My flange has fell off

[D.A.L.E.]

This happened on a ride last week. 20km in to a 200 (which I finished. I trued the wheel best I could, then put both headphones in to drown out the rattling and rubbing).

36 spoke Ultegra hubs FWIW



They've done 7500km in a little over 2 years and as such, the German retailer are washing their hands of them...

Any advice as to how to proceed? Buy a new wheel? Contact Shimano (or Madison)?

[mrcharly-YHT]

I think that 7500km is SFA for a hub, I have (cheaper than Ultegra level) hubs that have done much more than double that.

There are some signs of salt corrosion under some of the spoke heads, that might have started a crack. But surely an ultegra hub should have anodising thick enough to resist that sort of damage?

[Cudzoziemiec]

Certainly doesn't sound much mileage or age. Nothing at all really. But I guess the warranty is 2 years? (or only one?). Well done on finishing the ride. 

[D.A.L.E.]

Certainly doesn't sound much mileage or age. Nothing at all really. But I guess the warranty is 2 years? (or only one?). Well done on finishing the ride.

Yeah. Disappointing really as this isn't a run of the mill, wear and tear thing. The German retailer just aren't interested in it or running it up to Shimano on the off chance.

[D.A.L.E.]

I think that 7500km is SFA for a hub, I have (cheaper than Ultegra level) hubs that have done much more than double that.

There are some signs of salt corrosion under some of the spoke heads, that might have started a crack. But surely an ultegra hub should have anodising thick enough to resist that sort of damage?

It looks in pretty bad shape, but I promise it's not that bad! And certainly hasn't been stored or left in that state (Unlike winter/touring/commuter/fixed gear bikes I have, which are still trucking).

You'd just expect better, wouldn't you.

[Samuel D]

You can see from the discolouration of the crack face that much of it had occurred before the fresh crack on the right led to sudden failure. During this period, you would have seen a crack if you had looked (not that I bother checking this sort of thing more than once in a blue moon, mind you!).

What sort of spoke tension are we talking about?

[mrcharly-YHT]

I think that 7500km is SFA for a hub, I have (cheaper than Ultegra level) hubs that have done much more than double that.

There are some signs of salt corrosion under some of the spoke heads, that might have started a crack. But surely an ultegra hub should have anodising thick enough to resist that sort of damage?

It looks in pretty bad shape, but I promise it's not that bad! And certainly hasn't been stored or left in that state (Unlike winter/touring/commuter/fixed gear bikes I have, which are still trucking).

You'd just expect better, wouldn't you.

I would have expected better, and I wasn't suggesting it was bad (or all that dirty/corroded). Some of my older hubs, used for round year commuting, have looked utterly appalling by comparison and I haven't had any flange failures.

[mattc]

Wasn't there an identical failure posted on Facebook this week - probably in the AUK group (I don't use any obscure groups ... that I'm admitting to ... ) ? Don't think it was any local club.

Possibly a Mavic wheel - also 36holes, anyway. I remember folks speculating if 32hole flanges would have more metal => stronger!

[sojournermike]

Wasn't there an identical failure posted on Facebook this week - probably in the AUK group (I don't use any obscure groups ... that I'm admitting to ... ) ? Don't think it was any local club.

Possibly a Mavic wheel - also 36holes, anyway. I remember folks speculating if 32hole flanges would have more metal => stronger!

Possibly the case. Novatech and others tend to disallow radial lacing on hubs with more than 24 spokes for that reason.

[rafletcher]

I doubt that would have been covered by warranty anyway, it'd just be considered wear and tear. Unfortunate for you that your hub was one that failed sooner than average, as opposed to later than average.

[Brucey]

Shimano usually use forged hubshells that are very strong. They are not so prone to failure as many other types of hub.  However it is probably counterproductive that they anodised the hubshell; the anodising always  cracks when the wheel is built and you can get a very localised corrosive attack. Higher than normal spoke tensions don't help either.

Warranty is two years on most shimano stuff, three years on XTR and Dura Ace.

My suggestion; treat the flanges of built wheels with waxoyl, heated so it runs into the spoke holes. Wipe off the excess. Retreat once a year or after every very hot wash. Hubs that are used in all conditions invariably fare better if they have a light film of oil on the outside, since this stymies corrosion to some extent. By contrast, bone-dry flanges with odd dark marks around the spoke holes fill me with a sense of foreboding.

BTW I have seen numerous hubs that have been used once or twice (on purported dry days) in winter, that have gone on to fail due to SCC whilst the (unwashed) bike is stored.

cheers

[andrew_s]

I wonder whether keeping it relatively clean could be a drawback? That flange in all my hubs would have a fairly generous amount of old chain oil and associated muck around the spoke holes, which would keep any salty water off

[Brucey]

BTW there is another crack-starting mechanism; the underside of the spoke head is forged in a closed die, and very commonly there are two flash lines (made by the die closure) on the underside of each spoke head, that create themselves wee notches in the flange. Just the kind of notches that start cracks off.

If you build with spoke washers, the underhead flash lines don't get a chance to gouge the flange in the same way.

cheers

[JonB]

Looks very much like my 36 hole 105 hub which went on the Brian Chapman ride a couple of years back

[rogerzilla]

My Goldtec track hub did that in its third winter.  Salt kills them.

[mcshroom]

Wasn't there an identical failure posted on Facebook this week - probably in the AUK group (I don't use any obscure groups ... that I'm admitting to ... ) ? Don't think it was any local club.

Possibly a Mavic wheel - also 36holes, anyway. I remember folks speculating if 32hole flanges would have more metal => stronger!

Titus posted a picture of a 36h Deore rear hub that had gone the same way. I've had one too a couple years ago which was also a 36h deore rear.

[Tigerbiten]

That happens to the odd Rohloff as well.
You can buy Rohloff flange support rings which you fit before building the wheel if you want to reinforce the flange before using the hub with the likes of tandems or other heavy duty use.

[Brucey]

BITD such failures (in shimano hubs) were virtually unknown; it took years of wintery abuse to cause that sort of thing to happen.

These days rims are much stiffer and there is usually no obvious limit to spoke tension; [BITD excess tension would cause the rim to self-pringle and this would limit the maximum tension.]

Hub manufacturers don't usually place tension limits on the spokes but do mandate that radial builds should or should not be used. Maybe they should start to apply a tension limit to hubs.

BTW road salt is obviously  very corrosive but in some parts of the country the soil itself is alkaline and this will corrode aluminium given half a chance.

Regardless of the chemical agent, the process is always the same; the region around the spoke holes is the last to dry and the remaining solution of corrosive crud becomes super-strength, even if it wasn't before. The stress required to cause cracking in these conditions can be a small fraction of that required normally.

cheers

[rogerzilla]

My Goldtec was fine on the oily RHS.  Preventive maintenance could be as simple as smearing Vaseline on the flange before winter.  Get your minds out of the gutter.