Sure, but I also accept that the majority of my “efficiency” is going to come from gains in comfort and physical training, not improvements in the actual gear. I’m an ex ultra runner and LD biker, I believe that efficiency comes from within (training). I am also comfortable with acknowledging physcial limits and working within them, such as not being able to ride as far or as fast on a unicycle as I can on foot (trails) or on a bike (road and trails).
Okay, time for dweebiness:
Tom, you are making an argument that cannot be tested, which you support by saying that the proof is the test. Call it what you will, but that is not a logical argument, if anything it is a false deduction. Sounds a lot like another proof that requires belief without facts …
and so far not a single person has supported your belief. Don’t you find this odd?
I was curious about this too, and even though the topic of angular momentum has been discussed in this forum before, I don’t think it was phrased quite the way you are asking: How much mass would need to be added to give various wheel diameters the same angular momentum as a 36er? (assuming constant linear forward velocity)
Turns out if we neglect spokes and make a very, very gross simplification of the rolling system such that the rolling mass of the tire+tube+rim is treated as a thin cylinder (I=mr^2), the angular momentum L algebraically simplifies to:
L = rolling mass * wheel radius * forward velocity
Interesting! So, if we hold velocity and angular momentum L constant for a 36er, we get another simple relationship:
mass_29er = mass_36er * (ratio of diameters)
where the ratios can be:
36/29 = ~1.24
36/26 = ~1.39
36/24 = 1.5
36/20 = 1.8
So, the rolling mass of a 29er needs to be ~1.24x greater than that of a 36er’s rolling mass (~1.39x for a 26er, etc) to achieve the same angular momentum at a given forward velocity.
I noticed that Nurse Ben, who started this thread, has been amazingly persistent criticizing geared hubs and advocating 36-ers. As for me, I had started with a 36-er, than got a 26” Guni and finally sold the 36”. Currently I am pretty happy with my geared 26-er – it is challenging, compact and versatile. I can ride it anywhere, transport it everywhere in a bag, find plenty of tires for it (even spiked, which does make sense in places where I ride). I guess I will never switch back to a big wheel. Yes, 36-er is quite entertaining to ride and has both unique feel and look, but I find absurd to keep this “propeller-type wheel turbine” for 1-2 rides per year only. What it more, it does not belong the place where I live and ride – can’t imagine scaring babushkas on the pavement or joining crazy traffic on such a bulky wheel. It is a shame to find a place to store and to transport it. So, my case definitely confirms: more good geared hubs=less big wheels.
On the other hand, I know some people who just choose the biggest wheel they can get (yes, they are absolutely irrational and just like it big). Considering this, there will always be plenty of fans of 36-ers. Am I right that the majority of big wheels’ owners are of elder generation? Is it psychological? Does it mean that there will be a constant demand for 36-ers from people getting older? Who knows, perhaps I will change my mind
I can agree with the age part. If I was younger I think I would look at fixed 36er as a old peoples ride. The visual impact and easy speed sold me. I however have no need for a geared uni. Too fast and too much effort.
I’m happy with a usable novelty.
:o indeed it does. I did mean to put “if I’ve used the right formulae” at the end of my post, and clearly I didn’t - as a professional engineer I should know better. Checking what I’d been looking at, I think my mistake was looking at the KE formula and thinking that was angular momentum - should really have been obvious that with a velocity squared term in there it wasn’t. For KE the wheel size term does cancel out - the total KE of a rolling wheel is twice the KE of a non-rolling object moving at the same velocity, irrespective of the wheel size (assuming all the mass is at the outer edge of the tyre).
At least that clears up my thinking for me, and does go some way to explain why riding a 29er guni is much harder than riding a 36er unguni (not that I’ve ridden one of the latter, but my 29er guni is certainly more stressful to ride than I’d expect a 36er unguni to be from all reports I’ve seen). Though for reasons similar to those expressed by FatBird above, a 29er guni is far more appropriate for me (at the moment) than a 36er given I have a lot of narrow, steep and twisty bits with numerous pedestrians and parked cars to negotiate on my normal route I use that on - with the 29er guni I can just stick it in low for those bits. I would still like to be able to go as fast as possible, so a 36er guni may be in my future (once I’ve cleared the garage enough to make space), though I’m really not sure when I’d ride it apart from maybe a couple of times a year in mass participation bike rides - the problem then being that if I never rode it apart from that I’d not develop the confidence needed to ride it with lots of other riders around.
That’s what “begging the question” means; tasking as assumed that which should be proven.
But that’s not what I’m doing at all. I am presenting the obvious evidence that there is a huge amount of R&D that goes into bicycle racing to chase incredibly marginal efficiency gains. Here’s an article which talks about the custom jerseys, custom carbon fiber bikes, cranks, and other parts, custom helmets, and other equipment that the British cycling team develops to improve their performance. The bikes cost 20,000 pounds each. Having a rim or tire of a different size made would be absolutely no problem, if the teams thought they would be legal and faster. And they have sophisticated computer models which allow them to test hypotheses without having to go through manufacturing.
So, the extraordinary claim is the one you’re making, that wheels of a different size could be better than what we have, and that no one has thought about or tested the problem since 1895. That’s demonstrably untrue.
My claim is that of the wheel sizes legal in UCI races, the ones actually used in UCI races are close to optimal for the riders using them. My assertion is that wheels significantly larger than the ones in use today would not be optimal for the riders using them; I don’t have the facilities to test that hypothesis but it’s clearly testable.
That’s an interesting point. However, one of the important advantages of an ungeared uni is that it is lighter. Yes, that increase of mass is in the center of the rotating body, but I can tell you from experience that with the same size cranks, I can definitely accelerate faster on an ungeared uni. Since this course had tons of corners, the ability to accelerate quickly was a huge advantage.
Also, when cornering, a lighter uni will be able to corner tighter (less mass to accelerate - in a vector sense of acceleration). As a result, I could corner better. The primary reason that ungeared unis can corner better than geared unis is that they have shorter cranks (usually), but the weight of the uni also comes into play.
Hmm. We’re talking 800g difference here between a Schlumpf and a standard uni hub (maybe 1kg if you go for a superlight fixed hub). Given a typical total system weight of 80kg, that’s only 1% difference. 1% is well outside the range of differences a human being (even a well calibrated one) can possibly detect. Not that I’m doubting there might be a difference you can feel, but if there is one it’s very unlikely to be related to the difference in weight - I can believe that the slight backlash in the hub would make a difference (it certainly makes it impossible to perform a double-blind test, until such time as somebody makes a single speed uni hub with play ) but I certainly can’t discount placebo effect here.
As for the real difference that makes to your speed over the course, well I haven’t analysed unicycle racing, but looking at the numbers for bike racing on crit courses it’s clear that the amount of power expended on acceleration is actually very low, and a 1% difference in acceleration is lost in the noise. I see no reason why it should be different for unicyclists - if anything I’d expect the rate of acceleration to be even less significant.
Now the difference in cornering I can believe - I’m certainly not surprised that you can feel the difference, and it is plausible it makes a (very small) real difference. In that case you can more directly feel the difference in weight as it’s a far larger percentage of the weight of the unicycle on its own.
I think I’ve seen some, but they do look weird. Jacquie has two Rans recumbents; one with the wheel in front of the pedals and the newer one with the front wheel behind/underneath. The shorter ones are lighter. But recumbents are heavier than conventional bikes. In case anyone’s asking, why ride one? Because they’re frikkin’ comfortable! BTW, I used to have one as well, though Jacquie’s have much comfier seats. Oh and hers both have 26" rear wheels. I think the smaller wheels (20" in the front) are to reduce weight, as well as size. They sure don’t fit into cars very well!
Indeed, if not harder. But we’re talking about 2012.
Yes, but just as a set of physics equations on paper may be right, they’re seldom the whole picture. Scott knows his unicycle is lighter. Also, the cycle is separate from him, so the percentage should be calculated in relation to the unicycle and leave out the rider. We feel the performance changes in the cycle, not so much in the overall package. Also, like Scott said, the shorter cranks are also part of the equation. But what Scott left out is the largest factor in the equation, which is technique. I think the rider with the best cornering technique, confidence and fearlessness would have won that race on either machine, assuming equal training on both.
That doesn’t remotely address the question…you’re trying to change the topic.
A 155cm tall rider might ride a coker because it is the biggest easily available pneumatic sized tyre/wheel combination for an ungeared long distance unicycle. Will they continue to run this wheelsize on a hub with multiple gear ratios? Maybe, maybe not.
The question is, will this wheelsize (or 700c, or pick any size) be an ‘ideal size’ for both a 155cm tall rider as it is for a 195cm tall rider.
You haven’t said why you think a rider at either extreme of height would find a particular wheelsize as an ‘ideal’.
Either wheel size doesn’t matter when you have unlimited gears (which goes against your argument that a particular wheelsize is not ideal), or it matters but no one is spending money customising wheel sizes to different sized riders. Or, as mentioned by another poster, it merely selects for which riders will be successful in the sport.
20 thousand pounds is research??? The bicycle industry, if we’re lucky, might spend a few piddly million on research every year.
I work in the health care sector, with R&D budgets in the billions every year. It makes up a significant chunk of every countries GDP. Yet treatments take complete about-turns from previous best practice, despite eye watering investments on the original intervention in the first place. Just because you spend a few billion doesn’t make it effective, or correct.
Other times, medicine does things a certain way, because it has always been done that way, or based on protocols plucked out of thin air.
Computer modeling? I don’t think you would ever get any drug approved based on computer modelling alone. What works in theory doesn’t always work in practice.
An even better analogy is the concept of NNT (numbers needed to treat). If you have a heart attack and get thrombolysis, you have to treat 43 people to save one life. For everyone else, you are exposing them to treatment that can potentially cause harm. Yet in a remote centre without a cath lab, that’s what you would do. The same goes with the bicycle industry- a particular wheelsize does not have to be universally effective for all riders in order to be adopted.
If you are correct, then a trillion dollar industry should always get things right, not do things that are not evidence based, and only use treatments which benefit everybody.
It doesn’t work that way in medicine, and it doesn’t work that way in the bicycle industry.
Not when you’re talking about the rate of acceleration out of a corner it shouldn’t. In that case it’s the complete system weight which matters and you can’t possibly feel the unicycle accelerating faster because you’ve got to accelerate your body at the same rate if you don’t want to fall off the back.
Though the main point I was addressing was not which would feel faster, but which would be faster, as I figured that was more what Scott was interested in. I already suggested Scott used the same length cranks on a guni as on an unguni if he felt that was what was slowing him down on the guni (that comes from the thinking I’ve been doing about my guni use - I find it frustrating that I’m slower on some bits than with my unguni due to longer cranks, and figure that whilst there are less places I can push shorter cranks in high gear, it will be a net gain).
That’s £20k per bicycle - they have quite a lot of bicycles, and all sorts of other stuff they spend money on. Sure it’s less than the medical industry spends, but it’s certainly comparable (if not actually vastly more) to what the rest of the bicycle industry spends on research - and I don’t think the medical industry is a very valid comparison.
That’s my inference. £20k per bicycle vs, say $1 billion or so to bring a drug to market, with prescription costs varying from hundreds of dollars, to tens of thousands of dollars a year.
Sticking with widgets and hardware, compare a £20k per bicycle vs, say a Cochlear implant costing $50,000. Two of the biggest manufacturers (Advanced Bionics and Cochlear) issued massive product recalls of their latest models within the last 2yrs…despite hundreds of millions spent developing them.
So why isn’t it a valid comparison? Using Toms logic, if you had big budgets, you will be able to figure out what works best. Presumably before you implant them in people and find out it’s not as good as you think.
Poor example, given that the UCI wheel size limit is 70 cm. A standard 700c rim with a standard tire is close to that already.
Everything UCI is highly regulated, which is why all the bikes look basically the same. They don’t encourage innovation: “No technical innovation regarding anything used, worn or carried by any rider or other license holder during a race (bicycles, equipment mounted on them, acces-sories, helmets, clothing, means of communication, etc.) may be used until authorised by the UCI Executive Committee.”
A desire for extra stability and rollover capability has driven off-road bike folks to larger wheel sizes, even though bikes are exceptionally stable compared to unicycles. There’s every reason to think the optimal wheel size for a unicycle, on the same terrain, would be larger than the optimal bike wheel, even if that terrain is ordinary paved roads.
Your analogy is so incredibly bad that I’m not going to respond to most of it, but I’ll bring up this point: We have very good, effective computer models of fluid dynamics. We do not have very good computer models of the human body. The problems differ by multiple orders of magnitude in difficulty. Modeling and building a 25" wheel would cost essentially nothing compared to what developing a drug costs.
You’re still not comparing like with like - £20k for a single bicycle (one of many) or $1bn for a complete programme. The bicycle cost is actually more analogous to the prescription cost.
As I said, it’s not a valid comparison. The human body is a vastly more complex thing than the physics of riding a cycle. Also you clearly have a lot more issues over safety when developing medical stuff. Your mention of not being able to get drugs approved based on computer modelling is actually a good argument for my case, not yours, because you can get very accurate results from computer modelling of bicycle stuff.
) but I certainly can’t discount placebo effect here.