Handlebar shims--dangerous?
trent gregory hill
I'm writing to consult the collective wisdom of the NG regarding a piece
of advice that was given me in all seriousness this afternoon by one of
the parts guys at the largest LBS around here (Seattle). I stopped by to
pick up a set of shims to adapt a 25.4 handlebar to a 26.0 clamp. When I
asked the parts guy if they had any, he told me that they didn't carry
them because they were "dangerous," and if I really wanted to shim my bars
(which I shouldn't, under any circumstances), I should just cut up a pop
can. I thought to ask how and why the shim would be dangerous (I think he
said they didn't work and would cause bar slippage), but his initial reply
was delivered in such a tone of incredulity that I didn't think to ask for
clarification.
Now, as I said, this came from the parts counter at the largest LBS around
here, but from my experience they're also great dispensiaries of myth and
lore, so I'm curious either way.
Bemused,
Trent
Erik Freitag
<Pine.A41.4.44.030810...@homer10.u.washington.edu>,
trent gregory hill <tghi...@u.washington.edu> wrote:
> Folks,
>
> I'm writing to consult the collective wisdom of the NG regarding a piece
> of advice that was given me in all seriousness this afternoon by one of
> the parts guys at the largest LBS around here (Seattle). I stopped by to
> pick up a set of shims to adapt a 25.4 handlebar to a 26.0 clamp. When I
> asked the parts guy if they had any, he told me that they didn't carry
> them because they were "dangerous," and if I really wanted to shim my bars
> (which I shouldn't, under any circumstances), I should just cut up a pop
> can.
Sorry, I know this doesn't answer your question, but your post caused
the following flashback:
...
His handlebars had started slipping. Not badly, he said, just a little
when you shoved hard on them. I warned him not to use an adjustable on
the tightening nuts. It was likely to damage the chrome and start small
rust spots. He agreed to use my metric sockets and box-ends.
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 handebar
under the collar there and it will open up the collar to where you can
tighten it again. You use shim like that to make adjustments in all
kinds of machines."
"Oh," he said. He was gettiing interested. "Good. Where do you buy them?"
"I've got some right here," I said gleefully, holding up the 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 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 noticably haughty about the whole thing. Pretty soon he was
dodging and filling with all kinds of excuses and, before I had realized
what his real attitude was, we had decided not to fix the handlebars at
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 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!
...
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, 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.
- Robert M Pirsig, Zen and the Art of Motorcycle Maintenance
For what it is worth, I don't see how shim could be dangerous, even the
beer can kind, if you're careful about how you apply it.
Alex Rodriguez
tghi...@u.washington.edu says...
Probably a liability issue as much as a technical issue. they want to sell
you something that might cause an accident if not done properly.
---------------
Alex
Jeff Wills
> Folks,
>
> Now, as I said, this came from the parts counter at the largest LBS around
> here, but from my experience they're also great dispensiaries of myth and
> lore, so I'm curious either way.
>
> Bemused,
> Trent
Rivendell sells shims for handlebars:
http://rivbike.com/webalog/handlebars_stems_tape/16095.html
You should find a better bike shop.
Jeff
David Kunz
That basically applies to almost any bicycle part...
I've done it and had it work. I've also done it and had it not work
because I couldn't get the clamp to tighten enough (it rotated under
pressure). Thinking about it now, the one that worked may have had
ridges in both the clamp and the bars, and the one that didn't also
didn't have ridges at the clamping point of the bars.
YMMV
David
David Kunz
That basically applies to almost any bicycle part...
I've done it and had it work. I've also done it and had it not work
because I couldn't get the clamp to tighten enough (it rotated under
pressure). Thinking about it now, the one that worked may have had
ridges in both the clamp and the bars, and the one that didn't work
didn't have ridges at the clamping point on the bars.
YMMV
David
Qui si parla Campagnolo
piece
of advice that was given me in all seriousness this afternoon by one of
the parts guys at the largest LBS around here (Seattle). I stopped by to
pick up a set of shims to adapt a 25.4 handlebar to a 26.0 clamp. When I
asked the parts guy if they had any, he told me that they didn't carry
On a road bar, I would agree that it is not a good idea in that if the bar does
slip, it can really hurt. On a MTB bar, w/o barends, probably not a big deal
because of the leverage involved that may cause the bar to rotate.
Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
Qui si parla Campagnolo
http://rivbike.com/webalog/handlebars_stems_tape/16095.html
You should find a better bike shop. >><BR><BR>
For mustache bars and a 'priest' bar, whatever that is..still don't think it's
a good idea for road bars.
Jeff Wills
> jwills-<< Rivendell sells shims for handlebars:
> http://rivbike.com/webalog/handlebars_stems_tape/16095.html
>
> You should find a better bike shop. >><BR><BR>
>
> For mustache bars and a 'priest' bar, whatever that is..still don't think it's
> a good idea for road bars.
>
Well, I kind of *assumed* he was putting an "upright" bar in a "road"
stem. There's only a few drop bars that have a 25.4mm clamp area
(there's a couple, I know).
I think Rivendell has dropped the "priest" designation for "Dove" and
"Albatross": http://rivbike.com/webalog/handlebars_stems_tape/16123.html
Jeff
Tim McNamara
vecc...@aol.com (Qui si parla Campagnolo) wrote:
> On a road bar, I would agree that it is not a good idea in that if
> the bar does slip, it can really hurt. On a MTB bar, w/o barends,
> probably not a big deal because of the leverage involved that may
> cause the bar to rotate.
Well, if experience is anything to go by, here's mine. I've got an
old handlebar from a 1974 Raleigh-Carlton Super Course with a 25.4 mm
clamp section. It's flipped over and sawed off, mounted in a Salsa
stem with a 25.4 -> 26.0 mm aluminum seat post shim. It's been on my
single speed bikes for three years and has never slipped and doesn't
even creak. I be 6'4" and 207 lbs...
Chalo
> When I
> asked the parts guy if they had any, he told me that they didn't carry
> them because they were "dangerous,"
Hogwash. (Although slipping bars could be a sign of a more serious
problem that might itself be dangerous, e.g. a cracked stem.)
> and if I really wanted to shim my bars (which I shouldn't, under any
> circumstances), I should just cut up a pop can.
Aluminum cans run about .2mm avg., so you would likely need more than
one wrap to do the job. Better to get some real .012-.015" shim
stock, or one of those fancy Nitto stainless steel shims that's
already formed in the correct curvature.
> I thought to ask how and why the shim would be dangerous (I think he
> said they didn't work and would cause bar slippage),
I have used shims to fit 22.2mm -> 25.4mm and 25.4mm -> 26.0mm. No
problems yet with bars as high as 8". I fitted my sister's bike with
14" rise bars shimmed at the stem; likewise there have been no
associated problems.
You will want to use a stem with a secure clamp, ideally a 2-bolt
binder or a 4-bolt faceplate.
Chalo Colina
Werehatrack
Campagnolo) may have said:
>On a road bar, I would agree that it is not a good idea in that if the bar does
>slip, it can really hurt. On a MTB bar, w/o barends, probably not a big deal
>because of the leverage involved that may cause the bar to rotate.
Oddly enough, my daughter's old mtb had a problem with the bar
rotating which was solved by adding a coke-can shim; I did that after
reading some advice here, and it has been secure ever since. I think
the perception that an mtb bar isn't subject to exceptional rotational
forces may not fully take into account the fact that an mtb may get
used in situations that put a high shock load on the bar...and most of
the bars (of my experience, anyway) are not dead straight. Better
stems, of course, have a better grip; her old mtb was decidedly
low-end in that area.
--
My email address is antispammed;
pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.
Chris Zacho The Wheelman
bike. My problem wasn't a mismatches stem/handlebar though, it was an
annoying creak between the two.
A can of Bud fixed it up fine. Why pay good money for something that
works just as good (better?) and costs practically nothing?
May you have the wind at your back.
And a really low gear for the hills!
Chris
Chris'Z Corner
"The Website for the Common Bicyclist":
http://www.geocities.com/czcorner