Owing to a persistent issue with outer free hub bearings wearing prematurely, I’ve replaced it with an LLU/LLB bearing. This has resulted in quite a high degree of drag on the chain. Questions;
Will the drag lessen after some use?
Would using a lighter grease on the pawls reduce the drag significantly?
Anyone recommend pulling the LLB seal from the inside of the bearing leaving just the LLU to prevent contamination coming from the outside? Or just take out the LLU, turn the bearing around and live with the fact that the bearings don’t seal well and I’ll have to replace them regularly?
My first question would be, are you racing competitively? I wouldn’t compromise bearing protection for a bit less drag. You can certainly use thinner grease or oil on your pawls. I think the perceived drag is maybe greater than reality. Do you see chain sag as a result of the drag?
How is it wearing prematurely? Is it getting crunchy? Do you find it eventually purging rusty grease? Does the end cap cover the entire bearing, or is the bearing seal the only protection against the elements?
Also are you sure it’s the new bearing ‘s tighter seals that are causing the drag? I’d test by removing both seals but keeping the balls greased, and reinstalling, just to see how it feels.
Sometimes the bearing is simply sitting not quite straight. You can lightly tap it out of its bore a little and press it back in, and compare the drag.
Sometimes, the bearing bore is tight, with too much of an interference fit. Sometimes they’re designed that way. The hub could be intended for use with bearings with greater clearance. There is a clearance scale used for bearings, C1 - C(something). CN is the most common, I call it C-normal, and it’s between C2 and C3. C3 is probably the second most common specification, and it’s slightly looser, and the tight fit in the bore will squeeze all the extra space away.
As it happens, I did a 100kms spin and the issue effectively resolved itself. Initially there had been chain sag but that is all gone now and I’m happy to leave well enough alone.
The hub is a camapagnolo zonda, specifically the c17 generation. I find it surprising as I’ve had many many, many Campy free hubs over the years and never had to replace freehub bearings. With these wheels it’s the second time I’ve had to do this in a short period of time
I cannot tell what difference there is to prior generations which I am still running. Perhaps it’s the quality of bearings they are installing in the factory or any other variable?
I’d be pretty sure the bearing alignment in installation is OK but cannot be certain of that
This sounds like you have a bad freehub body with a slight differential between bearing bore centerline, an issue independent of whatever sort of bearing you’re pressing in. This roots from bad tolerances at the factory for that batch of FHs.
As painful as it is to say, there are good days at the Campagnolo freehub body machine shop, and there are bad days at the Campy machine shop. Yours likely were made on one of those bad days. I’ve seen this issue on Zipp hubs - where they eat bearings (regardless how how nice/durable the bearing seals can be and how much grease is used to seal at the endcaps) I am not sure if this is a warrantiable issue (maybe hit up a campag pro shop to get that sorted) but I would try to find another freehub (used or otherwise) to resolve your issue.
I was researching bearings and grease and such recently and a bearing industry professional said, to paraphrase, bike stuff is woefully low tech and lacking precision and accuracy, so the bearing itself is incredibly unlikely to be the issue.
I replaced the freehub bearings on the same wheels last week. They come stock with bearings that have the inner seal removed. No idea why and I always replace with bearings with x2 full contact seals and never have an issue with freehub drag.
Bearings are removed with the Noble (now Abbey) pullers and pressed back in with a press from wheels so I am confident the bearings are pulled and pressed squarely, this I feel is half the battle on these freehubs as I have worked on freehubs that destroyed bearings where the owner has previously knocked the bearings out with a hammer and pressed them in with a threaded bar and some washers. In that case a new freehub was fitted.