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Old 10-20-09, 10:09 AM   #1
rwortman 
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"Sealed" Hub?

I purchased a mail order bike a few months ago. All my bike wrenching experience is from many years ago. I read up on threadless headsets and indexed shifters so I was good to go. The wheels arrived with some funky looking rubber gumdrop thingies between the cone locknuts and the hub. Spinning the axle with my fingers showed signicant stiction from the rubber things and too tight bearing cones. I adjusted the cones and pried the rubber things off and discarded them, figuring them to be some sort of shipping device. I later thought perhaps they were some lousy engineer's idea of a bearing seal. After looking at some wheel pictures lately, I see that they were seals. My hubs have the normal dust cap ring on them and look just like any cup and cone hub has for decades. Do people really think having that rubber cup rubbing on their hub all the time is a good thing? Maybe if you ford streams everyday but for normal riding I can't see why you would want these. Thoughts?
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Old 10-20-09, 10:28 AM   #2
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Several Shimano MTB rear hubs came with a rubber cone betreen the locknut and hub body to act as an additional seal for hubs expected to be used in dirty and wet conditions. I've never seen them on road hubs.
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Old 10-20-09, 11:02 AM   #3
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I've got a rubber cap that sits on the cone nuts on my SRAM Dyno hub and it sits within 1-2 mm of the hub body as an additional protection to keep dirt and grit from actually getting to the bearings seal.

I don't have a problem with it.. but it doesn't rub the hub body. Are you sure yours did?

On a new hub most manufacturers will tighten the hub a little tighter because with the first 25-100 miles the bearings will break in and the axles will actually become loose.
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Old 10-20-09, 11:36 AM   #4
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The Shimano seals used on their cup and cone mountain hubs definetly rub. I've got a few Deore, LX and XT wheelsets and all have those "gumdrop" seals. It's a light contact but it's definetly there and yes when dry or greased and gritty they drag quite a bit.

I found that keeping them clean and lubing them with the occasional dab of automotive plastic and rubber detailer keeps them spinning as freely as possible. A drop of oil works too but of course then it attracts a LOT of grit and quickly turns into a grinding paste. The P&R detailer cream dries to a slick film that doesn't attract dirt and stays free running for a few hundred km's and continues to provide some benifit for a few hundred more. However riding in rain or muddy conditions along with the washing you do after a few such rides will help strip it away that much sooner. But pinch the seal to open it up again and put a drop of the P&R detailer in and it's good for a few hundred more kms. For dry riding it'll easily last much, much longer.

I've always reset the bearings when I get a new set since they are too tight even when just sitting there. Add in the axle compression from the skewer and suddenly they are tight and "coggy" as hell. Out of the 7 or 8 sets I've reset from new I've never had an issue with them going loose. But I do set them on the tight side of what I like to see and they do "smoothen up" after a while. Perhaps that "breakin" becomes a self fullfilling prophecy just due to the excess preload? I'd rather not be roll forming the cups and bearings in such a manner though.

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Old 10-20-09, 02:50 PM   #5
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re

These were definitely rubbing. I couldn't see a need for them and took them off. The bike is a Motobecane road bike with what is probably their house brand hubs. I have seen the same sort of rubber gumdrops on other lower priced wheelsets that I have looked at whilst shopping on line. It must be a sales factor to claim "sealed bearings". I can see an application for a mountain bike or other off road machine but not for a road bike. The hubs spin smoothly with no play after adjustment so I don't know how much better a pricey hub could be except for maybe a tiny bit lighter and real sealed bearings.
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Old 10-20-09, 03:16 PM   #6
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Cheap "joytech" hubs will come with large rubber seals that definitley impede the spinning of the hub - they are not shipping devices. They are part of the hub and you should use them.
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Old 10-20-09, 04:48 PM   #7
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I can't remember where now, but I remember some hub instruction saying that the seals will break in and loosen up with time. I would have left them on for a few weeks of riding, then see if the wheels still spin noticeably smoother without them.

There are no "real" sealed bearings. Bearings are moving parts, so either you have something rubbing or you have an opening. Do you mean cartridge bearings? Those aren't necessarily better than having the races built into the hub.

Last edited by CaptainCool; 10-20-09 at 05:40 PM.
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Old 10-20-09, 05:14 PM   #8
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Quote:
Originally Posted by rwortman View Post
These were definitely rubbing. I couldn't see a need for them and took them off. The bike is a Motobecane road bike with what is probably their house brand hubs. I have seen the same sort of rubber gumdrops on other lower priced wheelsets that I have looked at whilst shopping on line. It must be a sales factor to claim "sealed bearings". I can see an application for a mountain bike or other off road machine but not for a road bike. The hubs spin smoothly with no play after adjustment so I don't know how much better a pricey hub could be except for maybe a tiny bit lighter and real sealed bearings.
A cup and cone bearing should have a little play in it when not installed in the dropouts. The play will go away when you close the quick release and clamp the wheel. This provides the preload that is necessary for a properly adjusted bearing. The seals are dust seals and will keep the bearings cleaner a litle longer. The friction they add is not significant.
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Old 10-20-09, 06:46 PM   #9
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Cheap "joytech" hubs will come with large rubber seals that definitley impede the spinning of the hub - they are not shipping devices. They are part of the hub and you should use them.
Why should I use them? Other than that little lip that the "seal" rubbed on, the hub looks like every other hub I ever saw and spins as well as any hub I have had. Hubs worked fine for probably 100 years before some yahoo put a rubber condom on one. I can't see adding drag without a good reason. Is this supposed to be a reason not to maintain one's hub bearings? I kind of liked communing with my bike bearings once a year.

A quick run around the web seems to indicate the inexpensive hubs either have no seals or silly seals and better hubs have a contact seal that is small and probably causes very little drag. I will opt for old fashioned no seals until such time as I decide to spring for fancier wheels.

I don't know what they are using for cartridge bearings in bikes. I work with other types of machinery and I have seen bearings that have a thin seal that runs in a little groove in the center race and although they do make contact, it is not much and they have very little drag.
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