Steerer Tube Butting

[StrippedThread1992]

This is a bit of a strange one.


Frame is from 1992 built with Reynolds 531 with the matching original Reynolds 531 forks (blades, not sure about the steerer). It's manufactured for regular old 22.2mm quill stems (no odd French sizing etc).


Anyway, a 22.2mm quill stem will only insert 7cm into the steerer tube. I've tried multiple stems and I've tried with just the wedge and just the stem by itself. Essentially something inside the steerer tube is stopping anything with a 22.2mm diameter from being inserted further than 7cm.

A local frame builder has found that there's no damage to the fork and that the issue is actually that the butted section of the steerer ends approximately 7cm from the top of the steerer (so essentially the inside diameter of the steerer tube is narrowing at that point). The frame builder has some kind of gauge that measures the thickness of tubing and has confirmed his finding beyond doubt.

I've heard of this being an issue with very small frames which have very short head tubes and steerer tubes however this frame is 57cm C-T with a head tube of approximately 15.5cm.

My first thought is some kind of manufacturing error but to me it looks like the frame was probably ridden at least a little during the past 30 odd years. Perhaps the previous owner(s) bodged a French stem in there or sanded their stem down a little, who knows?


I'm not necessarily looking for any advice on how to proceed as I've left it in the hands of the very capable frame builder. But just thought it would be interesting to report it here and see if anyone else has ever encountered this..?


Cheers.

 

[StrippedThread1992]

"issue is actually that the butted section of the steerer ends approximately 7cm from the top of the steerer"

Should read "butted section of the streerer STARTS approx..."

 

[grantoury]

I had this with my Trek 710. The former owner (a thrift store) had jammed a rather long stem past the butted section and it was stuck. Took some doing to get it out. All forks are butted near the fork crown. 7cm from a 15,5cm steerer doesn't sound far off.

 

[jim haseltine]

He wrote 'head tube'. Both my 57cm frames have approx 15cm head tubes but the steerers are close to 20cm. Having said that, I checked an old stem I had handy and from the ring left by a headset top nut it wasn't inserted much more than 7cm but I never rode with a slammed stem so I'd expect it to drop another 3cm or so.

 

[StrippedThread1992]

Yea, the steerer tube is around 19.5cm so the butting is starting very close to the top. Normally I would expect the butting to start somewhere between 5-7cm from the bottom of the steerer, not from the top.

Using a Nitto Young-3 quill stem (has a 16cm quill and a wedge rather than a conical expander) I couldn't actually get it even close to the minimum recommended insertion.

Cinelli 1a I think has a 13-14cm quill and uses one of the conical expanders which would shorten it even more so you could MAYBE just about use that if you were happy to run your stem high. But the fork butting shouldn't really dictate to you which stem you need to use and at which height really.

 

[grantoury]

7cm from the top is pretty short. Just enough for a standard road stem, I would say.

 

[Woz]

But the fork butting shouldn't really dictate to you which stem you need to use and at which height really.

That's just the way the cookie actually crumbles with this old stuff some times. Stuff was designed to work as a complete system, using what was around then. If the frame was custom made too, it would have been optimised for the rider in question.

The conical bung type was replaced with the wedge type rather late really - even then I think it may have been the Japanese who invented that?

You would have been a lunatic to put a vintage French stem in a British / ISO steerer, it would have flopped about far too much at the top, probably would crack, and damage the steerer tube attempting to get it tight enough.

 

[StrippedThread1992]

That's just the way the cookie actually crumbles with this old stuff some times. Stuff was designed to work as a complete system, using what was around then. If the frame was custom made too, it would have been optimised for the rider in question.

The conical bung type was replaced with the wedge type rather late really - even then I think it may have been the Japanese who invented that?

You would have been a lunatic to put a vintage French stem in a British / ISO steerer, it would have flopped about far too much at the top, probably would crack, and damage the steerer tube attempting to get it tight enough.

Yea, maybe you're right and it could have been a specific request from somebody.

Supposedly one of the newer Cinelli 1a stems has a quill length of 13.5cm and the distance from the minimum insertion line to the top of the quill is 7.5cm meaning that the minimum insertion for that stem is 6cm. So someone could maybe have used something similar with little to no available adjustment. It just seems an odd design choice to me.


And I agree, even if you did bodge a narrower quill in there to extend it into the butted section it would be a bad place to engage the wedge or expander as it would be working on a slightly slanted surface meaning less engagement. That on top of the other problems you pointed out is not something I'm interested in testing out.

 

[pigman]

It's possible that the steerer tube was extended by inserting an inner tube and brazing it up. The "butting" could be that internal sleeve