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I tend to ride relatively modest gear (Tiagra/Ultegra), but when I'm riding near higher-end bikes, I sometimes notice that the clicking sound that comes from their cassette/free-wheel while coasting seems to be much louder and more distinct than on my bike. Why is this? Intuitively, one would expect that a quieter drive-train would be an indicator of greater efficiency, but that doesn't seem to be the case here. Is it something to do with different construction, or materials? Can you get 'quiet' high-end cassettes, or is being noisy while coasting the price you must pay for being efficient while pedaling?

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    I wouldn't call Ultegra particularly modest, the only range better is Dura – PeteH Apr 16 '13 at 20:12
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    It's important to note that the freewheel is part of the hub, and while you might have some or mostly Ultegra parts, many bikes are sold with parts that aren't all from the same groupset. When you say the cassette is loud, what you're actually saying is that the freehub is loud, at least when talking about higher end bikes. Low end bikes typically have a freewheel built into the cassette. – Kibbee Apr 16 '13 at 20:43
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    Loudness in the freehub/freebody is usually due to the very light oil used to lubricate the inner parts. Thicker oil can be used to lessen the noise and even grease in some cases, but it's high viscosity is pointed at for not being so efficient. – Jahaziel Apr 16 '13 at 20:53
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    youtube.com/watch?v=SG0uBDvgXu0 Noisy freehubs are definitely a design thing. I don't get it. – WTHarper Apr 17 '13 at 0:05
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    Campagnolo wheels are traditionally very noisy. And higher end bikes often use Campagnolo-made wheels, even under different brand. – Rilakkuma Feb 21 '15 at 7:59

10 Answers 10

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Most of the noise comes from pawls on the freewheel hitting against the splines on the engagment surfaces which makes up the racheting unit.

Some reasons for the noise between freewheels?

  • Tension on pawls could be higher causing more noise as they glide over the engagment surfaces

  • High end freewheels have more pawls and engagement points than lower end freewheels, so there are more ridges in the engagement surface and more pawls hitting the splines on the engagement surface. The reason this is desirable is that more pawls and engagement points means faster engagement when you start pedaling.

  • Different grease (or less grease) could also be used inside higher end freewheels that is less viscous and provides less resistance, allowing the spring action of the pawls to cause more noise as they float over the the splines on the engagement surface since they are less restricted by the grease.

    Of course there are exceptions to these. Some hubs don't use your standard racheting mechanism and use a 'roller clutch' instead. The roller clutches tend to be very quiet, but are more prone to failure.Here's a good description of how those work. http://pardo.net/bike/pic/mobi/d.winners-hub/index.html

    • Great answer. I would like to mention that more points of engagement become particularly using with mountain bikes -- especially when ascending a technical section in a very small gear. I personally don't see the need on the road. – Paul H Sep 10 '14 at 15:56
    • There is also probably something to be said for the amount and type of materials involved in the construction of the hub itself. However, I can't find anything definitive on this. I imagine if you had the exact same hub design made from steel, titanium and aluminum, all three would produce different noise levels, but I can't find any sort of transmission or dampening testing done to back that up. – Deleted User Jul 2 '15 at 22:34
    • Great answer. One thing I would add is that the carbon rims on higher end wheels will also act like sounding boards and amplify sounds coming from elsewhere on the bike, the hub included. – KevinC Jul 13 '17 at 18:33
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    I noticed this as well. In my experience, on higher end road bikes, the cassette that you put on the freehub body makes the most audible difference, versus the actual inner-workings of the freehub itself in most cases, i.e. normal, ratchet style freehub body.

    Example: I went from a Sram PG-1130 cassette to a PG-1170 recently. The lower end cassette (1130) construction is different, specifically the dome and spacers (which are plastic). On the higher end cassette (1170) the dome is lighter and stiffer, and the spacers are steel and attached to the cogs.

    The cassette acts like an amplifier for the sounds coming from the freehub. Thus, a cassette like the aforementioned 1170, with a very resonant dome and body, casts way more sound than the 1130, which is expected as it has plastic construction with deadens the sound considerably and a thicker dome, which also hinders resonance.

    I noticed immediately after the switch that the sound coming from my bike went from:

    click, click, click...
    

    to:

    ting!, ting!, ting!...
    

    Personally, I like the 'ping/ting' sound better and associate it with higher quality.

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      With Shimano it's the same, a previously quiet XT hub suddenly became loud when I put a Dura-Ace cassette on it. – ojs Mar 2 '16 at 18:06
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    I think loudness is not a good indication of efficiency, since loudness (and pitch as well) can be affected by many more factors at same or similar total energy consumption.

    • Producing noise requires power/energy. If a transmission is very loud it can’t be very efficient. Though a lack of noise doesn’t automatically mean more efficiency. – Michael Jul 2 '15 at 15:43
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      @Michael True but it doesn't require an awful lot of power to make quite a loud noise -- you can literally hear a pin drop and the amount of energy dissipated there is tiny. A mechanical device can still be pretty efficient, even if it's noisy. – David Richerby Feb 6 '17 at 13:08
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    Recently I replaced my 6800 groupset with a Chorus one. I am using a Mavic Ksyrium SLS wheel; that means I had to change my freehub body to a Campagnolo compatible one.

    Surprisingly, the new freehub has a different sound when coasting, and the noise is so much more reduced. I supposed the difference in the two freehub bodies is to accommodate different brands of cassettes.

    I had never like my Mavic wheels, but now they are so much more lovely.

    Not my knowledge to explain why, but it proves that the noise is not a matter of high- or low-end hubs.

    • Welcome to Bicycles. Just to let you know, we recommend that new members take the tour to make best use of the site. – andy256 Feb 1 '17 at 11:25
    • It's because the freehub body is new and all surfaces are covered with grease. Ride a few thousand kilometers and let the grease settle, and it will become much louder. – ojs Feb 1 '17 at 17:39
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    Louder means more force has been used to make the noise. A change in tone means that different materials have been used to make the noise. More contact points does not automatically result in more noise - if the sound was generated at the same time it would not increase the volume. If a noise gets louder then it is likely that an amplifier in the system - depending on the design, the space in the axel might act as an amplifier. The gear rings could act as an amplifier - this is not likely as the tension generated by the chain would act as a damper. Going back to the first point: if more force has been used that has resulted in a louder sound I would point to an increase in force being applied at the contact points - one obvious reason for a stronger force would be stronger springs in the freehub.

    • Stronger pawl springs would increase drag while coasting. I wonder if there's a measurable correlation ? – Criggie Jul 5 '17 at 0:14
    • Louder doesn't necessarily mean more force. As the rest of your answer goes on to say, it could be acoustics amplifying the sound. – David Richerby Jul 5 '17 at 9:21
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    I had deore xt hubs on my mtn bike, they were silent. I have rebranded Formula on my 2008 Bontrager Race Lites which have a nice clicky sound. Upon servicing I must have put too much grease in and it muted the sound. So perhaps there is a relationship between sound and pawl wear. I have DT Swiss star ratchet on my mtn bike now and they have an excellent sound IMO. Chris king hubs have a legendary sound, describe by customer quote "It rolls good with angry bee sound"

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      I seem to recall reading that Shimano designs their hubs to be quiet. Or perhaps it's that their hub design is inherently quieter. Something like that. – Paul H Sep 10 '14 at 15:58
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    I've got multiple sets of Campy Record freehubs and they are all quiet and no one has ever failed. Chris Kings on my old Klein winter mtb are louder but still somewhat quiet. The DT rear hub internals on my Lightweights are super noisy but the first one failed after only 3K miles (lots of mountain passes). They've been upgraded from the 18T original star ratched to the 36T design so the sound has changed but is still just as loud. So far, they have now been reliable. I don't notice any performance difference between the three systems and I would rate all high as far as quality is concerned.

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      Gidday and welcome to SE Bicycles. Please review the Tour at bicycles.stackexchange.com/tour to learn how this site is different to a common chatty forum. Your answer is relevant, but it doesn't answer the question of why higher-end freewheels are louder. Remember its all about the Answers to the Question, not a general purpose chat about the topic. From your statements, I'd infer your answer is "high end ones are not noticeably louder, its more variation across brands" so use edit to state that clearly. – Criggie Mar 3 '16 at 1:17
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    High end road bikes often use high profile carbon rims which act like a sound box. You'll notice not only the freewheel is louder, other rattling noises the bike makes (like on bad pavement) are louder as well.

    • This difference has been noted for 20 years, at least -- long before carbon rims were common. – Daniel R Hicks Feb 1 '17 at 12:48
    • True @DanielRHicks. It still is a factor (as are the increased amount of clutched and stronger springs but those have been mentioned) – thomas Feb 1 '17 at 16:01
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    Actually, mtb hubs can be just as loud as road hubs. So it really has nothing to do with riding in a group and being audible for the sake of other riders.

    As for the reason some are loud. Efficiency has a lot to do with it but It has more to do with the grade of punishment components can withstand and still perform well. I say that because if you have small components with less force being applied to them (i.e. Small pawl size and low spring tension holding them in position), the wheel will coast more silently.

    In some higher end components, parts are slightly oversized and/or under more torque or tension. This is to keep the performance of the components tight under stress. Imagine going face first down hill on your favorite double black diamond run trying to use campy components built for road. you will break more than just your campy group. The reason some hubs are loud is because the components are built to perform better than just "okay" and to last.

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    High end road bikes have a louder free hub so that riders in a peloton can have an audible clue that those ahead of them are coasting or braking.

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      Could you give any reference for that. It sounds plausible, however, some reasoning that this is not just a cool idea would be nice. – Benedikt Bauer Feb 21 '15 at 12:25
    • No, in a bunch everyone calls what's happening; becsuse if someone collides with you they often take you down with them. In a big bunch there are freewheels clicking on front of you, freewheels clicking beside you, and freewheels clicking behind you. You know what the other riders are doing by sensing it, then hearing their calls, not by clicking. Finally, the premise of the question is flawed: not all high end hubs click loudly, IME it's only medium level Campag. – andy256 Feb 21 '15 at 13:03

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