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Bearing friction

slowrob said:
I have shimano ultegra bottom bracket (external bearing type). When I spin the crank it only spins around 1-2 revolutions before stopping. Is this normal?
Within reason, yes, it's normal. You're looking at bearing seal drag and friction from the grease. If the BB turns smoothly in your had, with no binding or gritty feelings, then there's nothing to worry about.
 

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I'm the same way... My campy chorus BB spins like a top... now I have this new improved BB and it's got drag on it? Same goes for the pedals... SPD type with a sealed bearing. I'd rather have adjustable races, and spin without drag...
 

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if there is grease in the bearings, and shields to keep contaminants out of the grease/bearings, there will be drag. it doesn't matter...if you spun your crank and it went round and round 23 times, it's prob 'cuz there isn't any grease left in the bearings. this is bad. like the previous poster stated, if it's smooth when you spin it by hand, everything is fine. not sure why people think their cranks should spin a certain number of times...if you want that to happen, clean out the grease and put a few drops of tri flow in the bearings. then be prepared to do it every ride.
 

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Rodder07 said:
I'm the same way... My campy chorus BB spins like a top... now I have this new improved BB and it's got drag on it? Same goes for the pedals... SPD type with a sealed bearing. I'd rather have adjustable races, and spin without drag...
SPD's are adjustable. Every one that I've seen is a cup and cone loose ball type inside with the rubber seal on the spindle to keep dirt out. Pretty easy on most of them.

The external bearings have more seal drag because the bearing seal to spindle surface is larger. Even so, the bearings don't last as well as good ole square taper.

That said, seal drag doesn't amount to much.
 

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Thanks for the feedback,,, didn't want to ressurect an old issue, but my Campy BB when greased and adjusted is a zinger, comparatively. I was curious if the upper ended models of the external BB were more like my campy... perhaps the new one just needs breaking in?

I noted the Park site that the sealed bearing set on these new gizmo's are preloaded as well, which may have a little todo with it.

The SPD's that came with the bike have a sealed bearing and the seal you mentioned... perhaps I'll chuck the "wellgo's" and get a true SPD type. I was going to put my Look Carbons on, but at 1/3 the weight the new ones seemed like an improvement
 

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Rodder07 said:
Thanks for the feedback,,, didn't want to ressurect an old issue, but my Campy BB when greased and adjusted is a zinger, comparatively. I was curious if the upper ended models of the external BB were more like my campy... perhaps the new one just needs breaking in?

I noted the Park site that the sealed bearing set on these new gizmo's are preloaded as well, which may have a little todo with it.

The SPD's that came with the bike have a sealed bearing and the seal you mentioned... perhaps I'll chuck the "wellgo's" and get a true SPD type. I was going to put my Look Carbons on, but at 1/3 the weight the new ones seemed like an improvement
A coupla points:

The drag in the new bearings ought to be from the seals. If it's from the pre-load, the preload is too high. Properly adjusted 'naked' cartridge bearings will spin better than any properly adjusted cup-and-cone, although there's seldom a way to make that comparison directly.

The 'cost' of that seal drag is very minor. It's benefit is that it greatly minimizes the needed maintenance. And yes, it lessens a great deal over time.

Sometimes, those 'perfectly adjusted' cup-and-cones that would spin forever were in fact adjusted too loosely. The angular contact of a traditional bearing set requires a significant preload to mitigate spindle flexion under load. In all but perfectly lapped, cleaned, and maintained cases, a BB adjusted for maximum smoothness on the stand would have more friction under load than one adjusted slightly tighter.

Annular cartridge bearings avoid the problem. The only preload needed there is just enough to prevent side-to-side slop that can increase wear. Too much wears them even faster.
 
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