Outboard bearing drag/install question

[stackie]

So, I'm installing an XT hollowtech crank. I've got it on seemingly correct, but when I spin the crank, it sure seems like the drag is high. Doesn't feel like it is binding, but more like the mechanism is two teflon surfaces sliding rather than bearings. Not smooth like a traditional bottom bracket. It almost seems ok, just that if you spin the crank, it only goes about half a turn before stopping. I really don't think I tightened the left crankarm on to the spindle too tight and overloaded the bearings.

Any ideas?

Jon

[David Kirk]

Bottom bracket properly faced?

Dave

[Adam]

Lots of friction in the Shimano and FSA outboard bearings...Even installed properly. Now, the Campy Ultra Torque is the only outboard bearing BB system that spins almost as free as the square tapers of olde.

Adam

[stackie]

Dave,

I thought about that. Frame is used, so I assumed (we know what that makes) that it is ok.

If I spin the crank alone it will go around once. If I spin my dura ace octalink crank with chain and derailleur it goes around three times.

Jon

[MapleWelder]

After staying square taper for all these years (like the atavist I am), finally trying hollowtech II cranks. My shop owner said just what Adam did here about these designs implicitly having higher resistance... I just can't believe the cycling community at large has accepted this level of resistance as a trade-off for 100 grams!?

Am I missing something?

Have any tricks been developed for smoothing out these cranks...?

Strange form of progress... :confused:

[zap]

Oh, resistance is high even with a proper install. So high that this whole ceramic bearing matter is laughable.

I wonder what bb30 bearings are like.

I refuse to give up phil wood bb on some bikes and plan on swapping fsa mega to pw with davinci cranks on one of our tandems.

Some stiffness will be lost but it's not like I'm cranking out 1200 watt's all day long.

[oldpotatoe]

Oh, resistance is high even with a proper install. So high that this whole ceramic bearing matter is laughable.

I wonder what bb30 bearings are like.

I refuse to give up phil wood bb on some bikes and plan on swapping fsa mega to pw with davinci cranks on one of our tandems.

Some stiffness will be lost but it's not like I'm cranking out 1200 watt's all day long.

BB30 bearings, ceramic or no, are no better. You can do like some TdF wrenches and remove all the bearing seals, ride, then replace in short order.

For the OP, make sure the BB shell is faced, but yep, all BBs with sealed bearings are seal 'sluggish'.

And for a UT system, if you install it with lotsa grease, as you should, even on ceramic, it's not as smooth as cup and ball, which feels like it's running in water.

[rockdude]

Dave,

I thought about that. Frame is used, so I assumed (we know what that makes) that it is ok.

If I spin the crank alone it will go around once. If I spin my dura ace octalink crank with chain and derailleur it goes around three times.

Jon

Sounds normal to me..... You will never feel the difference when riding and it will loosen up over time.

[ultraman6970]

+1 is the nature of the beast and agree, riding u wont notice.

[stackie]

Had spoke with Paul Sadoff re this issue in the interim. He made the point that the crank may have less resistance than the old octalink BB when pedaled under load vs the work stand spin. I do not notice it when riding and this has been four years now!)

Jon

[foo_fighter]

The original GXP bottom bracket design had lots of seal drag but the newer "gutter seal" design is supposed to be a lot better. Enduro's aftermarket bottom bracket is supposed to be pretty low drag as well. I think they make both GXP and Hollowtech II BBs.

I agree that you'll probably only notice it with the "on the stand hand test."
Though if you look at some of those Youtube videos, they seems to spin forever.