Question for any framebuilders out there

[stevet1]

Is it possible to have a front end impact which alters the head angle by 1.5 - 2 degrees on a steel frame without having any visible evidence of it such as a crack or dent etc?

Is it possible for a frame to not be welded to the required head angle in the first instance.

Thanks.
Steve T.

 

[Ally]

I'm not a frame builder, but I would say:

Any impact which changes geometery that much and you would certainly have visible signs of damage.

Frames can easily vary from the brochure spec when it comes to frame angles. The better quality, or manufacurer of the frame, the less likely it is to happen though.

 

[stevet1]

Hmm and what about a hand-built frame where the builder swears its impossible that the frame left his workshop out of spec?

 

[cchris2lou]

if his jig was not set properly , you would have a difference , but surely he must have checked all that .

 

[stevet1]

Yep I'd like to think it would have been checked. Its very odd and I'm not sure what to do, I have no proof it was out of spec originally but I can't see how it can have moved that much and not leave a crease or something in the frame and neither can the builder. But he also denies it left him this way so I'm just looking for an explanation.

 

[cchris2lou]

surely it is his responsability till you receive the frame and are happy with it .

was the box damaged ?

 

[MikeD]

If the tubes are straight and there are no creases or paint cracks, then it's not moved. Which either means it was built wrong or it's being measured wrong. Or there's been a misunderstanding over fork length. Or you're running a very thin front tyre and a very fat rear one ;-)

 

[stevet1]

To elaborate more - its not a new frame (3 years old) and I have crashed it a few times (its a BMX). If there was a dent or a crease or even a ripple in the paint I'd happily accept it was my fault. The only evidence I can see is a very slight paint discolouration around the headtube / downtube junction but it is perfectly smooth. Could this be all I'd see? The frame is brazed with long gussets on the top and down tube.

My angle finder seems to be accurate, I've measured it 10 times or more hoping to be wrong, the seat angle is spot on and so are other BMX frames I've measured. I'm running the same tyres front and rear.

 

[beagle]

If it had moved due to an impact there would almost certainly be some signs. Even though two degrees makes huge a difference to how a BMX frame rides, it hasn't really moved that far if it is down to impact so maybe the signs wouldn't be as obvious. You'd think the paint would have cracked though. Maybe strip the paint around the headtube/downtube junction and have a look?

Out of curiosity, why has it only just become a problem if you've been riding the frame for three years?

 

[Ally]

Can you return it to him then for him to measure?

Whatever you are using to measure it, I take it you have checked the other frame angles and all is ok with them?

What led you to check it? When and how did this come about?
I.E. did you notice that the ride had changed, or did you just notice that it looked wrong/different?

Pics??? Before and after noticing the difference. Have you tried superimposing to see if there has been a change.

Can you post pics so we can see please.

What about frame alignment? If its had an impact chances are the alignment would also be out.