Wheel upgrades

[Cruzer]

I am currently using Entry level Easton circuit clinchers and am wondering what the actual BENEFITS are in upgrading other than the obvious weight advantage.

 

I am considdering the Easton 70 carbon SL's for sale in the classifieds, what benefit would I get if I bought them?

 

From a ride point of veiw?

 

From a speed point of view? 

[Weekend_Warrior]

acceleration will be the most marked improvement. Less rotational weight will spin up faster.

 

 

This is the same as when you have your fly wheel on you car lightened, it help to get the engine revs up faster but i also believe the car loses momentum faster as well, would this be the same in the case of lighter wheels?

[Johan Bornman]

acceleration will be the most marked improvement. Less rotational weight will spin up faster.

 

Also if the wheel is stiffer there will be less energy lost to flex. More road feel will be evident while cornering too.

 

Really? The two of you seem to have done the math. Please let us then have some figures. How much faster will you accellerate with a given weight difference of say 200 grams over the two weels, with this weight taken away entirely from the rim and tyres?

 

How much do you think wheel flex and where do they flex?

 

Describe this different sensation when cornering on the one wheel versus cornering on the other.

 

I'm keen to know.

 

 

[Cruzer]

Thanks!! It seems that they would be a good upgrade. Easton Circuit to 70 SL Carbon's

[Johan Bornman]

We have experimented with lighter wheels with our Racing motorcycles. It's a similar comparison but i think more exteme on the braking side...

 

On a motorbike the braking from speed with lighter wheels was the same at high speed' date=' but as the speed decreased, the lighter wheels stopped progressively faster.

 

They spun up faster as you would expect as well.

 

Compliance over bumps was reduced (feel more bumps) as the wheels react faster to any input.

 

I essence, your wheels will accelrate and decelerate faster than heavier wheels, you will feel more bumps in the road too. They will also be less resistant to changes in direction, so steering actoins will aslo be faster.

[/quote']

 

Am I then correct to summise that braking on a (your) motorbike is not a linear affair? You seem to say that speed reduction is less when the bike is going fast but the decelleration increases as the bike gets slower?

 

Have you any figures to show us? It sounds as if you've somehow plotted this against different wheels of different weights, but using the same brakes all the time.

 

You've apparently done the same type of experiment and gleaned the same data for cornering. Can you tell us how much faster the steering actions were and how weight affected this?

 

Please enlighten us.

 

 

[TNT1]

JB, you know that expression about talking to brick wall? You know by now most of these guys haven't the foggiest notion about wheels, except that more expensive and lighter must make them better riders.... You wont get any answers based on science, and there are clearly people here with money burning big holes....

[Johan Bornman]

JB' date=' you know that expression about talking to brick wall? You know by now most of these guys haven't the foggiest notion about wheels, except that more expensive and lighter must make them better riders.... You wont get any answers based on science, and there are clearly people here with money burning big holes.... [/quote']

 

I know, I know....but lets make them sweat in anyway. It is Friday and I won't be here for two weeks, so I must bank some challenges beforehand.

 

 

[Johan Bornman]

 

 

Flex' date=' From my understanding a wheel will flex from the most fixed point Ie the hub, and radiate outwards. The amount will obviously depend on how much side force is applied, from that i can say that sideways force will only make itself evident at the moment of turn and not during midturn. A more flexy wheel should be slower to react as some energy will be lost to forwards motion, inertia. Once your course of motion is stable again they will then be equal.

 

From what I have read - And I am no expert. but the heavier the moving object is, the more resistant it is to change direction.

 

The intial question was will I feel a difference, and the answer is yes.

[/quote']

 

You haven't been paying attention, have you? The are NO sideways (lateral) forces on a bicycle or motorcycle wheel when turning.

 

You have been reading bicycling magazines, I can tell.

 

 

 

 

[jabbathemutt007]

 

We have experimented with lighter wheels with our Racing motorcycles. It's a similar comparison but i think more exteme on the braking side...

 

Its not a similar comparison. Motorbike acceleration is several orders of magnitude greater than even this mythical Vernon Koekemoer guy that appears in some peoples signatures could manage on a bicycle. At the low accelerations possible on a bicycle, the mass of the wheel makes no measurable difference to acceleration. Wheel aerodynamics, particularly the front wheel may make some difference although the rider is still the biggest aerodynamic drag on the bike.

 

BTW who the hell is Vernon Koekemoer ?

 

 

 

 

[Johan Bornman]

Someone should tell the pro teams they're wasting a lot of money then...

 

Perhaps JB can tell us why they ride lighter wheels?

 

I wish you guys would come up with a better retort than "it has to be better because the pros ride it. "

 

This is the tech and science forum, not the marketing forum. Did someone mention a brick wall?

 

They ride lighter wheels because they want to save weight.

 

For the record...once again. Weight savings on a a wheel is just weight savings. Weight on a wheel has the same effect on accelleration as weight on your fat rolls, weight in your water bottle or weight on the padlock and chain wrapped around your seatpost. It has no magical mystical properties no matter what stories the drag racing entusiasts try and import into cycling.

 

 

[Johan Bornman]

What I am trying to say might more easily be felt like this:

 

Take a heavy wheel. hold the skewers in your hand and spin the wheel... In a straight line it feels stable...now try turn it.

 

repeat with a light wheel' date=' and observe the difference.

[/quote']

 

You are now describing the gyroscopic force exerted on a spinning disk changing direction around its axis.

 

Perhaps you want to elaborate on how that exerts a lateral force on a bicycle wheel in a turn?

[GoLefty!!]

Pro teams ride deep section wheels because it provides a bigger surface area for their wheel sponsor to advertise the brand of wheel.

In bunch riding there is no aerodynamic advantage to deep section wheels.

[niterider]

 

 

Pro teams ride deep section wheels because it provides a bigger surface area for their wheel sponsor to advertise the brand of wheel.

In bunch riding there is no aerodynamic advantage to deep section wheels.

 

Really?! So there is no measurable performance benefit to deep section wheels? The reduced power required to drive a more aerodynamic wheel is not maybe part of the reason?

 

Maybe in your bunch-riding you never spend any time at the FRONT of the bunch where the benefit would most definitely be felt.

 

What are all those time-trialists and triathlete's thinking?

niterider2008-09-14 22:54:03

[MarkD]

 

You are now describing the gyroscopic force exerted on a spinning disk changing direction around its axis - It's a relevant force is it not? We are actually riding these bicycles after all.

 

Perhaps you want to elaborate on how that exerts a lateral force on a bicycle wheel in a turn? - It doesn't exert a force - you do when you steer it.

 

Without proclaiming to be an expert on the forces at play with a rotating wheel, my only comment would be that if the wheel is rotating fast and you are trying to steer more than a fraction of a degree, I think that you should then be more worried about a couple of other forces which will suddenly become relevant:

 

1 - Gravitational force which will accelerate your body towards the ground, followed soon thereafter by...

2 - Frictional force between your body and the ground.  Note - this force will be affected by the roughness of the tar

3 - if you are really unfortunate there may be an additional impact resulting in extreme deceleration.

 

Of course, none of these forces depend in the slightest on which wheels you are using.....

 

The "gyroscopic" force I would think is largely responsible for the fact that the bicycle tends to stay upright when travelling in a straight line (note that it is generally easier to ride "hands-free" at faster speeds), but any significant "steering" at high speed is a recipe for disaster. 

 

 

 

 

MarkD2008-09-15 00:39:38

[Johan Bornman]

Pro teams ride deep section wheels because it provides a bigger surface area for their wheel sponsor to advertise the brand of wheel.

In bunch riding there is no aerodynamic advantage to deep section wheels.

 

This particular advantage of deep sections has never occurred to me but makes perfect sense. I like it.

 

I concur with your statements of no advantage in bunch riding.  I find it very difficult to sell that concept to my customers.

 

 

I maintain my sanity in this regard only thanks to one particular pro that puts his business my way. It's a box section rim for him each time.

 

 

 

 

[Johan Bornman]

 

 

Yes there are...however they are overcome by cornering force during a turn...thus nullifying them.

 

You have a skewed view of the forces acting on a bicycle/motorcycle wheel in a corner.

 

When turning or riding straight ahead, the bicycle wheel experiences ZERO  lateral force. All forces are purely radial. The centrifugal force generated by the turn is purely overcome by you leaning into the corner. The relevant vector of your weight in the lean equals the centrifugal force of the circle's radius which can be calculated by F=MV^2 /R

 

You'll notice from this formula that the larger the radius of the turn, the smaller the centrifugal force and hence the less you have to turn.

 

We know wheels experience no lateral force because they can't take much lateral force at all. The rear wheel of a modern deep-dished bicycle wheel is so weak in the left to right position that it can barey wishtand a force of 200 N before collapsing. This is nowhere near what the centrifugal force on the bike in a steep corner is and therefore we know empirically that it supports it in some other mode.

 

A simple force diagram will solve your dilemma.