New M-part steel fork – gap between crown race seat and steerer?

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Northern_Monkey
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Joined: 7 Jul 2013, 10:22am

New M-part steel fork – gap between crown race seat and steerer?

Post by Northern_Monkey »

Hi, did post the same question on another cycling forum to get a broader range of views so hopefully within the Cycling UK guidelines still :D

Trying to see if I’m over thinking this/being unreasonable or just used to seeing brazed or epoxied forks where the crown race seat is a bit neater/covered in grease?

Bought a heavily discounted new M-Part hybrid fork as the one on my current commuter bike needs repainting before winter and I still need to use my bike for work in the meantime.

Finish looks pretty tidy except there is a gap between the crown race seat and steerer body. Weld on the underside of the seat looks fairly substantial. I can slide a piece of paper 3-4mm in as shown in the pics most of the way around.

If it is safe, just a bit of Kurust and smidge of JB weld to fill the gap before getting it faced or should I return it to the seller if it is potentially unsafe?

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rogerzilla
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Joined: 9 Jun 2008, 8:06pm

Re: New M-part steel fork – gap between crown race seat and steerer?

Post by rogerzilla »

I wouldn't ride it.
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Northern_Monkey
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Joined: 7 Jul 2013, 10:22am

Re: New M-part steel fork – gap between crown race seat and steerer?

Post by Northern_Monkey »

@rogerzilla - Yeah, pretty much decided on that as well to be honest.

I will get in touch with the seller as it is just about the last part of the bike I would want to go wrong.
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Northern_Monkey
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Joined: 7 Jul 2013, 10:22am

Re: New M-part steel fork – gap between crown race seat and steerer?

Post by Northern_Monkey »

Retailer has accepted a return as they think it sounds faulty and confirmed the others in stock don’t have a gap so should be getting a replacement.
alexnharvey
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Joined: 10 Jan 2014, 8:39am

Re: New M-part steel fork – gap between crown race seat and steerer?

Post by alexnharvey »

That's not really structural though. It's just soldered in place.
rogerzilla
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Joined: 9 Jun 2008, 8:06pm

Re: New M-part steel fork – gap between crown race seat and steerer?

Post by rogerzilla »

It's usually part of the crown (maybe part of the middle tube on a unicrown fork, I don't know how that one's put together under the paint).
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531colin
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Re: New M-part steel fork – gap between crown race seat and steerer?

Post by 531colin »

Well, it doesn't matter now, if you are sending it back, but I think its probably OK.

The way these things are made is ....the fork blades are (usually)** welded directly to the steerer; the crown race seat is a "ring" that is dropped down onto the top of the fork blades and welded to the top of the blades and to the steerer at that level. There is a picture here https://bicycles.stackexchange.com/ques ... race-stays . The top of the ring/crown race seat isn't welded to the steerer, because you don't want to risk weakening the steerer there, and you don't want to ruin your crown race seat cutter trying to cut weld. I suppose a counsel of perfection would be to run some braze between the crown race seat ring and the steerer, after the structural welding is done..

**I have seen a re-inforcing sleeve fitted to the bottom of the steerer, and only welded to the steerer right at the bottom for the reasons above; the fork blades were welded onto the reinforcing sleeve....this might have been a tandem fork, recollection grows dim.

EDIT......bugger! I knew this came up before, could have saved a finger-end typing !! viewtopic.php?f=5&t=143784&p=1575781&hi ... n#p1575781
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Northern_Monkey
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Re: New M-part steel fork – gap between crown race seat and steerer?

Post by Northern_Monkey »

Thanks everyone, it was the kind with the fork legs welded directly to the steerer baseand the crown race seat dropped over the top and welded underneath.

Colin - Your link to the e-bike shows exactly the kind of failure I was worried about! 😅

The person in the shop confirmed the replacement one is fully supported behind the crown race and should be with me next week, they will be looking to get a credit from their supplier based on the pics I sent.
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