Bicycle Mechanics - potential dangers of what i have done??!!

I have this primo carbon fibre fork which I was determined to use in my current build. The steerer was too short and didnt give me any threads on which to put the top "nut" of my headset. SO.... i filed the bottom part of the steerer where the steerer meets the main part of the fork. I filed off about 4-5 mm of AL. By filing off 4mm have i made it dangerous?

Aside from a potential safety issue, I don't think your headset race will seat properly. Your fork might be scrap.... :(

George

Actually it works fine. I have lots of thread to put on the headset plus its seems seated pretty well. its not perfect but as AL is pretty soft so I think the uneven parts will eventually be compressed down to be even with the rest. If it does compress i will have to tighten up the headset more. Other than that safety is my only real concern. I am not an aggressive rider so i think that helps.

I think thats a bad idea, it will not eventually compress, if it does even out it is going go f up the bearings inside. I thought i had heard it all.

you, know what.... I appreciate non-negative comments.

Sounds unsafe to me. Providing the race seats, you could try some kind of stress test. But not knowing the actual forces a fork has to endure and how to duplicate it, you are on your own.

you, know what.... I appreciate non-negative comments.

In that case, yes it will work fine. You have no worries :p

How's your dental coverage hey? ;)

In that case, yes it will work fine. You have no worries :p

Heheheheh....

While I do not think what you did is a good idea, if you want to level the race seat, a good bike shop should have tool that will face everything to the correct spec.

you, know what.... I appreciate non-negative comments.

I may be confused... Are you asking whether or not it's safe, or are you asking to be told it's safe? ;)

-chris

My basic philosophy is this, if you're questioning what you did or are about to do, don't do it.

Actually Al is a fairly hard metal. That is why AL frames are stiff. So the AL that you have now thinned out, is in more danger of a sudden failure.

You are trusting your health and maybe life to this modified component.

Modifying any structural component (like a fork) is an unsafe practice. This doesn't mean that your fork is now unsafe - just that we don't know. None of us can determine that. To answer your question an engineer would have to analyse the modification and would need the original detailed design data for the fork.

It appears to me that you have removed material from a high stress area of the fork. In doing so, you may have created a 'stress riser' by making a tight corner that allows the forces to be concentrated. This can result in cracks and eventual failure of the fork. In addition, the filing of the aluminum you may have created rough areas on the surface that could do the same.

Whether to use the fork is up to you. If it were mine, I would buy a new fork and ride with no worry.

most times forks and frames and other parts are designed and built a certain way so that they are functional and will last for the intended purpose. When you go modifying them in a manner they were not meant to be, safety and function become subject to failure. By removing metal from a pretty critical area of the fork from a strength standpoint, it becomes a danger.

My .02

I would not ride it.

I have no clue what this guy has done to his fork

I have no clue what this guy has done to his fork

I think what he meant is that he filed 4mm of the crown race seat down so that more steer tube is exposed. Whatever the terminology, it's RISKY to use now.

I thought i had heard it all.



lol no sh*t hey?

4-5 mm is alot of material to take out of a critical area. Plus, by filing at the base, you've likely cut scratches into the steer tube right at the base; a high stress area. Normally, these have a nice smooth radius to reduce the likelihood a crack will initiate there. I'd certainly not risk using a fork with this kind of damage.

Let's end on the positive side: It may not crack for a long time, depending on how and where you ride. And, BC has universal health care coverage for you when it does.

How does the crown race fit on the steerer now? It looks like you removed the area that it fits onto. So now, not only have you created a stress riser, you have also created a situation that will wear the bearings more quickly.

Modifying any structural component (like a fork) is an unsafe practice. This doesn't mean that your fork is now unsafe - just that we don't know. None of us can determine that. To answer your question an engineer would have to analyse the modification and would need the original detailed design data for the fork.

It appears to me that you have removed material from a high stress area of the fork. In doing so, you may have created a 'stress riser' by making a tight corner that allows the forces to be concentrated. This can result in cracks and eventual failure of the fork. In addition, the filing of the aluminum you may have created rough areas on the surface that could do the same.

Whether to use the fork is up to you. If it were mine, I would buy a new fork and ride with no worry.

Nice explaination, I could not agree more.

In that case, yes it will work fine. You have no worries :p

ROFLMAO!!!!!!!

Having experienced catastrophic fork failure in a downhill race back in the late 80's, I know first hand, no, make that face first, what it means to have my fork disappear from in front of me. I do not mean to be negative, but it is real tough to put a positive twist on the experience. That said, I think you may want to rethink your search for positive vibes from the clan concerning this matter. Lose the fork.

"That said, I think you may want to rethink your search for positive vibes from the clan concerning this matter. "

I wonder why?

I appreciate those who gave CONSTRUCTIVE advice.

I guess i am not a bike purist and I guess I won't get any credit for creativity from this group.

"That said, I think you may want to rethink your search for positive vibes from the clan concerning this matter. "

I wonder why?

I appreciate those who gave CONSTRUCTIVE advice.

I guess i am not a bike purist and I guess I won't get any credit for creativity from this group.

"By filing off 4mm have i made it dangerous?"-Veganheart-

You asked this question, so don't get all sucky when the answers you get are not those you wanted.