It doesn’t matter since I’m not going to talk about planetary alignment today.  I’m going to talk about bicycle frame and fork alignment.  

    Among custom builders, frame alignment is often billed as a big issue.  It is a big issue, but maybe not as big an issue as we sometimes make it to be.  The goal of frame alignment is to build a bicycle where the frame centerline, fork centerline, and wheel centerlines are all in the same plane.  When we ride bicycles, they don’t stay that way.  

    On my randonneuse, the headlamp is fairly close to the front wheel.  When I get out of the saddle on a steep, slow climb, I can watch the wheel move toward the lamp and away.    Maybe, you’ve noticed this on your bike.  Sometimes, it is the chain touching the front deraileur cage when you pour it on or pump up a hill.  These interesting diversions, that we enjoy while climbing hills, are a result of our frames and wheels flexing -- that is going out of alignment one way and then the other.  At a spin class, walk behind the bicycles and watch how much the bottom brackets move when the coach tells everyone to shift up.  The big oversize carbon frames don’t look so stiff from the back of a spin class.

    Many accomplished cyclists ride bicycles that are out of alignment without ever knowing it.  A well known frame builder was out riding last fall when he found himself behind a rider on a high end production bicycle.  On a forum he mentioned that the wheels were not in the same plane and that this bothered him since his bikes are very well aligned.  The rider in front of him probably didn’t know how upsetting his bicycle was to the man behind him.  

    Years ago, I owned a Bianchi that appeared to be well out of alignment in the rear triangle.  It had horizontal dropouts so I shifted the wheel to line up between the chain stays.  One day, I had the rear wheel out to true it up a little and I checked the dish when I was done.  The wheel was out of dish.  The frame wasn’t bent.  Sometimes a frame that looks out of alignment is really a wheel that’s out of dish.  In fact, the frame the aforementioned builder noticed on the road, might have been fine.  Perhaps the rider didn’t seat the wheel all the way into the dropouts before flipping the skewer lever.  We’ve mostly all done that and then noticed the brake didn’t look right when we closed the release.

    On the other hand, if a bicycle is going to go out of alignment when it is ridden, it might as well be as well aligned as possible while it is waiting to be ridden.  And, if this is the case, the custom builder has the edge over the production shop in this area because the custom builder can keep an eye on alignment throughout the build process while the production shop, at the most, will check alignment after the frame is finished and tweak it into shape then.

    So where does alignment start?  Before we make the first cut.  Bicycle tubes are very expensive, high quality, pieces of steel, but they aren’t perfect.  So before I begin to build a frame, I put the the tubes in v-blocks, set up a dial indicator, and roll them to find if they have a bow to them.  If they do, it will be very slight, but I mark it and that goes top or bottom of the tube in the frame.  (I’ll use “I” here because I better just speak for myself, but the checks I do are pretty commonly done by other custom builders.)

    Once the tubes are all cut and mitered, they go into the frame fixture for a fit check.  I use a Henry James frame fixture that is designed in such a way that if you get all the tubes in without stressing them you have everything well in alignment.   If something doesn’t fit, you either set the fixture up wrong, or you cut the tube wrong.  After I make sure all the tubes fit, I pull them out, put the lugs on them and check again.  If everything still looks good, I pull it all apart, flux everything up, and put it all back in the fixture again.  

    You might get the idea here that a big production shop in Asia can’t spend this much time on a frame and I’d guess you’re right.  

    When it is time to braze, frame builders have a sequence they go through and it isn’t the same for everyone.  In fact, we pretty much all do it just a little bit differently, but we find a way that works for us.  This much is pretty constant for a true frame, we somehow fix the frame pieces so they don’t move out of plane while we braze them up.  This might be by tacking them or by pinning them, but this much is sure, if you  just braze where ever the urge strikes, your frame will not be true when it cools.

    I braze the main triangle, and the chain stays into the bottom bracket, then I pull that part of the frame out of the fixture and check the alignment; especially the chain stays.  I often find these out of alignment just a tad, but they are easy to deal with until you braze the seat stays on, then everything stops wanting to be fiddled with.  Once the chain stays are aligned and the dropouts are aligned to parallel each other, it is time to braze the seat stays in.  This is not as easy as it seems.  If you are not careful it is easy to warp and twist something as you braze in seat stay and chain stay bridges.  On the other hand, if you are careful, and take into account that they will pull in to some extent as they cool, it all comes out well.

    I do a lot of checks with some pretty simple devices like properly dished wheels, straight edges, and a frame gauge make by Park tools that is pretty handy.  I should say here, that these checks are probably all that anyone needs to do to build a frame and fork that will be well enough aligned to ride like a dream.  Since I have an alignment system built by Joe Bringheli, I put the frame on my Bringheli alignment table.  It is here that you can check and adjust misalignment to a maddening degree if you like, but if you’ve been careful and kept a handle on things as you go along, the alignment table is kind of a pat on the back.

    If you are talking to a frame builder who tells you about how perfectly his or her frames are aligned, encourage them because you’re talking to someone who cares about their work.  But, if you have a bicycle that rides like a dream, don’t worry too much about the alignment because it must be just about right as it is.

    For those of us who build bicycle frames, alignment is something we should be concerned about.  When I was in the Navy, we used to say that if you sweat the small stuff, the big stuff will take care of itself.  A builder who takes pride in frame alignment probably takes pride in all the other aspects of building a bicycle frame and that’s important to all of us.

    Oh, and keep your wheels true and dished.  Why should we stress over a millimeter if you’re going to put bent wheels in the bike anyway?