A question to frame vendors/repair shops regarding Standard bykes custom

[TpeHep]

My question is mostly about allowed precision error on a new BMX frame,
and from a repair shop point of view - what amount of rear triangle
displacement is required to tell that frame is untrue and needs fixing?

Some background story:

Last year I've ordered a custom frame from SBC, it was around october i think.
I was really happy to see it arrive a bit earlier than they have estimated,
just before my birthday. It looked truly great, and while looking it around,
i've looked at rear triangle alignment as a joke (as if it could be wrong on a new frame,
especially SBC one, you know). I can't really forward changes in my face expression
as recognition of assymetry there was becoming more clear with every second.

But, remembering where i ordered the frame, i was more likely to believe
my eyes are wrong, so i did pretty much every validation possible, triple-checking
everything, with things you can find around the house, and all methods kept telling me frame
is untrue.

There were some other minor issues too, which are outside of question topic.

Nothing to do, i had to mail SBC, giving a detailed description of a problem
i've seeing. After few mails (first they suggested to build frame and see how it works,
despite obvious flaws) i was asked to send frame back.

So i've sent frame back, asking to let me know how it is. After some month of silence,
i write again to check how it goes, and get a reply they have received it long ago
and there was nothing wrong with the frame.

What?..

Then I've got one of pics i made before to describe an issue, and created an animation out of it,
so that issue is obvious, and sent another mail with some flames.

After that it turned out their employee actually fixed frame before reporting
everything is ok with it. I'm not really sure how you can fix such a problem, tbh.
Well, ok, no problem.

By some wild chance frame arrived back after checking on friday 13th..
And guess what, not much has changed!

This order, i believe, is not less legendary than SBC itself.
I've mailed SBC again but didn't get another reply in two weeks, so i think they
don't want to talk to me anymore about this.

I don't have any problems with SBC whatsoever, they sure can work how they want,
it's more of my problem that i like or don't like their work. This story might
be valuable for people considering to order something there, though. But keep in mind that
my experience with SBC sure may vary from other's, and this is perhaps a somehow outstanding issue.
Maybe other Standard owners have seen similar issue?

Also, as i see it, no allowed precision errors are settled on during custom
frame build arrangement, so objections are not tecnically valid.



So i'm asking this question here just for myself, to know if
my overview of the frame i received is reasonable/valid. It could
be that most vendors do frames like this and it's totally normal.
My current frame, which is used for a while, and other frame i have
do not show such an issue when tested using same technique.

What are general allowed precision errors on geometry?
For example:
Headtube 74.5 degrees (+/- 0.05 degrees)
Rear dropouts: (+/- 1mm)

Is displacement shown on animation enough to consider (new/used) frame untrue?

Animation i made before sending frame back


After receiving frame back

[Dr. Steve Brule]

Do any local shops have a Park Tool alignment guide?

http://www.parktool.com/blog/repair-help/frame-alignment

There's always the string technique too:

http://www.mytenspeeds.com/My_TenSpeeds_1/Site%20Contents/How_To_Do_It/FrameSetPrep_5_StringingFrameSet.htm

[G]

With ANY welded structure there will be some movement. Setting a reasonable tolerance on this is open to debate and will obviously depend on the application.

Expecting a head angle to be within 0.05degrees is crazy. +/-0.25 of a degree is completely reasonable and most frame builders should have no problem hitting this.

For the straightness of the back end, I would expect most aftermarket frames to easily come within 2mm of true.

I have no idea how you made your animation and how accurate it is, but it looks pretty dramatically bent to me (though this could possible be achieved by camera angles etc) certainly a dropouts thickness or more out of true which I personally would not consider acceptable and I wouldn't be prepared to ride (not due to safety issues but just because it would mess up my riding).

I would echo the recommendation that you find a bike shop (or builder) that can check it for you and put a definite number on the flaw and go from there.

Good luck, I hope you get it resolved satisfactorily.


G. 

[TpeHep]

Do any local shops have a Park Tool alignment guide?

http://www.parktool.com/blog/repair-help/frame-alignment

There's always the string technique too:

http://www.mytenspeeds.com/My_TenSpeeds_1/Site%20Contents/How_To_Do_It/FrameSetPrep_5_StringingFrameSet.htm

Nice links, thank you!

With ANY welded structure there will be some movement. Setting a reasonable tolerance on this is open to debate and will obviously depend on the application.

Expecting a head angle to be within 0.05degrees is crazy. +/-0.25 of a degree is completely reasonable and most frame builders should have no problem hitting this.

For the straightness of the back end, I would expect most aftermarket frames to easily come within 2mm of true.

I have no idea how you made your animation and how accurate it is, but it looks pretty dramatically bent to me (though this could possible be achieved by camera angles etc) certainly a dropouts thickness or more out of true which I personally would not consider acceptable and I wouldn't be prepared to ride (not due to safety issues but just because it would mess up my riding).

I would echo the recommendation that you find a bike shop (or builder) that can check it for you and put a definite number on the flaw and go from there.

Good luck, I hope you get it resolved satisfactorily.


G. 

I sure agree that visual displacement may be a result of camera lens distortion, but at the same time i find it rather challenging to give a visual representation of such an issue using photo. This animation is best i could come up with. I can certainly see same issue with eye or other validation tech and agree this is not a best way to measure something.

Animation is a picture and it's mirror image.. first animation is made from photo (camera1), other from a video screenshot (camera2).

For second animation, i just made a video holding camera straight above frame, then took a screenshot
from a video, catching a point where seat tube is vertically aligned with a headtube (you can see HT gyro tabs under seat tube, they are symmetric and stand out for same distance, i've checked). An animation is made from that screenshot and it's mirror.

This means that actual displacement is visual displacement divided by 2. Dropouts are 6mm think,
meaning it's about +3mm displacement to one side (and -3mm on mirror, creating total visual displacement of ~6mm on animation, which is about dropout thinkness).

I'm not sure how to interpret ".. easily come within 2mm of true ..". Is this +/- 1mm from perfect or +/- 2mm from perfect? I'd say +/- 1mm from perfect is reasonable. Angle precision value of 0.05 was just for example, and perhaps not a very good one. +/- 0.2 seems reasonable.

I was also thinking if some bike shop could measure it for me, but i doubt i can find bike shops having such tools around. Perhaps i'll try to find a way to get a definitive measurement anyway.

I would say rear end is displaced too, but keeping in mind SBC authority is over 9000, i rather prefer to doubt my views.

Anyway, thank you for valuable advice! And for great hubs too, i'm sure you recognize Homer hub there

I should also note frame seems great otherwise.. And here's another photo, where you can see
changing hub to other side has no effect and wheel would be displaced against front triangle.

[stevet1]

Just to add a little to this discussion - I had an issue with my custom standard frame a few years back, I wanted a longer rear end than normal and specified how long it should be - original frame was at leat half an inch out. Took a few emails and I paid the return postage but eventually I got a frame I was happy with.

[paranoidmexican]

[streetStreet]

Well rep[ort back, I hope it all works Well because I was just speaking with JEss @ SBC for the past few weeks about getting a custom frame done.

[Sasha]

Not acceptable. BMX is cheap but you want what you pay for.

[master]

I'd return it for a refund and go elsewhere. It's sad that something that crooked came from SBC.

[@ss4oLe]

lairdframe.com

Sucks to pay so much and have stuff not be close to perfect.

[Prodigal Son]

Jess is rad. After my last bike got stolen I asked them if they had any rejects or whatever sitting around for a discount. They just hooked me up with what I wanted.

[G]

To clarify.

I would expect pretty much any aftermarket frame to be within 2mm of true (maximum). ie. each dropout within 2mm of where it should be. 1mm or less would be more acceptable for a higher end frame, and I personally probably wouldn't be very happy even at the top end of this. Anything over 2mm is very bad indeed and 3mm is taking the piss.

I would also suggest that you check the dropout spacing (should be 110mm) and parallel-ness (just measure spacing at the front and back, should be within 0.2mm or less I would hope) and also check to see whether the frame is twisted (put a wheel in the back and see how well it lines up with the seat tube).

With custom frames the jig needs to be adjusted to the buyers preference so there is always room for something to move by accident (a proper production jig would be tack welded in place to prevent this) OR it is possible that the frame just moved a lot when fully welded. Either way, any reputable builder should be keen to set things straight and fix it for you as long as you are understanding and patient.

I hope this helps.


G.

[TpeHep]

Well, thank you everyone for your input It's sure good to see i'm not completely insane yet.

I wasn't really looking at further interaction with Standard, as they
are already seriously compromised - by the fact that they could
come up with something like this alone, not to mention inability to
detect such a displacement. And sending me same crap twice.

Hopefully i will find someone properly capable later on..

But, keeping in mind previously entertaining experience, i though
i'd drop an extra email there. I've made a video with a string check
and linked it in email.

http://youtu.be/iWaXnKFB2Eg

During few following emails, Jess suggests that
"..  It fit in our alignment table perfect, it may "look" off, but it is true and that is what matters.  Please Build this thing up and ride it.   .."
and
".. The alignment is perfect and checked often for accuracy.  Build the bike, please.  .."
and
".. I saw the video.  Your video not tell me that the bike is not able to be ridden. .."
with spelling errors corrected.

Well rep[ort back, I hope it all works Well because I was just speaking with JEss @ SBC for the past few weeks about getting a custom frame done.

Due to mentioned above, i'm afraid i cannot recommend to build custom frames at Standard at this time.
This might still resolve somehow, and i will be honest to update accordingly, but for now - if you want to make something there, you probably should be prepared to deal with issues and wait for a year or so.
And make sure to ask about for allowed precision error

Custom fork they made seems ok, btw. You don't simply find someone to make a fork you ask for.
It could use a better steerer, though, but that's my opinion.

[@ss4oLe]

Lairdframe dot com

[master]

http://www.pedaldrivencycles.com/

FIFY