Handlebar shim/s

Discuss light weight issues concerning road bikes & parts.
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Joined: Fri Feb 21, 2003 1:00 am

by wally318

Anyone made or use handlebar shims made of Derin?
For eg. 31.8mm to 26.0mm.
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by Weenie

Posts: 475
Joined: Fri Feb 21, 2003 1:00 am

by wally318

Maybe I should clarify.
There are shims for seatposts made of both aluminum and
Delrin. But I only see handlebar shims made of aluminum.
Since the delrin seatpost shims work and in the subject
of saving weight 26.0 to 31.8mm full shims weigh 45 grams and
plastic is about half the weight of aluminum.
Just wondering if any have made their own Delrin shims or know
where to get them, and do they stand up.
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by bombertodd

I would think looking for a proper sized stem would be a better idea. Is there a reason for shims instead of a 26.0mm stem?

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by AJS914

Seatpost shims are a long longer so they have much more surface area to grip. I couldn't see delrin working for a stem. 26.0 stems should be plentiful on ebay or in the ancient parts bin at the local bike shop.

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by DeeHubbs

It all depend if you prefer a:
-Demental implant,
-Tooth-supported fixed bridge,
-Removable partial dentures, or,
- Resin-bonded bridge?
The dental implants will save about 12g per tooth, but will cost about $1300 per tooth more.

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by vejnemojnen

bid for 26.0 stem on ebay.

I managed to buy a syntace f99 for 2euros few months ago, weighs 107 grams with steel screws for a 120mm model..

by Weenie

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Joined: Wed Sep 20, 2006 1:03 am
Location: Madison, WI USA

by youngs_modulus

Creep is the reason you don't see plastic handlebar shims. Nearly all polymers, including Delrin, flow a bit under stress. This flow is called creep, or sometimes stress relaxation.

If you installed a Delrin handlebar shim and tightened the stem bolts to the manufacturer's designated torque values, your handlebar would work just fine. For a while, anyway. Over a period of days or weeks, the Delrin would flow (a tiny bit) out from under the clamp area, effectively loosening the clamp bolts.

You would probably discover the wonders of creep when gou rode over a bump on your hoods and your handlebars rotated ~80 degrees forward. You may or may not fall when this happens, but if you did, it wouldn't be pretty. DeeHubs suggested you'd lose a lot of teeth. This is plausible, but I think you're just as likely to break your collarbone (potentially losing teeth as well).

But DeeHubbs recommnded dental implants to save weight after your crash. He's relatively new to this forum, and so his suggestion is a little naïve. A true weight weenie would leave those heavy teeth on the road without replacing them. That's a lot lighter than even implants, and the $/gram ratio is off the charts.

In all seriousness, a properly installed aluminum shim should be fine. But don't mess with polymer shims for handlebars.

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