Old 08-05-12, 04:46 PM
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conspiratemus1
Used to be Conspiratemus
 
Join Date: Jan 2009
Location: Hamilton ON Canada
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Originally Posted by noglider View Post
I got a nice tandem but the seller couldn't find the stoker stem. No hard feelings, because he gave me an awfully nice deal overall.

Is it crazy to use a threadless stem? I've done so, using a thick shim. I see I need a thicker and taller shim to make it really safe. Should I fork out the big bux to do it by the book? I'd rather be frugal.

I could post this in the tandem section or the mechanics section, but you folks are my friends.
In the tandem forum they'd probably tell you to spend the bucks. But a threadless stem properly shimmed works great as a stoker stem, actually more robust than a purpose-built stoker stem. (Control-Tech specifically tells you not to attempt to use their stoker stems in the safety-critical front position on a tandem or a single bike.) The challenge you will face is finding one with the right combination of length and angle to place the stoker's handlebars exactly where she wants them. Most stokers on most tandems will want the stem to be angled above horizontal -- 10-15 degrees is a good place to start. The shorter the stem extension, the steeper it needs to rise. You will need one with 30 or 40 degrees of rise angle to compensate for the typical 72 degrees angle of the seatpost -- remember you are attaching the stem "backwards" so your usual 7-degree stem would end up pointing down.

On our now-secondary tandem, we use one of those fugly (but cheep!!) adjustable threadless stems with the big knuckle in the middle to get the necessary length and height without it fouling the rear end of the captain's saddle. It goes horizontal for a few centimeters then bends up abruptly once clear of the saddle. Works great.

You've probably figured most of this out already if you've already got one installed, but fussing around to get the stoker's position perfect is well worth the effort in getting the tandeming relationship off to a good start.
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