TiHabanero

One of my unused frames became a test mule for my rear drop out alignment experiment. Naturally a correctly aligned drop out is in the same plane as the seat tube/ top tube/ down tube. I aligned the rear drop outs 2mm off, tilting to the right. The bike now has a slight pull to the right, which makes sense as the rear wheel now wants to follow a slight curve to the right instead of a straight line following the front wheel. Kind of a fun thing to do and really demonstrates the necessity of frame alignment.

unterhausen

2mm? I think the pull is cognitive bias. Are you sure the rest of the frame/fork is straight?

Andrew R Stewart 

I assume the 2mm is the rear center is 2mm off plane from the main triangle. The drop outs generally are either side of that plane

For this experiment it doesn't matter if the rest of the frame/fork are well aligned because it's the difference from how the bike steered before and now, after, that is being noticed with the "only" change being the tear triangle being off from where it was before.

However 2mm is a rather small amount of off alignment. A bike's tracking is a complex result of machine, road, conditions and sometimes most importantly the rider. All have their range of contribution and it's only the rider that can fool themselves. Not saying what TiHabanero senses is wrong, just that when it's people's senses that are the gauge the perceptions can vary easily. Andy

TiHabanero

When I take my hands off the bar the bike pulls right. It did not do that before the modification. I will set the drop outs back to where they were and let you all know what the outcome is.

unterhausen

I made a frame a long time ago that had a bad no-hands low speed shimmy problem. When I decided to respace the dropouts to 130mm, it turned out it was off to one side by 10mm. That bike had no pull. There are tons of bikes that are out 2mm and nobody knows because they don't look at them too closely and there is no obvious handling issue. I didn't even know my bike was out at all except I knew something was wrong because of the shimmy.

I didn't use a fixture to build that frame, I figure I must have bumped the rear triangle before brazing it or something.

guy153

Interesting experiment! Really you need a blind test. Do you have a friend you can put on the bike and ask if he can feel any difference and if so what? You can tell him you moved the alignment but not which way.

Doug Fattic 

I've aligned hundreds (maybe more) of steel frames in 46 years of refinishing frames. If I got a chance, I asked the owner later if they noticed a difference. The reaction was mixed. Some say they can really tell and other didn't notice. I think that reflects personal differences and awareness. In my own case I've had personal bikes that seem to lose a little something over time. When I straighten it out again (usually it wasn't all that much) the frame comes back to life.

Years ago pro riders used to claim that a steel frame "went soft" and didn't ride as well as it used to. The best ones would like to get a mid season new replacement to avoid their frame going bad over use. This was a hot topic many years ago. Of course from a metallurgical standpoint, this makes no sense. If anything a frame would work harden and not "go soft". I think what happens was that a frame from heavy use would go somewhat out of alignment and that is what caused their impression.

Here is a story that sounds like boasting but never mind that, it illustrates my point that working carefully makes a difference. Many years ago I made a frame for a shop owner in Mississippi. When he got it, he wanted to know my secret on why it rode better than any other of the 50 frames he had bought for himself over the years. I said I didn't have a secret like why 17th/18th center Verona violins are supposed to sound better. What I believe to be the case is that if care is taken with every detail like alignment and mitering and temperature control, then you get a noticeably better result. Maybe each factor is only a percent or two but they add up.

We are custom frame builders. Our responsibility isn't to work down to find what is tolerable but rather to make the very best and leave the mediocre and why that is okay to someone else to defend.

TiHabanero

Reporting back after realigning to original drop out set up. Call me nuts, but it made a difference. My wife says I'm not sensitive and I tend to trust her on this, so I figure I am not sensitive to frame alignment, but there has to be something to this. I set the drop outs back to being misaligned and sure enough the bike has a just so light pull to the right again. I am going to try it on another frame and see if I get the same results.

TiHabanero

Have a correction of sorts to make. I have been misinterpreting what was being experienced with the intentional misalignment of the rear drop outs. The bike does not have a "light pull to the right", but more of a willingness to steer to the right. For example when I carve into a right hand corner the bike tracks into the corner more willingly than it does when the drop outs are properly aligned to the main tubes. Therefore I stand corrected in that the drop out misalignment did not change the frame alignment in the way I had thought, it only changes the feel of the bike into a right bender, and does not appear to have a detrimental affect on straight line stability.