Philatio

I usually will just line of sight it with the frame and the wheel, then ride it a couple meters to see how it feels and adjust accordingly. I would imagine there has to be a better way?

DieselDan

Do you know how to properly sight a rifle?

Philatio

yes

this method just doesn't seem very accurate to me

rmfnla

I'm a little anal about this.

I position my head directly above the stem and eyeball the front of the fork dropouts in relation to the front of the handlebars.

Helps me sleep at night...

SoonerBent

I've ridden and worked on bikes for many years. The only way I've ever found that works it to ride the bike. No matter how straight the stem is sitting still it always seems a little off the first ride.

SB

HillRider

I use a metal yard stick that I place edge-on over the stem and sticking out over the front wheel. Center the yard stick on the stem (or top cap) fixing bolt and the center of the handlebar clamp. The part sticking out front should just bisect the front tire when the stem is aligned properly.

rmfnla

Last time I sighted in a rifle I fired a few shots at a target and then adjusted the scope knobs to move the point of impact.

How do I do that with a bicycle stem..?

capwater

Real men don't use scopes.........

Stand above the stem and align it with the tire.

rmfnla

Dude, most of my rifles don't even come with iron sights.

catatonic

Remove the seatpost entirely.

Place the bike along a curb or such object so both wheels are perfectly straight.

Straddle the rear wheel in a way that keeps it vertical and crouch down, perring along the top tube.

Now adjust the stem so that it is part of the perfect straight line that the toptube makes. Once it is perfect, tighten the bolts, and give it another check.

Put your seatpost back on, and make it straight by using he toptube method, and enjoy!

Calvin Jones

It can help to use a straight edge to extend the top of the fork crown. Sight your handlebar center, which has a straight section on most bars, relative to the straight edge held to the fork crown. The two should be parallel.

In the image here, the two are not aligned. The stem is off to the left.

capwater

Surprised you can even own a gun in LA!

Dave Moulton

I always used to put a square on the front edge of the handlebars and sighted the opposite 90 degree edge with the side of tire.

jsharr

I wrap a velcro strip through the front wheel and around the downtube to center the wheel with the frame and then align the stem with the wheel frame. As others have said though, it seems the more effort you spend in centering the stem, the more likely you will be to find it slightly off center on your first ride after adjusting.

aerodave

Last time i did it, i got really anal about it, for no good reason. I put the bike in the trainer to hold it vertical. Then, I used one of those laser levels that projects a level line on a far wall (like this not like this). I turned it so it projected a plumb line, and pointed it head-on at the bike. Then, I adjusted the position of the bike slightly until I had that plumb line painted up the center of the head tube and the seat post, so the frame's alignment was certain.

Then, I turned the wheel until that same line was painted right up the centerline of the tire. This step is why lining up the frame is important when doing it with a laser, because you're not going to be able to get the line to run up the tire unless it's vertical. If it's turned relative to the frame, it won't be straight up and down, either. Finally, I turned the stem until the mounting bolts were in the path of the same beam, and tightened her down.

While I was at it, I made sure that the nose of my saddle was in the beam, too. And it was...virtualy dead on. Confirmation to me that the eyeball job I had done on the seat probably would have sufficed for the stem, too. Moreover, it was confirmation that being that anal about things is pretty stupid.

well biked

Get a good beer buzz going, and close one eye as you stand in front of the bike and sight down the front wheel, stem, top tube, and seatpost. It works, and it's more fun than any of the other responses.

P.S. Wait 'til the next day to ride the bike, though.

roadfix

A flashlight and the triple eye parallax method always works for me.......even re-aligning a steel frame.

Psimet2001 

With stems I just eyeball, but aerodave's idea is one that I have used in many other areas on the bike. Laser "levels" are so prevelent and cheap that I have created a lot of basic methods I use to check derail alignment, chain line on fixed, saddle position, bar position, etc. I use a laser, plumb line, machinists square, and basic fluid protractor (sp) extensively when recording all cockpit dimensions.

DieselDan

A scope? I'm not talking about a scope. I just got better at stem alignment after learning how to sight a rifle from my father.

spunkyruss

I'm surprised that Park doesn't make a $85 tool to aid in stem alignment.

Park makes great tools, but some of their stuff is a bit silly.

roadfix

......like their third hand tool which I purchased about 10 years ago and never once bothered to use it...

Peek the Geek

This is how I do it, too. (Picture doesn't work for me, though)

bellweatherman

Trick -
1) loosen the stem slighty, but still tight enough where there is some resistance.
2) Now, turn the bike upside down so that the floor makes contact with the saddle and either the handlebars or the brake hoods. In this position, the handlebars are exactly perpendicular to the top tube.
3) Tighten the stem. Voila!

Noam Zane

This is getting silly. How do some of you ever actually finish assembling a bike? Flipping a bicycle upside down? Lasers and straight edges? Chalklines and GPS?

Just quickly do the best you can by eye then fine tune it by feel when the bike is on on its shakedown ride. If you can't do that you have no business messing with tools.

HillRider

That's fine if it's your bike and you know how to readjust it during or after the first ride. It's more of a problem if it's a customer's or friends bike and they are the ones who have "no business messing with tools." Then you really want to get it right the first time.