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Old 02-22-09, 09:55 AM   #1
pistolpedro
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North Road problems

Have north road bars fitted on my bike,



problems is they seem to move round in the stem quite a lot, when you lean on the bars you can feel them drop slightly, after about an hour ride the had shifted over an inch (end of the grips) downwards

I think its a Cinelli stem and it looks like a thin shim is fitted between the bars and the stem, I have tightened the allen bolt up on the back side as much as i dare (I removed it and it has a very fine thread which i'm frightened of striping) but the problem still persists

Is there anyway to fix this problem?

pete
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Old 02-22-09, 10:04 AM   #2
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A couple of things:

-Given the shape of your bars they will act as pretty long efficient levers to spin them in their clamp. Much more so than most any other shape of bar. So, you need to get a good solid solution to this problem.

-You have a shim between the bars and stem which means they are mismatched. The ideal solution would be to get a stem with the right clamp size. Given my first point, you might want to seriously consider this as the right solution. There is nothing wrong with a shim, in principle, but do know that it gives you twice as much chance for slippage as one without. With a shim, there are two friction surfaces that you have to hold tight: bars to shim, and shim to stem.

At the very least, I would consider removing that shim and seeing what you have to work with. Maybe degreasing it or slightly scuffing it up would give it enough traction. Or maybe you need a somewhat thicker shim (I am betting on this).

You are right to be cautious about stripping the stem by just cranking away. At the very least, make sure the threads of the clamp bolt are cleaned and well greased. And remember to grease the underside of the head of the clamp bolt too. If you are not confident in your ability to judge how much torque is too much, a torque wrench is probably in order.

If it were mine, I would go right for the shim and see if a thicker and cleaned and scuffed one will solve it. Easy and free to test this solution. If that does not hold it steady enough, then you need to go stem shopping Or, I guess, bar shopping.

jim
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Old 02-22-09, 10:08 AM   #3
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cinelli stem with 26.4mm clamp?
I never knew anyone made shims for that size, and this could be part of the problem with size mismatch
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Old 02-22-09, 11:19 AM   #4
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Are the bars steel? Steel bars tend to slip. The stem clamp can't get a good bite in them.
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Old 02-22-09, 12:22 PM   #5
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You have a 26.4 stem on 26.0 bars. Quill stems with no faceplates have a non negotiable diameter for bars. Stop running that or prepare yourself for a new face. I'm glad you did not attempt to overtighten it in order to get the bars to stay. You might've already damaged it though, who knows.
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Old 02-22-09, 01:01 PM   #6
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Unless he has stripped out the bolts (which he says he has been cautious about), then I do not think the amount of bending of the clamp has hurt it. Aluminum does not like to bend, but this would really be an insignificant amount of bend so far.

I agree with the spirit of what you write though: trying to make up .4mm by tightening alone will not solve the problem. I think it is worth trying a bigger shim however to fix it. If it were mine I would try that before starting the drudgery of removing grips and levers from bars to remove the bars.

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Old 02-22-09, 01:16 PM   #7
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I think it is worth trying a bigger shim however to fix it. If it were mine I would try that before starting the drudgery of removing grips and levers from bars to remove the bars.

jim
You're likely to waste much more time than a stem replacement on finding the proper shim. But hey maybe the OP has something laying around that would be exactly .4mm and doesn't compress.
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Old 02-22-09, 01:31 PM   #8
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Thanks guys for all the input so far its very helpful: )

I only picked the bike up last week (brand new) and it was the first ride this morning, its a bit disappointing that its should have such a design flaw, dont know what to do really, should return it under warranty and get them to sort it out however the shop i got it from is a 50 mile round trip alternatively there is a small place round the corner though which seems to know their onions,

I'll ring up the supplier in the morning and see what they suggest

thanks again


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Old 02-22-09, 02:02 PM   #9
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Forgot to add I think the bars are chrome plated steel
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Old 02-22-09, 05:47 PM   #10
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Get some aluminum bars and use a Nitto stainless steel shim.
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Old 02-25-09, 03:02 AM   #11
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Hi Guys

Bit of an update, had a good look at it again last night, the shim thats currently fitted is a one piece shim, you can see its the bars that are twisting the shim stays in place

I have found a nitto stainless shim here in the uk, it is a two piece shim and is 25.4mm to 26.0mm would fitting this help? Could it be used with my existing chrome steel bars?

Also I noticed that the allen bolt is starting to round off, are these avaialble seperately ?

pete

Last edited by pistolpedro; 02-25-09 at 07:45 AM.
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Old 02-25-09, 02:21 PM   #12
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if it is brand new take it back and get the proper stem!
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Old 02-25-09, 03:18 PM   #13
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Hi

Yes i agree that i should take it back, unfortunately by the time i've taken it back and picked it up again it'll be the best part of 100 miles

Took the stem out earlier today and its stamped cinelli 12.5, looking at the specs this does have a clamp diameter of 26.4 mm as stated in the above posts
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Old 02-25-09, 03:59 PM   #14
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Get yourself a new stem and be done with it...or drink a beer and use part of the can as a shim.
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Old 02-25-09, 04:05 PM   #15
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You're likely to waste much more time than a stem replacement on finding the proper shim. But hey maybe the OP has something laying around that would be exactly .4mm and doesn't compress.
Shim stock perhaps ?
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Old 02-25-09, 05:45 PM   #16
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oh the lovely 26.4mm cinelli clamp. I would just get a new stem that has the proper clamp diameter.
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Old 02-26-09, 03:56 PM   #17
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maybe a phone call to your LBS and they can send you the replacement stem in the mail
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Old 02-27-09, 07:42 PM   #18
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I have a Nitto north road bar set and a steel stem that I thought was the right diameter. I had to tighten the clamp bolt pretty tight to get the bars to stay put. All was well until I switched from a geared setup to a single speed. After a few weeks of working the stem hard on the up-hills, an amazing thing happened!

I was riding pretty fast along the southwest corridor bike path when I saw the binder bolt head go flying ahead of me me with a loud ping! The handlebars suddenly became loose and I had to quickly grad the stem for steering with one hand, while hanging onto the loose bars with the other. I was lucky that it didn't happen while I was riding through downtown! I'm now very interested in all aspects of the stem/handlebar interface. I found this thread very interesting as I look for a new stem.

Matt
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Old 02-27-09, 08:00 PM   #19
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I have a Nitto north road bar set and a steel stem that I thought was the right diameter. I had to tighten the clamp bolt pretty tight to get the bars to stay put. All was well until I switched from a geared setup to a single speed. After a few weeks of working the stem hard on the up-hills, an amazing thing happened!

I was riding pretty fast along the southwest corridor bike path when I saw the binder bolt head go flying ahead of me me with a loud ping! The handlebars suddenly became loose and I had to quickly grad the stem for steering with one hand, while hanging onto the loose bars with the other. I was lucky that it didn't happen while I was riding through downtown! I'm now very interested in all aspects of the stem/handlebar interface. I found this thread very interesting as I look for a new stem.

Matt
Hence my post #5.
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