Do deep section carbon rims create irritating noise?
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Dodgy, think I get what you mean mate but I don't think Stephen Hawking would have cottoned on without a bit of extra explanation!
OP - if you are not convinced about this deep section malarky (as I'm not) just ask the shop to swap them out for a decent pair of normal wheels. More practical, much better looking (except on a proper TT bike) and no discernable difference in performance except in the minds eye.0 -
+1...... and thinking about it why ask us if the noise is irritating? You've obviously heard it and if you think it's irritaing then it's irritating, if not then it's not. If you're worried about bothering other people with the "noise", well, that's a ridiculous way of thinking.siamon wrote:
OP - if you are not convinced about this deep section malarky (as I'm not) just ask the shop to swap them out for a decent pair of normal wheels. More practical, much better looking (except on a proper TT bike) and no discernable difference in performance except in the minds eye.
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It takes energy to accelerate mass. You've a finite amount of energy available. Any energy that's expended without contributing to propelling you and your bike is a loss. The word "waste" implies that the loss is unnecessary. Some losses are unavoidable some are not (at least not without othre compromises).smidsy wrote:.....dennisn - I still believe that the noise is a by-product of speed rather than a negative of power output. Noise (or more accurately sound) is a pressure wave which obviously does move the air but I can not see how that translates to wasted energy....
Energy isn't generated, it's spent. I'm not being pedantic, this is critical to what you're saying. You use energy to generate power. The proportion of that power that you can get to contribute to forward motion is your efficiency. The higher your efficiency, the higher your speed for a given power input.smidsy wrote:....The energy is already generated and the noise then emits due to the air movement against the deep rim. I do not see how this equals lost speed.
Since you ask - Yes I trained as an aerodynamicist although I don't work inthe field.smidsy wrote:Obviously air resistance is the enemy and the faster you go the more power you need to push against the pressure to increase the speed (any aerodynamics folk about?) - but this applies always and not specifically to deep rims. Frontal area and smooth surfaces help but I do not see how deep rims negatively affect this,
I remain to be convinced but also accept that i may be wrong (just do not see how yet).
I'd expect deep rim wheels to have a much lower coefficient of drag than a typical shallow rim. the main reason is not frontal area which seems to be the main measure of "aerodynamicness" in the bike world. I'd expect the biggest savings to come from improved flow where the rim forms the trailing edge of the profile not where it's the the leading edge. A low pressure turbulent wake can produce a massive amount of drag. However I've never studied the aerodynamics of a rotating shape like a wheel and that makes things a little more complex so there might be other stuff I'm missing.
I've only started doing sportives recently and hadn't realised there was any noise issue until I noticed one or do as they went by. As I'd only noticed a couple of bikes (and it may even have been the same one twice!) my question was really whether this was typical of all deep carbon rim wheels. I'd have to have another listen and preferably ride a deep rimmed bike to know if it would bother me.dennisn wrote:
+1...... and thinking about it why ask us if the noise is irritating? You've obviously heard it and if you think it's irritaing then it's irritating, if not then it's not. If you're worried about bothering other people with the "noise", well, that's a ridiculous way of thinking.siamon wrote:OP - if you are not convinced about this deep section malarky (as I'm not) just ask the shop to swap them out for a decent pair of normal wheels. More practical, much better looking (except on a proper TT bike) and no discernable difference in performance except in the minds eye.
I was referring to wheel sound in general from carbon deep rims but I definitely heard some crunching/clunking sounds that I assume were either coming from the road or the drive train and being amplified by the wheel rim. Accoustics aren't my speciality but I think what probably happens is that the vibrations from whatever source are transfered to the air via the rigid wall of the rim whereas in a shallow aluminium rim the vibration would be damped by flex in the rim and tyre without there being a suitable medium for transferring this vibration efficiently into sound waves.dennisn wrote:Interesting to say the least. Intially, when I first saw the topic I thought the OP was referring
to the somewhat "crunching" sound that full disc wheels seem to give off, along with a sort of "whoosh". I always chaulked it up to sort of an echo effect that they created within the wheel itself. Are echos a form of ampliefied sound or just sound bouncing around?
If that's correct it doesn't mean deep carbon rims are less efficient than quieter rims and reduce the power available. It may well be the case that they simply dissipate more power via sound but that the total losses are lower.
This topic of this conversation changed completely a while back. I don't think anyone is claiming that accoustic losses are significant in comparison to aerodynamic losses.
Aidan0 -
Ai_1 wrote:dennisn wrote:Interesting to say the least. Intially, when I first saw the topic I thought the OP was referring
to the somewhat "crunching" sound that full disc wheels seem to give off, along with a sort of "whoosh". I always chaulked it up to sort of an echo effect that they created within the wheel itself. Are echos a form of ampliefied sound or just sound bouncing around?
I was referring to wheel sound in general from carbon deep rims but I definitely heard some crunching/clunking sounds that I assume were either coming from the road or the drive train and being amplified by the wheel rim. Accoustics aren't my speciality but I think what probably happens is that the vibrations from whatever source are transfered to the air via the rigid wall of the rim whereas in a shallow aluminium rim the vibration would be damped by flex in the rim and tyre without there being a suitable medium for transferring this vibration efficiently into sound waves.
If that's correct it doesn't mean deep carbon rims are less efficient than quieter rims and reduce the power available. It may well be the case that they simply dissipate more power via sound but that the total losses are lower.
This topic of this conversation changed completely a while back. I don't think anyone is claiming that accoustic losses are significant in comparison to aerodynamic losses.
Aidan
I know the topic has changed but, to be honest, there isn't much more anyone can say about irritable or not noise. This is much more interesting. 0 -
So I am right??...well at least in my head.
My point in simple terms is that the wheels are already turning at a speed relative to the effort you have put in - the fact that some sound is created does not mean that you are going slower.
They may create a different or more pronnounced sound than normal rims but If deep section rims made you go slower no-one would use them - simples!!!Yellow is the new Black.0 -
No - they're not necessarily slower, they are just dissipating energy in an audible format ... arguably, if you could eliminate the sound without transferring the loss somewhere else then you'd be able to go faster for the same effort - but in the real world, the level of energy lost by the creation of sound is so minimal in that situation that it is not significant - and certainly less than the energy lost in drag by shallow section rims.smidsy wrote:So I am right??...well at least in my head.
My point in simple terms is that the wheels are already turning at a speed relative to the effort you have put in - the fact that some sound is created does not mean that you are going slower.
They may create a different or more pronnounced sound than normal rims but If deep section rims made you go slower no-one would use them - simples!!!
If you think of audio amplifiers - measured in watts - and speakers - again, measured in watts - just how big an amp & speaker would you need to create the volume of sound you get from the wheels.... don't forget, the amp and speaker will have energy losses too - so it'll be surprisingly little...0 -
smidsy wrote:
My point in simple terms is that the wheels are already turning at a speed relative to the effort you have put in - the fact that some sound is created does not mean that you are going slower.
They may create a different or more pronnounced sound than normal rims but If deep section rims made you go slower no-one would use them - simples!!!
Agree. I think any wheel spinning through the air makes noise. Whether it's audible or not depends on the wheel itself? I'm still running the "echo factor", with respect to deep rims, through my head. Maybe there is this "echo factor" that is produced by deep carbon rims and thereby makes the wheels sound like they are making more noise than they actually are, as opposed to actually being a noise amplifer. Please note that I have used the words "I think" and "maybe". My theories are based on scientific educated guesses. :?0 -
Iirc The term is Soundboard ...0
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Which is faster, an electric-guitar or an acoustic-guitar? The acoustic-guitar is noisier but that noise is irrelevant to its movement.slowbike said:Just think ... all that sound they create ... takes energy to do that ... that energy isn't being used to propel you up the hill! ... wasted!
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Ahahahahahahadowsett2004 said:
Which is faster, an electric-guitar or an acoustic-guitar? The acoustic-guitar is noisier but that noise is irrelevant to its movement.slowbike said:Just think ... all that sound they create ... takes energy to do that ... that energy isn't being used to propel you up the hill! ... wasted!
- Genesis Croix de Fer
- Dolan Tuono0 -
A toyota prius is faster than a F1 car, because the F1 car looses all kinds of energy making those loud noises.0
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Congrats in using your first post to dig up an eight year old thread, in order to post a meaningless comment about guitars....dowsett2004 said:
Which is faster, an electric-guitar or an acoustic-guitar? The acoustic-guitar is noisier but that noise is irrelevant to its movement.slowbike said:Just think ... all that sound they create ... takes energy to do that ... that energy isn't being used to propel you up the hill! ... wasted!
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