I am rebuilding my son’s mates BMX. I have put the BB cups and spacer in (mid BB), but the spindle isn’t turning the bearings – if that makes sense. It will just turn in the hole.

Nothing has changed – it’s the same BB and spindle that came out a few days ago….

will it sort itself out when I tighten it all up?

When you bolt the crank arms on it will clamp the inner bearing race between the crank and centre spacer. The bearings should then be turned.
If the bearings still don’t move or bind something is wrong.

It doesn’t seem to be working. This is what the thing looks like:

The spindle isn’t turning the inner race – and doesn’t appear to be when everything is bolted up.

These are the spacers etc I have for this side:

but no matter how hard I tighten up the arm, it’s not binding.

Is it shagged?

Are the bearings ****? Have you tried turning them with your fingers?

Have you hammered/pushed the bearings all the way in (as far as thew will go) to the BB cup?

Wher is this BBQ? Can we come?

The bearings turn OK with my finger (or with pressure on the spindle) – and they are hammered all the way in…

There’s a fraction of a gap between the spindle and inner race.

As for the BBQ, I will send a sausage to anyone that can help me fix this.

So the axle is slightly to small?

is it only one side thats no turning the bearings, or both?

It looks like one of those cheap setups, does the axle have a “flange” on one side that prevents you from moving it through any further?

What sort of sausage?

If it’s a mansausage i’ll help you.

So the axle is slightly to small?

Yep – although it’s the same axle I took out when I dismantled the bike to get it powdercoated. It’s a GT BMX

is it only one side thats no turning the bearings, or both?

It’s ‘loose’ both sides, although I can easily turn the bearings with my finger on both sides.

Van Halen up there said When you bolt the crank arms on it will clamp the inner bearing race between the crank and centre spacer. The bearings should then be turned. which kind of makes sense – the washer/spacer thing protudes on the inside edge which looks like it should engage the bearings with enough pressure. Trouble is – when I apply the pressure – it all siezes up!

It looks like one of those cheap setups, does the axle have a “flange” on one side that prevents you from moving it through any further?

No – it will drop through if I let it

Thanks so far!

What sort of sausage?

If it’s a mansausage i’ll help you.

Well, it looks like there’s a bit of a gap in the picture, although it could be a shadow.

Axle is probably 19mm or something, and the bearings are the wrong size. Best bet is to measure the axle and the bearings and then get bearings to suit. Or coke can shim it…

Are you sure you dont have any other parts that might fit on the axle and take up the gap?

So – the spindle should definitely be tight in the bearings? If that’s the case, I’ll try shimming it. Sorry for the stupid questions, despite my notoriously bad bike mechanic skills, I seem to be the only dad willing to help the lads out 🙁

How big is the gap?

And the axle should slide in easily, but it shouldnt fall through if you let go of it.

The gap is less than .5mm – If I put slight lateral pressure on the spindle, it will turn the bearings.

Sounds odd. I dont have a clue. something could be worn (axle or bearings race?) but unlikely cos they’re both steel.

You could always measure the axle and buy new bearings to suit.

A coke can shim shaped a bit like a top hat may well work.

Thanks very much – really appreciate your help. I have been looking at it all day, so going to call it a night now and let the stress begin again in the morning.

If it binds when you bolt up the cranks then either the bearings are not fully seated or the central spacer is not right. are the bearings symmetrical? Could it be in inner races have worn off centre and you’ve put them back in the other way? I don’t think the axle gap is a big issue. Is it an original crank setup or could it be cobbled from a few sources?

Cheers v-h. The inner spacer is a bit loose, it moves around a bit. I am going to pop the bearings out tomorrow, add a spacer in between and re fit.

It’s an original set up, so I’m sure I’ll get it fixed. Thanks for the input…

Did you not take note of where everything went when you took it apart?

🙂

Course I did stu. All the bits in the box came from the white bike 🙄

You put all the bits in a box?

You’re getting betterer at this kind of stuff. 😀