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-   -   hubs feel "slow" after repacking (https://www.bikeforums.net/bicycle-mechanics/42574-hubs-feel-slow-after-repacking.html)

brunning 12-20-03 12:16 AM

hubs feel "slow" after repacking
 
i disassembled my ultegra hubs, replaced the bearings with new ones of the correct size, cleaned everything out and repacked them using a generous amount of park tools polylube 1000 grease. when i pulled the old bearings out, there was only a light coating of the old grease.

i followed the instructions in Barnett's, measured the exposed axle and replaced the nuts in the same positions. i tightened the cone holding the bearings to what i felt was the exact point where the last bit of play disappeared from the axle, and then tightened down the locking nut, making sure i held the cone in position with a second cone wrench.

once everything was tightened down, i found that the axles didn't spin very easily. they turned freely and smoothly as i rotated them, but before i opened them, you could give them a spin and they'd turn a few times on their own.

the wheels, when mounted in the frame, turn very smoothly and it doesn't feel like there is much resistance, so is this just a function of the fresh grease causing some friction or is there a further adjustment i can make?

mike 12-20-03 03:11 AM

You probably overpacked your bearings with grease. Ride your bike and the grease will be squeezed 'out-of-the-way".

Hold the axle in your hands and give the wheel a light spin. It should spin freely and gradually come to a very smooth and gradual stop. If there is any jerkiness or if the wheel eventually stops abruptly, you have tightened the bearings too tight and need to loosen up the cones just a hair.

gazedrop 12-20-03 05:13 AM

Yeah, the grease would "slow" the wheel down. It's called viscous drag.

In top auto racing, you can get special ultra-light gearbox oil that looks like cooking oil but has the consistency of water. (Regular gear oil has the consistency of honey...) Around $100 a gallon. Good for one race only.

In addition to everything mike said above, use your sense of touch. While holding the ends of the axle in your fingers, see if it feels like there's any metal-to-metal contact while the wheel is slowing down.

The only time that too much grease would be a problem is if it prevented the pawls in the rear hub from re-engaging after coasting. If this isn't happening, don't stress the excess; it'll help prevent water intrusion.

mike 12-20-03 09:16 AM


Originally Posted by gazedrop

The only time that too much grease would be a problem is if it prevented the pawls in the rear hub from re-engaging after coasting. If this isn't happening, don't stress the excess; it'll help prevent water intrusion.

I don't use grease on the pawls of the Freewheel/Freehub for this reason. I know guys that use a very light film of grease, but I always find that it gums up the pawls or something - problems just seem to follow. I always use oil in the freewheel/freehub.

brunning 12-20-03 10:46 AM

thanks for the answers, guys. this is what i figured.

the wheels do turn smoothly and stop as expected with no grinding of any sort. i'm quite certain the cups are appropriately adjusted, so i suppose i'm asking if there's any harm in living with the extra grease for a while (i assume the resistance will lessen as the grease breaks down), or if i should clean them out.

thanks!

mike 12-20-03 01:50 PM


Originally Posted by brunning
thanks for the answers, guys. this is what i figured.

the wheels do turn smoothly and stop as expected with no grinding of any sort. i'm quite certain the cups are appropriately adjusted, so i suppose i'm asking if there's any harm in living with the extra grease for a while (i assume the resistance will lessen as the grease breaks down), or if i should clean them out.

thanks!

Brunning: You should be OK, assuming there is somewhere for the grease to go. If you didn't pack grease between the axle and the hub body, the grease will end up there which isn't bad. Unless you have a tight fitting dust cap, the grease can also work it's way through it to the outside of the hub. Be sure to wipe this off as it attracts dust and dirt which can eventually be sucked back into the hub.

miamijim 12-20-03 02:42 PM

Brunning...odds are it isnt the grease. When you adjust the bearings there should some 'play' or 'looseness' to the adjustment. If there is no play before you clamp them down then you can bet they'll be over tightened when you clamp the quick releases. When the quick release is clamped down the cones and locknuts get compressed. This compression takes up the intial 'looseness' that was intentionaly adjusted in. A test you can do to see if your adjustment is to tight is to flip your bike upside down. Rotate your wheel so the valve stem is at the '11' or '1' O'clock postion. The weight of the valve stem should should cause the wheel to rotate with the valve moving to the bottom. If it doesnt, your adjustment is to tight.

I adjust my hubs based on the amount of play when they are clamped into the frame/fork. I loosen them untill there's play then tighten them down a fraction. Needless to say my wheels spin forever.

ChezJfrey 12-22-03 11:02 AM

If using a quick release, follow miamijim's advice - the post is spot on. There should be some play before clamping down and a well adjusted wheel will allow the stem to fall to the bottom of the arc.

Calvin Jones 12-22-03 11:34 AM

Hub adjustment procedures
 

Originally Posted by brunning
i tightened the cone holding the bearings to what i felt was the exact point where the last bit of play disappeared from the axle, and then tightened down the locking nut, making sure i held the cone in position with a second cone wrench.


As stated on some other posts here, the problem is most likely in your adjustment. The quote above implies you checked play where the locknut and cone were not secure. Re-read that chapter. Never check for play unless the locknut and cone are tight against each other. The cone has slop on the threads, and the cone is pushed futher into the bearings by the locknut.

See also http://www.parktool.com/repair_help/howfix_hub.shtml

MichaelW 12-23-03 12:45 PM

I sometimes have problems re-using bearings that are not exactly spherical. Its more of a problem in headsets, but you should probably replace bearings when you strip a hub. Use ISO grade 25 balls.

Don Cook 12-23-03 03:51 PM

A couple of observations regards how you rebuilt your hubs:
1. A light film of bearing grease is all that is needed. As you noticed yourself, from the factory there was but a light film of grease in the bearing cups.

2. Never take all of the side play out of the hubs as you adjust the cones. Instead, adjust your cones until you can still detect just the slightest amount of hub "wiggle".
Then when you mount the wheel, adjust the skewer so that it just takes the "wobble" out of the hub.

In this way you have the very least amount of side to side tension on the hub bearings and yet you have reduced the wobble to zero. Before doiong anything to the bearings or cones on a hub, I apply a known force to the wheel to make it rotate. I do this a few times and then average the number of complete rotations the wheel makes before coming to a stop. Then I perform whatever maintenance that needs doing. When finished I apply the same exact rotational force and once again measure tha number of rotation the wheel makes before stopping. I have found that by adjusting the cones in the manner I've described, the number of rotations that a wheel will make before coming to a stop, always increases and sometimes by as much as 50%.

brunning 12-24-03 09:26 AM

thanks!
 
ok, i took everything apart again, used substantially less grease and reassembled with a little bit of wiggle left in the axel. the wheels feel now feel much better... they spin faster and there's no lateral movement. thanks!


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