Cycling UK Forum

Not true, but I'm wondering why many non-shimano freehubs are so noisy ? Is there any technical reason why the pawls can't be designed to be quieter. I realise I'm getting older and more retrogrouch...but those damn noisy freehubs that my missus and other cycling colleagues have are drowning out the bird song & tranquil stuff. I may have to ditch them all and just cycle on my tod.

It bothers me too. I wonder if it has something to do with many non-Shimano freehubs not being self-contained, sealed units that come away from the rest of the hub with all their innards still sealed as Shimano units do. Perhaps they are noisier because they operate in a resonating chamber. I think they may also act directly on the main hub shell, which may amplify noise.

Yes that's the sort. I can see pawls working directly on the hub may be the issue.

They are only noisey when you freewheel - so keep pedaling?
On the plus side they are an audible warning to others.

The freehub on my Bianchi is loud, but not as bad as a modern Chris King. It does work as a audible warning as well.

I'd have to tell the missus to keep pedalling to solve the problem...which might cause another.
May be I should investigate how much grease is on the pawls and load with Semi Fluid Grease ? Might deaden the sound a bit.

yes slightly heavier lube will make many freewheel mechanisms more quiet.

In conventional designs (with readily accessible pawls) the noisiest ones are often those with individual springs on each pawl. These are susceptible to being quietened to some extent. However those with 'face ratchets' (Chris King etc) shouldn't be dosed with heavier lube; they may start to become unreliable.

cheers

pwa wrote:It bothers me too. I wonder if it has something to do with many non-Shimano freehubs not being self-contained, sealed units that come away from the rest of the hub with all their innards still sealed as Shimano units do. Perhaps they are noisier because they operate in a resonating chamber. I think they may also act directly on the main hub shell, which may amplify noise.

Sounds like the best explanation I have heard. Of course Shimano has the freehub patent which stops others from using the same construction. It must be expiring soon though.

Told this story before.
May have all been superseded by now, but what I say is valid.

Campagnolo have (had?) two different hubs.
One is/was used in the lower groups ........ Xenon/Mirage etc, the the other in the higher groups Chorus/Record/Super Record etc.

The lower one is/was very noisy - very noisy indeed.
The higher one is/was almost silent.

Why?
Because of the number of teeth on the ratchet ring, the size of the pawls, and the spring system. Higher groups have/had a single circular spring and the lower groups individual spiral springs one each for the three pawls.

All these design differences make a huge difference to the noise.

hamster wrote:

pwa wrote:It bothers me too. I wonder if it has something to do with many non-Shimano freehubs not being self-contained, sealed units that come away from the rest of the hub with all their innards still sealed as Shimano units do. Perhaps they are noisier because they operate in a resonating chamber. I think they may also act directly on the main hub shell, which may amplify noise.

Sounds like the best explanation I have heard. Of course Shimano has the freehub patent which stops others from using the same construction. It must be expiring soon though.

as Mick says it Is a contribution but it is not the whole story by any means. For example freewheel mechanisms which use a single 'loop' return spring on the pawls are almost invariably a lot quieter than those which use individual springs, even though other aspects of the design might be near-identical.

BTW one of the faults that can occur (especially with freehub pawls which are set on a small diameter) is that the pawls may not engage at the same time; one-pawl drive is to be avoided, because it always ends in tears.

Freewheel mechanism designers often seem overly keen to make the pickup lash as a small as possible. Some riders (eg in trials) are very keen on this, but for others it ought to be less important. If you find yourself wanting more than ~18T or so (which is typical for shimano freehubs) on the road, I suggest a treatment which includes riding around on an old SA hub with both clutch lash and a 10T (dog ring) freewheel for a while; that'll cure you!

As a bonus you will learn to engage drive smoothly, rather than smashing the pawls into drive, and this will give any freewheel mechanism you subsequently use an easier life.

Anyway, it doesn't seem to matter how you try and reduce lash in a conventional freewheel mechanism, it always seems to increase the chances of one-pawl drive. For example sometimes there can be four pawls in two pairs such that an opposed pair is engaged and drives, whilst the other pair is not loaded. The dog ring appears to the user to have twice as many teeth as it actually has, because the other pair are ready to engage when the first pair are half-way between teeth. Engagement speed-wise there is some point but engagement quality-wise this arrangement is arguably pointless vs having twice as many teeth in the dog ring, because you have still doubled the chances of one-pawl drive.

If you turn a wheel very slowly forwards, you can often hear the freewheel pawls clicking back. If the mechanism is 'perfect' all the pawls will click back simultaneously, with a single 'click-k' sound. However if the mechanism is imperfect you will hear individual clicks, not just one, and worse yet if the dog ring is even slightly eccentric the interval between clicks will vary depending on the wheel position, and the mechanism is basically a 'no-hoper'.

A recent realisation is that whilst the 'loop' type pawl spring is never as forceful as individual springs, it may also decrease the chances of one-pawl drive due to another effect. This other effect is that usually, the pawls are not all sprung effectively unless all the pawls on the same spring are free to move; if one pawl tip is not yet free to spring back, this reduces the force on the other pawls too, so (provided they remain seated properly) they are presumably that bit more likely to work in unison.

cheers

I was amazed to discover recently that there are videos and discussions on t'internet about how to make the freehub mechanism noisier.

Advice usually included flushing out all the grease with WD40 or similar. It was acknowledged that this would drastically shorten the life of the bearings ... but this was apparently considered a fair exchange by some

Beware the denizens of the dark corners of cyberspace!

I briefly watched a GCN review of some new, stunningly expensive wheels.

The first thing the reviewer did was spin the wheel and hold his ear closer to the loudly clacking axle and emit a sigh of satisfaction.

I think it's purely a fashion statement, if you're 'cool' you have cleats that engage with the pedals with and ear shattering crack and free-hubs that clatter like a steam train. The manufacturers have cottoned on to this and are going overboard.

Or am I being too cynical?

Usually most purchasers of a new entry-level MTB (basic Shimano hubs, steel coil SR Suntour fork, Alivio/Deore drivetrain) in Indonesia will 'upgrade' by fitting a 'wasp' model freehub. The labour costs are about £2, so why not, and it's seen as a better upgrade than good quality suspension or decent tyres
Here are some men with pricier bikes comparing freehub volume
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And here's some making their freehubs noisier

[youtube]hPVVl3nJIVhM[/youtube]

I think the amount of watts 'spent' making annoying noises is not that high, but you might as well add cards to the spokes or a farting saddle if you like your bicycle to make unnecessary noises.

thelawnet wrote: or a farting saddle if you like your bicycle to make unnecessary noises.

Like the Campag Electa pneumatic saddle.

hoogerbooger wrote:Not true, but I'm wondering why many non-shimano freehubs are so noisy ? Is there any technical reason why the pawls can't be designed to be quieter. I realise I'm getting older and more retrogrouch...but those damn noisy freehubs that my missus and other cycling colleagues have are drowning out the bird song & tranquil stuff. I may have to ditch them all and just cycle on my tod.

If you think they're loud on a bike, you should try riding a velomobile with one. The bodywork acts as a sounding board, but fortunately(?) my better half is slightly deaf, and doesn't ride her MTB much, so has not noticed the louder rear wheel it now has