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Freehub failure - what happens?

by quiff
Mon, Apr 06, 2020 14:23
11

Apologies if there is already a thread on this (I'm sure there is, but the site search isn't particularly helpful in finding it).

I have a 2013 Mavic Ksyrium Elite wheelset. The freehub normally emits a loud clicking, but recently has added an intermittent Chris King esque angry buzz into the mix - usually at speed when freewheeling on a descent. Initially I thought it was some brake rub or dodgy indexing, but I'm now pretty sure it's the freehub, and am taking it very easy, soft-pedalling down descents while on the brakes to avoid the dreaded buzzing and any hospital visits that may ensue.

But because I have no mechanical nous, what actually happens when a freehub fails? I'm imagining the cassette suddenly becoming permanently engaged, the bike effectively becoming a fixed wheel, and me being thrown over the bars. But is that what happens, or does a failed freehub fail 'safe' so you just end up with no engagement or drive?

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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11 comments

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quiff | 3 years ago
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Thanks for the helpful replies. Booked in for a service and I've stuck to running in the meantime just in case! Looking forward to getting back in the saddle at the weekend. 

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huntswheelers replied to quiff | 3 years ago
0 likes

quiff wrote:

Thanks for the helpful replies. Booked in for a service and I've stuck to running in the meantime just in case! Looking forward to getting back in the saddle at the weekend. 

Pretty straight forward job..... about 15 mins all in....the Mavics are not a fan of grease... they love oil but... In the workshop...a viscous wet chain lube has been proved to be the best option for the freehub.... with a cheeky light smear of bearing grease in the hub.... never had one come back between services or during the winter...

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quiff replied to huntswheelers | 3 years ago
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I'm really not a confident or competent mechanic, so I can assure you it wouldn't be 15 mins for me, even if I had the tools! Anyway, had it assessed by local repair shop and the rims are also past their wear indicator, so I'm now in the market for some new wheels...  

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paulBN | 4 years ago
0 likes

It could be the infamous Mavic squeal. You sometimes have to pedal down hills because of it.

However it’s a easy fix - it just needs a bit of oil on the white plastic washer on the inboard end of the freehub.

There are plenty of instruction videos on how to remove Mavic freehubs.

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chocim | 4 years ago
1 like

My wife's Mavic freehub failed in a quite dangerous manner - giving her mighty kicks on descents because it decided to become a fixed drive every few seconds. By all means get it looked at and fixed, riding a bike with a faulty hub can be hazardous.

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Rod Marton replied to chocim | 4 years ago
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I've had a Mavic freehub fail in the opposite way, i.e. becoming completely free. It started by disengaging for a fraction of a pedal stroke, then got steadily worse and worse until it failed to engage at all. Though this is probably the less dangerous failure mode, it isn't very pleasant, so if you are at all worried get it looked at.

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Roadee | 4 years ago
0 likes

I had the same prob Quiff, on a 2007 Elite hub, due to the freehub insert wear along with the mounting hub wear after many miles over the years. I bought a new insert from these guys, BikeWCM, in NE, USA, via ebay:

https://www.ebay.co.uk/itm/STD-Mavic-Crossmax-Freehub-BUSHING-Freewheel-...

You can buy 'standard' inserts of different wear sizes or measure the mounting hub and get a custom sized insert. The replacement insert went in easily enough and has performed perfectly since (18 mths). And only $12 shipped I recall. Prompt service too.

I had not experienced any hub mechanical failure, just noise, but the howling certainly disappeared post bush replacement.

 

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bike_food | 4 years ago
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I ignored a noisy freehub for too long one winter, eventually it gave up on me and I had a weirdly enjoyable 10 mile scoot home with a completely disengaged drive.

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ibr17xvii | 4 years ago
1 like

Deffo get it looked at or have a go yourself.

I used this when I looked at mine & believe me I'm no mechanic. I believe it's used to prevent what's called the "Mavic squeal of death" i.e. when your freehub needs regreasing:

https://www.slowtwitch.com/Tech/Mavic_hub_How-To_4006.html

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ktache | 4 years ago
1 like

My Shimano freehubs always died by becoming part time fixed drive, no or very draggy ratchet.

I have met people whose hubs have died by proving no drive, which if you are pushing hard could, say pulling away from stopping at traffic lights it could be very nasty, as Podc says, get it looked at, you have at least been given a warning.

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Podc | 4 years ago
2 likes

No engagement/drive can also be dangerous if you are trying to accelerate - much like a chain snapping.

I'd get it looked at if I was you 👍🏻

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