Alignment question: File a dropout?

[Will Outlaw]

All, I got the chainstays attached to Son of FrankenFrame today and ran into an alignment issue.

I am 99.97% positive that the left stay is about a hair (maybe 1/2 to 1mm) lower than the right (Grrrrrr.) The left and right wheelbases are the same, I checked the dropout alignment relative to each other with my Park alignment bells and they're spot on and the string around the headtube check shows maybe 1/2mm difference, so I'm pretty confident that the rear triangle is actually centered relative to the seat tube.

Still, looking from the rear with a wheel (or my T-gauge) the top is obviously leaning a touch to the left (non-drive side). Flipping the wheel shows the same effect, so I'm certain it's alignment and not dish.

So, since the seat stays aren't attached yet I figured I'd get this sorted before moving on.

If I push up ever so slightly on the left stay with the wheel in place everything goes beautifully into alignment, which leads me to two thoughts:

1: Try to cold set the left stay, which I have no experience doing and which will probably wind up doing more harm than good

or

2: File the left dropout 1mm or so to get the wheel into alignment

Keeping in mind this is a frame for me, and the 2nd one I've ever built, are than any hazards with just filing the dropout a bit to, in effect, get the left side of the axle to move up slightly and correct the alignment problem?

I kind of figure the stay is happy where it is and cold setting it or trying to hold it in place when I attach the seat stays is just going to add stress that doesn't need to be there.

Filing the drop out seems a bit, um, non-Zen and the Art of Motorcycle Maintenance to me, but it also seems like the lesser of two evils. To my inexperienced brain it just sort of made sense.

Thoughts? Is tweaking the dropouts with a file to correct a slight lean insane? Common? A cop-out?

[e-RICHIE]

On your second frame it's too soon to wax spiritual about margins of error.
Get a rat tail file and show it who's boss atmo.

[edoz]

The seatstays aren't attached yet? If it's just a mm or so and you're not using super duper heat treated uber thin tubes, I'd bump each stay about half way. It won't take much.

[Will Outlaw]

I'll grab some Twizzlers, stop pussy footing about and get it done one way or the other. :-)

On your second frame it's too soon to wax spiritual about margins of error.
Get a rat tail file and show it who's boss atmo.

[jon_norstog]

All, I got the chainstays attached to Son of FrankenFrame today and ran into an alignment issue.

I am 99.97% positive that the left stay is about a hair (maybe 1/2 to 1mm) lower than the right (Grrrrrr.) The left and right wheelbases are the same, I checked the dropout alignment relative to each other with my Park alignment bells and they're spot on and the string around the headtube check shows maybe 1/2mm difference, so I'm pretty confident that the rear triangle is actually centered relative to the seat tube.

Still, looking from the rear with a wheel (or my T-gauge) the top is obviously leaning a touch to the left (non-drive side). Flipping the wheel shows the same effect, so I'm certain it's alignment and not dish.

So, since the seat stays aren't attached yet I figured I'd get this sorted before moving on.

If I push up ever so slightly on the left stay with the wheel in place everything goes beautifully into alignment, which leads me to two thoughts:

1: Try to cold set the left stay, which I have no experience doing and which will probably wind up doing more harm than good

or

2: File the left dropout 1mm or so to get the wheel into alignment

Keeping in mind this is a frame for me, and the 2nd one I've ever built, are than any hazards with just filing the dropout a bit to, in effect, get the left side of the axle to move up slightly and correct the alignment problem?

I kind of figure the stay is happy where it is and cold setting it or trying to hold it in place when I attach the seat stays is just going to add stress that doesn't need to be there.

Filing the drop out seems a bit, um, non-Zen and the Art of Motorcycle Maintenance to me, but it also seems like the lesser of two evils. To my inexperienced brain it just sort of made sense.

Thoughts? Is tweaking the dropouts with a file to correct a slight lean insane? Common? A cop-out?

Woutlaw,

When I was starting out I did use a file to trim dropouts on occasion. However, since you haven't brazed up the seatstays, you can easily tweak the chainstays into line. Check the spec to see which stay gets the tweak. One mm is nothing to worry about, IMHO.

I usually check rear end alignment constantly as I braze up the seatstays. A light tacking is best, in case you have to undo a stay and adjust. Before you braze things up tight, make certain the wheel is centered and true, and that it is in plane with the front triangle. I think you will find it fairly easy to get the alignment right.

good luck!

jn


"Thursday"

[Will Outlaw]

Thanks guys.

Since I'm so darn new at this I worry about everything. Gotta remember that it's just metal.

It's funny, I got the rear-end alignment a bit wonky on FrankenFrame, not bad, just offset slightly.

So this time around I was obsessive over it, made two tiny tacks, triple checked that the stays were centered and the wheelbases correct, even remembered to check the bottom bracket drop (which I got wrong on FrankenFrame as well because I sort of forgot about it), albeit on one side only. See where this is going? :-)

In fact, I was so concerned about not repeating the same mistake I left everything in my ad-hoc jig and didn't pop a wheel in and just look at the damn thing before brazing it up nice and solid.

So it was a new mistake, but another great learning experience.

That rear triangle is by far the hardest bit for me, but it'll come out better on the next one.

I am so glad that I'm building these early frames without a jig: Just the sky, a tape measure, an angle finder, some files, a bit of string, my hands and my eyes. It's (slowly) giving me a feel for the metal and an understanding of the process I don't think I would be getting with a fixture in between us.

I can't describe how the top tube on Son of FrankenFrame "felt" better than it did on FrankenFrame when after an entire day of tweaking the miters it was fitted up, but it did.

Or at least I think it did. I still don't know what I don't know, but at least I know a little bit more what I don't know. :-)

Cheers!

Will

[Will Outlaw]

Just an update.

I munched on some Twizzlers, thought about it for a while then thought "what the hell, it's only a bicycle." So I grabbed a broomstick and had at it.

2012-05-21_09-49-43_152.jpg

A few minutes later the rear wheel alignment was vastly improved and I was slightly less terrified of cold setting chain stays. Such is life on the near-vertical side of the learning curve. :-)

[Luke]

Just an update.

I munched on some Twizzlers, thought about it for a while then thought "what the hell, it's only a bicycle." So I grabbed a broomstick and had at it.

2012-05-21_09-49-43_152.jpg

A few minutes later the rear wheel alignment was vastly improved and I was slightly less terrified of cold setting chain stays. Such is life on the near-vertical side of the learning curve. :-)

Hells yeah! I keep a pipe next to every work bench for just such an occasion. (and for customer relations from time to time.)
I like the bit about it 'only being metal'.
It is what it is.
Keep crackin'.
Luke