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Threadless stem sizing

Old 09-19-10, 10:25 AM
  #1  
Randallissimo
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Threadless stem sizing

I think my stem may be too long, since I can't take my hands off the bars very easily and my seat is all the way back. I'd like to experiment with different size stems. How do I know what size mine is, or how to measure it?
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Old 09-19-10, 10:45 AM
  #2  
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First try moving your seat forward. As for stem sizing they are measured in mm. anywhere form 60 to 130. Also the rise is 0 to + or - 17 degrees.
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Old 09-19-10, 10:45 AM
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Life isn't as easy as it used to be.

Back in the days when men were men and bike stems had quills, virtually all stems had a 72 degree angle which roughly matched bike's head tube angles so the stem was roughly parallel to the ground. Stem length was measured from the centerline of the quill anchor bolt to the centerline of the handlebar clamp. Guessing which stem length would fit you was relatively easy.

Stem selection today is a lot more of an art form. Threadless stems today are commonly sold by "extension" which is the length along the stem from the centerline of the fork's steerer tube to the centerline of the handlebar clamp. The problem is that stem angles can be anything and, the more the stem is angled upward, the closer the handlebar is positioned to the rider so the stem affects both height and reach.

My suggestion is to carefully consider where you think your hands to be positioned. Then buy the cheapest stem that will position your hands there. Ride your bike like that for a month or so before spending the money on a nicer stem.
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Old 09-19-10, 11:06 AM
  #4  
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Originally Posted by kycycler View Post
First try moving your seat forward.
Please don't, the seat is positioned (or at least should be positioned) where it is because it places your hips in the proper position for optimal pedalling efficiency. By changing the for/aft adjustment on the seat to affect reach,you may put yourself in a very uncomfortable position for actual pedalling.

As far as fixing the reach problem, Retro Grouch did a fine job explaining it. However, since it is somewhat baffling, you can also just take your bike to your favourite local bike shop and let them have a go. Many of them will even have 'loner stems' you can try out for a few days.
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Old 09-19-10, 11:08 AM
  #5  
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OD of steerer, 1" or 9/8". extension.. steerer tube center to handle bar tube center.
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Old 09-19-10, 12:29 PM
  #6  
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Get yourself an angle finder like this. Hardware stores sell them. Accuracy varies, that's why you buy them in store.... to check them. http://www.amazon.com/Johnson-Level-...4920655&sr=1-5

Measure the angle of the stem, minus your head tube angle.

Don't mess with your seat, it's never to be used to modify your reach.
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Old 09-19-10, 01:03 PM
  #7  
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Originally Posted by kycycler View Post
First try moving your seat forward.
I think the seat is where it should be. It's a Lemond Zurich, and it is my understanding that the geometry is such that it puts you a little aft of the pedals. I just want to try a couple of shorter stems to see if that helps. But first I have to know what size mine is. I think I can figure it out from the posts here. Thanks. I would have thought that it would be labeled, unless it is and I am missing it.
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