Bicycle Mechanics - Dura Ace 7850 Hubs and freewheel noise
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03-30-09, 09:43 PM
I recently purchased a new set of rims with Dura Ace 7850 hubs and there is a intermittent sporadic loud clicking noise when coasting. I never owned Shimano hubs previously, so I am not sure if this is normal. It is definitely the hubs since I removed the tire and cassette and the noise was still present. Is this normal or could there be a damaged bearing? I am a bit hesitant to bring them to my LBS, since I purchased them online and that retailer is on the other side of the country.
03-30-09, 09:55 PM
My money is on the freehub. The hubs themselves have nothing in them to generate a 'click' sound. But do check them to see that they are not binding, while also seeing to it that there is no lateral play. They should be tight with no binding whatsoever. If they are adjusted correctly - then rule those out. Sounds like your freehub needs some lubrication as a clicking sound usually indicates that the pawls are bone-dry.
Here you go:
My money is on repacking the bearings. I was told by a mechanic who used to work for Shimano that it is not a bad idea to take apart and repack new shimano hubs. He was of the view that the hubs, wheels etc have to travel from a tropical Malaysia to North America, and in some cases, some of the grease used in the hub packing could have thinned and seeped out on the trans-pacific journey. And this does not make for a hub that will be at optimum efficiency.
I would thus advise to regrease and repack your hub bearings.
03-31-09, 04:57 AM
While re-packing hubs when new is an unspoken 'of course!' - can you explain how a hub makes a 'click' sound? Let's see if Sheldon can help:
03-31-09, 10:49 AM
To determine whether the noise is coming from the hub or freehub; remove the wheel from the frame:
1) Hold the axle and spin the wheel (don't touch the cassette; let it spin with the rest of the wheel), then
2) Hold the axle and spin the wheel again, but this time touch the cassette so it does not spin (this will make the freehub spin).
If you only hear the noise in scenario 2, it's probably the freehub. If you hear it in both scenarios, it may be the hub (or other parts that are spinning, but you said you've already eliminated other parts).
You said you only hear it while coasting, which would indicate the freehub, but it's helpful to test it up close.
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