Quick bottom bracket question
Moderator: robbosmans
I just had work done on my bike to have a new 12-speed ultegra crank installed. I noticed after I got home that there is a 1-2 mm gap between the non-driveside crank arm and the bottom bracket (T-47) where you can see all the way to the spindle; is this normal? I don’t remember there being this big of a gap before and am wondering if there should normally be a spacer or something there to fill the gap so debris doesn’t get in.
Thanks in advance.
Thanks in advance.
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- Posts: 110
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If there is a 1-2mm gap between the NDS crank and the BB you should have very noticeable side-to-side movement, i.e., play, in your crank. Do you have a photo?
Chris
Chris
Is it currently setup with the stock BB - an external cup on the DS and internal on the NDS?
- wheelsONfire
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Ofcourse they need to install an adapter if it's not fitted with a BB that is made especially for Shimanos 24mm crank axle!
Bikes:
Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)
Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.
Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)
Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.
Were they replacing one Shimano crank with another Shimano crank?
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- Posts: 110
- Joined: Sun Aug 18, 2019 10:40 am
It's hard to judge without seeing it. But if the NDS crank is not kissing the dust cap of the BB bearing this means there is no preload on the bearings. Maybe the spindle is sitting very tight in the bearings and you didn't put down too many watts so you didn't notice it, but there will be play in your crank. If it's not fixed, your BB bearings will wear out in no time.
I see two options: either the shop didn't mount the NDS crankarm properly or they simply forgot a spacer during the reassembly. Both should be very easy to fix.
I see two options: either the shop didn't mount the NDS crankarm properly or they simply forgot a spacer during the reassembly. Both should be very easy to fix.
Grab the left crank at the end and pull it sideways left and rightto see if there's any play. If the bearing has no preload, there might be some play in the crank.
Next, try hitting the left crank with the palm of your hand. The whole crankset (both sides) will move to the right if there's a missing adaptor.
Tbh, I'd just get the crank out and try the spacers that came with the bike until one is right. Removing and fitting a hollowtech crank is less work than taking a bike to a shop.
I have a 12s Ultegra crank fitted (on bb86 BB shell and standard Shimano BB). Can take a pic of the NDS crank/BB interface if that's helpful.
Next, try hitting the left crank with the palm of your hand. The whole crankset (both sides) will move to the right if there's a missing adaptor.
Tbh, I'd just get the crank out and try the spacers that came with the bike until one is right. Removing and fitting a hollowtech crank is less work than taking a bike to a shop.
I have a 12s Ultegra crank fitted (on bb86 BB shell and standard Shimano BB). Can take a pic of the NDS crank/BB interface if that's helpful.
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