agmetal

My boss gave me a couple old French Mixte frames (a Mercier and a Vita Sprint) to do whatever I want with, and I've been trying to figure out what to do with them. We were going through the bins of old parts last night, and came across a GUID branded stem, which fits quite happily into the steer tubes, unlike the various Japanese-made ones I've tried, which, unsurprisingly, won't fit. Somewhat psyched that I've found a stem that'll actually fit correctly, but now I'm questioning the bar clamp on it. It looks a bit rough, as though it's maybe been sanded or filed, and my calipers measure it anywhere between 25.7mm to 26.0mm, depending on angle and side. I have a French bar around (25.0mm, TA branded), which basically just flops around in it. I also tried putting in a 26.0mm bar, but it wouldn't even fit through. I guess 25.4mm is the way to go with this one, then...but is it safe to do so?

juvela

iirc this is one of the badges employed by Belleri.

suspect clamp must have been enlarged post manufacture to get it out to the sizes you quote.

verktyg 

Contrary to all of the urban myths and fantasies about using calipers for making accurate measurements of inside diameters it's just that... (not a personal attack... just the facts ma'am)

One reason is the difficulty of keeping the knife edges of the caliper positioned parallel to the walls of the hole and centered at the largest diameter. This becomes more of an issue when the hole is not round - smaller in places and larger in others....




That said, it's a little difficult to determine what was done to the bore on the stem. It looks like someone could could have run a 1" (25.4mm) drill through the 25mm bore.

Because of the light depth of cut - .008" or .2mm per side - the outside of the flutes at the tip of the drill tend top grab the walls and can cut oversize in places plus the clamp are can spread and when the drill is removed the area springs back to the original diameter.

More important, it looks like there are casting voids in the rear of the bore - the semicircular black spots. Based on that, I wouldn't use that stem... That's the kind of flaws that earned sand cast stems the reputation of "death stems".

If you intend to ride the bike a lot, many Nitto cast and forged stems that are marked 22.2mm are actually 22.1mm and will fit into a lot of French steerers. You can find them to fit either 25.4mm and 26mm bars.

If it's just for looks then I'd find a WELL MADE French cast aluminum stem like a Pivo, Phillipe or Milremo.



One other thing... When you use an olde stem with an expander slit, make sure to drill or file a round area at the top of the split to help prevent cracks.



Cracks forming at the top of the splits or split is a common failure mode in old stems. The bottom of the stem can break off and your left holding the unattached bars!




verktyg

Chas.

agmetal

Thanks for the detailed reply! I'll take a closer look at those spots the next time I'm at the shop. I don't think I'm likely to ride either of these frames very much myself, but I was thinking about building one up for a friend whose bike was recently badly damaged. I'll take a look around for Nitto stems...I've got a Nitto "Young" stem around here at home, I think, although I haven't been able to get it off the bar it's currently on. Might need to go at it with the hacksaw.

rhm

The French stem has a 22.0 mm quill, while most others (including the Japanese ones) measure 22.2 mm (7/8"). That 0.2 mm is why they don't fit.

If it fits, fine, but if not, don't force it. A stuck stem is really hard to remove.

Edit, oops, I see Chas has already covered this.

dddd

I bought three of the very-inexpensive Origin-8 stems for my various projects.

The sizing was listed as 22.2mm quill and 25.4 bar diameter.

These stems slid right into the three French-dimensioned forks I had, a 1972 Peugeot, a 1960's Urago and an Austrian (26mm OD x 22mm ID) Sears Roebuck.

These stems came in 10cm length, look quite sturdy and traditional, and were well under 20 bucks each.

Here's a picture as mounted, and the clamp-enlargement to 26mm that I also undertook to the thick metal at the clamp end:

verktyg 

Several additional suggestions:

Put a slight chamfer with a file or sandpaper in the opening of the steerer. It will remove any burrs and make insertion smoother.

Also clean out the gunk inside the steerer with some solvent and use a hone or some sandpaper to remove any corrosion.

Loosen the top lock nut a little before inserting the stem. After you tighten the stem you can readjust the headset.

Last, put some grease in the steerer and on the stem. It will help prevent a seized stem.


BTW, here's the reason why some inch size stems will fit a metric steerer: Many stems are slightly undersize. The original standard for metric stems was 21.9mm so that they would fit into a 22.0mm hole. Same thing for 22.2mm inch size stems.

Also, the bores in steerers are frequently oversize...


verktyg :20:

Chas.

agmetal

Yeah, I was also quite familiar with this already. The strange part only had to do with the handlebar clamp apparently being different from the usual 25.0mm French size.

I did manage to get the Nitto stem mentioned in my earlier reply off the bars it was stuck on last night...seems like the inside of the clamp somehow got damaged at some point, which must be how it got stuck when I tried to remove the bars so many months ago.






For the record: one of the frames I'm dealing with actually doesn't currently have a headset installed, and I have the lock nut removed from the other one, so I've been putting the stem(s) straight into the steerers.

noglider 

@verktyg, you are a wealth.

verktyg 

The rough surface inside the bore is galling also called cold welding or pressure welding. Pressure and friction caused the transfer of metal from one surface to the other. It can easily happen with softer metals, even titanium and stainless steel.

Someone may have forced a 26mm bar into a 25.4 stem... Check out the deformation at the bottom of the clamp ears from something used to wedge it open.


One suggestion for removing and installing bars - remove the clamp bolt and gently spread the clamp area with a wide wedge shaped tool like a very large screwdriver, or small pry bar. You only need to spread the clamp a millimeter or so. If the bar doesn't come loose easily, apply some light oil or penetrating oil.

Leave the stem in the bike or carefully clamp the bar or stem in a vise with some protection like pieces of wood so they don't get damaged by the vise jaws.

Spreading the clamp too much can result in this:






"Oh, there's just one more thing..."

If you have a set of 25mm or 25.4mm bars clamped into a stem that was made for 26mm or 26.4mm bars, let a sleeping dog lie! Don't try to spread the stem to take a larger diameter bar. That's what happened to the broken Cinelli stem pictured above.

verktyg

Chas.

verktyg 

Merci beaucoup....

I was hard headed and had to learn things the hard way...

verktyg

Chas.

agmetal

The deformation from something being used to pry it open is actually from me trying to remove it from the bars!

Weird bit is, it originally happened an inch or so off-center, while I was sliding the stem off the bar...it had started moving quite easily, then got stuck somehow. Really weird!

verktyg 

It's likely the galling started when the bars when installed???

verktyg

Chas.