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I adjusted my stem height the other day, and since then, the stem hasn't felt straight. I've attempted to straighten it a few times, but because I'm just eyeballing it, the handlebars don't quite seem right when I ride.

(I have similar problems when I try to straighten my saddle or brifters; is this hard for other people, too, or do I just have some sort of alignment-blindness? :)

Is there a simple way to make the stem objectively straight instead of relying on my subjective (and wrong) judgment?

  • 2
    One thing I do to help get the stem straight is use a nylon strap (anything will do really) to secure the front wheel to the down tube. It isn't flawless, but it keeps the wheel from flopping around. – WTHarper Jun 18 '13 at 20:28
  • @WTHarper Would you consider adding that as an answer? It seems like something I should try. – amcnabb Jun 18 '13 at 20:28
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    Keep futzing with it until you go crazy and it looks straight, even thought it's tilted at 45 degrees. – Daniel R Hicks Jun 18 '13 at 20:34
  • @DanielRHicks That's almost exactly what I did! :) – amcnabb Jun 18 '13 at 21:45
  • Fat Cyclist posted about this today, so at least I'm not the only one stressed out about this: fatcyclist.com/2013/07/24/… – amcnabb Jul 24 '13 at 18:44
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This approach works well for rigid forks and might work well for suspension forks too.

You need a straightedge or aluminium profile.

Put the straightedge through the wheel and push it against the fork:

Putting the straightedge in place

Ensure you do not stress the spokes, though it might help clamping the straightedge.

Look down from your handlebar and align the straightedge with the handlebar:

Look down the handlebar to alig the handlebar with the straightedge

Move your head until you almost covered the straightedge with the handlebar. If the handlebar is straight, you shall see the straightedge equally on both sides.

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    You made me find this question and I was about to post a similar answer for wider MTB forks: on these, one might not even need the straightedge and can simply align the bars to the fork crown. You might want to add this to your answer :-) – anderas Jan 6 at 8:14
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A problem many hit when trying to straighten the stem is that they end up aligning the stem with the bike while the wheel is almost straight. A degree or two isn't noticeable until you are riding and then it really bothers you.

Instead of trying to align three things (bike, stem, wheel), turn the wheel about 45 degrees. Now align the stem (I generally do it with the wheel trapped between my legs and the bike in front of me) to the wheel. It's much easier to ignore the bike when it's not even close to in-line.

Happy riding.

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After making sure your handlebar is properly centered in the stem clamp and it is not bent (from a crash for example) locate the bike over the lines of a straight and well installed tiled floor. Use the crossed pattern as a guide: Align the front wheel with lengthwise lines and compare the handlebar ends with a crossed line. As the Handlebar halves are longer than most stems, any misalignment would be magnified at the ends, thus making it easier to "see" the error and correct it.

To further increase the "precision" of this technique, use only one eye, and try to align that eye with the vertical plane of the front wheel, that means shifting your head an approximately inch to one side.

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I sight down the middle of the bike and line up components on the bike centerline, like the stem, top tube, seat tube, BB shell, etc.

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This works for me...first eyeball it. Then for the fine adjusments take a string and stick one end to the center of your wheel (right at the top of the wheel) then measure the distance to one end of the handlebar (just take the other end of the string to the end of the handlebar) and then compare it to the other end of the handlebar...if it is aligned it should be the same lenght on both sides.

After doing this you can go to bed at ease lol

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Take off the front wheel

Place the bike on flat ground. Preferably inside the house where the ground is hard and flat.

Drop a plumb line from center of the stem to a length where it is just a millimeter off the ground.

Align the stem so that he plumb line is in the centre of the fork. Use a ruler to determine the centre of the fork if you must

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  • Trying to visualise this solution - you rest the fork dropouts on the ground to do this? Sounds like an interesting technique. – Criggie Nov 17 '18 at 19:29
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    @Criggie Yes, dropouts on the floor, I think. – David Richerby Nov 18 '18 at 11:24
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It is shocking that many bike mechanics does not know how to fit the stem properly, leaving me to do the work for myself.

I'm now writing this answer in hope that people never have an anguished scream in their head about this mis-alligned stem.

1)Tie a ribbon/cord or anything that hanging on the stem.

2)Make sure the ribbon touches the wheel.

3)Allign the stem

4)Learn that after tightening, the stem generally move a few degrees depends on where the tightening bolts are.

5)Once knowing which direction the tightening bolts causing the stem to rotate, offset the stem (remember to use the ribbon as indicator/marking)

Repeat until you satisfy, but generally it wont be more than 3 times

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    What if the bike is leaning slightly to one side? – BSO rider Aug 3 '15 at 22:56
  • I dont have a problem with that. But if you insist, tie the ribbon onto the wheel and rotate the wheel so it can pull the stem straight. – Nhân Lê Aug 4 '15 at 0:46

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