AdelaaR

There is offcourse allways loss of energy everywhere like on the chain or the pedalbearings or the dustseals ... basicly everywhere.
But this has next to nothing to do with the weight of the bike and the energy required to keep or get it at speed.
Like Sixty Fiver said, a heavy bike will be easier to keep at speed, simply because mass in motion wants to keep it's motion.
The weight of the bike and rider does not, if properly pedalled, matter much on a flat surface while keeping the same speed.
The rider mainly has to battle the air resistance and a little bit of rolling resistance and a very tiny bit of other energy losses.
While climbing or accelerating however, weight starts to make much more difference.

If one were to ride on the moon, where the air resistance is almost nil, speeds of 1000km/h could be reached with a bike using the same power output that riders here on earth use to keep 40km/h.

Talldog

So in effect ... yes (?), it is an acceleration/deceleration function.


I suppose so in theory, but my lighter bikes are invariably easier to maintain a constant speed on, for whatever reason. Maybe it's the bearings, LOL.

Sixty Fiver

Lighter bikes also have a tendency to be more aerodynamic and have better quality parts... weight does not matter on flat ground but since few of us ride the salt flats the road rises and falls and the lighter wheels are easier to bring back up to speed.

prathmann

The last statement only applies if 1) the wheel weight is entirely at the outer edge of the tire, and 2) you're only considering the energy required to accelerate the wheel and not the energy required to raise it up a hill or due to the increased rolling resistance of a heavier bike. When climbing Mt. Ventoux, an extra pound on the wheel will count almost exactly the same as an extra pound elsewhere on the bike.

And I thought 'meanwhile' made it clear that when he was talking about reducing body weight that this was not of someone in perfect condition but rather someone with some extra fat to lose without having any effect on power output.

meanwhile

I'm sorry and I know that you are already upset, but this doesn't mean anything or make any sense whatsoever. Why should only KE stored in the wheel matter? It's trivial compared to rider KE. What does "true" mean? How can you say that the energy of anything is less than the force of something else? This is like comparing the volume of a sound to the brightness of a light.

meanwhile

What I said was that with constant power a reduction in bike weight creates extra climbing speed in proportion to the weight of the rider plus the bike. I.e. if you switch a 200lb rider from a 20lb bike to a 10lb one he won't climb twice as fast - the improvement will be more like 0.5%.

meanwhile

Amateur cyclists have convinced each of this (with a lot of encouragement from PR people and the cycling journalists whose ad sapce they buy) but in reality, for any sane definition of "huge" - no:

So - that's more minuscule than huge. But as I said earlier, there are special circumstances where rolling weight can have much greater influence:

..but this has little to do with making a hybrid ride better in typical use. And knocking 4.4 kilocalories off a total of nearly 1500 still isn't most people's idea of huge.

Re. climbing:

The above is cribbed heavily from that MIT Press book "Bicycling Science". It's not hard to read and it's a staple among bike designers and racing team managers and engineers responsible for configuring their riders' bikes . The above is not only based on physics that has been well understood since the seventeenth century, it has been confirmed empirically many times. And, really, if someone can prove that bicycles don't follow the physics above then they will either receive a Nobel or be murdered by annoyed physicists - its pretty fundamental stuff.

Perhaps the biggest reason why the importance of wheel weight is over-estimated by consumers is that weight is easy to understand, measure and compare - everyone knows what a gram or ounce is. And people like things that are easily measured (even if they don't mean much.) By comparison if you start giving people metrics for wheel stiffness, which can be more important in a high performance bike, they won't have any idea what you're talking about - they won't even know if a higher or lower figure is better.

Talldog

Aaahhh ... I think that may be from one of your "unimpeachable sources"


Play the semantics game if you like, but you know what I mean.

Don't be. I have come to terms with who and what you are .. and am decidely not upset.

Talldog

LOL ... do you even ride bikes ?? OTOH ... never mind.

khutch

For the most part moving the weight around has no effect but if you are running you have indeed contrived a situation where it would matter. When you are running with ankle weights you lift your ankle by some amount with every stride and then drop it back to the ground where a lot of the energy you stored into it on the way up is lost when your foot hits the ground. There is no way for it to be converted into forwared motion. Well there is a way that is little known and therefore seldom used and certainly illegal in any competition. Someone designed a spring "foot" you can wear to increase your running efficiency quite a bit by using the energy lost by lifting a dropping your leg/foot mass to propel you forward instead of being converted into heat. It would work with ankle weights too. Now that I think about it there is a second way, spring loaded running tracks have been built and tested to do the same thing.

I suppose that to some extent, depending on how you move the bike and various parts of your body while climbing, that the weight distribution can have some effect but it will be secondary effect at best, probably tertiary. When you are climbing the bulk of the resistance you face is gravity pulling you back down the hill and the effect of gravity depends on the total mass, not where it is located. Managing a secondary or tertiary effect correctly will win a race or get you to the top of the hill before your buddy but it won't make you feel significantly less tired at the top. All you have to do to win is to be a meter ahead, all you have to do to "smoke" your opponent is to be 100 meters ahead. Neither distance represents a significant change in the amount of work you did on the way up, that is determined by the total weight.

Ken

AdelaaR

Meanwhile is right about what he says about expensive light components being overrated by people.
This has a few reasons:
1) salesmen want to sell you very expensive stuff and lure you into thinking it'll be much better.
2) people want to have an excuse for buying pro stuff, mainly because they want to brag about their pro stuff.

Do not underestimate the power of the placebo effect.
People sense what they want to sense ... there are numerous proven examples of this in many fields.

As I said before: A lighter bike is allways better for climbing, no-one will argue about that as it is obvious.
But how much better?
A few percents max.
Is it worth spending thousands of dollars on a few percents?
For a common man, just wanting to ride: no.

meanwhile

If you mean the idea that comparing energy and force as if they are the same thing is idiotic and meaninglss, then yes. (Btw I do have a degree in theoretical physics from one of the world's top 5 science universities..)

And whining about sources when you haven't provided any (while I have quoted the work of an MIT engineer!) just makes you look like a hypocrite.

No. I know that you think that you mean something, but in fact your ideas are a combination of mush and self-contradiction. Any teenager who passed high school physics should have been incapable of the mistakes you have made.

Now, there's nothing (very) wrong with being scientifically innumerate... until you start insisting that you're an expert on classical physics. At which point you become just as much as an idiot as a man who can't speak French insisting that everyone in the world should accept his translation of Remembrance Of Things Past as the definitive one.

meanwhile

And the effect of social consensus. (See 2. above.)

Exactly. The main things to concentrate on in looking for a new bike are in fact

1. Suitability for your purpose - if you want to climb steep hills, get the right gearing; if you want a safe comfortable mile eater then don't get a bike with the short wheelbase, narrow tyres and sharp angles of a criterion racer

2. A good fit for your body

3. Good welds, expertly built wheels, and excellent assembly work by the bike shop

But none of these are easily compared, so they don't appeal to the human instinct for comparing things and creating hierarchies of prestige and satisfaction.

Talldog

Yea ... but I'm pretty rich

AdelaaR

That actually explains a lot.

mrbuku

I have a Giant Escape 1 and find it a bit easier to climb versus my Windsor Wellington 1.0, Giant Defy 5 or Masi Premaire 1 carbon bike. I just find that bike more comfortable and with the side grips on the bars, my hands fair better in a hybrid position than a road bike position. I do lose a bit in average speed of rides, but climbing with the Escape 1 hybrid is worlds easier than the road bikes. I do have three gears which allow me far more room to play with to allow spinning. Steep climbs I have taken on road bikes have almost made me give up on biking lol.. But I am still learning proper gearing and how to anticipate climbs and where I need to be gear wise. But I do feel Hybrids are under estimated, mine is a Sport Hybrid and when riding in town I often pass road bikers with ease on the slightly heavier bike. But it IS all about the motor, not always the gear..

giantcfr1

I think most of those debating this thread 5 and a half years ago have left the building.