#1
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Advice on cranks not spinning freely after BB installation
I just installed a Chris King 24mm ThreadFit BB and some Ultegra cranks, and when I give the cranks a spin (without a chain) they only turn about 2.5 times before stopping. My other bike's cranks spin for a dozen times when I spin them the same way, so I'm worried I installed something too tightly.
Video here. The manual says to install the BB shell at 30ft/lbs, which I did, and then I hand-tightened the cranks with that little round plastic Shimano tool. I'm wondering whether I do indeed have a problem and how to diagnose what it is I'm doing wrong. There is no play in the cranks and I don't feel any grit or unevenness or anything when I turn them. The BB was purchased used so I suppose it's possible there's something wrong with the bearings but I think user error is much more probable. |
#2
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They will be fine. Tight seals and fresh grease slow things down a bit. You will never notice while riding.
Providing things are free and smooth, it dosent really matter how they spin in the stand. They are fine. |
#3
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If the bottom bracket was already used, it should spin reasonably well. Bottom brackets don't have to just spin to a silly degree because it's all about how they perform when loaded, not unloaded like in your spin test.
However ... what could be happening is that your bottom bracket isn't faced properly and the two halves of the bottom bracket aren't quite collinear. That can cause the whole thing to slow down, and can also lead to premature failure of the bottom bracket. I see this all the time, so if you have any hesitation at all about whether your bottom bracket was tapped and faced to ensure that it would perfectly align the bottom bracket, I'd have a shop or a builder do so quickly for you. |
#4
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Quote:
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#5
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is that a brand new king BB?
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http://less-than-epic.blogspot.com/ |
#6
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#7
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i once had a BB spindle that would stop to turn nice and smooth when i fastened the countering. In that case, the faces of the BB casing on the frame weren't perfectly parallel. Once that was fixed, all was fine.
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Jeremy Clarksons bike-riding cousin |
#8
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Yup, what he said. In addition, put your hand on seat tube when you spin cranks(no chain) and if it feels smooth...go ride.
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Chisholm's Custom Wheels Qui Si Parla Campagnolo |
#9
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Quote:
I suspect you just are feeling a little resistance in the bottom bracket bearings that isn't a sign of anything wrong. Not only do you have seals and grease and such that can slow it down, even in a used bottom bracket, but also King sets their bearing cartridges pretty tightly with the idea that they relax ever so slightly under load. I only mention the issue above because it's always a good idea to double check how the headset and bottom bracket are faced and/or threaded. You'll probably never have to do it again, but it's about the only other issue that could be affecting your bike. |
#10
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I think your BB is fine. When I went from square taper to outboard BB I thought I must have did something wrong, I didn't. It's in the nature of the beast, once you get on the bike you won't notice any difference
Last edited by bobswire; 05-30-2017 at 11:40 AM. |
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