So I have a surly LHT. I got the frame used a few years back for cheap and built it up slowly, taking my time to get all the parts that were right. After 2 years of riding I decided to upgrade my drivetrain recently. So when I went to put a new bottom bracket in I noticed the removable cup was really going in rough for the last portion of the threads but not so much to make me think I was going to strip it. But even before putting cranks on, spinning the axle of the bb around I could tell it was not spinning totally straight. I put the cranks on to confirm this and sure enough there was a massive side to side movement, easily seen by looking at the chain rings. Almost as if all the chain rings were bent together. it was visible looking at the non drive crank as well. So I figured the new bb was a dud. I took it out and popped in another bb that I know is good and the same wobble was present. Even sighting down the bb from the non drive side I could see the space between the bb and the inner shell wall was not even all the way around.

So after some research I figured getting my shell refaced and the threads chased would solve the problem. Chasing the threads did help the bb go in but my bike is simply unridable like this.
I am having a difficult time trying to visualize in which way the bb shell would even be out of wack.

the only solution I can think of now is to get one of those threadless bb's like the velo orange grand cru. But will this even be appropriate? The threadless bb uses the faces of the shell, so perhaps this will go smoothly especially after refacing. On the other hand I wonder if its the threads that are misaligned. My understanding of the refacing tool is that it threads in and used the threads as the reference for cutting the face. So if the threads are off will the faces be equally off?

Anyone had experience with this type of thing?

You might have a spindle made for a narrower BB than you bike has. There are at least 3 sizes of spindles. They are made for 68 mm, 70 mm and 73 mm BBs. If you are trying to use a 68 spindle in a BB that that is 73 you will never get it tight. 68 is standard, 70 is Italian and 73 is many mountain bikes and maybe Surleys as well. Roger

Thanks Roger. I dont think its that though. These are all cartridge bottom brackets I'm dealing with. The shell is certainly a 68. So isn't the only other dimension I have control over the length of the spindle. Everything is pointing to this being an issue with the bb shell its self, sinced I tested it with several bottom brackets at this point

I'm unable to tell if the spindles are bent, if the crank spider arms are bent, if the BB is loose within the shell or... But a crooked in shell Bb with a straight spindle will cock the crank in only one arrangement, spinning the cranks will not produce a "out of true" look as the crank will just not be parallel to the frame's plane.


With out either better descriptions and/or photos showing the issue this is when the LBS is your best friend.


As to the shell's condition- The threads are no indicator of the faces and visa versa. The threads can be cut off axis yet the faces could be parallel to each other and to the frame's plane. But with most modern threaded and tapered square BBs as the spindle is held within the outer casing (that has the drive side threading) and that the non drive side "cup" (actually retaining sleeve) the spindle is far less dependent on the shell faces to sit properly within the frame. Andy.

I will try and post up a video today. That will make it a lot more clear. The crank is ruled out because Ive put both it and the bottom bracket on a another frame and it runs perfectly. I agree with you that it doesnt really make sense for it to be spinning in an ovalized way rather than spinning correctly just not parallel to frame. I should also mention that there is no looseness or play in the bb or crank. And when the bb is taken out it spins fine.

it is very slight but I see that my shell might be slightly ovalized because I see what looks like a little gap in one part of the non drive side

anyway I will get some photos and make this easier to diagnose.
I already went to my local bike guy and he was a bit dumbfounded, and unfortunately that is the best bike shop around (the only shop that even had a refacing tool).
Thanks a lot for the help

Cross threaded bb cups?

Here is a video. Its difficult to see but it is definitely noticeable. I attempted to put in a threadless bottom bracket but didnt have any luck getting it to fit. Seems my bb shell must be out of whack but I still can't figure out why.
I decided to put everything together to see if riding the bike like this would even be manageable. And it is indeed not as bad as I had supposed but it is still incorrect.

Okay, now realizing I can't post links until I've mad ten posts.

If you search on youtube my username + the word 'bb' it will come up

Uninvited response but I always wondered why Surly LHT owners didn't instead pick up Craigslist Cannondale ST bikes.

Lighter frames
Incomparably stronger frames and can carry higher touring loads
Stiffer frames, track more predictably under load, less wattage lost due to frame flex
C'dale sport touring bike could be actually be raced in a pinch and performs embarrassingly well in a sprint
Climbs like a mountain goat

So Avoiding brick and mortar LBS visit? why?

you are paying now , aren't you.? Bought new? have the sales receipt ?

Max Way Ltd TW, is the OEM factory Surly/ QBP Goes to.. FWIW..



actually testing the BB not being in alignment needs an alignment table, bike frame makers may have one ..





...

Video assist.


Looks normal to me.

+1 internet points for interested kitty.

I've seen MUCH worse lateral movement of the chainrings from new cranksets. You're fine. Stop thinking, start riding.

In the video, I do not see the distance between the chain rings and the chain stay varying at all.

.
...the only thing I can think of given your story, that you got the thing rethreaded but still can't get the correct BB replacement unit from Velo Orange to install, is that maybe your BB shell is a little bit ovalized. It's not that uncommon in production bikes.

Chasing the threads with a tap pushes the BB out round again while you're tapping it, but it usually goes right back to oval as soon as you remove the taps, because you've not exceeded the elastic limits of the steel BB shell. If that's the case, you can usually determine it by using a Vernier caliper to measure in several directions inside the BB, and see if there's variation.

The simplest and cheapest solution is to carefully get your sealed unit BB replacement started in straight on both sides, and then use brute force to thread it the rest of the way in on both sides. I've done it a couple of times at the co-op on cheap Chinese bikes for people who had no other alternatives, but it's not the ideal situation. If that's the problem, and you decide to go this route, use plenty of grease on the threads before you install the unit.

Logically, if the BB shell was twisted, the chainrings would still run true (no wobble).

Chainrings not running true would be attributable to 4 things (or a combination):

1. Bent bottom bracket spindle
2. Bent Crankset/Chainring spider
3. Bent chainrings
4. Crankset/bottom bracket interface not perfectly in alignment.

For vintage chainrings, it used to be common to true them slightly after installation. I'm not quite sure why it was necessary, but perhaps it had to do with the design and manufacturing of square taper cranksets not getting everything perfectly aligned.


After installation, mechanics would just take an adjustable wrench (or similar) and bend the chainrings slightly to align them.

Yes, a crooked BB would not cause side to side movement - the crank would just be tilted but would spin concentric.
Since it's a new BB the spindle can't be bent.
So either the crank spider or the chain rings are bent.

So it was fine until you tried to fix it.

I'd hope that it was the bottom bracket but you say that you've tried two different ones and they both did the same thing.

I'm betting that you cross threaded the replacement bottom bracket and now the threads are all buggered.

...measure your shell across several interior diameters (in different directions) with a caliper and report back.

This is the best advice so far. Just ride the bike. Lesson learned, unless your bike is totally destroyed dont bother upgrading anything.

I'm going to look into the shell being ovalized. That seems like a reasonable possibility. I agree with everyone saying that the bb being crooking shouldn't cause the crank to spin in an eccentric way, and yet it seems to be. Just to be clear again the crank and the bottom bracket have both been control tested, ie. crank put on different bb and frame, same bb different frame, different bb same frame, etc.. which has shown to me that the crank itself is not the culprit. Still open to any possibility though. I appreciate the input from everyone.
The video is a little difficult to see but I can see the wobble in the video. I should have taken to chain off so that middle ring is easier to see.
Also just to clear this up, I did not cross thread my bike or try to put the bb in the wrong way. I've done this once when I was first working on bikes and you better believe I'll never do that again.

Also should mention that since getting threads chased the bottom bracket has been going in very smoothly. Im no longer having to force the removable cup through the last several turns. And yet the problem was there. As for the velo orange threadless bb I tried... It would not fit at all.