pm
But then my 3.0GHz 8-core Intel Xeon-based Mac Pro will crunch thru huge photo files faster than anything else...even faster than i crunch thru wheels
- Kid_Carbine
- Posts: 1300
- Joined: Tue Aug 14, 2007 11:35 pm
- Location: Southern Tablelands N.S.W.
Postby Kid_Carbine » Tue Nov 27, 2007 12:25 pm
You & me both.toolonglegs wrote:No wonder I flunked it!sogood wrote:Relax. It's all just high school level math.toolonglegs wrote:
When we get down to as little as 0.2% difference in performance between component specs I begin to wonder if the thrust from a bloody good fart would make the difference in the final few yards.
OK, I'm getting silly here & in reality I will never have the fitness to be competitive, nor the money to afford the ultra components, but I must confess this has been a particularly educational thread, even if I will never actually benefit from the final conclusions.
Thanks to all.
Now that's AUSTRALIAN to the core.
- toolonglegs
- Posts: 15463
- Joined: Fri Jun 29, 2007 7:49 pm
- Location: Somewhere with padded walls and really big hills!
Postby toolonglegs » Tue Nov 27, 2007 12:27 pm
Yes 0.2 isnt much,especially when you are about as aero as a busKid_Carbine wrote:You & me both.toolonglegs wrote:No wonder I flunked it!sogood wrote: Relax. It's all just high school level math.
When we get down to as little as 0.2% difference in performance between component specs I begin to wonder if the thrust from a bloody good fart would make the difference in the final few yards.
OK, I'm getting silly here & in reality I will never have the fitness to be competitive, nor the money to afford the ultra components, but I must confess this has been a particularly educational thread, even if I will never actually benefit from the final conclusions.
Thanks to all.
-
- Posts: 118
- Joined: Fri Feb 23, 2007 11:27 am
- Location: Sydney
Postby artemidorus » Tue Nov 27, 2007 12:27 pm
Never had one in 14 years! I'll keep waiting.sogood wrote:2) Enjoy virus threats on PCs.
- sogood
- Posts: 17168
- Joined: Thu Aug 31, 2006 7:31 am
- Location: Sydney AU
Postby sogood » Tue Nov 27, 2007 12:35 pm
Ummm... Where should we stick that age variable in the equation? I am sure it'll significantly affect the calculation.mikesbytes wrote:So in plain english, if a 82kg 46year old with extra wide (poor aerodynamic) shoulders is riding at 40kph, how much difference is 100gms of rim (each) going to make?
RK wrote:And that is Wikipedia - I can write my own definition.
- sogood
- Posts: 17168
- Joined: Thu Aug 31, 2006 7:31 am
- Location: Sydney AU
Postby sogood » Tue Nov 27, 2007 12:46 pm
I should qualify to say that I do not know if the weight difference (rim or combined bike) would have a significant effect as I don't know just how much of a difference would affect one's ability to catch another wheel. However, I can feel a difference in terms of "liveliness" b/n my Bianchi and Ridley, a difference in wheel weight as well as overall weight (1-1.5kg). But the difference could also be in the stiffness of the frame.Kid_Carbine wrote:I tend to go with Sogood here. The maths are undeniable but when it comes to that sprint at the finish, would the rider with the heavier rim/tyre combination [ALL other things being equal] be at a disadvantage or not.
On my Mac OS X 10.4/10.5 machines, I don't even need to run any AV or 3rd party firewall program in the background to sap my CPU cycles. Unix has firewall built-in and virus threat just isn't there. The only AV program I have on the same Mac is Norton AV, running within Windows XP that I occasionally runs through VMware virtualization environment.Virus? Well, so far so good, our constantly updated AV programs have kept us free from problems, so that's not an issue at the moment, thank goodness.
RK wrote:And that is Wikipedia - I can write my own definition.
- MichaelB
- Posts: 14849
- Joined: Tue Feb 20, 2007 9:29 am
- Location: Adelaide, South Australia
Postby MichaelB » Tue Nov 27, 2007 12:47 pm
Depends if you are directly behind the farter (i.e. you are the fartee) or not.Kid_Carbine wrote: When we get down to as little as 0.2% difference in performance between component specs I begin to wonder if the thrust from a bloody good fart would make the difference in the final few yards.
Depends also on the consistency, type & length of fart
- sogood
- Posts: 17168
- Joined: Thu Aug 31, 2006 7:31 am
- Location: Sydney AU
Postby sogood » Tue Nov 27, 2007 12:57 pm
Bear in mind that those are all primarily static state calculations. Weight is only important when there's acceleration involved (basic F=ma) eg. Gravity (9.8m/s^2), hence the difference in climbing up hills. So for a racing rider needing to suddenly jump and catch an attacking opponent on the hill, the acceleration and forces required would be more significantly affected by the weight parameter. So I have just that tiny residue doubt over this matter. But as I said, this is irrelevant for those non-competitive riders.artemidorus wrote:On the flat, none. Up a steep hill, 0.2% difference.
To date, I have not seen anyone include this parameter in their calculations. I guess the recalc isn't too hard given the change in speed and the time it takes for the transition can be estimated for the chase rider, hence acceleration. But I am too damned lazy to go through with it. In any case, I need some justification, even if it's just a lingering one, for the existence of that second bike. Don't anyone blow it for me!
RK wrote:And that is Wikipedia - I can write my own definition.
- sogood
- Posts: 17168
- Joined: Thu Aug 31, 2006 7:31 am
- Location: Sydney AU
Postby sogood » Tue Nov 27, 2007 12:59 pm
Don't forget to keep that AV proggie running in the background and keep it updated every few days.artemidorus wrote:Never had one in 14 years! I'll keep waiting.sogood wrote:2) Enjoy virus threats on PCs.
RK wrote:And that is Wikipedia - I can write my own definition.
- sogood
- Posts: 17168
- Joined: Thu Aug 31, 2006 7:31 am
- Location: Sydney AU
Postby sogood » Tue Nov 27, 2007 1:02 pm
Doesn't work, as one, they are pointed in the wrong direction, and two, that lycra and pad was designed to dissipate the jetstream laterally, similar to how a recoil-less gun works.Kid_Carbine wrote:When we get down to as little as 0.2% difference in performance between component specs I begin to wonder if the thrust from a bloody good fart would make the difference in the final few yards.
RK wrote:And that is Wikipedia - I can write my own definition.
-
- Posts: 118
- Joined: Fri Feb 23, 2007 11:27 am
- Location: Sydney
Postby artemidorus » Tue Nov 27, 2007 1:18 pm
What are you doubting?sogood wrote: So I have just that tiny residue doubt over this matter.
- sogood
- Posts: 17168
- Joined: Thu Aug 31, 2006 7:31 am
- Location: Sydney AU
Postby sogood » Tue Nov 27, 2007 1:22 pm
Exactly what I outlined earlier. The amount of extra force/energy required for a chase rider to make that jump (ie. Extra acceleration on top of static gravity pull) to catch an opponent. When a rider is working near capacity, that extra difference may just mean the difference b/n able or unable to attach to the opponent's rear wheel.artemidorus wrote:What are you doubting?sogood wrote: So I have just that tiny residue doubt over this matter.
RK wrote:And that is Wikipedia - I can write my own definition.
-
- Posts: 118
- Joined: Fri Feb 23, 2007 11:27 am
- Location: Sydney
Postby artemidorus » Tue Nov 27, 2007 1:31 pm
Noone said that 0.2% wasn't significant at an elite level, or even if you're sprinting uphill against your mate. It's not only going to increase the steady state workload uphill, but it is going to increase the wattage required for a given acceleration, slightly. Nothing to doubt.sogood wrote:Exactly what I outlined earlier. The amount of extra force/energy required for a chase rider to make that jump (ie. Extra acceleration on top of static gravity pull) to catch an opponent. When a rider is working near capacity, that extra difference may just mean the difference b/n able or unable to attach to the opponent's rear wheel.artemidorus wrote:What are you doubting?sogood wrote: So I have just that tiny residue doubt over this matter.
- General Australian Cycling Topics
- Info / announcements
- Buying a bike / parts
- General Cycling Discussion
- The Bike Shed
- Cycling Health
- Cycling Safety and Advocacy
- Women's Cycling
- Bike & Gear Reviews
- Cycling Trade
- Stolen Bikes
- Bicycle FAQs
- The Market Place
- Member to Member Bike and Gear Sales
- Want to Buy, Group Buy, Swap
- My Bikes or Gear Elsewhere
- Serious Biking
- Audax / Randonneuring
- Retro biking
- Commuting
- MTB
- Recumbents
- Fixed Gear/ Single Speed
- Track
- Electric Bicycles
- Cyclocross and Gravel Grinding
- Dragsters / Lowriders / Cruisers
- Children's Bikes
- Cargo Bikes and Utility Cycling
- Road Racing
- Road Biking
- Training
- Time Trial
- Triathlon
- International and National Tours and Events
- Cycle Touring
- Touring Australia
- Touring Overseas
- Touring Bikes and Equipment
- Australia
- Western Australia
- New South Wales
- Queensland
- South Australia
- Victoria
- ACT
- Tasmania
- Northern Territory
- Country & Regional
Who is online
Users browsing this forum: No registered users
- All times are UTC+10:00
- Top
- Delete cookies
About the Australian Cycling Forums
The Australian Cycling Forums is a welcoming community where you can ask questions and talk about the type of bikes and cycling topics you like.
Bicycles Network Australia
Forum Information
Connect with BNA
This website uses affiliate links to retail platforms including ebay, amazon, proviz and ribble.