Old Cinelli stem not clamping well

[zmudshark]

Originally Posted by cgolvin

These millimeter differences are really starting to pi$$ me off; of course it's my own fault.

OK, sounds like I need to fashion a shim. Should I be fancy and try to cut a piece of aluminum can that matches the varying clamp of the stem or just cut a piece that matches the narrowest width of the stem?

Much appreciated.

Check the wedge to make sure it hasn't cracked. I have found old, flat, spark plug feelers to be excellent as shims. The thickness is marked on them

I have also found that the proper bar/stem combo is better than shims.

YMMV.

[cgolvin]

Originally Posted by zmudshark

I have found old, flat, spark plug feelers to be excellent as shims. The thickness is marked on them

Excellent suggestion. In my experience those things are pretty flexible, any pro advice on how to get them bent around and inserted?

Originally Posted by zmudshark

I have also found that the proper bar/stem combo is better than shims.

Yeah, probably better to prioritize safety over aesthetics.

[zmudshark]

Check the wedge first. If it is even slightly cracked, no go.

[zmudshark]

Originally Posted by cgolvin

Excellent suggestion. In my experience those things are pretty flexible, any pro advice on how to get them bent around and inserted?

Not pro, but wrap it around something smaller, 1/2" socket extension, or whatever you have. Grease is not your enemy.

Originally Posted by cgolvin

Yeah, probably better to prioritize safety over aesthetics.

I'm a big fan of Cinelli 64 bars, and can make them work with 10s Campy, which is as far as I'll ever go.

[cmbicycles]

I'm having a similar issue with a Mavic stem and Cinelli bars. Stem is supposedly 26.0, bars measure just under 25.8 and the stem comes close to bottoming out when tightened so stem might be a little over spec. Going to try shimming it for now, until I find a bar stem combo I like better.

[11.4]

I've worked with a bunch of these over the years. I would not recommend a shim. With the 1-R they don't clamp evenly and that's necessary for stable clamping. The 1-R basically wasn't a design that clamped evenly and over the years the wedge piece will deform slightly so when you take it out, it doesn't fit properly. It wasn't super-hardened alloy so it may not have broken and simply bent, but either way, it doesn't fit. Further, over time the recess it fits into also gets misshapen, plus the hole that the allen bolt inserts up into. Simply a bad design, plain and simple. If you really want a panto stem, order a Nitto Pearl in the right length and get one of the panto shops to do a really pretty job on it. I'd hate to see you injure or kill yourself. When these go bad they don't recover.

[rwsaunders]

A little more refined than a beer can.

https://www.benscycle.com/nitto-stai...70-049/product

[Duende]

Originally Posted by 11.4

I've worked with a bunch of these over the years. I would not recommend a shim. With the 1-R they don't clamp evenly and that's necessary for stable clamping. The 1-R basically wasn't a design that clamped evenly and over the years the wedge piece will deform slightly so when you take it out, it doesn't fit properly. It wasn't super-hardened alloy so it may not have broken and simply bent, but either way, it doesn't fit. Further, over time the recess it fits into also gets misshapen, plus the hole that the allen bolt inserts up into. Simply a bad design, plain and simple. If you really want a panto stem, order a Nitto Pearl in the right length and get one of the panto shops to do a really pretty job on it. I'd hate to see you injure or kill yourself. When these go bad they don't recover.

Exactly! I liked the looks of the 1R back in the day, but 1A was the tried and true model.

[Black Dog]

Cinelli stills makes the 1A stem and it comes in 26.0. Buy a new one and have it pantographed as was mentioned above. 100% safer.

[oldpotatoe]

Originally Posted by cgolvin

My old Cinelli (believe the model is "1R") stem seems to have lost its clamping power. I have to really torque the hell out of the bolt to get it to hold and am afraid of overdoing it (need to see what the torque actually is right now, will check later and update this post with data). I recently swapped my old Cinelli bars for a newer Nitto and the behavior's the same.

The stem is pantographed so I really don't want to substitute it -- is there anything I can do (e.g., some compound on the bar-stem interface) that will improve the clamping?

thanks

"Cinelli 1R, comes loose in about an 'R'"...very common..you can take the guts out, clean and inspect..maybe replace if you can find the wedge, etc but pretty common with this stem..26.4mm handlebar required, BTW..Does Nitto make a 26.4mm?

[El Chaba]

As this conversation has unfolded, I have a few more comments about the 1-R. Many of the above comments about things that can happen to a 1-R all stem (pun intended) from the fact that it is not a design that withstands a lot of mechanical ham-fistedness. What causes most of the problems with this stem is a little lack of care when adjusting the bar angle, and it's not hard to make the mistake. If you don't loosen the mechanism to a large degree, the wedge piece with the serrations that press against the bar will gouge away at the wedge/bar interface. This radically decreases the mechanism's purchase on the bars and then you have to tighten the mechanism extra to get it to hold. At this point the clamping force can often deform the bar where the wedge presses introducing another reduction in clamping purchase. The wedge mechanism itself can also deform, but when overtightened to this degree, they usually crack or break....decreasing the purchase even more. As I mentioned in my first post, you can often salvage a stem that has been overtorqued a bit by-inspecting the wedge and verifying no cracks, greasing the wedge interfaces, adding a shim if needed to the wedge interface to take up a bit of space to atone for past sins. The important part is to use good BARS that have not been deformed or gouged as they take the brunt of the abuse from overtorqeuing with this setup. There is nothing inherently wrong with the design...You just have to be a little careful with the bars during setup

[Polyglot]

Originally Posted by cgolvin

These millimeter differences are really starting to pi$$ me off; of course it's my own fault.

OK, sounds like I need to fashion a shim. Should I be fancy and try to cut a piece of aluminum can that matches the varying clamp of the stem or just cut a piece that matches the narrowest width of the stem?

Much appreciated.

Do not try to use a shim with a 1R stem, it will never work properly. The iR stem foresees the "teeth" of the wedge imbedding in the bars to make a positive lock. If the teeth are rounded off, the bars will not hold well. If you use undersized bars the teeth will not have sufficient hold, if you use a shim the teeth will likely imbed in the shim material but the shim material will not imbed in the bars, so they will still likely twist. You are best to use original 26.4 Cinelli bars and proactively replace the wedge. If you over tighten, you risk the stem shearing across the front of the stem where the plastic emblem is located (don't ask me why I know)

[El Chaba]

Let me clarify that when I refer to a shim it is to be placed between the two angled pieces of the clamping mechanism...NOT between the bars and the serrated piece of the clamp that pushes against the bars....

[oldpotatoe]

I know the 1R is pantographed and all but get one of these(new 26mm Cinelli 1A), keep the nitto bars and go ride.

[unterhausen]

the original wedges were not steel. They went to steel later, probably due to faceplants. It's quite possible that the OP has one of the non-steel versions. I really liked these stems, but I think it's time to give up on them for daily use. I can see using one on a retro build that doesn't get ridden much. I hated the creaking, I guess I was one of the people that ham-handedly just tightened them as much as I could.