Rear Triangle Alignment -- Will 6mm make a difference I can feel?

On Fri, 13 Mar 2009 11:25:01 -0700 (PDT), Jeff
wrote:

On Mar 13, 10:16*am, wrote:
On Fri, 13 Mar 2009 10:10:11 -0700 (PDT), Jeff





wrote:
On Mar 12, 5:46*pm, jim beam wrote:
Jeff wrote:
On Mar 12, 2:47 pm, wrote:
On Mar 12, 5:38 pm, Jeff wrote:

I just bought a new carbon road bike frame, and when I measured the
rear triangle, I found it offset 6mm to the left.
[snip]
the wheel is centered because of spacers on the axle ? how did you
measure to determine the offset ? care to name the manufacturer of the
frame ?

I used the rear wheel from my current road bike. *The rear spacing on
the carbon frame is correct (130mm) so the wheel goes right in and is
centered left/right in the triangle. *Looks to me like the whole rear
tirangle was laid up wrong (jigging error) at the factory...

I measured the offset using a Park frame jig that grabs the frame at
the BB and has an adjustable "slider" arm (similar to the one on the
Park rear derailleur hanger tool) that you can adjust to pick up the
desired part of the frame. *The you reverse the frame (without
changing the slider arm setting) and pick up the same point on the
other side of the frame. *This is a nice heavy-duty stand that makes
coldsetting steel frames as easy as that operation can get. *(I'm not
sure Park makes that stand any longer -- couldn't find it on their
website.)

if it's the tool i think it is, are you measuring to the outside or the
inside of the drops? *if you're measuring to the outside, you can easily
measure a difference, yet the frame is perfectly straight. *different
thickness drops, etc. *what matters is that the two wheels are centered
wrt each other, and that's measured on the *inside* of the drops.

I guess I could take my current steel frame and introduce a similar
6mm misalignment to see if I can feel the offset when I ride it, but I
was hoping that someone would say "Nah, you won't feel it" or "Yeah,
it will be unrideable" to save me the work and mental anguish of
coldsetting an error into a perfectly good frame...

fwiw, i've seen frames with different thickness rear drops set
"centered" for their outside, not their inside, and thus they were
off-center. *apparently it's a simple mistake to make.

and yes, it does make a difference to ride.


Thank you for pointing that out -- I'll measure the dropout thickness
this evening. *The "6mm" figure I stated was an eyeball; last evening
I actually measured the offset and it is 3.7mm. *I still think that is
a lot...

Dear Jeff,

What's the alignment on your current bike on the same Park jig?

Cheers,

Carl Fogel

Hello Carl!

When I built my current steel bike, I cold set it on the same jig for
equal measurments on each dropout. I built it with Campy dropouts
which are the same thickness on the left and right... That was some
years ago, but I haven't crashed the bike (or backed into it with a
car!) so I assume it is still square.

Dear Jeff,

Sounds reasonable to me.

I see some vague concerns in this thread, but I can't help wondering
if anyone can detect a 3.7 mm axle offset by just riding the bicycle.

Apart from the natural wish to have the damn thing dead center, since
it's brand-new, what would a 3.7 mm offset actually do, assuming that
the wheel spins and the pedals turn without hitting the frame?

Make the bike pull to one side? If so, which side? Increase rolling
resistance? Make it more prone to shimmy?

I'm not arguing, just wondering what the specific expectations are.

Cheers,

Carl Fogel

On Mar 13, 1:29*pm, " wrote:
Thank you for pointing that out -- I'll measure the dropout thickness
this evening. *The "6mm" figure I stated was an eyeball; last evening
I actually measured the offset and it is 3.7mm. *I still think that is
a lot...

Note that it would very easy to be measuring _twice_ the alignment
error.

If you set the probe to touch and the flip it to the other side the
gap will be twice the error.

-Brian

Mea Culpa! You are certainly right, Brian. The difference at the
probe is 3.7mm, this is what I have been incorrrectly calling the
"offset", when in reality the offset is half of this or 1.85mm. I'm
now wondering: much ado about nothing?

On 2009-03-13, wrote:
[...]
I see some vague concerns in this thread, but I can't help wondering
if anyone can detect a 3.7 mm axle offset by just riding the bicycle.

Apart from the natural wish to have the damn thing dead center, since
it's brand-new, what would a 3.7 mm offset actually do, assuming that
the wheel spins and the pedals turn without hitting the frame?

Make the bike pull to one side? If so, which side? Increase rolling
resistance? Make it more prone to shimmy?

I'm not arguing, just wondering what the specific expectations are.

One minor problem is the brakes, which could be adjusted to work
satisfactorily, but would suffer from some kind of asymmetric cosine
error of some kind.

For years I rode a bike with the dish completely wrong on the back
wheel but it seemed to ride perfectly all right.

On Mar 13, 1:49*pm, wrote:
On Fri, 13 Mar 2009 11:25:01 -0700 (PDT), Jeff





wrote:
On Mar 13, 10:16*am, wrote:
On Fri, 13 Mar 2009 10:10:11 -0700 (PDT), Jeff

wrote:
On Mar 12, 5:46*pm, jim beam wrote:
Jeff wrote:
On Mar 12, 2:47 pm, wrote:
On Mar 12, 5:38 pm, Jeff wrote:

I just bought a new carbon road bike frame, and when I measured the
rear triangle, I found it offset 6mm to the left.
[snip]
the wheel is centered because of spacers on the axle ? how did you
measure to determine the offset ? care to name the manufacturer of the
frame ?

I used the rear wheel from my current road bike. *The rear spacing on
the carbon frame is correct (130mm) so the wheel goes right in and is
centered left/right in the triangle. *Looks to me like the whole rear
tirangle was laid up wrong (jigging error) at the factory...

I measured the offset using a Park frame jig that grabs the frame at
the BB and has an adjustable "slider" arm (similar to the one on the
Park rear derailleur hanger tool) that you can adjust to pick up the
desired part of the frame. *The you reverse the frame (without
changing the slider arm setting) and pick up the same point on the
other side of the frame. *This is a nice heavy-duty stand that makes
coldsetting steel frames as easy as that operation can get. *(I'm not
sure Park makes that stand any longer -- couldn't find it on their
website.)

if it's the tool i think it is, are you measuring to the outside or the
inside of the drops? *if you're measuring to the outside, you can easily
measure a difference, yet the frame is perfectly straight. *different
thickness drops, etc. *what matters is that the two wheels are centered
wrt each other, and that's measured on the *inside* of the drops.

I guess I could take my current steel frame and introduce a similar
6mm misalignment to see if I can feel the offset when I ride it, but I
was hoping that someone would say "Nah, you won't feel it" or "Yeah,
it will be unrideable" to save me the work and mental anguish of
coldsetting an error into a perfectly good frame...

fwiw, i've seen frames with different thickness rear drops set
"centered" for their outside, not their inside, and thus they were
off-center. *apparently it's a simple mistake to make.

and yes, it does make a difference to ride.

Thank you for pointing that out -- I'll measure the dropout thickness
this evening. *The "6mm" figure I stated was an eyeball; last evening
I actually measured the offset and it is 3.7mm. *I still think that is
a lot...

Dear Jeff,

What's the alignment on your current bike on the same Park jig?

Cheers,

Carl Fogel

Hello Carl!

When I built my current steel bike, I cold set it on the same jig for
equal measurments on each dropout. *I built it with Campy dropouts
which are the same thickness on the left and right... *That was some
years ago, but I haven't crashed the bike (or backed into it with a
car!) so I assume it is still square.

Dear Jeff,

Sounds reasonable to me.

I see some vague concerns in this thread, but I can't help wondering
if anyone can detect a 3.7 mm axle offset by just riding the bicycle.

Apart from the natural wish to have the damn thing dead center, since
it's brand-new, what would a 3.7 mm offset actually do, assuming that
the wheel spins and the pedals turn without hitting the frame?

Make the bike pull to one side? If so, which side? Increase rolling
resistance? Make it more prone to shimmy?

I'm not arguing, just wondering what the specific expectations are.

Cheers,

Carl Fogel- Hide quoted text -

- Show quoted text -

I think you've summarized the crux of the matter, Carl. Will I feel
the difference or not? I'm not a club racer, but I do like to hammer
on the downhills (usually to catch the group that dropped me on the
climb!), and I *did* notice a marked difference in the fast downhill
handling of my steel (Columbus SL) bike when I switched out the
Columbus fork for an Easton aluminum. My point here is that I'm not
totally numb, and I'm guessing that any handling quirks caused by the
offset would be most apparent at high speed, where I like to ride. If
it is a "No harm, no foul" situation, then it wouldn't bother me that
the triangle was offset. In fact, you can't really see the offset
with the "naked eye" because the rear wheel is centered correctly in
the triangle, and if the handling/tire wear/whatever is not adversely
effected by the offset, over time I'd probably forget that it was
there. The 60's will do that to ya'...

On Mar 13, 5:49*pm, wrote:
On Fri, 13 Mar 2009 11:25:01 -0700 (PDT), Jeff





wrote:
On Mar 13, 10:16*am, wrote:
On Fri, 13 Mar 2009 10:10:11 -0700 (PDT), Jeff

wrote:
On Mar 12, 5:46*pm, jim beam wrote:
Jeff wrote:
On Mar 12, 2:47 pm, wrote:
On Mar 12, 5:38 pm, Jeff wrote:

I just bought a new carbon road bike frame, and when I measured the
rear triangle, I found it offset 6mm to the left.
[snip]
the wheel is centered because of spacers on the axle ? how did you
measure to determine the offset ? care to name the manufacturer of the
frame ?

I used the rear wheel from my current road bike. *The rear spacing on
the carbon frame is correct (130mm) so the wheel goes right in and is
centered left/right in the triangle. *Looks to me like the whole rear
tirangle was laid up wrong (jigging error) at the factory...

I measured the offset using a Park frame jig that grabs the frame at
the BB and has an adjustable "slider" arm (similar to the one on the
Park rear derailleur hanger tool) that you can adjust to pick up the
desired part of the frame. *The you reverse the frame (without
changing the slider arm setting) and pick up the same point on the
other side of the frame. *This is a nice heavy-duty stand that makes
coldsetting steel frames as easy as that operation can get. *(I'm not
sure Park makes that stand any longer -- couldn't find it on their
website.)

if it's the tool i think it is, are you measuring to the outside or the
inside of the drops? *if you're measuring to the outside, you can easily
measure a difference, yet the frame is perfectly straight. *different
thickness drops, etc. *what matters is that the two wheels are centered
wrt each other, and that's measured on the *inside* of the drops.

I guess I could take my current steel frame and introduce a similar
6mm misalignment to see if I can feel the offset when I ride it, but I
was hoping that someone would say "Nah, you won't feel it" or "Yeah,
it will be unrideable" to save me the work and mental anguish of
coldsetting an error into a perfectly good frame...

fwiw, i've seen frames with different thickness rear drops set
"centered" for their outside, not their inside, and thus they were
off-center. *apparently it's a simple mistake to make.

and yes, it does make a difference to ride.

Thank you for pointing that out -- I'll measure the dropout thickness
this evening. *The "6mm" figure I stated was an eyeball; last evening
I actually measured the offset and it is 3.7mm. *I still think that is
a lot...

Dear Jeff,

What's the alignment on your current bike on the same Park jig?

Cheers,

Carl Fogel

Hello Carl!

When I built my current steel bike, I cold set it on the same jig for
equal measurments on each dropout. *I built it with Campy dropouts
which are the same thickness on the left and right... *That was some
years ago, but I haven't crashed the bike (or backed into it with a
car!) so I assume it is still square.

Dear Jeff,

Sounds reasonable to me.

I see some vague concerns in this thread, but I can't help wondering
if anyone can detect a 3.7 mm axle offset by just riding the bicycle.

Apart from the natural wish to have the damn thing dead center, since
it's brand-new, what would a 3.7 mm offset actually do, assuming that
the wheel spins and the pedals turn without hitting the frame?

Make the bike pull to one side? If so, which side? Increase rolling
resistance? Make it more prone to shimmy?

I'm not arguing, just wondering what the specific expectations are.

Cheers,

Carl Fogel- Hide quoted text -

- Show quoted text -

I think you might find your rear wheel more prone to sliding out when
leaning into a hard corner- I'm not sure, it was a long time ago and
my early wheel builds using a manure truing stand ( centred in the
stand but visbly off in the frame), so it could be something else.

On Mar 13, 6:08*pm, Jeff wrote:
On Mar 13, 1:29*pm, " wrote:

Thank you for pointing that out -- I'll measure the dropout thickness
this evening. *The "6mm" figure I stated was an eyeball; last evening
I actually measured the offset and it is 3.7mm. *I still think that is
a lot...

Note that it would very easy to be measuring _twice_ the alignment
error.

If you set the probe to touch and the flip it to the other side the
gap will be twice the error.

-Brian

Mea Culpa! You are certainly right, Brian. *The difference at the
probe is 3.7mm, this is what I have been incorrrectly calling the
"offset", when in reality the offset is half of this or 1.85mm. *I'm
now wondering: much ado about nothing?

2 mm is nothing unless you are going for the hour perhaps.

On Mar 13, 4:34*pm, Jeff wrote:
Will I feel the difference or not?

I should think so, but I am amazed at what people have not noticed
about their bikes in the past.

Chainline, and crank clearance are obvious concerns, but how the bike
will track when you sit up to ride hands free is another. You will
likely have to cock your body off to the side to get it to track
straight, which gets old. If it is new, I would get it replaced. No
reason to have a new product which was build wrong be your problem.
Demand better from the maker.

Chris

Jeff wrote:
On Mar 13, 1:29�pm, " wrote:
Thank you for pointing that out -- I'll measure the dropout thickness
this evening. �The "6mm" figure I stated was an eyeball; last evening
I actually measured the offset and it is 3.7mm. �I still think that is
a lot...
Note that it would very easy to be measuring _twice_ the alignment
error.

If you set the probe to touch and the flip it to the other side the
gap will be twice the error.

-Brian

Mea Culpa! You are certainly right, Brian. The difference at the
probe is 3.7mm, this is what I have been incorrrectly calling the
"offset", when in reality the offset is half of this or 1.85mm. I'm
now wondering: much ado about nothing?

sounds increasingly likely. what make is the frame?

Just bought a used 1978 Trek 531 frame that had been spread to fit a
10 speed by just settng the drive side. Of course it was out of
alignment and it was interesting how it felt as I worked on it.

Original setup rode fine as long as my hands were on the bars. No
handed it pulled to the left dramatically. Using the sting around
head tube method, I set both sides of the triangle roughly and tried
it again. There was a great improvement, but it still pulled to the
left.. Another run at it with more care and now it rides pretty
straight. Not perfect but the string method is not as accurate as
your setup.

Wayne