Weightless bike: what would change?

[Vorpal]

I'd have room in my shed for more.

[hercule]

Weightless - not a problem. Just add some helium balloons carefully adjusted to the bike’s weight. You’d still have the bike’s mass to contend with for accelerating, cornering, braking. And a weather balloon or two would add more than a little aerodynamic drag.

Massless - rather more difficult!


I'm a trendy consumer. Just look at my wobbly bog brush using hovercraft full of eels

[Brucey]

...But if weightless bicycles are of no interest, what's the point of spending millions trying to get the weight down further from where it is?

Weight having little significance to most people is not the same as weight having no significance to anyone. A lighter bike does work better, if only a little bit. Even if reducing weight didn't have any practical benefit, light bikes feel nicer, and thus are preferable in the same way that nice-tasting food is preferable to gruel, even if they are nutritionally identical.

yup. Traditionally lighter bikes have (up to a point, as long as you don't overdo it) also been bikes that have been better made, that ride better over the bumps, and even last longer because they are made in better quality materials etc. It is these palpable qualities (rather than the weight (or mass) per se) that usually make/made a lighter bike better to ride. The fact that you are also working a bit less hard up the hills is easier to understand and is therefore latched onto by many folk. Of course any tiny difference can be important in competition but outside of that you might not even notice the difference.

Just today I slung a lightweight wheel and tyre into my hack bike (that is normally differently shod) and to me it rode and steered more like a bike that was six or seven pounds lighter.

Today, lightweight bikes are made in all kinds of materials and 'lighter' just promises less weight; the other things are not in any way more or less likely; I have ridden some very light bikes that were frankly rather horrid, like the blokes that designed them understood nothing about why previous bikes were designed and built in the ways they were....

In this brave new world we are expected to put up with plank-like framesets and to make the bikes acceptably comfy by using fat tyres. Like a wheelbarrow does....

cheers

[bogmyrtle]

Passing gates on windy days is bad enough on a normal bike. I think a weightless bike would get blown out from under the rider.

[Peter W]

If a bike was truly weightless it would have NO inertial force, whereas the rider would still be all too real and solid. Hasn't it occurred that it would be more difficult to ride and, perhaps, even balance?

Imagine climbing a very steep hill, with those usual surging pedal strokes. Bike, being weightless would shoot ahead trying to loop, leaving all too heavy rider clattering down off the back, unless, of course, he quickly develops the tricky knack of 'body language' leaning, to counter balance.

I once tried towing a weighty cabin cruiser in a very light weight inflatable. It's lack of inertia meant instant stop if the rope went slack and caused a jerk with me tumbling over backwards. I can imagine trying a panicky grab of the brakes on a weightless bike when hurtling down a very steep descent and being hurled forward over the bars! (Unless I leapt off the back of it first!! )

[Mike Sales]

If a bike was truly weightless it would have NO inertial force, whereas the rider would still be all too real and solid. Hasn't it occurred that it would be more difficult to ride and, perhaps, even balance?

Imagine climbing a very steep hill, with those usual surging pedal strokes. Bike, being weightless would shoot ahead trying to loop, leaving all too heavy rider clattering down off the back, unless, of course, he quickly develops the tricky knack of 'body language' leaning, to counter balance.

I once tried towing a weighty cabin cruiser in a very light weight inflatable. It's lack of inertia meant instant stop if the rope went slack and caused a jerk with me tumbling over backwards. I can imagine trying a panicky grab of the brakes on a weightless bike when hurtling down a very steep descent and being hurled forward over the bars! (Unless I leapt off the back of it first!! )

The usual technique for towing a rather heavier boat with an inflatable is to lash the smaller boat firmly alongside, so that the two boats are one unit. This works fine, I have done it many times.
I would imagine that a bike and its rider are firmly connected in the same way, and whether the bike is a fraction of the rider's weight or no weight at all, there is no problem.
Putting rather lighter wheels on a bike does affect the response of the machine to rider input, but is quickly adapted to. It seems that the gyroscopic force makes a difference, but my guess is that having none is something one could handle. Balancing is managed by normal sensitivity to gravity and response, by steering or leaning to keep the wheels underneath.

[Mike Sales]

If a bike was truly weightless it would have NO inertial force, whereas the rider would still be all too real and solid. Hasn't it occurred that it would be more difficult to ride and, perhaps, even balance?

Imagine climbing a very steep hill, with those usual surging pedal strokes. Bike, being weightless would shoot ahead trying to loop, leaving all too heavy rider clattering down off the back, unless, of course, he quickly develops the tricky knack of 'body language' leaning, to counter balance.

I once tried towing a weighty cabin cruiser in a very light weight inflatable. It's lack of inertia meant instant stop if the rope went slack and caused a jerk with me tumbling over backwards. I can imagine trying a panicky grab of the brakes on a weightless bike when hurtling down a very steep descent and being hurled forward over the bars! (Unless I leapt off the back of it first!! )

The usual technique for towing a rather heavier boat with an inflatable is to lash the smaller boat firmly alongside, so that the two boats are one unit. This works fine, I have done it many times.
I would imagine that a bike and its rider are firmly connected in the same way, and whether the bike is a fraction of the rider's weight (as is usual) or no weight at all, there is no problem.
Putting rather lighter wheels on a bike does affect the response of the machine to rider input, but is quickly adapted to. It seems that the gyroscopic force makes a difference, but my guess is that having none is something one could handle. Balancing is managed by normal sensitivity to gravity and response, by steering or leaning to keep the wheels underneath.

[Peter W]

Yes Mike, but you've clearly misunderstood what I meant by inflatable. I meant one of those 'toy' blow up things with little plastic oars, as kids use. It was hurriedly pressed into service to rescue, and tow in, a stranded (anchored) cabin cruiser with a broken down engine, the owner of which was shouting for help! There was no way I could have rowed, or propelled and STEERED it, if lashed beside the boat.

As for the weightless bike,are you sure it would behave as you claim? No one has ever tried it!

[Mike Sales]

Yes Mike, but you've clearly misunderstood what I meant by inflatable. I meant one of those 'toy' blow up things with little plastic oars, as kids use. It was hurriedly pressed into service to rescue, and tow in, a stranded (anchored) cabin cruiser with a broken down engine, the owner of which was shouting for help! There was no way I could have rowed, or propelled and STEERED it, if lashed beside the boat.

As for the weightless bike,are you sure it would behave as you claim? No one has ever tried it!

You are right, I had not imagined anyone would attempt to tow a boat with a toy.
I don't think your analogy is useful though. I have tried towing with a yacht type inflatable, and it works with neither oars nor engine, for the reason you found. With the boat lashed alongside rowing would be impossible, of course. One would move in circles! With an engine, propulsion and steering is no problem.
The difficulty is that one is trying to move a much heavier object, with much more inertia. Whereas the bike has, even if not weightless, much less weight, which is connected to the source of energy relatively firmly, not by a single rope.

As you say, noone has tried it, we are all speculating here.

[Cyril Haearn]

Experiments could be done with a 60 kg person on a 20 kg bike (30%), then a 100 kg person on a 7 kg bike (7%)

Then one could extrapolate, are there bikes even lighter than 7 kg?

[Mr Evil]

...are there bikes even lighter than 7 kg?

7kg? That's a boat anchor, not a bike. You need to get down below 3kg before it's truly light.