Cinelli Quill Stem and handlebar angle problem
 

I feel like I'm flooding this forum with questions but at least I'm learning.

I'm trying to change the angle of my handlebar as to make the brakes a little easier to reach -- without making the whole thing look ridiculous. What I don't understand is that beyond a certain angle, the bolt on the bottom part of the stem is very hard to screw in, as if the stem and the handlebar were designed only for a specific range of positions. I tried to screw the bolt in anyway (quite tightly) and felt like I had managed to obtain a pretty comfortable angle, but today I hit a bump and nearly crashed when the handlebar dropped.

Am I missing perhaps missing something? Could it be that the handlebar and/or the stem lost its circular shape over time? I don't wanna overtighten the bolt and damage the handlebar.

https://cimg1.ibsrv.net/gimg/bikefor...c21edccb40.jpg
https://cimg5.ibsrv.net/gimg/bikefor...563971fcca.jpg

(and my nice R600 in the back..)

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...those Cinelli closed loop stems with the wedge driven by the bolt to force it against the bar were always a little problematic. Things you might try would be to remove the bolt and the bar, and check out the condition and position of the wedge (they break sometimes...and are almost impossible to find used). On reassembly, lubricate both the wedge and the bolt with a light coating of grease. Inspect the bar to see if it might be damaged in some way from being overpressured by the stem wedge, leaving some sort of depression or divot.

I always thought they were a poorly engineered design anyway, but I do still have one or two of them on bikes here that seem to work if I don't fiddle with them once they're set up.

Thanks for the tip. I'll think about it. Right now the bike has the original leather handlebar tape and I don't think it could be reused if removed. The bike already is slightly too small for me so it might not be worth it to start this whole process if I end up selling it (and setting the handlebar back to its "default" and secure position)

That should be a 26.4 clamp on a 26.4 bar. Measure to make sure. If it's a 26mm bar, no amount of tightening will actually make that combination safe, at any angle.
If the sizing matches, disassemble as others have suggested to ensure that the wedge is not cracked. If it is, touch base with Wayne Bingham at Velo Classique. Last time I checked, he had new ones in stock.
The wedge face has a series of grooves cut into it; the bar clamping area also has a series of grooves. These grooves should work together to keep the bar from rotating. If the 'teeth' on the grooves are worn smooth, the clamping action will be weak.
Sometimes, things just wear out; that may be the case here.

the bolt pulls a wedge down, the shoe with the matching wedge ramp, is semicircular in the front, it is pushed forward.
I'[m using a 26.0 bar not a Cinelli specific 26.4 in my 1R, Bar a heat treated Nitto Bar.. with a doubling sleeve..

I don't ride that bike daily or that often.






...

I was actually having a hard time figuring out how the stem worked. This makes it clearer. Kinda means the actual diamenter of the bar does not really matter (26 vs 26.4) as you seem to say?

Not that I plan to put a 26... It's the original handlebar so I'm assuming it's the correct size, i.e. 26.4

Sorry for the triple post but I found an explanation here that totally corresponds to my problem:

"Actually the stem IME works, the problem turns when you want to change the angle of the handlebars w/o losing the wedge 100%. Common mistake is to lose it like 50% and then change the angle of the handlebar, that will scratch the edges of the teeth of the wedge and will file the indentations in the handlebar too and then that's it, 4 or 6 modfications and the stuff dont work too good no more. You have to tight the thing like hulk and then nothing works as intended.

Since the users just overtight the whole mechanism to make it work the piece that is inside (behind the wedge) starts getting flatter and flatter, really soft metal and then w/o even noticing you eat like 1 mm off the tips of that piece too. The stem once locked needed to stay there probably forever, well we are dealing with old cinelli standards and those back in the day were not good. Sometimes you measure the handlebars and arent 26.5 but close to it, and that doesnt help too much because the handlebar needs to me exactly what they say it should be."

why Assume? .. Measure.


Cinelli quit being unique after a while, and started making theirs in 26.0 too.. improved sales that way..


...

Actually just found out that there is no grooves in the handlebar. It is a Cinelli hexagonal handlebar, but as opposed to this model : https://www.ebay.com/itm/NOS-CINELLI...-/303481702199 ; mine has no groove. See below.

https://cimg1.ibsrv.net/gimg/bikefor...e9157b6145.jpg

Here is a photo of the back to the wedge "ramp". I don't know if the flat top is natural but I don't see this being the cause of my problem.


https://cimg4.ibsrv.net/gimg/bikefor...f55b518296.jpg

Here is the wedge which is pulled down by the bolt. Looks in good shape. There also was a small metal plate between the two pieces as you can see.

https://cimg6.ibsrv.net/gimg/bikefor...185dd3869c.jpg

The only issue I can detect is with the shape of the handlebar. It seem to match the ramp quite well when you put the bar in a lower position, as below (sorry for the dirty hands):

https://cimg0.ibsrv.net/gimg/bikefor...aadcc18793.jpg

But the ramp does not perfectly match the surface when you put them in a higher position. There's a small gab I can't get rid off. I imagine the bar isn't perfetly circular, although it's tough to detect just by looking at it.

https://cimg9.ibsrv.net/gimg/bikefor...4706a6b90f.jpg

Even though this is not highly scientific, I tried to match the wedge with another cinelli bar, just by hand, without actually installing them in the stem, and the problem does not seem to occur.

It is possible that the bar lost its original shape due to excess pressure? Would that mean that the bar is kaputt, for such a small detail? Wouldn't it stil be safe to ride it in a lower position?

Sure sounds like excessive clamping pressure might have distorted the handlebar clamping area. I'km often amazed at how much some people reef on their stem and handlebar binder bolts.

Cheers

Beats me.
Discussed this with Wayne Bingham the other day and his opinion was, once you move the handlebar from it’s original location with this combination of bar and stem, it will never hold fast again.

.... in another position? I mean, I could technically put it back the way it was, no? those Cinelli hex don't come cheap :(

A lot depends on the particular bar, wedge and condition. Apparently those little grooves in the wedge are very sharp but very soft and once the bar slips in the stem it bends them over and they just never grip as well as when new.
https://cimg0.ibsrv.net/gimg/bikefor...aadcc18793.jpg

Your picture says it all- notice how rounded off the groove edges are?
An aesthetically pleasing stem, but perhaps designed less than perfectly.
One reason why the only Cinelli stems I have on my bikes are 1A's...or Nitto Dynamics. They just work well all of the time as long as you use the correct size bar.

sizes DO matter, why do you think they're measured to 2/10s of a mm? a cast piece like a stem
has 0% elasticity. the guy using a 26.0 bar with a 26.4 stem is at risk; if you ask a stem to move
past where it's supposed to it will crack. usually not right away and usually without warning.

So someone suggested that a put a layer of carpet tape around the clamp area to add a little bit to the diameter. Has anyone ever tried this trick?

"Someone said" ?
 

Metal, typically bronze/brass, shim stock is made in precisely measured thicknesses.. it's an automotive/ machine thing..

what is that 'someone's' mechanical background?

The design is fine. It just depends on users doing things properly, which shouldn't be too much to ask. At least in theory.

But even with some wear to the groves of the bar and stem, if you match the right sizes it should be able to lock in just fine even if the teeth aren't pristine.

For the archives: I ended up being able to secure the handlebar in the position I wanted by simply buying an almost NOS 26.4 cinelli on ebay for a reasonable price. The other one had lost its shape, apparently.