# 1 inch disc fork safety concern



## Golem builder (Jul 31, 2009)

Someone is asking me to bulid a replacement fork for a Koga Signature touring bike. 

The current one is built with a threaded 1'' steerer and lugged crown. It failed at the right fork blade where the canti stud is brazed. It was alerady built with a disc tab and used with disc brake.

I'm I right to raise concerns about a 1'' steerer strength?

If I'd build it, I'd weld a massive slug below the crown race so disc brake suitable blades can be welded.

Thanks for your input.

Guillaume


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## tfinator (Apr 30, 2009)

Plenty of bikes were made with 1" steerers and disc brakes and worked fine. 

It's not as stiff, but it is not going to fail for that reason.

Sent from my Moto G (5) Plus using Tapatalk


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## scottzg (Sep 27, 2006)

I have no right to be dispensing fork building advice, but it seems like 1" x .120 straight gauge should be plenty stiff and strong for that application.



tfinator said:


> Plenty of bikes were made with 1" steerers and disc brakes and worked fine.


Not to disagree, but I don't know of any. Seems like 1" steerers disappeared long before disk brakes arrived.


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## seren (Dec 6, 2013)

Several thousand km Touring, loaded, gravel, off-road this year on a set of Handbuilt 1” threaded, 853 disc bladed Pacenti crowned forks, no issues... 👍🚲😀


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## m-gineering (Feb 5, 2012)

Golem builder said:


> Someone is asking me to bulid a replacement fork for a Koga Signature touring bike.
> 
> The current one is built with a threaded 1'' steerer and lugged crown. It failed at the right fork blade where the canti stud is brazed. It was alerady built with a disc tab and used with disc brake.
> 
> I'm I right to raise concerns about a 1'' steerer strength?


let me get this straight. The forkblade broke, the steerer held up. You worry about the strenght of the steerer?

( the steerer doesn't really know what kind of brake is down below, although a crummy rimbrake might make life easier than a proper disk, same goes for the downtube)


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## Eric Malcolm (Dec 18, 2011)

And the disc caliper is on the left hand side....

Eric


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## dr.welby (Jan 6, 2004)

Golem builder said:


> It failed at the right fork blade where the canti stud is brazed.


Can you post a picture of this? That's an interesting place for a failure.


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## PHeller (Dec 28, 2012)

If any builders might be interested in trying such a project, PM me. I've got a 1" fork that I'd like to recreate with disc tabs.


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## Golem builder (Jul 31, 2009)

Hi

I'm going ahead on this one. In fact it was the interface of the unicrown fork blades (29/21mm oval) with the 25.4mm steerer that bugged me. But with the 1 3/8 slug it will be more than fine.

Here are the pictures the Customer sent me. When I asked he did not remember how it happened, but to me it looks like the wheel slipped from the left dropout (no layer lips and rear facing opening) from the disc braking efforts but somehow stayed hanged on the right one and bent the blade.


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## briderdt (Dec 14, 2012)

Some leaned on the bike when it was attached to a fork-mount roof rack?


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## Golem builder (Jul 31, 2009)

briderdt said:


> Some leaned on the bike when it was attached to a fork-mount roof rack?


I have a lot of hypotheses in my mind. I think we'll never know what truly happened.

I'll post pictures of the replacement fork once finished.

cheers


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