Fork + Hub problem ?

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8/27/2016 2:59 PM
Edited Date/Time: 8/28/2016 4:03 AM

Hi all,

I searched around the web for some info about it and didn't find anything.
(but maybe it's a lack of technical vocabulary for searching the right thing)

Long story short I've bought my first bmx this week and I noticed a problem around the fork.

The bike came with 2 pegs (right side).

I didn't notice it at first, but the front peg was not straight with the wheel axle.

I did I the bike check this afternoon, and well, I don't know what to think about it.

First pic : peg removed. You might see that the end of the right branch of the fork is bent (on the left, lol I took the photos from the front of the bike, so...).
Photo

Close up on the end of the left branch. Looks okay.
Photo

Close up on the end of the right branch. Looks .. well.. "less okay".
Photo

I think the bearings, etc of the wheel are not dead yet. I've held the axle in my hands and let the wheel turn, I've heard a few clicks but nothing scary. The threaded part is bent.
Photo

An ultimate shitty attempt at showing a global picture.
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I'm a bit worried about this, as the bike is really CLEAN actually (I've bought a lot of second hand road bikes and mtbs, and none of them were in such a nice shape lol).
There's almost no scratches, the seat is like new, the wheels are true, etc. etc.

It looks like the hub is noo narrow for the fork width.
As we are supposed to tighten and lock the nut on the fork, I don't see a better solution than putting some kind of spacers on each side, between the hub and the fork, to get that missing width back.

The wheels are stock (same brand and look as the frame). They should be fitting... o___o
Maybe the previous owner fucked up something when he has installed the pegs.

Any ideas ?

I t̶h̶i̶n̶k̶ hope it's not a big problem, any wrench-ninja help would be truly welcome. smile

(edit: syntax errors smile )

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8/27/2016 4:22 PM

I personally wouldn't ride it because the bend may lead to cracks and a possible break and I wouldn't want to end up on my face when I am riding. If you can't get a new fork than I would try to hammer out the bend a little so that it doesn't press against your hub and cause hub problems. The axle being bent could potentially cause some issues and really suck if it breaks but than again I have ridden a bent axle for months now. I would buy a new fork and even front wheel if you could afford it but mostly the fork.

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8/27/2016 5:23 PM

Fork is fucked you're gonna have to get a new one unless you plan on bending it back into shape. Your front hub should be fine , but the spacing might be off ... I think the standard is like 142mm or some shit , yours might be less. Which is why it's fucked

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8/27/2016 11:40 PM
Edited Date/Time: 8/27/2016 11:41 PM

The distance between the drop outs should be 100mm, and so should the width of the hub from lock nut to lock nut. Measure those two distances and you'll find out which one is causing the problem. The forks may be twisted too which would put extra strain on the axle/bearings. Your local shop should have a gauge and be able to check that for you, they may even be happy to bend the dropout straight.
You could probably pick up a new axle for the wheel pretty cheap and replace it, which I'd recommend

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8/28/2016 6:19 AM
Edited Date/Time: 8/28/2016 6:26 AM

Ok guys, many thanks for these replies.

You were right. The problem comes mainly from the fork, and it has bent the hub axle.

Yesterday after posting my thread, I came back to the bike to put it back together and tidy everything.
I haven't been able to put the wheel back on.
Before removing the wheel it looked like the hub was too narrow and the nut was applying too much pressure on the fork end.
Actually the end of the fork is bent and pushing on the hub, and that's why the axle is bent now and why I cannot put it back on.

I've sent a mail to the previous owner to ask if he knew something about this.
FYI the bike is a Blank Cell 2012, and I've bought it 90€... I hope I will be able to keep the repairs under 110€ to stay in the "beginner bike budget" I've set at first.
(I also wanted to buy 2 more pegs, to work on silly flatland stuff and to have more possibilities to practice before being able to bunny hop, and was thinking about a few more extras... but I'll have to think about it later sad)

Maybe the fork was bent just because of grinds ... (the twist is on the side where the peg was installed)...
(Seriously are forks supposed to die this fast ?)

I think I'll try to remove the rear wheel too, too check if everything looks fine. I won't be able to buy a new frame if I have the same issue.
(I don't have the right key size for the rear wheel nuts)

So here's a few more pics :

The wheel mount, without the wheel:
Photo

On this side, 100mm is ok :
Photo

... but here's the origin of the "extra strain" :
Photo

So I could eventually try to bend it the right way, but actually the entire arm is twisted (I tried my best at taking a "line of sight" photo to see it, maybe you will notice the right arm goes up on the end)
Photo
Photo

So I guess that even if I bend the wheel mount back, the fact that the actual ARM is twisted will continue to break wheels down ... (right ?) So I have to change it. sad

Now about the axle :

9mm diameter:
Photo

Length: approx. 160mm. iPhone6 bend.
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Even the neck where the ball bearings roll has a problem.
Photo

So the best thing I have to do is to go to the bmx shop.
I don't know much about local shops but I'll give this one a try: https://www.brosstore.fr/

I will have to change the fork, but I would like to try to save the wheel ...
Buying a decent fork and a decent wheel is a bit overkill for my current "skills".

Anyway thanks again for your replies, it really helped me to figure out the problem.
This forum is really awesome :D.







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8/28/2016 10:05 AM

Chances are, there was a heavy load on the peg, which bent the axle and dropout. You should get new cones with a new axle, so that problem will be sorted. But loose ball hubs are notoriously weak, and bending the axle again is an almost definite after a few grinds.
The forks are a little twisted, but they may actually still be within tolerance (I've seen much worse on brand new bikes), so I'd suggest bending the dropout back with and adjustable, and seeing if the wheel with a new axle fits better. If the hub is still narrower than the gap between the dropouts, you could use your current locknuts to act as spacers on the new axle to space it out, prevent the forks having to flex inward when tight

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8/28/2016 12:55 PM

Oh... didn't see that from that perspective.

I've searched a bit about front wheels and saw the difference between loose ball hubs and sealed bearings hub. Axles from sealed bearings hubs are less likely to bend on grinds ?

Didn't think that grinding would be a determining factor for bending the axle ...
So the actual bend could be here from a normal use (grinds, etc.) of the bike ?

In the meantime, the previous owner answered my mail. He confirms that no violent hit or particular event happened, and wondered if he had tightened the peg too much. I think he is honest and didn't even knew the axle was bent.

If I sum up everything :

1) My wheel is fragile (because low end). If an average rider (not me, someone able to grind, etc) were riding it, he would have to check the axle sometimes to straighten it out.

2) The previous owner just used the bike like it was supposed to, and the axle ended up bent. As no repairs were done, the dropout started to bend too, and the peg was pointing upwards.

2bis) The peg on the rear weel looks straight (don't have the right key size to get into the peg and untight it, I'll check that later). On the other side, I can see the axle and it's bigger than the front wheel. So with the same use of the bike, (grinding, etc) the rear wheel doesn't have these problems.

3) If I want to change my fork, I should change my wheel first. If I don't, I will probably have the same problem soon.

4) Tomorrow I'll go to the bike shop, to see if I can buy a replacement axle to fix the wheel.

5) The right side dropout of the fork is bent. . I started to try to straighten it, but I'll wait to fix my wheel first to try to finish that.

6) The right arm is slightly twisted, but it should not be a problem if I get a clean assembly of the wheel and dropouts.

Now, supposing I'll be able to put it back together:

7) This is entry level gear after all. I don't need a 200€ front wheel to learn manuals. Let's try to fix it and ride it until the wheel/fork is dead !

8) Remove pegs. I don't even know how to bunny hop yet.

9) Ride it but safety first. Before going out, check the wheel alignment and the right dropout (as straighten it will make it more fragile) to see if theres no cracks.

10) If the wheel dies first and the fork still does its job, just buy a new wheel. A decent one.

11) It the fork dies first, change the fork and the wheel to avoid these problems.

(sounds okay ?)

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8/28/2016 4:14 PM

A bent axle shouldn't bend a dropout. It was probably one impact that bent both at the same time. I'm guessing it would've been an accident if there are no signs of loads of peg use.
If the forks have twisted post manufacture, they could damage the bearings/axle by preventing the wheel hub from sitting straight, putting extra force in a certain area.

Other than that, it sounds like a good plan. Buy an axle, fit it, put your front wheel on, if it doesn't sit straight I'd recommend investing in new forks. You'll know because the wheel won't spin freely, and may make a ting or popping sound as the wheel spins when it's tightened

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