Is steel still real?

[Bustedknuckle]

Yes, quite possibly, at you.
Amazing you you conveniently ignore some facts presented to you as it suits.
You always come back to "Take 200 grams of the wheels, then take 200 gram of the rider, it has the same effect."
Except it doesn't for the two reasons out lined, (Moment of Inertia and Rotational Dynamics)THEY are facts
What's more the rider is actually a constant.

Same rider 90 kg on Bike A which weighs 10kg, inc 2 kg wheels (100kg total) and Bike B with 8 kg inc 2 kg wheels. The difference is not just the 2% (for those reasons outlined), and even if it was Bike A would still be faster! (That is the Moment of Inertia)
Quite simply Bike A requires more energy to accelerate, since the constant (the rider) supplies that energy it must be slower

If we compare Bike B, with another Bike C, which is 8kg but with 1.5kg wheels, so the same total weight, then this bike has a further benefit (due to Rotational Dynamics) that requires less energy for the wheel to be accelerated, however, on a perfectly flat course this will be negated because the wheel will roll longer (this is also called a flywheel effect)... if it is perfectly flat, that is...


Now none of this has anything to do with the initial question, but that is a long way gone now

YES, moment of inertia differences DO exist but the differences in energy required to spin a rim twice the weight is something on the order of .1 of 1% .

This horse is dead. If you wish to ride a light bike with light wheels, go right ahead and I hope being pleased with the resulting ride is the result you get. You then ride lots cuz that's the idea, yes?

 

[Notso Swift]

For the example above where the 90kg rider has an 8kg bike with either 1.5kg or 2.0 kg wheelset, To go from 300 rpm to 600 rpm (20kph to 40 kph) it is 6 times the effective weight.
Now that 6 times is only on the rim and tyre, (as the hubs are negligible for rotational dynamics), so lets halve it to 250 grams, and based on that 250gr being 33cm from the axis (wheels are 35cm) = effectively moving 1.5kg more
The energy to maintain on a level surface is the same, and the stored energy is actually higher in the heavier wheel, but not to accelerate
That is not .1 of 1%!

 

[Hangdog98]

Steel

Aside from Newton's Laws which are truly indisputable facts used in the engineering of anything that moves, regardless of how you may have justified the purchase of the cheaper heavier wheels believing that rotating mass has no effect on acceleration, there are two other 'Laws of Cycling' that need to be considered.

1. A $5000 carbon frame will weigh less than a $1600 steel frame and offer better performance, BUT, much of the weight savings from expensive frames comes from the dramatic weight reduction experienced by the purchasers wallet.

2. A comfortable steel frame that you can ride anywhere will get ridden more and for longer and over more varied terrain. The resulting weight loss and aerobic gains experienced by the rider will compensate for the heavier frame at a rate of 254% minus your age. Your card is the 6 of diamonds.

I had a gorgeous Columbus Nemo frame that I rode everywhere. I sold it and bought a crazy expensive SC7000 framed 'green-jersey-winning' French masterpiece which hurts my bottom. I want my steelie back.

 

[TopCarbon]

For the example above where the 90kg rider has an 8kg bike with either 1.5kg or 2.0 kg wheelset, To go from 300 rpm to 600 rpm (20kph to 40 kph) it is 6 times the effective weight.
Now that 6 times is only on the rim and tyre, (as the hubs are negligible for rotational dynamics), so lets halve it to 250 grams, and based on that 250gr being 33cm from the axis (wheels are 35cm) = effectively moving 1.5kg more
The energy to maintain on a level surface is the same, and the stored energy is actually higher in the heavier wheel, but not to accelerate
That is not .1 of 1%!

now, my head hurts

 

[mattfatcyclist]

Well.....

I was 262 riding a full carbon light wheeled bike(time). Bike was 16.2# now I weigh 203 ride a steel bike with 1700 grm wheels. I climb much faster. I imagine that once I am 180 I will be faster still.Can't we ALL just get along?

 

[Bustedknuckle]

I was 262 riding a full carbon light wheeled bike(time). Bike was 16.2# now I weigh 203 ride a steel bike with 1700 grm wheels. I climb much faster. I imagine that once I am 180 I will be faster still.Can't we ALL just get along?

I weigh .1 of a ton, my beautiful steel bike weighs right at 20 pounds(SBW-Standard Bike Weight). If I lose 20 pounds my bike weighs ZERO....

 

[mattfatcyclist]

I weigh .1 of a ton, my beautiful steel bike weighs right at 20 pounds(SBW-Standard Bike Weight). If I lose 20 pounds my bike weighs ZERO....

Is that with wheels or without??

 

[Black Dog]

Since rotational mass has such a dramatic effect on performance, I have decided to get ride of the rims, spokes, and tires. I will now ride on the hubs and expect to win the tour next year. I will file the hub flanges down if Alberto or Andy give me any trouble. Let this thread teach us all the belief is a force more powerful than fact.

 

[Hangdog98]

Physics 101

OK, so who was too busy out riding their bike when they should have been in physics class learning about moments of inertia? You'd better have a note!

Seriously though, lighter wheels accelerate faster and with less effort. For the same reasons that 4 valves per cylinder allow higher RPM's. Like why a lighter flywheel will allow your Corvette LS6 to spin up faster than stock. It's a logarithmic thing. It's OK if you don't get it, it's not so easy to visualize if you don't understand the math but it is real, just like steel.

I like steel bikes, columbus steel in fact, but I'm fat and slow and I like the comfort and the feel, the 'snap' if you will. I also like heavier rims (Mavic open pro's thanks) 36 thin spokes (Sapim X-Rays are my fave), low flange hubs and 25mm tires at 90ish psi. Right now I don't have that combination but that's what I'm going back to. Yes, you will be faster than me but my girlfriend is prettier than yours

 

[Polyarmour]

On Wheels

All those calculations earlier that were based around F = MA were inaccurate for a bike with spinning wheels as the moment of inertia needs to be added to the equation.

Rotating wheels need to be treated separately. One way of looking at it is like this.

The kinetic energy contained in a rotating wheel is ½mv2 + ½Iw2 (the 2's are squared signs)

where

m = mass of the wheel
v = translational velocity of the wheel
I = moment of Inertia of the wheel
w = angular velocity of the wheel

In essence this formula says that the energy of the wheel is tied up in two movement components, translation and rotation.

For a bike wheel these two terms are approximately equal. (ie ½mv2 = ½Iw2) In other words the amount of energy tied up in moving the wheel along roughly equals the amount of energy tied up in rotating the wheel. This fact gives rise to the old saying "a pound on the wheels = two pounds on the frame", It's not a myth, it's not an old wive's tale, it's a well established fact borne out by the physics.

 

[Anonymous]

congratulations

OK, so who was too busy out riding their bike when they should have been in physics class learning about moments of inertia? You'd better have a note!

Seriously though, lighter wheels accelerate faster and with less effort. For the same reasons that 4 valves per cylinder allow higher RPM's. Like why a lighter flywheel will allow your Corvette LS6 to spin up faster than stock. It's a logarithmic thing. It's OK if you don't get it, it's not so easy to visualize if you don't understand the math but it is real, just like steel.

I like steel bikes, columbus steel in fact, but I'm fat and slow and I like the comfort and the feel, the 'snap' if you will. I also like heavier rims (Mavic open pro's thanks) 36 thin spokes (Sapim X-Rays are my fave), low flange hubs and 25mm tires at 90ish psi. Right now I don't have that combination but that's what I'm going back to. Yes, you will be faster than me but my girlfriend is prettier than yours

fat, slow AND the prettiest girlfriend? I got 2 out of 3 so guess I better trade up to an iron bike...
but seriously now, anyone have experience with Gunnar cycles? Look like good bang for the buck.

 

[Black Dog]

All those calculations earlier that were based around F = MA were inaccurate for a bike with spinning wheels as the moment of inertia needs to be added to the equation.

Rotating wheels need to be treated separately. One way of looking at it is like this.

The kinetic energy contained in a rotating wheel is ½mv2 + ½Iw2 (the 2's are squared signs)

where

m = mass of the wheel
v = translational velocity of the wheel
I = moment of Inertia of the wheel
w = angular velocity of the wheel

In essence this formula says that the energy of the wheel is tied up in two movement components, translation and rotation.

For a bike wheel these two terms are approximately equal. (ie ½mv2 = ½Iw2) In other words the amount of energy tied up in moving the wheel along roughly equals the amount of energy tied up in rotating the wheel. This fact gives rise to the old saying "a pound on the wheels = two pounds on the frame", It's not a myth, it's not an old wive's tale, it's a well established fact borne out by the physics.

All very true. However, since the rotational mass in wheels is still a small percentage of the total rider + bike package it is safe to discount the effect, when looking at general effects, since differences between wheel-sets are indeed small. Another aspect that is often ignored as that heavier wheels require more energy to accelerate but return that energy in momentum.

 

[stephens]

Another aspect that is often ignored as that heavier wheels require more energy to accelerate but return that energy in momentum.

But how much benefit does the momentum provide? Because I live in hilly terrain and going a little faster on the uphill beats going quite a bit faster on the downhill: At roughly 8mph on the up and 40mph down, if I go 1% faster on the uphill I'll be faster overall than going 6% faster on the downhill). And then how about real life stop-and-go city riding where one spends more time getting up to speed than he does cruising at that speed?

My point is just that real life is much more complicated than the "weight on the rider is the same as weight on the bike" guys want to acknowledge.

 

[Black Dog]

But how much benefit does the momentum provide? Because I live in hilly terrain and going a little faster on the uphill beats going quite a bit faster on the downhill: At roughly 8mph on the up and 40mph down, if I go 1% faster on the uphill I'll be faster overall than going 6% faster on the downhill). And then how about real life stop-and-go city riding where one spends more time getting up to speed than he does cruising at that speed?

My point is just that real life is much more complicated than the "weight on the rider is the same as weight on the bike" guys want to acknowledge.

True, in a stop and go situation the extra inertial mass is not good. As well this is true in serious climbing efforts. Any time the brakes are used that inertia is converted into heat. You are right about the multiple factors at play here and that is why a few hundred grams does not make a big difference one way or the other no matter where on the bike or rider it is. Those that claim it does make a difference do so with out any evidence to back their claims. It is marketing and placebo.

 

[Polyarmour]

All very true. However, since the rotational mass in wheels is still a small percentage of the total rider + bike package it is safe to discount the effect, when looking at general effects, since differences between wheel-sets are indeed small. Another aspect that is often ignored as that heavier wheels require more energy to accelerate but return that energy in momentum.

It depends what you are doing on the bike. If you are just riding to get fit or for social reasons the difference is barely noticeable I agree. If you are racing however the difference is significant. Even 1-2% differences add up over the course of a race. People who can keep up early in the race start looking for that 1-2% when they are on the verge of being dropped. I was in a race on the weekend and I lost contact with the main group very close to the top of the only mountain in the race. Then I was on my own and couldn't get back to the group and finished 10 minutes behind them. I believe if I had lighter wheels I could have maintained contact over the mountain and finished in the bunch.

 

[Hangdog98]

fat, slow AND the prettiest girlfriend? I got 2 out of 3 so guess I better trade up to an iron bike...
but seriously now, anyone have experience with Gunnar cycles? Look like good bang for the buck.

OK, you got me. She ran off with the fast guy who had the lighter wheels.

When I bought my fancy Scandium bike with the superlight wheelset I took it for a ride with my buddy and we got to the part where we usually have a little sprint. It's slightly uphill and about 150m long. Now I don't know how much the stiffer rear triangle and the overall reduction in weight had to do with it but I accelerated so fast my brain wasn't ready for having to shift so soon. I don't think the placebo effect played a role here.

Is Placebo made by Pfizer?

 

[stephens]

If it is, it must be their best seller, because the whole rest of the world thinks weight matters except the few people here who are convinced they are smarter than everyone else.

 

[Black Dog]

It depends what you are doing on the bike. If you are just riding to get fit or for social reasons the difference is barely noticeable I agree. If you are racing however the difference is significant. Even 1-2% differences add up over the course of a race. People who can keep up early in the race start looking for that 1-2% when they are on the verge of being dropped. I was in a race on the weekend and I lost contact with the main group very close to the top of the only mountain in the race. Then I was on my own and couldn't get back to the group and finished 10 minutes behind them. I believe if I had lighter wheels I could have maintained contact over the mountain and finished in the bunch.

Proof of the Placebo... The 1-2% figure is in reference to a few kilos not a few hundred grams. The wheels represent a 0.1 - 0.2% difference...about the same mass as a good poop.

 

[Black Dog]

If it is, it must be their best seller, because the whole rest of the world thinks weight matters except the few people here who are convinced they are smarter than everyone else.

Seriously...the rest of the world thinks ______________ (the sun goes around the earth, the earth is flat, the world was created in 7 days...) therefore it must be true. No one here thinks that they are smarter than anyone else. Questioning conventional 'wisdom' is not a way to act superior. The folks who are doing so are not stuck in the past and against progress. These negative comments suggest that people are insecure in their beliefs threatened by the possibility that their notions of reality may not be correct. Weight does matter when you get into the big numbers; for the values we deal with it does not matter nearly as much as the 'rest of the world' thinks. Perception is not evidence, perception is not reality.

 

[Polyarmour]

Proof of the Placebo... The 1-2% figure is in reference to a few kilos not a few hundred grams. The wheels represent a 0.1 - 0.2% difference...about the same mass as a good poop.

My wheels, tyres and tubes weighed 2190g.
Others in the race had combinations that weighed around 1400g

That's a difference of 790g.

Since it is a spinning mass you can double it in terms of its energy penalty, that's 1.58kg. I weigh 80kg so that's around 2% in terms of its energy impact to me.

That's a big poop Black Dog!

Wheels are significant, why do you think the pros are on light wheels?

Think of it this way.

Cycling involves lots of repetitions of a low weight. If you do a 100km race you might rotate the peddles 20,000 times with an average force equivalent to (say) 10kg of weight (taking into account the ups and downs of the course). With my heavy wheels I might have had to use an average of 10.1kg of force equivalent. (that's 1% difference). There is no way I can tell the difference between 10.0kg and 10.1kg, I agree. However after 18,000 reps towards the end of the race, my muscles are fatiguing and I'm feeling that 0.1kg because that 0.1kg has been through 18,000 reps. That's 1800kg of extra "work" my muscles have had to deal with. And even if I get some of that energy back on the downhill sections it won't help at the next attack when I have no legs to go with them.

 

[Black Dog]

My wheels, tyres and tubes weighed 2190g.
Others in the race had combinations that weighed around 1400g

That's a difference of 790g.

Since it is a spinning mass you can double it in terms of its energy penalty, that's 1.58kg. I weigh 80kg so that's around 2% in terms of its energy impact to me.

That's a big poop Black Dog!

Wheels are significant, why do you think the pros are on light wheels?

Think of it this way.

Cycling involves lots of repetitions of a low weight. If you do a 100km race you might rotate the peddles 20,000 times with an average force equivalent to (say) 10kg of weight (taking into account the ups and downs of the course). With my heavy wheels I might have had to use an average of 10.1kg of force equivalent. (that's 1% difference). There is no way I can tell the difference between 10.0kg and 10.1kg, I agree. However after 18,000 reps towards the end of the race, my muscles are fatiguing and I'm feeling that 0.1kg because that 0.1kg has been through 18,000 reps. That's 1800kg of extra "work" my muscles have had to deal with. And even if I get some of that energy back on the downhill sections it won't help at the next attack when I have no legs to go with them.

That is a big poop and fat-******* would be proud of such a load. 1400grams all in? That is a sub 1 kilo wheel set!

However, 1800kg is simply nonsense. You can not just add numbers; the mass differences only apply to acceleration and climbing and some of that energy is returned. And the effects of acceleration are further mitigated as velocity increases due to the exponential increase in wind resistance which quickly overwhelms the penalty of the mass difference. It does take more energy to ride with extra mass, no arguments. The amount is disputable.

 

[Hangdog98]

Clearly the best strategy here is to train heavy and race light and to make sure you do a giant poop before the race. I did a 790g one just this morning. I normally weigh them before recycling the corn and the peanuts.

 

[marathon marke]

Wheels are significant, why do you think the pros are on light wheels?

That's the question I've been waiting to get answered. If the weight wasn't significant, then why would pros risk riding on something that clearly isn't going to be as strong or durable?

 

[bobs nob]

Clearly the best strategy here is to train heavy and race light and to make sure you do a giant poop before the race. I did a 790g one just this morning. I normally weigh them before recycling the corn and the peanuts.

I'll be right back after I am done getting sick.

 

[stephens]

That's the question I've been waiting to get answered. If the weight wasn't significant, then why would pros risk riding on something that clearly isn't going to be as strong or durable?

Because "placebo" isn't on the banned drug list? Seriously though, no one in his right mind should doubt that weight (of the bike, independent of rider weight) makes a huge difference in how a bicycle rides. If he believes it doesn't matter, it's not that the rest of us have drank the koolaid, it's that he's just perceptive enough to feel the difference.