Yet Another Cycling Forum
General Category => The Knowledge => Topic started by: PeterB on 09 August, 2017, 10:54:47 am
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Has anyone experiences this problem?
I have a son 28 dynamo hub. Bought in December, so a new model.
I am in Italy at the moment and, after fixing a puncture, I refitted the front wheel.
When tightening it up with an Allen key, something went crack
The wheel seemed to be attached okay but when I rode the bike it made a horrible grinding noise.
The bike shop here does not know what to do, so I have has the wheel rebuilt with a new hub.
Has anyone else experiences this or have any idea what to do about it.
Ta.
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first , obvious, thing is to try another skewer, if you have over tightened it, it may have stripped the thread in the nut end, not completely, butit may have slipped a couple of threads, so the wheel will stay in there, but not grip it firmly. The grinding noise, maybe its the serrated washers on the ends of the axle moving round in the forks, as the resistance of the dynamo,is greater than the grip the skewer has. when rotating the wheel, and its grinding away, look at the 2 terminals, and see if they are rotating as well, they shouldn't do, and my theory could be correct. Let us know won't you ?
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It sounds like you are correct. However, the bike shop were baffled by my problem. Bike shops, huh? I thought they would know. Bike is with them. Got them to rebuild the wheel with a new hub.
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I had a schmidt dynohub wheel built up by ' an extreemly well respected' independent wheel builder, who proclaimed summit wrong wi' that hub, making a grindin' noise'He built up the wheel any way, and on collection I noticed the serations were marked where the hub had rotated in the wheel jig , because the skewer was not tight enough. ::-)
Knowing the Italians, they wont have started it yet, might be worth nipping down the shop! are they replacing it with another schmidt? If so, change the skewer as well, and keep the old hub! post it home if need be . :thumbsup:
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if the serrations are no longer gripping the dropouts you would (with the most common type with wired connections) presumably notice because the connectors will be dragged round....?
If the QR has springs and the dropouts are not very thick, sometimes the springs need to come out before you can get a good grip.
But..... I have a different theory: if it isn't a QR problem I think you have perhaps cracked a bearing. All it takes is a tiny radius on the axle shoulder, or a spacer that isn't flat or has been deformed/worn and the bearing (usually the centre part) can audibly crack in two under applied QR pressure leaving the hub to grind itself to atoms. So it might be that....
The hub is meant to have a (5 year?) warranty so if it is that, it can go back to the manufacturer....?
cheers
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Okay thanks.
Perhaps it is your second suggestion as the connectors are not spinning. Have to sort it out on my return.
Thanks!
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Thanks to you both.
Blodwyn pig, no, they are replacing it with a Normal hub.
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enjoy the rest of your tour. :thumbsup:
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Thanks. Will do if it is ever fixed!
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Don't SONs also have to be fitted the right way round to stop them unscrewing themselves? Curiously, for a German hub, this means the wiring is on the correct side for a British fork blade-mounted light.
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Theoretically yes (edit: Klassic) but they are done up quite tightly (Loctite?) and a few folk have run them backwards without problems.
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Don't SONs also have to be fitted the right way round to stop them unscrewing themselves? Curiously, for a German hub, this means the wiring is on the correct side for a British fork blade-mounted light.
it varies with the model. Basically you don't really need to worry if the hub isn't designed to have the generator part removed without disassembling the wheel. This cross section shows a Son with screw-in innards, which does need to be installed the correct way round
(http://www.bikestation.fi/info/fileadmin/content/images/schmidt/SON28klassik/info_bikestation_schmidt_son28_schnittbild_1.jpg)
the screw thread is RH, which in this case means it need to be installed on the RH side of the bike in order not to vulnerable to the effects of precession. Many shimano generators are similar, but most recent models of Son are no longer constructed this way, and are not vulnerable in the same way either. Threadlock can deter such effects to some extent, but I have encountered plenty of generators that have become unfeasibly tight in use, presumably through precession.
Incidentally the cross-section also shows how the QR load passes through the inner parts of the cartridge bearings; a tiny flaw plus QR pressure can (very rarely) be enough to break them.
cheers
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Assuming I have damaged the hub in this way, has anyone any experience of claiming under the warranty or will they just say user error, get lost.