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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, 2013 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, 2013 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, 2013 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, 2013 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, 2015 at 7:59

12 Answers 12

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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

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    • 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, 2014 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, 2015 at 22:34
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      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, 2017 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, 2016 at 18:06
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    I'm just getting onto BMX freewheels for a project and it seems that sealed bearing versions can use a lighter oil for the pawls. Ones with loose bearings or open bearings share the wheel bearing grease with the pawls and are quieter (and much cheaper). For less rolling resistance and faster engagement the oil would be better. Maybe this applies to freehubs too. Some say you can grease the noisy types to quiet then down if you want to. This seems to be the difference between my Shimano XT MTB hubs (cup and ball/quiet), and my Mavic hubs on my XC bike (Sealed bearings/oiled pawls/noisy). The White ENO BMX freewheel has 36 clicks per revolution and a sealed bearing. The cheap Dicta freewheel is very quiet and oozes grease out of it's unsealed bearings. Trails bike freewheels go from 72 to 140 clicks, so they get real loud.

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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.

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    • 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, 2015 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, 2017 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.

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    • 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, 2017 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, 2017 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.

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    • Stronger pawl springs would increase drag while coasting. I wonder if there's a measurable correlation ?
      – Criggie ♦
      Jul 5, 2017 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, 2017 at 9:21
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      @Criggie My ENVE SES wheel has a much louder freehub than my DT Swiss wheelset and also has significantly more (quite noticeable) drag when coasting. It doesn't bother me much, because there aren't a lot of times I am coasting, but it is a thing. So that's a start with a sample size of 2...
      – JakeD
      Sep 9, 2020 at 17:40
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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, 2014 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, 2016 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.

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      This difference has been noted for 20 years, at least -- long before carbon rims were common.
      – Daniel R Hicks
      Feb 1, 2017 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, 2017 at 16:01
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    Here is one example of high-end noise. It's called DT Swiss Ratchets. They use two individual ratchets with either 18, 36 or 54 teeth on their sides, each ratchet then is squeezed together by two springs on both outer sides. When installed, the teeth of the two ratchets face one another and are lubricated. As the bike coasts the two ratchets slide side-by-side making the buzzing sound -- the more teeth on the ratchets the higher the buzz sound. It's a high-end design making for tight engagement for instant power -- the more teeth the tighter the engagement also resulting in a higher-pitched sound. The noise you hear is a sweet sound if you're into serious cycling.

    Rephrasing: DT Swiss Ratchets are a high-end freehub, and have a distinctive buzzing sound because they have 18/36/54 teeth, a lot more than the standard 3 or 4 pawls found in a common freehub. 54 teeth clicking around will make more noise than 4 pawls.

    Note, "the more teeth the higher the pitch"... and logically, of course, the more of anything is louder when banging against one another. But the key here is quicker engagement and the sound, vanity.

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    • Hi, welcome to bicycles. This doesn't answer the question why it's louder, especially not in the general case as was asked. You may have intended this as a comment on another post, in which case you should wait until you earn a bit more reputation. Please read How to Answer.
      – DavidW
      Feb 18, 2020 at 16:03
    • So how's this to refocus this as an answer? "DT Swiss Ratchets are a high end freehub, and have a distinctive buzzing sound because they have 18/36/54 teeth, a lot more than the standard 3 or 4 pawls found in a common freehub. 54 teeth clicking around will make more noise than 4 pawls. "
      – Criggie ♦
      Feb 18, 2020 at 23:34
    • ...and then explain how some other brands like Chris King, Mavic and Campagnolo aren't loud.
      – ojs
      Feb 19, 2020 at 14:02
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      Actually, I believe CK is very loud, and that Campy is quite loud. I think Shimano is relatively quiet. Back to the answer, I think it does allude to why DT is relatively loud - there are a lot of points of engagement. My issue is that this post doesn't answer the question well: it describes why DT Swiss buzzes, but it doesn't say why DT Swiss is higher-end, and it only focuses on DT Swiss. And, side note, high points of engagement is meaningful in mountain biking, but not necessarily in road cycling.
      – Weiwen Ng
      Feb 19, 2020 at 19:39
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      I know they are :) So, I think the question is why high end freewheels are designed to have loud and distinctive sounds when Shimano's example shows they could be quiet. BTW, DT doesn't have 54 discrete parts but two discs with teeth banging against each other.
      – ojs
      Feb 21, 2020 at 8:39
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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, 2015 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, 2015 at 13:03

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