Stem Shims

[duncan]

I'd like to run a BMX stem and bars on my Mountainbike. It has 1" threaded forks, but the inside diameter is just too big for a close fit.

The original Mountainbike stem quill diameter (and inside fork steerer diameter) is 22.2mm, but my BMX stem is 21.1mm
Is there anywhere I can buy a shim/adapter to fit into the forks?

It does tighten up as it is, but not sure I'd trust it over any rough ground, plus there's a little side-to-side bend given the extra millimetre between quill and steerer.
Has anyone successfully tried this before using their own solution (cut up coke can etc)?
I know I could buy a Profile Boa stem which was designed for this very purpose, but I'd like to use my old Redline Forklifter if possible.

Thanks.

[oberonspacefruit]

 i reckon the coke can thing would be fine. its alloy so it wont rust. i doubt if you would get a shim. though you can get shims for seatposts, see what sizes they do in those....

[theRuler]

use some thin metal - the coke can sounds best

a shim with a 0.45mm wall would be pretty delicate so i doubt you can buy them

[duncan]

Thanks for the replies,

Something that confuses me is that many webpages call a 22.2mm stem a 1" stem.
1" = 25.4mm, they're obviously referring to the 1" fork size, but it makes hunting for the right sized shim very confusing.

Is a shim sized by the stem it fits onto, or the outer diameter of the forks it fits into?
As they're split and can expand, I suppose it doesn't matter as long as it can fill up the extra 1.1mm space.

I did find this: http://www.billys.co.uk/english/group.php?prod=smid-quillshim
It's a convertor sleeve for 1"quill to fit 1 1/8" Steerer, not quite the right size but I'll keep looking.
I think I'd need something like a 15/16" to 1" shim.

I'll give the coke can method a try if I don't find something soon.

[duncan]

This is the one I need, made by Wald, model number LLC #905:
http://www.bikepartsusa.com/product_info.asp?f_c=Seat+post&f_c2=shim&cp=2&p=01%2D127648

It's a seatpost shim, that converts 13/16" to 7/8".
Just so happens it can also be used to convert 21.1mm to 22.2mm for a stem!

No international shipping there, but I have located it elsewhere.

[billstup]

Why don`t you contact them and ask if they`ll send it over here,they can only say no. 

[duncan]

I'll have to start asking about shipping, you're right, as there's a few small items on Ebay I'd like but they're US only - a seatclamp for one.
I got the shim on Ebay, and have asked if he has any more as a spare would be handy.

[oberonspacefruit]

use a coke can.
have you read zen and the art of motorcycle maintenence?

[oberonspacefruit]

When he brought his motorcycle over I got my wrenches out but then noticed that no amount of tightening would stop the slippage, because the ends of the collars were pinched shut.

"You're going to have to shim those out," I said.

"What's shim?"

"It's a thin, flat strip of metal. You just slip it around the handlebar under the collar there and it will open up the collar to where you can tighten it again. You use shims like that to make adjustments in all kinds of machines."

"Oh," he said. He was getting interested. "Good. Where do you buy them?"

"I've got some right here," I said gleefully, holding up a can of beer in my hand.

He didn't understand for a moment. Then he said, "What, the can?"

"Sure," I said, "best shim stock in the world."

I thought this was pretty clever myself. Save him a trip to God knows where to get shim stock. Save him time. Save him money.

But to my surprise he didn't see the cleverness of this at all. In fact he got noticeably haughty about the whole thing. Pretty soon he was dodging and filling with all kinds of excuses and, before I realized what his real attitude was, we had decided not to fix the handlebars after all.

As far as I know those handlebars are still loose. And I believe now that he was actually offended at the time. I had had the nerve to propose repair of his new eighteen-hundred dollar BMW, the pride of a half-century of German mechanical finesse, with a piece of old beer can!

Ach, du lieber!

Since then we have had very few conversations about motorcycle maintenance. None, now that I think of it.

You push it any further and suddenly you are angry, without knowing why.

I should say, to explain this, that beer-can aluminum is soft and sticky, as metals go. Perfect for the application. Aluminum doesn't oxidize in wet weather...or, more precisely, it always has a thin layer of oxide that prevents any further oxidation. Also perfect.

In other words, any true German mechanic, with a half-century of mechanical finesse behind him, would have concluded that this particular solution to this particular technical problem was perfect.

For a while I thought what I should have done was sneak over to the workbench, cut a shim from the beer can, remove the printing and then come back and tell him we were in luck, it was the last one I had, specially imported from Germany. That would have done it. A special shim from the private stock of Baron Alfred Krupp, who had to sell it at a great sacrifice. Then he would have gone gaga over it.

That Krupp's-private-shim fantasy gratified me for a while, but then it wore off and I saw it was just being vindictive. In its place grew that old feeling I've talked about before, a feeling that there's something bigger involved than is apparent on the surface. You follow these little discrepancies long enough and they sometimes open up into huge revelations. There was just a feeling on my part that this was something a little bigger than I wanted to take on without thinking about it, and I turned instead to my usual habit of trying to extract causes and effects to see what was involved that could possibly lead to such an impasse between John's view of that lovely shim and my own. This comes up all the time in mechanical work. A hang-up. You just sit and stare and think, and search randomly for new information, and go away and come back again, and after a while the unseen factors start to emerge.

What emerged in vague form at first and then in sharper outline was the explanation that I had been seeing that shim in a kind of intellectual, rational, cerebral way in which the scientific properties of the metal were all that counted. John was going at it immediately and intuitively, grooving on it. I was going at it in terms of underlying form. He was going at it in terms of immediate appearance. I was seeing what the shim meant. He was seeing what the shim was. That's how I arrived at that distinction. And when you see what the shim is,in this case, it's depressing. Who likes to think of a beautiful precision machine fixed with an old hunk of junk?

I guess I forgot to mention John is a musician, a drummer, who works with groups all over town and makes a pretty fair income from it. I suppose he just thinks about everything the way he thinks about drumming...which is to say he doesn't really think about it at all. He just does it. Is with it. He just responded to fixing his motorcycle with a beer can the way he would respond to someone dragging the beat while he was playing. It just did a big thud with him and that was it. He didn't want any part of it.

At first this difference seemed fairly minor, but then it grew -- and grew -- and grew -- until I began to see why I missed it. Some things you miss because they're so tiny you overlook them. But some things you don't see because they're so huge. We were both looking at the same thing, seeing the same thing, talking about the same thing, thinking about the same thing, except he was looking, seeing, talking and thinking from a completely different dimension.

He really does care about technology. It's just that in this other dimension he gets all screwed up and is rebuffed by it. It just won't swing for him. He tries to swing it without any rational premeditation and botches it and botches it and botches it and after so many botches gives up and just kind of puts a blanket curse on that whole nuts-and-bolts scene. He will not or cannot believe there is anything in this world for which grooving is not the way to go.

That's the dimension he's in. The groovy dimension. I'm being awfully square talking about all this mechanical stuff all the time. It's all just parts and relationships and analyses and syntheses and figuring things out and it isn't really here. It's somewhere else, which thinks it's here, but's a million miles away. This is what it's all about. He's on this dimensional difference which underlay much of the cultural changes of the sixties, I think, and is still in the process of reshaping our whole national outlook on things. The "generation gap" has been a result of it. The names "beat" and "hip" grew out of it. Now it's become apparent that this dimension isn't a fad that's going to go away next year or the year after. It's here to stay because it's a very serious and important way of looking at things that looks incompatible with reason and order and responsibility but actually is not. Now we are down to the root of things.

My legs have become so stiff they are aching. I hold them out one at a time and turn my foot as far to the left and to the right as it will go to stretch the leg. It helps, but then the other muscles get tired from holding the legs out.


What we have here is a conflict of visions of reality. The world as you see it right here, right now, is reality, regardless of what the scientists say it might be. That's the way John sees it. But the world as revealed by its scientific discoveries is also reality, regardless of how it may appear, and people in John's dimension are going to have to do more than just ignore it if they want to hang on to their vision of reality. John will discover this if his points burn out.

That's really why he got upset that day when he couldn't get his engine started. It was an intrusion on his reality. It just blew a hole right through his whole groovy way of looking at things and he would not face up to it because it seemed to threaten his whole life style. In a way he was experiencing the same sort of anger scientific people have sometimes about abstract art, or at least used to have. That didn't fit their life style either.

What you've got here, really, are two realities, one of immediate artistic appearance and one of underlying scientific explanation, and they don't match and they don't fit and they don't really have much of anything to do with one another. That's quite a situation. You might say there's a little problem here.

[duncan]

A bit of old beercan on me Can 'o ale?, really, the mere idea of it..

I'm not averse to a bit of Heath Robinson style fixing, I had a pair of cranks that were rounded out, so I packed round the square axle with solder and tightened up the bolts - worked a treat as the solder moulded itself into little shims.

I hadn't read that book, enjoyed reading the part you posted. It's very true, an obsession with form over function, I'm as guilty of that as anyone.

Anyone got a NOS 80's cokecan for sale?...

[oberonspacefruit]

lol,,,
good lad

[RATTY]

You could allways sell me the forklifters for my rl20, and get another set of bars............

[duncan]

Sorry, it's just a Redline Forklifter stem I've got, not the bars.

I'm hoping to get a Tuf Neck stem for the BMX, as I had one briefly before swapping it for the Forklifter, not the best deal I've made but who knew...
So the Redline stem will be free to put on the mountainbike, I could do with a more upright position, it's bad for the posture the way it was.

[RATTY]

Sorry, it's just a Redline Forklifter stem I've got, not the bars.

I'm hoping to get a Tuf Neck stem for the BMX, as I had one briefly before swapping it for the Forklifter, not the best deal I've made but who knew...
So the Redline stem will be free to put on the mountainbike, I could do with a more upright position, it's bad for the posture the way it was.