Cannondale bad boy bottom bracket
Cannondale bad boy bottom bracket
Hi, I have an occasional “creak” that sounds like it comes from the bottom bracket/crank area of my bike. Looking this morning I noticed the shell on the non drive side of the bottom bracket has a lot of thread sticking out. The bottom bracket is a Shimano BB UN55. I stripped it all down and when putting back together noticed there was an inner flange on the shell that stopped the shell from screwing all the way in. The width of the bottom bracket appears correct, but just seems to be the wrong shell on the non drive side. Is it possible to get a new shell or does it require a new bottom bracket? If it is possible where from as I am struggling to find anywhere?
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Re: Cannondale bad boy bottom bracket
The "bottom bracket bearing unit" is supposed to be fully "home" in the "cup" on the non drive side, and therefore supported by the bit of the cup with the reduced diameter.
Bottom bracket threads are often slightly less than perfectly formed, and it can make the correct installation difficult.
I think you should proceed as follows.....
grease the threads
screw in the NDS cup (normal thread) until there are 3 or 4 threads showing.
screw in the bearing unit (left hand thread) ...hopefully, it will go all the way home, and you can tighten it fully against the bottom bracket shell
fully tighten the NDS cup.
If the NDS cup won't fully tighten, it means the bearing unit isn't central to the cup; back the bearing unit off a turn , and try to screw the cup in...eventually, you will get them to line up.
Bottom bracket threads are often slightly less than perfectly formed, and it can make the correct installation difficult.
I think you should proceed as follows.....
grease the threads
screw in the NDS cup (normal thread) until there are 3 or 4 threads showing.
screw in the bearing unit (left hand thread) ...hopefully, it will go all the way home, and you can tighten it fully against the bottom bracket shell
fully tighten the NDS cup.
If the NDS cup won't fully tighten, it means the bearing unit isn't central to the cup; back the bearing unit off a turn , and try to screw the cup in...eventually, you will get them to line up.
Bike fitting D.I.Y. .....http://wheel-easy.org.uk/wp-content/upl ... -2017a.pdf
Tracks in the Dales etc...http://www.flickr.com/photos/52358536@N06/collections/
Remember, anything you do (or don't do) to your bike can have safety implications
Tracks in the Dales etc...http://www.flickr.com/photos/52358536@N06/collections/
Remember, anything you do (or don't do) to your bike can have safety implications
Re: Cannondale bad boy bottom bracket
You appear to have the incorrect size of non-drive-side shell -- it is too long. I presume you bought the bike as used. The previous owner must have had some reason for putting a different shell in. Compare what you have in the second photo to this photo.
In your photo see how many extra threads there are compared to the photo above. [edit] It looks to be 5mm too long. Is it a shell from a 73mm BB?
In your photo see how many extra threads there are compared to the photo above. [edit] It looks to be 5mm too long. Is it a shell from a 73mm BB?
Re: Cannondale bad boy bottom bracket
I must admit I've never seen a Shimano NDS cup with so many threads,Linus' photo on a UN55 is the norm.Are you sure it's even a Shimano NDS cup?
-----------------------------------------------------------
"All we are not stares back at what we are"
W H Auden
"All we are not stares back at what we are"
W H Auden
Re: Cannondale bad boy bottom bracket
Is there a chance the LH cup has been swapped at some point, replacing a 68mm wide shell LH cup for one for a 73mm wide BB shell?
It is or used to be the case that the only difference between a 68mm and 73mm shell Shimano BB was the lenght/depth of the LH cup.
It is or used to be the case that the only difference between a 68mm and 73mm shell Shimano BB was the lenght/depth of the LH cup.
Re: Cannondale bad boy bottom bracket
Gibber wrote:Is it possible to get a new shell or does it require a new bottom bracket? If it is possible where from as I am struggling to find anywhere?
Get a new BB and use the cup on that until the existing BB wears out. Then install the new BB. The axle length should be written on the BB. If it isn't you need to measure the one you got -- one end of the axle to the other. I am of course assuming you have the correct size axle length. Others may be able to advise on the correct axle length for your chainset. <-- this is very important. UN55s are widely available
https://www.wiggle.co.uk/shimano-un55-bottom-bracket/
Re: Cannondale bad boy bottom bracket
NDS cup with as many threads.....
But mine doesn't have the "double step" on the inside...
If the existing NDS cup will screw all the way into the frame, it isn't a problem.
However, if the frame doesn't have enough threads then the NDS end of the bearing unit will be un-supported.
But mine doesn't have the "double step" on the inside...
If the existing NDS cup will screw all the way into the frame, it isn't a problem.
However, if the frame doesn't have enough threads then the NDS end of the bearing unit will be un-supported.
Bike fitting D.I.Y. .....http://wheel-easy.org.uk/wp-content/upl ... -2017a.pdf
Tracks in the Dales etc...http://www.flickr.com/photos/52358536@N06/collections/
Remember, anything you do (or don't do) to your bike can have safety implications
Tracks in the Dales etc...http://www.flickr.com/photos/52358536@N06/collections/
Remember, anything you do (or don't do) to your bike can have safety implications
Re: Cannondale bad boy bottom bracket
Colin
Is that a Shimano UNXX BB?
Is that a Shimano UNXX BB?
-----------------------------------------------------------
"All we are not stares back at what we are"
W H Auden
"All we are not stares back at what we are"
W H Auden
Re: Cannondale bad boy bottom bracket
Yeah, its a good 20 years old, been in my spares box for years. Its the one with a hollow spindle, UN 72 or something?
If the OP's NDS cup was for 73mm bracket shell, wouldn't the flange (thingy) to support the end of the bearing unit be offset 5mm towards the midline of the frame?
If the OP's NDS cup was for 73mm bracket shell, wouldn't the flange (thingy) to support the end of the bearing unit be offset 5mm towards the midline of the frame?
Bike fitting D.I.Y. .....http://wheel-easy.org.uk/wp-content/upl ... -2017a.pdf
Tracks in the Dales etc...http://www.flickr.com/photos/52358536@N06/collections/
Remember, anything you do (or don't do) to your bike can have safety implications
Tracks in the Dales etc...http://www.flickr.com/photos/52358536@N06/collections/
Remember, anything you do (or don't do) to your bike can have safety implications
Re: Cannondale bad boy bottom bracket
Hi, I have a spare cup for for a UN55 which is identical to a new one (for a 122.5mm wide cartridge) from a box (picture),it looks the same as the one in Linus' picture up-thread.
I got this free from a local charity bike scheme, you are welcome to it if you think it might help you out.
....But..... the reason I got this was because the new one I have has excessive clearance between the NDS cup and the cartridge body. This is likely to cause fretting to the drive side bb threads, the non drive side is likely to not be securely supported in my opinion. It might be worth you checking your existing one off of the bike to see if it has similar play, possibly causing the creaking you described above, or possibly why yours may have been replaced ?
The spare I have has a similar amount of clearance (I just checked), so might need a shim wrapped round it possibly to take out any play. I have some 5 thou' of an inch aluminium shim material I could put in the envelope with the cup, it might work (Araldited to the cartridge perhaps?). It's a problem in the future for me .
I have a UN70 BB on one of my bikes and it is an exact sliding fit as you might imagine, Shimano appear to have changed the design for some reason. Strangely the cup off of the UN70 will not fit over the UN55 cartridge, I will probably have to get a bit skimmed of off the internal diameter to be able to use it at some time in the future on my UN55 cartridge, or try the shimming bodge myself.
I got this free from a local charity bike scheme, you are welcome to it if you think it might help you out.
....But..... the reason I got this was because the new one I have has excessive clearance between the NDS cup and the cartridge body. This is likely to cause fretting to the drive side bb threads, the non drive side is likely to not be securely supported in my opinion. It might be worth you checking your existing one off of the bike to see if it has similar play, possibly causing the creaking you described above, or possibly why yours may have been replaced ?
The spare I have has a similar amount of clearance (I just checked), so might need a shim wrapped round it possibly to take out any play. I have some 5 thou' of an inch aluminium shim material I could put in the envelope with the cup, it might work (Araldited to the cartridge perhaps?). It's a problem in the future for me .
I have a UN70 BB on one of my bikes and it is an exact sliding fit as you might imagine, Shimano appear to have changed the design for some reason. Strangely the cup off of the UN70 will not fit over the UN55 cartridge, I will probably have to get a bit skimmed of off the internal diameter to be able to use it at some time in the future on my UN55 cartridge, or try the shimming bodge myself.
Nu-Fogey