Opinions on wheel weight article in Cyclist Magazine?
Comments
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Imposter wrote:Well, you needn't have bothered, because nobody has ever disputed that accelerating a light rim requires less energy!! It will also deccelerate quicker - we've been through all this before. We seem to be going round in circles here (pun intended).
Ok we agree a lighter rimmed wheel will accelerate more quickly than a heavier rimmed wheel of the same weight.
Climbing at a constant speed is actually a constant acceleration against gravity (Energy = mass * acceleration * distance).
So why won't a lighter rimmed wheel climb more easily?Music, beer, sport, repeat...0 -
blinddrew wrote:Imposter wrote:Well, you needn't have bothered, because nobody has ever disputed that accelerating a light rim requires less energy!! It will also deccelerate quicker - we've been through all this before. We seem to be going round in circles here (pun intended).
Ok we agree a lighter rimmed wheel will accelerate more quickly than a heavier rimmed wheel of the same weight.
Climbing at a constant speed is actually a constant acceleration against gravity (Energy = mass * acceleration * distance).
So why won't a lighter rimmed wheel climb more easily?
We've done this before and you still aren't getting it. I think you may be trolling.0 -
Imposter wrote:We've done this before and you still aren't getting it. I think you may be trolling.
You're half right, I don't get it, but I'm not trolling. I've set out, as requested, my maths. If this is wrong, I'd genuinely like to know. Objects of the same mass but different moments of inertia will accelerate downhill at different speeds, the smaller the moment of inertia, the faster they accelerate. Do we agree on that?Music, beer, sport, repeat...0 -
Neither side is trolling here as far as I can see. It's a healthy if occasionaly heated debate. But as long as we stay in the realms of theories and equations and ignore real world data, then both sides can claim to be right. If the experience of pro teams is that when a real man on a real bike goes up a real hill is that he goes up more efficently* if weight is moved away from the rims to another part of the bike then that is real data. They don't make these decisions on a whim.
*(using less energy or going faster with the same energy, take your pick).
If your theory says that real world data can't be true, then your theory contains errors or is incomplete. This is part of the scientific method of developing our understanding of the world. Newton's understanding of gravity came not from wondering about an apple, but by studying reams of real world data from Galileo and Kepler on planetary positions, tide measurements from around the world over several years and other various measurements (size of the earth, distance of the moon from earth). He never explained what gravity was (how an object like the sun can affect the behaviour of an object billions of miles away) but gave an accurate description of its properties and effects.
Without data this argument will not be solved.0 -
Is the answer to this possibly that the effect of a light rim is generally insignificant, however in a race scenario it is significant as racing is all about accelerations?
If you are riding with the bunch, whether on the flat or uphill, it is generally manageable until an acceleration occurs, i.e. an attack. If you cannot match that acceleration at that point in time a gap opens. When a gap opens and you are on your own you lose the drafting advantage of the group and the power required to get back on to the group jumps massively (you need to accelerate and overcome the extra wind resistance also).
Anyone who has raced knows that closing a gap is difficult in a group of evenly matched riders when they are riding hard. The group usually pulls away as they still have the drafting advantage.
In this scenario the fact that you decelerate more slowly than a rider with light rims is irrelevant, you are out of the game. When you are riding at your limit tiny advantages (e.g. 1% higher power output required to accelerate vs the rider with light rims) become significant as you are dropped and then require a huge increase in power output to get back on to the group again.
In this scenario your overall time for a given distance whether on the flat or climbing becomes much longer than the group because they ride off into the sunset with the aid of drafting which you have lost (obviously less significant on a climb but dropped is dropped).0 -
Yes. The more accelerations one does the more important a lighter rim is, especially when momentum is scrubbed through braking. In a single acceleration TT there is probably no discernable benefit from lighter rims whereas in a criterium with a series of accels into heavy braking, lighter rims are significant. Of course, rim stiffness and aerodynamics are also a factor ro the overall benefit of a set of wheels.GGBiker wrote:Stuff game.
As far as climbing is concerned, assuming a steady-state single accel at the start and no braking, I think that overall bike weight is important but that any benefit from lighter rims (but same overall bike mass) is irrelevant. However, if I was racing and I expected to be accelerating on the climb to attack or respond to attacks, I'd choose lighter rims.
So, what do I ride?
For crits I have a set of super light tubulars (light rims)
For days out and training I have cheapo factory wheels or a heavy rear powertap because performance is irrelevant.
For road racing I have a set of Ksyrium SSC SLs (heavier rims than the tubs but I prefer clinchers to tubs).
For a hill climb I'd use the lightest wheels because I don't have to worry about a UCI min weight and lighter wheels reduce the overall weight of my bike.0 -
Grill wrote:cbr6fs wrote:Grill wrote:Both Wiggo and Froome use AX-Lightness rims on mountain stages. Good enough for me.
They also make their living cycling, their entire earnings are based upon their cycling performance results, have crews on standby with spare wheels and they don't pay for their own wheels.
In my track car i have removed the seats, interior and anything that lets me add lightness while not reducing safety.
On my road car it makes no difference if it's 2/10ths quicker around certain corners so weight is not as critical.
The cyclist you mentioned are at their peak physical condition, any gain or help they can get that gives them 0.01% advantage over the competition, or saves their legs for the 2nd week of race has to be worth it.
For training and non competitive cycling the very very slight differences over a wide range of uses don't really matter as much.
Don't get me wrong, i'll still throw money at my bike in the vain attempt to get my Sundays rides a bit faster, it's my money my choice.
It's just that i don't pretend that there is a real world justification for my spending.
Spoken like a man who has never ridden an epic wheelset.
Spoken like a person who has had their ass handed to them on a plate and has no response other than wildly, unsubstantiated, incorrect conclusion jumps 8)mrfpb wrote:Personal experience via theoretical understanding: an example.
A few years ago I watched professor Marcus Du Sotoy explian how air turbulence affects irregular spheres in flight, eg golf balls and footballs, and how this can be used to make balls curve on the horizontal plane, eg when taking a free kick. The equations belong to the chaos theory branch of mathemetics. Prof du Sotoy is a keen footballer, but can't actually apply the principles to make a decent free kick.
As far as I'm aware David Beckham does not understand the equations relating to air turbulence but has kicked footballs in excess of 100,000 times (possible exageration) and can bend a ball around a defensive wall to score a goal.
Now then, if the practice of pro-teams is to put lighter rims on their bikes before mountain stages and take a weight penalty elsewhere, then this is going to be borne out of realistic experience rather than a limited / incomplete understanding of the physics of bikes. Remember recent reports that said we don't fully understand why bikes stay upright!
Pro teams will also go to great lengths to make marginal gains, so their practices are not necessarily beneficial to a non competitive rider or commuter. However if bling wheels gives you bragging rights go ahead and buy them.
Pro teams have also used heavy (in comparison) disc wheels and deep dish wheels on flatter time trial sections.
If i were a professional cyclist i'd take any gain i can get, even if that gain is more physiological than real world.
As a amateur though i don't have the luxury of having a team following me around with various wheels depending on the type of riding i do.
It's not often i do 25km to 30km or pretty much constant climbing during a ride either.
Like i said before your talking about athlete at their peak physical condition, they ride, train and eat to total dedication.
Once you get up that level then the human body is pretty much maxed out so even if lighter wheels gave a inconsequential gain of say 0.001% it's still worth it to them.
I'd hazard a guess that the vast vast majority of members here are not at that sort of level.
Reading through the threads over the years i'd say the vast majority of members here don't race.
Even with the ones that do, rider fitness, rider weight, air resistance and rolling resistance play a MASSIVE in slowing us down, far far more than anything a slightly lighter rim will offer.
As i say i'm not judging anyone, i'm as guilty as anyone for throwing money at my bikes instead of getting fitter.
I just think that the real world gain of a lighter wheel rim is inconsequential compared to rider fitness, rider weight, air resistance and rolling resistance.1994 Diamond Back Axis TT (Fully Rigid)
Trek Fuel EX 70 -
cbr6fs:
A lot of people who do race (amateur) are maxed out physically so look for other gains. When I say maxed out physically this is within the constraints of the time they have available for training/racing as most will have full time jobs, families etc. Most don't drink much alcohol if at all and most have body fat at low levels.0 -
GGBiker wrote:cbr6fs:
A lot of people who do race (amateur) are maxed out physically so look for other gains. When I say maxed out physically this is within the constraints of the time they have available for training/racing as most will have full time jobs, families etc. Most don't drink much alcohol if at all and most have body fat at low levels.
I can understand that.
We all do what we can within the time and financial commitments we have in our lives.
My point was though, it's not really much of a comparison between the gear used by professional cyclists who's earnings are 100% based on their results, and what works best for to most of us amateur cyclists.
Yes pro's use lighter wheels sometimes, they also train for 8 hours a day 7 days a week, have spare wheels on standby in a following support truck, don't pay for their wheels and are often given a brand that is a sponsor of the team.
Pro's have been looking for a edge for years, be it Lemond using tri-bars, bio/oval cranks, suspension on events like the Paris-Roubaix
Tri-bars add weight, but still in certain conditions you'll go faster using them.
Are they good for hill climbing = Nope
Would you use them all the time = Nope
If we are competing then i can understand that even as amateurs we try and push for the best results we can.
This does not mean that light wheels are the best solution for every scenario though.
For something like a flat 25 mile TT in good conditions without any wind i'd happily swap 100g for some deep dish or disc wheels.
While training on poorly lit B-roads at night, i'm happy that my wheels are reassuringly heavy and my tyres have a decent sized air chamber.1994 Diamond Back Axis TT (Fully Rigid)
Trek Fuel EX 70 -
blinddrew wrote:Imposter wrote:We've done this before and you still aren't getting it. I think you may be trolling.
You're half right, I don't get it, but I'm not trolling. I've set out, as requested, my maths. If this is wrong, I'd genuinely like to know. Objects of the same mass but different moments of inertia will accelerate downhill at different speeds, the smaller the moment of inertia, the faster they accelerate. Do we agree on that?
I don't think he is coming back mate.
He's off to find a new "greatest thread ever on BR"
"You really think you can burn off sugar with exercise?" downhill paul0 -
Charlie Potatoes wrote:blinddrew wrote:Imposter wrote:We've done this before and you still aren't getting it. I think you may be trolling.
You're half right, I don't get it, but I'm not trolling. I've set out, as requested, my maths. If this is wrong, I'd genuinely like to know. Objects of the same mass but different moments of inertia will accelerate downhill at different speeds, the smaller the moment of inertia, the faster they accelerate. Do we agree on that?
I don't think he is coming back mate.
He's off to find a new "greatest thread ever on BR"
There's nothing else to say that hasn't already been discussed ad nauseam. Not that you've actually said much, mind - apart from a couple of inane, juvenile posts here which seem to be directed at me. Maybe you could invent some new physics to keep us all entertained in the meantime...0 -
Imposter wrote:
Nobody's trolling here
Like I said in my original reply to you. None of what you said was necessarily incorrect - it's just there's a bit more to it than that. Nobody has ever said there is not a difference between light wheels and heavy wheels - only that it doesn't really matter where the weight is. But you will never realise that, because you won't read the other thread. Ironic that someone involved in the education/training world should refuse to take an opportunity to further his own knowledge...
Ha! Ok so, without giving away personal information please, how did you find that out?!
Was wondering if it was something to do with my personal settings on here, but either way, a little unnerving!0 -
Your email addy was displayed under your username (except you've changed it now) and I am familiar with the company you work for. Don't worry, it's nothing mysterious 0
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Imposter wrote:Charlie Potatoes wrote:blinddrew wrote:Imposter wrote:We've done this before and you still aren't getting it. I think you may be trolling.
You're half right, I don't get it, but I'm not trolling. I've set out, as requested, my maths. If this is wrong, I'd genuinely like to know. Objects of the same mass but different moments of inertia will accelerate downhill at different speeds, the smaller the moment of inertia, the faster they accelerate. Do we agree on that?
I don't think he is coming back mate.
He's off to find a new "greatest thread ever on BR"
There's nothing else to say that hasn't already been discussed ad nauseam. Not that you've actually said much, mind - apart from a couple of inane, juvenile posts here which seem to be directed at me. Maybe you could invent some new physics to keep us all entertained in the meantime...
Your refusal to correct blinddrew's maths leads me to conclude that either he is right or you have no understanding of them and have been blagging it?
Or maybe both of the above are true?"You really think you can burn off sugar with exercise?" downhill paul0 -
Charlie Potatoes wrote:Your refusal to correct blinddrew's maths leads me to conclude that either he is right or you have no understanding of them and have been blagging it?
Or maybe both of the above are true?
Where have I 'refused to correct' his maths? In any case, his calculations are irrelevant, as has already been pointed out by others. Why am I even wasting my time replying to you when you have nothing to contribute?0 -
Imposter wrote:Why am I even wasting my time replying to you when you have nothing to contribute?
Indeed. blinddrew has contributed much to this thread but you will not afford him the same courtesy?"You really think you can burn off sugar with exercise?" downhill paul0 -
Charlie Potatoes wrote:Imposter wrote:Why am I even wasting my time replying to you when you have nothing to contribute?
Indeed. blinddrew has contributed much to this thread but you will not afford him the same courtesy?
Are you his mother?
All anyone has to do is come up with some figures which demonstrate that Newton's laws of motion are incorrect. Until then, I think we can all rest easy... 0 -
Imposter wrote:blinddrew - none of what you say changes the basic physics. And if you are convinced that lighter rims climb better than any other type, the onus is on you to explain - preferably using the laws of physics that are already established.
blinddrew has done this. He has corrected his maths and asked you to show where he is wrong.
Rather than do this you abuse him by calling him a troll.
The onus is now on you to explain why you think he is wrong."You really think you can burn off sugar with exercise?" downhill paul0 -
Charlie Potatoes wrote:blinddrew has done this.
What - blinddrew has disproved Newton's laws of motion..??? Does the Royal Society know? 0 -
Imposter wrote:Charlie Potatoes wrote:blinddrew has done this.
What - blinddrew has disproved Newton's laws of motion..??? Does the Royal Society know?
The onus is on you to explain and not hide behind inane and juvenile one liners."You really think you can burn off sugar with exercise?" downhill paul0 -
Sorry fella - Newton's Laws of Motion - with specific reference to the conservation of momentum - hold true for a bike/rider going up hill. Anything else is secondary. It's for him (or you) to disprove that - not me.
Good attempt at recycling one of my replies to you though - nice one. That's me done now, by the way - until something else comes along worth replying to - and to be fair, that's probably not going to be one of your posts.0 -
Imposter wrote:Sorry fella - Newton's Laws of Motion - with specific reference to the conservation of momentum - hold true for a bike/rider going up hill. Anything else is secondary. It's for him (or you) to disprove that - not me.
Good attempt at recycling one of my replies to you though - nice one. That's me done now, by the way - until something else comes along worth replying to - and to be fair, that's probably not going to be one of your posts.
Yep! My work here is just about complete.
Good day to you Imposter."You really think you can burn off sugar with exercise?" downhill paul0 -
Imposter wrote:What - blinddrew has disproved Newton's laws of motion..??? Does the Royal Society know?
First law: When viewed in an inertial reference frame, an object either is at rest or moves at a constant velocity, unless acted upon by an external force.
Second law: The acceleration of a body is directly proportional to, and in the same direction as, the net force acting on the body, and inversely proportional to its mass. Thus, F = ma, where F is the net force acting on the object, m is the mass of the object and a is the acceleration of the object.
Third law: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction to that of the first body.
The equations I've set out are directly derived from those laws. I'm not being facetious here, if I've gone wrong, I want to know where I've gone wrong.Music, beer, sport, repeat...0 -
Maybe this will help. I'm not presenting it as irrefutable science - but if it helps your understanding, then that has to be a good thing. The article is a couple of years old, admittedly - but then I guess the physics is about 350 years older...
http://biketechreview.com/reviews/wheel ... erformance0 -
Imposter wrote:Maybe this will help. I'm not presenting it as irrefutable science - but if it helps your understanding, then that has to be a good thing. The article is a couple of years old, admittedly - but then I guess the physics is about 350 years older...
http://biketechreview.com/reviews/wheel ... erformance
"wheel inertia is a third order effect (nearly 100 times less significant)."
That would tie in with my rough maths above (once I'd corrected it of course, sorry about that), shifting 200g from the rim to the hub would be in the order of 1% of the energy required to shift a 8kg bike and 75kg rider.Music, beer, sport, repeat...0 -
blinddrew wrote:Imposter wrote:Maybe this will help. I'm not presenting it as irrefutable science - but if it helps your understanding, then that has to be a good thing. The article is a couple of years old, admittedly - but then I guess the physics is about 350 years older...
http://biketechreview.com/reviews/wheel ... erformance
"wheel inertia is a third order effect (nearly 100 times less significant)."
That would tie in with my rough maths above (once I'd corrected it of course, sorry about that), shifting 200g from the rim to the hub would be in the order of 1% of the energy required to shift a 8kg bike and 75kg rider.
Sorry, scrap that, I'll read the whole article rather than skipping to the conclusion. That'll be tomorrow though as I have an open mic night to sort out tonight.
CheersMusic, beer, sport, repeat...0 -
Imposter wrote:Maybe this will help. I'm not presenting it as irrefutable science - but if it helps your understanding, then that has to be a good thing. The article is a couple of years old, admittedly - but then I guess the physics is about 350 years older...
http://biketechreview.com/reviews/wheel ... erformance
quicker article than I thought and yes it helps a lot. Conclusion is that it does make a difference but when compared to the other forces you're working against it's neglible.
(the 1% I mentioned above was solely looking at gravitational effects and not taking any account of wind resistance).
So to go back to the original question I was trying to answer "do light rims climb better", the answer is yes but you'll never notice it (unless you're taking a kilo off each rim!).
This makes sense to me and I am now happy
My parting shot will be that as your speed lowers on a climb, that tiny amount of inertial difference will become a larger proportion of the total picture - but probably still not noticeable Music, beer, sport, repeat...0 -
So what if you shift 200g from each rim and lighten the bike by 400g? On a 20% slope?0
