Mr_Pickles3

Hi everyone

I have a late 70s Motobecane and have been cleaning it up. Today, I was adjusting the stem height, and sprayed a small a bit of GT-85 to loosen it as it was really stuck and hard to move even when the bolt was fully loose. This did the trick, and it was much easier to move.

Unfortunately, I couldn’t get the stem to stop moving, even after tightening the bolt hard. I took the stem out and wiped it and the inside of the head tube down, which helped a little bit but not much: I’ve managed to get it so the stem only moves when the handle bars are twisted with reasonable force and the front wheel is between my legs.

Whilst I seem to have gotten rid of the movement, there is now play in the stem (not the headset) which I didn’t notice before. I’m really not sure how this has happened, or why the stem is harder to tighten than before.

Does anyone know what I may have done to cause this play and problem with tightening? Is it a safety issue?

dsbrantjr

Make certain that you do not have the stem all the way down into the butted section of the steerer. https://www.sheldonbrown.com/handsup.html#danger
Try moving it a little higher in the steerer and see if it stays put better.

Mr_Pickles3

I’ve moved the stem further out so this shouldn’t be a problem, and it does not seem to stay put any better. The wedge used is an expanded cone type which I haven’t used before.

Could it just be that it was seized after 40 years, and that by lubricating it, it’s back to how it was originally?

CliffordK

Probably not the issue with "play", but check for cracks in the bottom of the internal wedge type stems.

jadocs

By "play" do you mean:

1. You can tighten the stem, but can still twist it with force ….. or
2. You can tighten the stem and it wiggles in place.

Andrew R Stewart 

Quill stems need a certain amount of insertion depth for safe use. The OP mentioned he raised the stem a bit but do we know how much stem is not in the steerer? The usual insertion amount is around 2.5". Also besides the chance of a cracked stem bottom, where the wedge expands the stem, there's also the chance that the stem has cracked or bulged the steerer. Especially if the stem/wedge was aligned with the steerer's threading. The consequences of a failed stem to steerer connection are pretty bad... Andy

jadocs

Andy for my own learning...what do you mean by this?

Edit: I think I know what you mean...stem raised up high enough that the wedge is expanded where the steerer threading is?

Mr_Pickles3

Both: I can twist it with force, and it wiggles slightly in the headtube. I can't see any bulging in the headtube externally nor did I notice any cracking in the bottom of the stem. Although I'm paranoid now so I'll have to check again later

I give up with bike mechanics...I only seem to ever make anything worse!

cranky old road 

Does a 70's Motobecane have French dimensions? https://sheldonbrown.com/velos.html

alcjphil

Does the bike have the original fork or was it replaced?

Mr_Pickles3

It's the original French fork. As far as I can tell, the stem hadn't moved until I got it.

CliffordK

It should be French. But, that would tend to mean a smaller stem, so it would be hard to mess it up.

Unless the fork has been replaced with a non-French fork. Or, perhaps the stem was an ISO stem sanded down to fit by a previous owner.

CliffordK

If the stem doesn't have a minimum insertion mark, then insertion should be about 2".

Steertubes can also be bulged from over-tightening, and perhaps cracking through the anti-rotation slot.

joeruge

I had a 72 Peugeot PX10. It was my first 'serious' bike. The bike was $250 and I was 15 years old. If I remember correctly, the quill diameter is (still have the bike) 22mm. The then current standard was 22.2 mms. Much later when I had access to a lathe I was able to turn down a Cinelli stem (I know, sacrilege!) To fit in the steerer tube.

As for the current topic and mentioned previously, if the original fork was replaced with a non-French fork and the original quill was still used, it would have a little 'wiggle' room, though I would still think that the wedge would tighten up enough to make it difficult to twist. I'm not sure what this would mean for the original headset - Would likely cause some kind of problem.

Also mentioned, with a bike so old, the wedge could have bulged, not the head tube, but the steering tube, which can not be seen from looking at the frame. You would have to remove the fork to check this out. Also look carefully at the stem in question. Maybe there is something wonky with it. Measure it carefully. Determine if it is in fact 22 mm or 22.2. Insert it to various depths and see if it does snug up properly somewhere. This might tell you something about what's going on.

Iride01 

This statement perplexes me.

For one, if you got to the point where there are bulges in the headtube, then you will have for certain locked up the steering altogether. As well, there'll be things that are stressed beyond belief and about to fail if they haven't already.

However since you don't see bulges, then we can be pretty sure none of the above applies. However since you said that, it makes me wonder if what you are describing having done and experienced is what I and others are actually envisioning.

Two....... cracking in the bottom of the stem? I assume you are describing the old fashioned stems since you talk about a quil, but how are you seeing the bottom of the stem? Are you just saying that when it was removed you didn't see any cracks or are you talking about some other part when the stem is installed?

I know you say there is no play in the headset, but are you certain? When you experience the play, it is only in the stem? Be certain there is also no play in the forks where they go into the headtube. If there is, then tightening the quil is the wrong thing.

And you swear you haven't mucked around with that big nut on top the head tube recently? If so, then I'm going say you've got play in the headset and not the stem.

But...... you might have as others suggested a slightly bulged steerer tube or even a cracked steerer tube. But it might be difficult to tell for certain without removing the fork from the headset. Then again, what if somehow you've gotten something with a 1 1/8 steerer tube and an 1 inch stem?

Might need some a bunch of pics. Or just take it to your LBS.... I've never had any around me gouge me. I even feel like they don't charge enough for what they have done for me.

Iride01 

Is everything original to the bike? In the mid to late 70's many manufactures were switching from what was their standard to what is considered the world standards. So if the fork or stem was replaced, it might be that one isn't the right size for the other.

A french std stem might rock in a ISO std steerer which is .2mm bigger in I.D.

Mr_Pickles3

I took the stem back out and it didn’t have any cracks in it as far as I could see. I haven’t touched the headset, and when I wobble the stem I can see a very slight gap between the top of the headset and stem. This is only visible when putting reasonable force into twisting the ends of the handlebars

AFIK, the components are all original to the bike. I’m super concerned now because I really don’t want a steerer tube failure
Is it possible to crack a steerer tube by over tightening the bolt?

Iride01 

Never done it myself nor have I seen it. So I can't claim to know. I'd personally think the quill bolt would break or strip first. However I've seen others claim that bulging the steerer has happened, and if you can bulge the steerer tube, then cracking it is possible too, at least I'd think it so.

Moe Zhoost

Does the stem have two slots for the expander or only one? The two slot stems have a reputation for developing cracks at the top of the slot. I know that you pulled the stem and did not see any cracks, but you may want to do it one more time. This time, clean it well and look for cracks starting at the top of the slots as you gently tighten up the expander into the stem. Use a magnifier and bright light.

Mr_Pickles3

My thoughts are that if I can still twist the handlebars out of alignment without excessive force, then the stem can’t be so tight that it’ll bulge/crack the steerer tube...right?

Mr_Pickles3

It has just the one slot.

Moe Zhoost

I think I would still pull it and check once more to satisfy any residual OCD issues. Pictures or video would be helpful.

Iride01 

If I could do that with my bikes, then I'd think I haven't tightened the quill anywhere near tight enough for safe riding. However I would agree that if you can do that that it's not tight enough to damage the steerer tube.

The steerer tube being the thing attached to the fork that is what you stick the stem into.

Mr_Pickles3

Problem Fixed

It turns out that the wedge was binding with the bottom of the stem and not moving upwards properly when the bolt was tightened. Greasing the wedge and threads of the bolt has solved the problem: no play and tightens much easier than before