Bottom bracket bearings won't squeeze into frame

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9/12/2020 12:54 AM

I have an Eastern BB kit and trying to put a new cranks set up into a newly bought frame.

The BB sealed bearings DO fit into the frame hole but only around 25% in, then just won't go in no matter how perfectly I hammer.

Yes I did grease. Please help.

Thanks.

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Control of my bars helps me feel in control of my life.

9/12/2020 1:08 AM

Did you use the middle spacer?

If yes, then did you ensure it wouldn’t be too long?

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Scooter kid trying to ride a bike.
@scootereyn

9/12/2020 1:13 AM

readybmxer wrote:

Did you use the middle spacer?

If yes, then did you ensure it wouldn’t be too long?

It's not a spacer issue. A professional bike mechanic did a video call with me he said all I need to do is hammer it in with a rubber mallet, taking lot of care not to hit the black PC area in the middle of the bearing. When I kept telling him on call it's not hammering down (I was smacking it down hard), we just gave up...

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Control of my bars helps me feel in control of my life.

9/12/2020 5:15 AM

Make a bearing press

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It’s all bmx

9/12/2020 6:15 AM

did you grease the frame / bearings?

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9/12/2020 6:32 AM

Grease, double check the spacer width. You can hold the bearings and spacer all together on a spindle and hold it outside your bb to make sure the whole assembly isn’t wider than it should be. Some frames are just really tight and stubborn.

You can try putting a piece of hard wood on the bearing to distribute the load, that’s worked before for me.

What I do now for bbs is i use an old set of cranks as a bearing press. It works well for me because the splines aren’t crazy tight on my old cranks so they come apart pretty easy, and pressing bearings is wayyyyy easier than hammering cause they stay lined up the whole time and you get mechanical advantage. It never takes me more than like ten minutes to install a new bb now. My setup from one side to the other is this:
Crank arm-spindle-shitty old bearing that I don’t care about-new bearing-bb spacer, slide that through your bottom bracket, then the other new bearing-another shitty bearing I don’t care about-the other crank arm. Use the compression bolts for the cranks to squeeze it all together till the new bearings are fully seated. The shitty old bearings distribute the force across the new ones so no damage occurs to them.

If it’s all too wide at first to get the bolts threaded in, take out one of the shitty old bearings and use a spacer, you’ll be pushing on the inner race of one bearing using this method. The first 25% or so goes in real easy then you have room to swap for the old shitty bearing which is better for it.

If the crank arm bolts bottom out on both sides before it’s all together, take off a crank arm and add some bb spacers. Keep squeezing till the new bb is fully seated.

Hope this helps!

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9/12/2020 6:33 AM

Btw, the next time you put bearings in that frame it’ll be easier. New frames are always a bitch to get bearings into.

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9/12/2020 7:26 AM

pnj wrote:

did you grease the frame / bearings?

A lot

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Control of my bars helps me feel in control of my life.

9/12/2020 7:28 AM

jboozer4 wrote:

Btw, the next time you put bearings in that frame it’ll be easier. New frames are always a bitch to get bearings into.

Thanks yes this frame is tight AF

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Control of my bars helps me feel in control of my life.

9/12/2020 8:27 AM

Assuming you have the right bb for the frame, grease the bb bearings and inside the frame and use a bearing press. If I was able to install mine cleanly anyone can.

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9/12/2020 8:34 AM

It can be a bitch hammering them in a new frame if it’s too crooked too. If one side starts to go in too much hammer it back out with a 3/8 ratchet extension and start over. A hard piece of wood does help too

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9/12/2020 9:39 AM

I have the same problem with my frame. The bearings barely fit in and they fit so tightly that it's putting drag on the bearings.

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9/12/2020 11:21 AM

What frame do you have? I recall when I bought my Eastern BB, the bearings were slightly thicker than my last since my Eastern frame was also thicker than my last. I never looked into whether or not the Eastern BB is specific to the brand’s frames.

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Scooter kid trying to ride a bike.
@scootereyn

9/12/2020 12:52 PM

Big C clamp and a couple 50¢ pieces...

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9/12/2020 12:56 PM

readybmxer wrote:

What frame do you have? I recall when I bought my Eastern BB, the bearings were slightly thicker than my last since my Eastern frame was also thicker than my last. I never looked into whether or not the Eastern BB is specific to the brand’s frames.

Mine is an eastern ace of spades. If it was eastern specific that would make sense as to why other BBs don't fit properly

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9/12/2020 4:54 PM

Post photos of the bearings & bearing seats, maybe there's something you're overlooking

A problem with using just a rubber mallet is you're hitting the bearing dead on, you're not spreading the force all around the bearing, so if it starts going in a little crooked and you continue hitting it, that's probably your issue. Gotta straighten it out. It's also possible the rubber mallet isn't allowing you to hit them hard enough. I personally hate using one of those, and the block of wood method. I feel like it's too spongy and takes longer and more force to get in. I prefer a bearing press or metal hammer and a punch or something, but I only recommend the punch option if you're careful and know what you're doing otherwise you risk damaging them. Couple hits on the outer bearing race evenly all around and it'll go right in. It's got more of a direct contact I guess idk.

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9/14/2020 5:26 AM

Block of wood and real hammer.

Also try removing a little paint from where the bearings rest in the frame. That has helped me in the past.

Then, failing the hammer and wood method, go to the hardware store, get some SUPER THICK washers that are the same size as your bearings and a bolt that is both thick and long enough to go through all of the parts and frame. Put a washer on the bolt, then bearing, then spacer, then through the frame, then bearing, then washer then the nut for the bolt. Two wrenches, tighten it.

You just made a bearing press for a few bucks, and got your BB in.

And boom goes the dynamite.

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"Hey anybody ever make that mistake like right when you wake up in the morning and you believe in yourself?" -Kyle Kinane

"BIKES!" -Tom Segura

9/14/2020 7:17 AM

[img]https://static.grainger.com/rp/s/is/image/Grainger/3H697_AS02?hei=536&wid=536&$adapimg$=[/img]

And a cordless (or corded) drill. Buff out some material from the bearing cup and give her hell.

Also, a bearing press would help. Others have outlined how.

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BMX over 30: Eat clean, Stretch, and Pray.

9/14/2020 8:03 AM
Edited Date/Time: 9/14/2020 8:09 AM

There is a solution to this. I'll explain what causes it and how to remedy it below.
This is a common problem with cheaply manufactured or damaged frames.
I've dealt with this 3x already and tested with used bearings, brand new ones, used frames, brand new ones etc and solved it on each one.

Firstly, Your bearing and shell is designed and supposed to fit snug and tight but not that it makes the bearings stop turning smooth and you literally can't get the bearing in without UNREASONABLE force. (Reasonable being that it should move at least a bit every time you give it a smart whack with a hammer). If it's not moving or your bearings are starting to seize, it's due to one of the reasons below.

1. The bb shell is slightly ovalized or "out of round" due to impact from use, or warping from overheating during the welding process. (Ever see frames advertise that the bb is "post weld machined")? This is because sometimes with thinner shells or large heating zones the metal can actually warp and go out of round so they machine it internally back to a perfect circle afterwards, to make sure the bearing has a smooth fit. (Check youtube for videos on now they do this).

2. The bb shell was not machined precisely. Possibly because they bought it premade from a cheap supplier with poor quality control or due to inexperienced folks working on the the in-house production, or just having the tolerance too tight when they machine it out.

In either case the solution is to "machine out" your BB shell.
Check which side of the shell the bearing is "grabbing on" the most by putting it in just a bit. Take some 220 grit sandpaper, put some gloves on, and start sanding the area inside your shell (especially where its grabbing most) to remove a bit of the metal. (Remember you're eating away the metal so its gonna be a bit tedious and might take some time so mentally prepare for that).
Test the fit, if it's starting to go in easier, finish it up with 320 then 600 then 1000 grit sandpaper to smooth it out, then go over your bearings surface with the 600 grit too to smooth everything together. That's it. Just grind out the metal, smooth it out, grease it well and you should be good to go.
I've done this already 3x and had success with each. Just remember to not overdo it or it'll end up loose.

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