Does Wheel weight matter

Croicyclist

Currently running Mavic Aksiums at 1900 g

Looking to spend a few quid on the bike to work scheme

Will lighter wheels make a big difference to me

Have any of you upgraded and noticed a big difference on your speed

cheers

Beasty

Croicyclist wrote: »

Looking to spend a few quid on the bike to work scheme

They'll be attached to the bike you are looking to get under the scheme I take it?

(Scheme is for complete bikes and certain safety accessories only)

Croicyclist

But of course

Lumen

Better wheels are better. Some lighter wheels are better, some are worse.

Many people claim that riding pleasure is increased with nicer wheels.

Regardless, they won't give you a big speed difference. Even wheels with zero mass and zero drag would only give a marginal improvement in speed.

langdang

Croicyclist wrote: »

Will lighter wheels make a big difference to me

Have any of you upgraded and noticed a big difference on your speed

Simple answer - yes.
Long answer - depends how much you are shaving off? I've taken nearly a kg off a set off budget-tastic MTB wheels just by changing tyres and tubes and that made a huge difference. I suppose 200g saved on a road bike that traveled 5 times the distance in one spin would give the same overall gain?

BryanL

Lumen wrote: »

Regardless, they won't give you a big speed difference. Even wheels with zero mass and zero drag would only give a marginal improvement in speed.

A bit like training then?:D

Everything matters on the bike, just most of the time the cost of saving weight, through equipment rather than a skiny backside, is prohibitive.

I ride 440 tubs racing and notice the difference over my askiums.

Quigs Snr

Nice wheels = Placebo effect. Small improvements to be had, but differences between a set of Askiums and a top end wheel in real world numbers for the average cyclist I would say would be inside the margin of error.

But don't be so practical... get whichever ones make you feel all funny in your pants.

CheGuedara

Yes - if you are pointing your bike up hill.

I've a pair of Mavic Cosmic Carbones that come in at ~2,520g (1740g plus tyres @410g/pair, tubes @140g/pair & cassette @236g) and a pair of Campag Eurus Tubless @ ~2300g (1490g plus tyres @580g/pair & cassette @236g).

Cosmics - lovely n fast on the flat or descending, definitely do their aero job but can definitely feel the extra weight at the rim when made to climb - just means using a lower gear and spinning a bit faster to hold the same speed.

Not sure you'll be able to buy just a pair of wheels on the bike to work though (unless there's some sly, sneakness going on )

Edit: I'd largely agree with Quigs though - real life effect is probably marginal and limited to riding in a different gear unless you're racing. And a big plus 1 on buying the ones that you LIKE the most

IIRC in one of those roues artisinales wheel tests the aksiums fared quite well in aero and stiffness terms against some much more expensive wheelsets,

langdang

Even on a performance car (developing a fair bit more power to overall weight than a human) lighter wheels will make a difference to acceleration. That's the real reason for "proper" alloys - not the awful tacky ones that are probably heavier than steel wheels.
You are accelerating the wheels a lot more often than you think on a bike...

Quigs Snr

He will have no probs picking up a set of wheels on the scheme as long as the shop spells Zipp 404 as "Mountain Bike" on the receipt.

To add my tuppence worth, I feel faster on steep uphills on my 5.9kg Cervelo R3SL with 1040gram 2008 model Reynolds DV46 UL Tubular wheels than I do on my 8.8kg Cervelo S1 with 1770g Mavic Cosmic Carbones. However this does not seem to translate to actual speed for me and the data from my rides backs this up. My conclusion is that I am the reason I can no longer climb and I cannot buy any of that speed back with fancy wheels or bikes (and I have tried!). Your mileage may vary.

Lumen

langdang wrote: »

Even on a performance car (developing a fair bit more power to overall weight than a human) lighter wheels will make a difference to acceleration. That's the real reason for "proper" alloys - not the awful tacky ones that are probably heavier than steel wheels.
You are accelerating the wheels a lot more often than you think on a bike...

Putting aside the car wheel thing (which is a different debate), the "repeated acceleration" argument makes no sense, since the energy is returned directly when you ease off, i.e. decelerate more slowly.

For your argument to make sense, you need to demonstrate where the lost energy has gone. This applies when you brake for a corner, as the kinetic energy is converted to heat at the brake pad/rim. It also applies to a tiny degree when climbing a hill, since although you will descend microscopically faster with heavier wheels, higher speeds are more aerodynamically lossy. There is no lost energy when just pushing along the road.

langdang

Are wind resistance and rolling resistance not constantly trying to slow you down, so considering even with clipless pedals you can't have an absolutely smooth power delivery, there will many many mini accelerations even when it looks like you are at a constant speed? (overthinking it maybe, but depending on your "sampling window" you would see accelerate-decelerate-accelerate-decelerate constantly) Never mind a few eejits ahead of you who keep oscillating the pace?

Off road obviously you are doing way way more acceleration due to bumps robbing your speed

Lumen

langdang wrote: »

Are wind resistance and rolling resistance not constantly trying to slow you down, so considering even with clipless pedals you can't have an absolutely smooth power delivery, there will many many mini accelerations even when it looks like you are at a constant speed?

Yes, but those cycles don't lose any energy. In fact, you are more efficient with very heavy wheels, since a more constant speed is more efficient.

With respect to accelerations within a race situation, the energy required to accelerate 1kg is absolutely tiny compared to the wind resistance you have to overcome doing so.

There is a fuller analysis here.

langdang

Lumen wrote: »

Yes, but those cycles don't lose any energy. In fact, you are more efficient with very heavy wheels, since a more constant speed is more efficient.

OK, I get what you're saying there, heavy wheels store energy and smooth out a yoyo cycle like that.

Lumen wrote: »

With respect to accelerations within a race situation, the energy required to accelerate 1kg is absolutely tiny compared to the wind resistance you have to overcome doing so.

There is a fuller analysis here.

I'll read it later, must have another think about the off-road significance also!

tunney

Beasty wrote: »

(Scheme is for complete bikes and certain safety accessories only)

Since when?

Chips Lovell

tunney wrote: »

Since when?

Since the start.

tunney

Lumen wrote: »

Yes, but those cycles don't lose any energy. In fact, you are more efficient with very heavy wheels, since a more constant speed is more efficient.

With respect to accelerations within a race situation, the energy required to accelerate 1kg is absolutely tiny compared to the wind resistance you have to overcome doing so.

There is a fuller analysis here.

Nice, you've taken a proper report and then used it as "proof" of your point which is unrelated to the study. Show me the bit about roll down in there, I must have missed it.

I rarely disagreed with someone as strongly as i disagree with you here Lumen.

Question for you : on a flat stage of the TdF why don't we see the pro-tour riders riding heavy wheels?

tunney

el tonto wrote: »

Since the start.

OT but nowhere does it mention "safety". Just equipment and accessories.

Lumen

tunney wrote: »

Nice, you've taken a proper report and then used it as "proof" of your point which is unrelated to the study. Show me the bit about roll down in there, I must have missed it.

My point (relating to the "small accelerations from crank torque variations being more lossy on a heavy wheeled bike" idea) is evident from basic physics; I used the report to give some concrete numbers relating to inertia which I couldn't be bothered to calculate myself.

tunney wrote: »

Question for you : on a flat stage of the TdF why don't we see the pro-tour riders riding heavy wheels?

Because heavy wheels are slower, and because they're sponsored.

tunney wrote: »

I rarely disagreed with someone as strongly as i disagree with you here Lumen.

I find that very difficult to believe. If you're going to argue, at least argue in detail.

Chips Lovell

tunney wrote: »

OT but nowhere does it mention "safety". Just equipment and accessories.

Yes it does:

Section 7 of the Finance (No.2) Act 2008 introduced an exemption from an income tax charge under section 118 of the Taxes Consolidation Act 1997 in respect of a benefit in the form of a bicycle or associated safety equipment provided to a director or employee by his or her employer, where the bicycle/associated safety equipment is used by the employee or director mainly for qualifying journeys.

tunney

el tonto wrote: »

Yes it does:

Ah right, good job I never abused it then.

tunney

Lumen wrote: »

My point (relating to the "small accelerations from crank torque variations being more lossy on a heavy wheeled bike" idea) is evident from basic physics; I used the report to give some concrete numbers relating to inertia which I couldn't be bothered to calculate myself.



Because heavy wheels are slower, and because they're sponsored.



I find that very difficult to believe. If you're going to argue, at least argue in detail.

Mah - rotational weight doesn't matter near as much in triathlon/TTs.

But the energy required to spin a wheel up is more than what it "gives back" on roll down. Spinning a heavier wheel costs more than a lighter wheel. Here is a link to a study on the effects of eggs on cholesterol About as relevant as the artisans one

Anyone remember the wheels with the weights on the spokes? idea being that the weights fell to the hub and went out to the spokes at other times to "give back more". Never really caught on.

Lumen

tunney wrote: »

But the energy required to spin a wheel up is more than what it "gives back" on roll down.

Where does the energy go?

edit: thanks for the link to the eggs report, I've been meaning to look into that

DirkVoodoo

What are the energy losses between cheaper and more expensive bearings? It looks like that test only really accounts for accelerating the mass of the wheel and not any energy lost in friction between bearing surfaces.

I'm sure it's tiny, I've not been impressed with any "lighter" wheels except when they matter: uphill.

Lumen

DirkVoodoo wrote: »

What are the energy losses between cheaper and more expensive bearings? It looks like that test only really accounts for accelerating the mass of the wheel and not any energy lost in friction between bearing surfaces.

Depends. Lighter seals have less drag, but let in more crud, which adds bearing drag.

FWIW, a pair of 70cm 1kg discs spinning at 1200rpm have less than 10 joules of rotational energy between them.

niceonetom

I have some vague memory of someone using a very heavy rear wheel for an attempt on the hour record... Moser? Or maybe that 7 foot tall polish guy who got done for doping... can't remember or be bothered to look it up.

Chips Lovell

niceonetom wrote: »

I have some vague memory of someone using a very heavy rear wheel for an attempt on the hour record... Moser? Or maybe that 7 foot tall polish guy who got done for doping... can't remember or be bothered to look it up.

It was Sosenka. 3.2 kg.

blorg

el tonto wrote: »

It was Sosenka. 3.2 kg.

Sort of difficult to imagine how you'd get that rear wheel up to 3.2kg even if trying, it wasn't a disc or anything (they were after all not allowed):



Maybe it was both wheels? Total bike weight was 9.8kg I note.

mloc123

That is some amount of seatpost

Lumen

blorg wrote: »

Sort of difficult to imagine how you'd get that rear wheel up to 3.2kg even if trying, it wasn't a disc or anything (they were after all not allowed)

Apparently it was a disc. I have sources but none authoritative.

blorg

Lumen wrote: »

Apparently it was a disc. I have sources but none authoritative.

It can't have been though, or he would not have got the UCI hour record for it. Discs were not allowed. There are plenty of photos of him doing the attempt on the bike above.

@mloc123- the bike was apparently designed that way to allow him to get very low while keeping his arms relatively straight (for comfort.)

FISMA

Wheel weight does matter: it is only a matter of how much and what you're riding style is.

Not only do wheels go in the direction of your body's motion, they rotate as well. Rotational - translational motion.

There's a reason why many of us can afford Lance's frame, fork, and group, but not his wheelsets.

The concept is called the moment of inertia (I). Mass is a measure of how difficult it is to accelerate in a straight line. The moment of inertia is a measure of how difficult it is to accelerate in a circle.

The moment of inertia depends upon mass. So lighter rims are easier to [angularly] accelerate. However, the moment of inertia also depends upon where the mass located (dist from pt of rotation). Actually, where the mass is located is a larger factor - squared term in the equation, as opposed to mass which is not.

So, hubsets, close to the center of rotation, do not matter (mass wise) as much as rims. Heavy tires/tubes, being furthest from the center of rotation matter more.

Have you ever seen an ice skater spinning? As she brings in her arms, she decreases her moment of Inertia. Less moment of inertia means it is easier to spin. In order to conserve angular momentum, she increases her rate of spin.

So yes, it does matter, but probably more to racers than to weekend warriors.

This is a very expensive game to play - the gram game. You'll find that as the mass of components decreases, the cost increases exponentially.

I like my Mavics (Kysriums Elite), they do just fine.

The Askiums are a fine trainer rim, however, you won't find them raced too much, they are heavy.

You could easily drop a pound by getting a decent set of wheels that will not rival the cost of a nice car.

Here's the next pair I have settled on

BTW - you sure know how to start a holy war!:)

Golfanatic

better acceleration if there lighter due to less rotating mass inertia i think its called