staehpj1

I think perhaps we agree on most of the specifics and disagree mostly on the significance of their effect. I am sure that significance is greater or lesser depending on who you ride with, how you ride, and where you ride.

Actually I am not getting dropped, but I would be on some rides if I was carrying a couple extra pounds on the wheels and tires. I haven't ridden club rides over major passes like we toured on in the Rockies or Cascades, but I bet 5 pounds could easily make the difference under those situations too. I do have to work harder on local group rides when on a heavier bike especially if the extra weight is in the wheels and tires. No I don't feel it on the flat straight sections, but I do on the climbs and the accelerations out of the corners.

Absolutely, IF you ride alone and are not riding for a measured performance, but there are real life non-racing situations where that is significant.

On tour riding with a small group on the Trans America, we adjusted weight by a few pounds a number of times. These adjustments were sometimes done by sending stuff home and sometimes by shifting community gear between us. I have no doubt whatsoever that these changes made the difference in whether a rider kept up or not either in terrain where there were lots of short ups and downs or areas where there were long multi-mile multi-thousand foot climbs. If fact the difference might have been the difference between finishing the 4200+ mile ride and giving up and going home.

On two recent long rides in similar terrain I rode with my daughter. On one ride we were both on our touring bikes and on the other I rode my road bike. The difference in aerodynamic drag is an obvious factor that favored the road bike. Also rolling resistance is a small but not insignificant factor since she is running 28 mm tires at 100 psi. When we were both on 30 pound bikes she kicked my @ss on the climbs. When I was on a 20 pound bike, she dropped back a bit on each climb and had to catch up. Since the difference was on the climbs I think it is reasonable to say the the weight was the major factor.

That is pretty funny; since I didn't know you were before
If you want proof go get it yourself. It is a well accepted fact that weight has a significant effect when accelerating, particularly if the weight is in the wheels. So it is not whether it makes a difference, but how much. I do agree that weight matters very little for flat roads and steady speeds. It quickly becomes more important as accelerations become more frequent and/or faster. So for the case where you are in no hurry to accelerate out of corners and are not climbing, within reason weight is a very minimal factor.

Since I ride with riders who are usually 30-40 years my junior and pretty aggressive, accelerations are quick and weight especially in the wheels is not insignificant. For other riding it may be.

invisiblehand

I don't think you have shown this. Maybe what people call a club ride varies, but here there are a lot of pacelines with categorized riders; one of the effects of being in a club with ~4000 riders. Five pounds will pull you out of a group of roughly equal riders over a long ride.

Bacciagalupe

Staephj1: I think you're right, we basically have different opinions on the contexts where weight would be significant.

My only caveat is that I believe aerodynamics and RR are much more important than weight, and that people attach far more importance to bike weight than is actually warranted by the evidence I've been able to accumulate so far. I.e. a 20" wheeled bike is going to accelerate faster not because of weight issues, but because of aerodynamics.

As to proof, unfortunately I'm not sure I can pick up a PM or schedule a day in a wind tunnel before the global economic crisis destroys my disposable income. I use an HRM, but as I indicated earlier I don't think it's a precise or consistent enough measure to resolve this issue.


I'm in the NYCC, which has around 2,000 members. As you well know, clubs of that size will have a full range of riders of varying abilities. I've seen riders on "B18," and even some "A" rides, stretch out far more than 30 seconds on very short climbs -- usually as I'm passing 3/4 of them on my 26+ pound bike, by the way.

That said, as best I can determine 5 extra pounds on the bike will cost you about 1 watt on the flats and 2 on a steep (7%) climb.

Your ability to produce power will vary at least that much on an average day anyway, yes? Not to mention that your body weight will vary by a few pounds from day to day, too.

Meanwhile, riding in the drops instead of the tops will save you 40 watts on the flats, assuming you don't lose the ability to generate power due to the position. And if you switch to wheels that are heavier but more aerodynamic, you'll have a net benefit unless you're you're climbing Monte Zoncolan all day long at 6 mph.

What can I say, it merely seems obvious to me that numerous other factors -- particuarly aerodynamics, rolling resistance, rider fitness, and environmental factors -- have substantially greater influence on your performance than weight. I can see how the small amounts might be critical in a race but on a club ride? Even a fast one? Seems unlikely. You'd have to already be pushing your limits if you're OTB du to a 1-2 watt difference.

Ergo, if you're getting smoked on the Gimbels ride, 5 extra pounds on the bike isn't a reason... it's an excuse.

invisiblehand

Ahhhhh, I did not say that other things don't matter more. That isn't the point. The point is whether the three seconds from 5 pounds on a 1/2 mile climb at a 5% grade will matter -- I just used https://www.kreuzotter.de/english/espeed.htm and modified the default settings. It does since in these fast club rides, getting marginally dropped on each climb and having to fight the wind back into the group will be significant. That is, it matters a lot precisely because aerodynamics matter so much and staying within a tight group is such a benefit.

Bacciagalupe

Well, we may have to "agree to disagree" here. But....

Another way to put it is, per Kreuzotter: On a 5% grade, 200 watts, 20 pound bike, on the tops, your speed is 9.2 mph. With a 25 pound bike, it's 9.1 mph. On the flats, 18.8 vs 18.7.

Are the leaders and riders on your club rides so perfectly consistent and in control that they can hold their speed within a tolerance of 0.1mph? Or, do you typically go OTB because the leader boosts his/her speed by 0.1 mph? Are they making cruise control for bicycles now?

Besides, the idea behind a club ride is to "hang with the gang," not ride fast for 30 miles and outsprint/outride your opponents in the last 5 seconds (or earlier, if you've got the legs and/or guts). You may not even want to ride terribly close to LT, unless it's your "hard" day on your training schedule.

I.e. if you are so maxed out that you can't dig up another 1-2 watts to keep up -- as opposed to a race, where the goal is to beat the other guys up the hill -- then it seems to me like you're on the wrong ride.

staehpj1

No that isn't the point. If the going gets tough it is one of three places.

1. The cumulative effect of multiple fast accelerations out of the corners.
2. The cumulative effect of multiple short fast climbs.
3. One very long climb, probably after also experiencing items one and two.

A small change in the steady speed is irrelevant as it allows one to hang in due to drafting.

Ummm no, not always. There are rides like that and there are more aggressive and competitive rides. There are pure racing clubs and pure racing components in non racing clubs. Those rides can be essentially simulated racing in many cases.

Then there are some riders that are just competitive wherever they are, even on loaded tours. I have ridden with folks who will go as far as taking turns dropping off the back in front of a rider and sprinting back to the group to drop them. This is usually done to a stranger or a new guy and they consider it practice of racing tactics.

makeinu

The point I think you're missing is that producing a constant 200 watts of power is a fantasy so any discussion premised on the notion of a constant power at the pedals is almost completely irrelevant to actual riding. As you said, people can't hold a constant power output to a good tolerance and one of the things that determines the power they can output is how hard they've been working thus far. So working 1-2 extra watts harder at the start of the ride could end up costing you 200-300 watts in your fatigued muscles at the end of the ride (and one should note that acceleration is always the first to take its toll and is thus more likely to have its effect multiplied than any other mechanical factor). After all, 75% of the power your body produces gets lost before it even reaches the pedals, so there's little point in considering the relatively insignificant factors of aerodynamics or rolling resistance until you've considered the body.

Your whole perspective is completely misguided because you imagine that somehow the power going into the pedals is independent of the mechanical losses. You're right to note that using HRM measurements is difficult and inconsistent, but there's really no other option and although using Kreuzotter analysis or speeds normalized by power meter measurements makes for simpler considerations, it does so at the expense of the most important real factors. The question is a hard one and although switching to an easier question makes things easier, it doesn't get you any closer to the answer.

Can't you see that a 5% loss calculated by Kreuzotter is meaningless in the face of the fact that there are 75% losses elsewhere (unaccounted for by Kreuzotter)? I agree that subjective reports are likely to be inaccurate and make for pretty slim evidence, but even something likely to be wrong or inaccurate is better than something we know to be wrong for sure (like Kreuzotter).

Bacciagalupe

Uh... I'm sorry to say that you do not appear to understand how power meters and the corresponding mathematical models work.

Power meters measure the exact power applied to the bicycle, i.e. they're measuring the actual torque generated by the rider, not "how many calories the rider is burning" or "how many watts the rider's body needs to generate." They are usually installed in the crank, bottom bracket or as the rear hub. So, when we talk about a rider applying an average of 200 watts over 20 minutes, that means that the pedals are receiving 200 watts of power from the rider.

That's why a power meter is a more objective measure. It doesn't matter who the rider is, how good or bad their aerobic system happens to be working that day, or the temperature, or whether you're climbing or descending, or whether the rider has more or less mechanical losses for some reason, or if you're sore (or if your blood glucose is low) from the previous day's efforts, or if that yogurt you had that morning was too close to the expiration date, and so forth. The power meter doesn't care; it's just measuring power that is actually applied to the bike. Thus if the rider is applying 200 watts to the pedals, they're applying 200 watts to the pedals and that's exactly what the power meter records.

The Kreuzotter and other mathematical models are also using this as their measure. Thousands of riders are comparing their power meter results to these calculators as well. As I may have said before, obviously it will be simplified compared to the real world, but it's generally good enough for these types of questions and would be corrected if they were off by orders of magnitude.

By the way, the actual measure is of "watt-hours." Going from an average of 200 watts over 2 hours to 201 watts over 2 hours really isn't terribly significant -- unless you're in a race or, per staephj1 and invisiblehand, an extremely competitive club ride.

invisiblehand

Hah! Well everyone has their way to pleasure. That you enjoy being dropped on every climb is yours. Either that, or stop riding with a bunch of slackers.

Actually, that there is fluctuation in the group makes acceleration more important not less.

makeinu

I understand quite well how it works and I also understand that the power meter measurement is typically used to try to factor out the influence of variations in power applied to the pedals. That's how you were proposing to use it earlier in this thread and that's exactly the opposite of how it should be used. Filtering out "whether the rider has more or less mechanical losses for some reason" is not an objective way to consider the influence of bike weight when that reason is bike weight. On the contrary what it is is a very objective way to rig the numbers to get the answer you want.

Moreover, there is a bit of a difference in the importance of power at the pedals between racers and nonracers. For a racer the only thing that matters is how much power he can apply and how far it will take him. So a racer doesn't care if it takes him 1000 watts or 2000 watts to apply 200 watts to the pedals as long as he gets 200 watts at the pedals. However, for the rest of us the 1000 or 2000 watts being exerted is the most important thing and not the 200 watts leftover at the pedals and that 2000 watts a power meter does not measure. So considering how the users of such calculators and power meters are self selected to be mostly racers (and of those mostly amateurs who only want to flatter themselves on rides where they can experience their moments of glory, unhindered by the realities of everyday acceleration) it wouldn't be at all surprising to find that the results of the Kreuzotter calculator going uncorrected by orders of magnitude (especially considering the strong psychological tendency for most people to believe anything masquerading under the name of "science" or "math" regardless of actual scientific or mathematical validity).

Going from an average of 200 watts over two hours to 201 watts over two hours could be massive if it means a difference of 1000 watts in actual energy expended by the body. This is typical of muscles. For example, although bench pressing a 10 pound weight takes no more power "at the bar" than bench pressing a 500 pound weight (in both cases it's zero), the difference in power exerted ranges from nearly insignificant to more than your body can generate.

So if a difference of 0 watts at the body machine interface can be the difference between easy and impossible (and it can) then it hardly makes sense to conclude that a difference of 1 watt isn't terribly significant. It can be massive and it's not just important for competitive folks, but for everyone. The fact is that less than 1 watt is the difference between a world class athlete and your average joe. I said it before and I'll say it again because you don't seem to understand it yet. 200 watts is not 200 watts is not 200 watts. At least not measured at the pedals it isn't.

P.S. By the way the actual measure is watts. Watt-hours would be energy, but we were talking about power.

Raxel

Here are some hard facts I know.

-Given same size, wheels with low inertia accelerates faster. However, bear in mind that small wheels have to spin more to move the same distance, but their radius is smaller too. So we can assume that acceleration property of wheels are somewhat proportional to its weight.

-Small wheels are generally lighter than large ones.
I have two 406-sized wheels which weighs 992g and 1147g respectively. Dahon's 406 rolf wheelset (w/o pantour hub) also weighs 992g. You just CANNOT find any clincher wheelset this light without spending some ridiculous sum of money.

-Small wheels have smaller contact area than large wheels, and their rolling resistance is actually lower than large ones. From the test data I've seen, 406 sized 28c stelvio tires are better than 23c GP4000 tires (They are very good tires and my dad's using them on his road bike)

Conclusion here is that 'good' smallwheelers can accelerate faster than road bike. From my experience, main disadvantage of smallwheeler is its harsh ride and unstable handling which add up to rider's fatigue.

Quantative analysis will be possible with powermeter, but I have not seen anyone using SRM or PowerTap with smallwheeler yet. I know someone with iBike though.

datako

One thing to remember when comparing tyres is that comparisons can only be made between tyres of the same construction.

Bacciagalupe

Raxel: iBike should be interesting... It's not as good as a real power meter, but it may be the only option for a 20" wheeled bike.

A correction to your post, though.... Small wheels have more rolling resistance; see https://www.users.globalnet.co.uk/~hadland/rolrec10a.pdf for details. I believe the issue is that the tires, and therefore the contact patch, is wider; the shape may also have an effect. Smaller wheels are faster because, even with wider tires, they are aerodynamically superior to 26" / 700c.



I'm afraid you are incorrect. The power meter will quantify exactly how much power the bike needs in order to, for example, increase speed.

If Bike X moves at 22mph when you apply 200 watts to the pedals, and Bike Y moves at 23mph @ 200 watts, we can objectively say "Bike X is more efficient / performs better / faster."

Bike weight will NOT increase the rider's mechanical inefficiencies. They're two different systems in that respect. Those mechanical inefficiencies are altered by factors like: Muscle soreness, low blood glycogen levels, injuries, a rider position that impedes or aids muscle function, rider fitness, aerobic vs anaerobic efforts.

The power meter quantifies how much extra that 5 pounds makes you work; and everything indicates that by almost any measure, it's a very small amount. Staephj1 and Invisiblehand pretty much get it, by the way; I'm only disagreeing with them about the situations where this small amount does become critical.


I agree there is a big difference between racers and non-racers, but not the one you are describing. In terms of power, a trained cyclist will be able to sustain a much higher power output for longer periods of time and in a more efficient manner, but that's really about it.

A racer will definitely want to be as efficient as possible. If you need to work twice as hard as your competitor in order to maintain the same speeds, you will lose.


OK, let's say that your body is generating 620 watts in total, you lose 70% to mechanical losses, that leaves 186 watts on the pedals. To increase by 1 watt to 187w, you'd have to generate, oh, 624 watts instead. That's a 0.6% increase.

By the way, maintaining that increase means you'll burn an extra 1 or 2 calories per hour. Wow. That's huge!

You sure you want to pursue this line of argument?


It isn't. So it doesn't.

The only way that 1 watt can have a huge effect on your efforts is if you are already at LT when you generate 200 watts, and that extra watt makes you go anaerobic. At that point, your body becomes much less efficient, you burn lots of fuel, and it gets harder to recover from your efforts. This can definitely happen -- I've even referenced this scenario a couple of times re: club rides -- but you have to be right on the line the entire time, which is not exactly a common scenario.


This is absolutely incorrect.

A typical / non-trained rider will put out roughly 150-200 watts. An amateur racer will be in the 200-300 range. A pro is 300-400 or more. And yes, we are talking about consistent, multi-hour outputs here.

And again... Just going into the drops, instead of riding on the top of your bars, saves you about 40 watts. If you lower your handlebars by 1/4" you'll likely get a bigger performance boost than by dropping 5 pounds.

1 watt is the difference between "me on Tuesday" and "me on Wednesday." Seriously, in a non-competitive context it is negligible.

makeinu

Why do I feel like I'm talking to a wall? The point is not how much power the bike needs, but how much power the rider needs.

I don't deny that the power meter will quantify how much power the bike needs in order to increase speed. What I deny is the relevance of this quantity. Objectivity in itself does not mean anything. We could objectively measure the color of a bike with a spectrometer but that won't make it any more relevant. A bike without a rider that is both willing and able to produce the required power isn't going anywhere and unfortunately for us there is no simple and objective way to measure it because the will and ability of a rider to produce power is intimately mixed with many subjective factors in addition to the mechanical properties of the bike itself.

This just isn't true and it seems to be the main source of your confusion. As I already noted, it is simply an empirical fact that asking your muscles to produce a high amount of power for a brief moment (as when accelerating weights straight up in a gym) can quickly drive them from a highly efficient mode to 100% losses even if the average power is low. You can't argue with that.

They are not separate systems because forcing yourself to work harder to accelerate a heavier bike in the same amount of time will alter factors like muscle soreness, low blood glycogen levels, etc.

So it's not a question of if bike weight will increase the rider's mechanical inefficiencies, but how much it will increase them in typical riding. This is not a point of dispute, but a matter of fact.

And that's all it has to be. If an untrained cyclist is much less efficient then that difference in efficiency has to manifest itself somewhere. If manifest in the ability to cope with the increased demands of accelerating a heavier bike then we have an avenue for weight being massively important for all but elite racers.

You can say whatever you want, but the fact of the matter is that the biomechanical losses are not merely a fixed fraction of the power generated by your body.

As I've said many times, it only takes 0 watts to bench press 500 pounds "at the bar" which implies a 100% loss. Since biomechanical losses are not always 100% we know that assuming the power at the pedals is input power times some percentage is wrong.

The biomechanical losses obviously vary as a function of load. So if your body is losing 70% when generating 620 watts it may start losing 90% when generating 624 watts in which case you'd actually be getting fewer watts into the pedals. There's no guarantee that the power at the pedals is an increasing function of power exerted and we can actually observe this kind of phenomena when pushing yourself too hard actually reduces your capacity.

The biomechanical losses can also vary as a function of past inputs. So if your body is losing 70% when generating 620 watts right now, it may start losing 80% when generating 620 watts 10 minutes from now. So not only is there no gurantee that biomechanical losses are a fixed portion of the power being generated, but there's also no guarantee that the power at the pedals will even be the same when the same power is currently being generated and we can actually also observe this phenomenon as riders get tired over the course of a ride (or even tired from an initial acceleration overtaxed by extra bike weight).

Of course a trained athlete would be skilled enough to navigate around such dips in the function relating input power to power at the pedals, but that wouldn't be your typical rider.

And would it not bear to reason that untrained cyclists have a lower anaerobic threshold? I'd think that accelerating away 5 or 6 times over the course of a few miles could be enough to put most cyclists on the border right there. Not just club rides.

No, a typical rider is not riding for multiple hours at all. That's your problem, you think everyone is out there training themselves, riding around with few or no stops, and purposely putting themselves in only those scenarios where biomechanical losses due to bike weight and other factors can be minimized or eliminated so they can achieve their moment of glory for the weekend (for amateurs) or the day (for professionals). Not so.

I don't deny that Lance Armstrong's coach, Kreuzotter, or any of the other sources you cite are a good approximation for recreational riding with artificial rules and constraints, but I have no doubt that the artificial rules of racing, club riding, or any of the other pansy ass activities participated in by "cyclistes" have little to no bearing on vehicular riding in general.

But aerodynamic losses are more spread out compared to the effects of weight which hit you in spurts every time you accelerate. This makes all the difference. Everyone knows that interval training pushes your body harder (ie increases biomechanical losses).

You're comparing apples to oranges, but since you've weighed them both in grams you think they're the same. Your body cares just as much about when and how it needs to deliver power as how much power needs to be delivered.

You still don't get it. Viewing power at the pedals as the sole indicator of performance is an incomplete point of view. It's like saying $20 can buy you a soda at the soda machine. It misses the point because you can't use a $20 bill at the soda machine, but if you have quarters then you won't even need that much.

The fact that 1 watt at the pedals is the difference between you on tuesday and you on wednesday while 0 watts "at the bar" is the difference between the worlds greatest weightlifter and me means that the power at the human-machine interface is not what we should be looking at.

You're blinding yourself to the most relevant dimension of the problem. You think that since you have a $20 bill in your pocket you have enough for 10 sodas, but I'm telling you that since you don't have any quarters you don't even have enough for one soda. Needing to generate 200 watts is not the same as needing to generate 200 watts is not the same as needing to generate 200 watts.

Speedo

If you guys solve the "Does five pounds matter?" issue that has vexed cycling for a century, could you move on to the "What is the correct amount to spend on education?" question that continues to plague the country.

Personally, I suspect that the answer is you're all right. Bacci's got the power and energy calculation down, and in an absolute sense, it doesn't add up to a lot. I once calculated that over a particular 50 mile hillyish route marginal weight would cost a solo rider of about my ability ~30 seconds per pound. Invisiblehand et. al. have the wa of the group ride down. If you are at the limit of your ability, that few extra joules required to stay in the pack can make all the difference. That has certainly lead to the equipment "arms race" you can see at the beginning of just about any club ride.

To each his own. Personally I've given up on the weight arms race in favor of comfort items. Fenders, a big seat bag to carry food and maybe gloves and a jacket. I'm finding that overall I'm happier with rides where I remember more of the scenery than the wheel in front of me!

Speedo

Raxel

I've seen the data chart, and it only include conti GP 406 tire. (Which has RR of 0.0066)
I suppose stelvio 406 (28c), comet 451 (19c), and new durano 406 (27c) have lower RR than conti GP.
(I have seen a test which shows stelvio has lower RR than conti GP)
And german magazine Tour has tested a number of 700c tires years ago. You can google the web for exact data, and I here I show some of those tires which are 'slower' than conti 406...

Conti GP3000: 0.0067
Hutchinson Top Speed: 0.0069
Stelvio Tublar 0.0069
Tufo Elite jet 0.0073
Montello 300 tublar 0.0075
Tufo Hi-composite carbon tublar 0.0077
Conti GP Attack/Force: 0.0073/0.0057

I was quite surprised to see that widely used 406 tires such as stelvio are comparable to some of best 700c tires around, which means they rolls better than most 700c tires. There are some tires with RR as low as 0.0038, but I think it is not fair to compare a quite cheap and durable tire like stelvio 406 to expensive, race-specific tires with very shot life.

noteon 

Heretic.

jur

Look again. That table actually shows that the small wheels are up there with the best of them. It most certainly does not show that smaller wheels are worse. Especially considering that small wheelers have to use the rather small selection of tyres available and compete against the best the industry throws forward for 700c.

BruceMetras

Here's a linky to a couple of cool radio shows that were recorded recently.. for Moulton enthusiasts, they are a must listen... for those interested in how small wheels are applicable to frame designs, biking comfort and overall efficiency, might also be worth a listen.

https://thebikeshow.net/2008/09/29/th...-one/#more-271

and part 2 dealing with the space framed models can be heard..

https://thebikeshow.net/2008/10/06/th...tory-part-two/

StuAff

Bruce read my mind- I was thinking 'what about Moultons then?', fast fast bikes by any stretch of the imagination, and then he posts the above. Bike Show's well worth a listen. Went to the Cycle Show in London on Saturday, had a good (metaphorical) drool over the Double Pylon & talked to Shaun Moulton (General Manager of Moulton & Dr Alex's great-nephew). If only I had a spare £8k.....

coffeesnob

Question will a bike with smaller wheels take more physical stamina, strength etc..than a bike with larger wheels. Everything else being equal as much as it can get.

fietsbob

Obviously a larger circumference wheel does have to rotate less frequently per mile , than a smaller one..


smaller wheel, bigger chainring , can get you the same gear - inch rolling down the road..

gear ratio..x wheel diameter..





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Nightdiver

Grrr... Arrgg...
11 years = epic!