Weight! Does it really matter?

[knapdog]

After analysing everyone's replies I choose to conclude that we and the bike are not separate, but that they both combine to total ONE weight and it is this one weight that we pedal around. Therefore, it is just as beneficial to our progress if we lose, for example, 2kg from our body mass as shaving 2kg off the weight of the bike. Of course, I may still be wrong!!!!!!!

 

[MacB]

here's a linky for you

http://www.smartcycles.com/bike_weight.htm

 

[swee'pea99]

Well, that seems pretty unambiguous. According to that article, it makes no difference whether the weight is in the bike or the rider - it is only the 'total package weight' that matters.

Have to say I'm sceptical. I reckon there is a bigger advantage in knocking a kilo off the bike than off the rider. I also reckon it makes a significant difference where you knock that weight off.

I've heard it said that 'an ounce off the wheels equals a pound off the frame'...I think there's a lot of truth in that. And if there is, it does kind of call into question the rather simple assumptions made in that article.

 

[tyred]

A lighter wheel will be easy to rotate and get up to speed but then again there is the question of momentum once you have your wheels up to speed.

It's similar to the difference between fitting a car engine with a heavy or a lightweight flywheel.

Isn't one of Alex Moulton's arguments in favour of small wheels is that they are both lighter and stiffer than a large wheel?

 

[knapdog]

Does a heavier wheel add more centrifugal force to the circumference when rotating, which, in turn, could make the bike heavier?

 

[swee'pea99]

Does a heavier wheel add more centrifugal force to the circumference when rotating, which, in turn, could make the bike heavier?

Ingenious but deranged. If you think about it, the centrifugal force is acting equally in all directions - eg, up exactly as much as down. So it can't be 'making the bike heavier'.

I can't get my head round the physics of the thing at all, but I do know from personal experience that swapping for lighter wheels might make only a very marginal difference - way under a kg - to the 'total package weight'...but it makes a helluva difference to the ride.

 

[Woz!]

Heavier wheels will have more of a gyroscopic affect than lighter ones...

 

[dodgy]

Does a heavier wheel add more centrifugal force to the circumference when rotating, which, in turn, could make the bike heavier?

Here's a fun experiment, take off the front wheel (less messy) and hold it at the quick release with both hands (one hand each side of the wheel hub), then spin it as fast as you can with your fingers (maybe ask someone to help). Once the wheel is spinning, try to turn the wheel so it tilts around as if you were steering it.

Come back and tell us how it feels

 

[tyred]

Bicycle wheels and tyres are usually very poorly balanced. If you had wheels like that on your car, it would be a struggle to drive it.

 

[jimboalee]

Here's a fun experiment, take off the front wheel (less messy) and hold it at the quick release with both hands (one hand each side of the wheel hub), then spin it as fast as you can with your fingers (maybe ask someone to help). Once the wheel is spinning, try to turn the wheel so it tilts around as if you were steering it.

Come back and tell us how it feels

Take the skewer out.
Spin it REALLY fast at an angle to the ground.
Now hold the wheel on one fingertip.

Precession


Lighter rims are easier to turn because of the shorter radius of gyration.

 

[Dave5N]

Take the skewer out.
Spin it REALLY fast at an angle to the ground.
Now hold the wheel on one fingertip.

Precession


Lighter rims are easier to turn because of the shorter radius of gyration.

I did that.

I got nutation

 

[jimboalee]

I did that.

I got nutation

I'll nod my head to that.