Bicycle Mechanics - Ultegra Crank and BB
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Hello, I'm in a middle of putting my first bike togather and I have a question about Ultegra Crank and BB.
After I install my BB and crank, I spun the crank to see how smooth they are but it only turned a couple of full turns and then stop. When I spin the crank, I can feel the resistance around the BB area. My question is, if this is normal and I need to break-in(?). Or is there something wrong with my BB bracket? All these parts are new and I didn't have any problem installing any parts. Thanks in advance
This is sort of subjective and depends on how much angular momentum that the crank and chainwheels have....I think that you are probably just fine and just feeling normal grease and seal drag on a new bb. Mine do loosen up in 50mi or so. But if when you ride, you feel creaking or grinding, obviously something is not right.
04-28-06, 02:14 PM
This has been an observed trait concerning the Shimano Hollowtech II BBs. There are many among us who feel that the bearing drag present in these cartridges is too high. FSA has begun marketing an outboard bearing BB utilizing ceramic hybrid deep groove bearing cartidges this season in response to feedback.
It should be pointed out that there is probably no need for a ceramic bearing in these applications. The drag is mainly due to the viscosity of the packing greese and contact seal design in the cartridges selected by the manufacturer.
As long as the drag you feel is consistant throughout the pedal stroke then this is what you are experiencing. If you find upon closer inspection that the drag is more noticable in certain crank positions then you are more likely experiencing binding of the crank spindle. This can happen when the BB shell surfaces are not machined parallell each other, and perpendicular to the centerline of the BB shell threading.
I ran into that issue last night (thanks Felt). If this latter situation is more like your problem then it can be corrected by having the BB shell faced. Most good LBSs have the tooling to accomplish that.
04-28-06, 03:24 PM
Agree with posts above, although my experience is with a 105 BB and crankset. After install it seemed there was more resistance than you'd think. By comparison, my front wheel, when spun by hand, will spin for a really long time...my rear wheel, not as long...and my crankset with the chain removed, not long at all. Remember most of the weight of the combination is close to the center so you don't get a lot of stored energy like you do with a wheel. Bottom line...sounds normal to me.
04-28-06, 03:51 PM
Agreed. Normal - to mfg. specs.
Keep in mind that the bearings that they are using are industrial use pump and motor bearings that are designed to operate at elevated temperatures and at high rpm. Not exactly application specific.
I miss the old days of loose bearing adjustable BBs. Probably because I tend to like the time spent working on bikes as much or more than even riding them.
Yes, the resistance is consistant. My beater with Truvativ Touro Crank spins with less drag.:mad: I'll put the bike togather and give it a go. I'll check with LBS later just to make sure. Ya...when I install the BB, I felt the grease being too thick. I really didn't wanted to go to LBS though, because they are j@ckA$$es. Hmmm:rolleyes:
04-28-06, 08:22 PM
Almost all bottom brackets have some drag. I just built a bike with Campy Chorus, their next to top line, and the bb had noticable stiffness even before it was installed. It's normal.
Peek the Geek
04-28-06, 11:20 PM
What you are experiencing is, as I have found, completely normal. I, too, was concerned when I first got my Ultegra equipped bike. I was used to cranks that'd rotate very freely and thought something was wrong when a good spin of the Ultegras produced only two or three revolutions.
So I posted here, checked with bike shops, and even pulled apart the BB to see if this was normal or not. Conclusion....that's just the way it is. Your cranks and BB are fine.
Now have fun with your build.
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