Steerer Tube Threading/Compression Bolt Size and Fork Failure

[got bike?]

1mm is far enough to add the strenght it needs. One millimeter seems nothing to us but it's actually adding 1/3.5 of wall thickness.

Thats nearly one third of wall thickness.

[LeonLikesToRock]

I've seen them snap for dudes that run their stems super high (I guess most people do these days). I tend to run my stem as low as possible, so I think the threads end inside my stem on most forks. If the stem is higher than the threads they have more leverage over that cut out bit.

[weedbix]

More likely, I can see that. But do forks really fail here? I cannot recall seeing a fork failing here.

Yeah they do. Nothing like your stem coming off for no reason

They also ovalise way too easy too

[G]

I'm responsible for the 24mm thread.

When I first came to work with Odyssey and we started on forks, I wanted a big enough top bolt to run a front brake cable with the housing and be able to withdraw it without messing with the brake too much. But I also wanted to remove the heat and stress concentration of a welded insert. So that led me to looking at threading the steerer directly and using a big hollow aluminium bolt.
M25 was the nearest off the shelf size, but in a 28.6mm steerer that left a wall thickness of just 1.8mm and WITH the added stress raisers of all the thread tips. So instead I drew up the steerer as a multi-butted tube with a "thick bit" where the bolt goes and to use a 24mm (non standard) thread. This leaves 2.3mm wall thickness whilst keeping the weight reasonable.
I also added a longer "fat" section at another critical area just above the bottom headset seat where there is a lot of stress.

Our competitors obviously looked at these forks and took them to Cyclogic and CWI and said something along the lines of "copy this". But butting the steerer is expensive and difficult, commissioning a 24mm custom tap is more money and more work than just picking up a 25mm off the shelf and so they came up with the brilliant plan of just using a plain bore and shoving the tap in... OK so its massively weaker but it "looks" the same and who REALLY gives a shit right?!? 

So now, our forks are one of the more expensive options, but mysteriously everyone else's lifetime warranties have had to be scaled back and have lots of caveats attached... wonder why that might be...

We aim to make the best, strongest, safest forks we can. We work damn hard at it and go to the added expense of having an actual engineer (me) design them, doing proper testing and not cutting corners. Because snapping forks isnt just "annoying" and might leave you with a warranty claim that doesn't get honored... its fucking horrible.


G.

[Dr. Steve Brule]

Yeah I see so many videos online where forks are snapping and it doesn't seem to be the lower headset cup where they used to break it's always the fork breaking at the top and the stem part coming off. I wouldn't want to imagine this happening at the bottom of a big stairset or something.

[master]

I'm guessing that FBM buys their steerer tubes pre-threaded from their tubing supplier...

And G: thank you for putting the work that you do into your parts.

[badlight]

haha yes,  sparky's literally keeps 25mm alive

Bonedeth, Mutiny, Shadow and Subrosa do all use 25mm...

But so do Colony, Deco, Demolition, Fly, Kink, Macneil, Premium, Snafu, Stolen, Total, Verde... (as far as I can tell).

statistics will be taken into account as soon as someone actually runs something from one of those brands

What kind of dirty Canadian are you, not running Macneil parts. For shame...

[sans.terre]

haha i think the best ive done is pick up an Alliance shirt back in the day. might be the only decent product we ever put out up north of the border.
the OG ruben stem was dece' tho!

[red_spectre]

I'm responsible for the 24mm thread.

When I first came to work with Odyssey and we started on forks, I wanted a big enough top bolt to run a front brake cable with the housing and be able to withdraw it without messing with the brake too much. But I also wanted to remove the heat and stress concentration of a welded insert. So that led me to looking at threading the steerer directly and using a big hollow aluminium bolt.
M25 was the nearest off the shelf size, but in a 28.6mm steerer that left a wall thickness of just 1.8mm and WITH the added stress raisers of all the thread tips. So instead I drew up the steerer as a multi-butted tube with a "thick bit" where the bolt goes and to use a 24mm (non standard) thread. This leaves 2.3mm wall thickness whilst keeping the weight reasonable.
I also added a longer "fat" section at another critical area just above the bottom headset seat where there is a lot of stress.

Our competitors obviously looked at these forks and took them to Cyclogic and CWI and said something along the lines of "copy this". But butting the steerer is expensive and difficult, commissioning a 24mm custom tap is more money and more work than just picking up a 25mm off the shelf and so they came up with the brilliant plan of just using a plain bore and shoving the tap in... OK so its massively weaker but it "looks" the same and who REALLY gives a shit right?!? 

So now, our forks are one of the more expensive options, but mysteriously everyone else's lifetime warranties have had to be scaled back and have lots of caveats attached... wonder why that might be...

We aim to make the best, strongest, safest forks we can. We work damn hard at it and go to the added expense of having an actual engineer (me) design them, doing proper testing and not cutting corners. Because snapping forks isnt just "annoying" and might leave you with a warranty claim that doesn't get honored... its fucking horrible.


G.

Thanks!

[badlight]

haha i think the best ive done is pick up an Alliance shirt back in the day. might be the only decent product we ever put out up north of the border.
the OG ruben stem was dece' tho!

Word. I still have my old Alliance shirts. I wanted a PSI pretty bad as a little grom. You werent the dude walking around the Toronto Bike show last year in a brand new Alliance shirt, were you?

[red_spectre]

haha yes,  sparky's literally keeps 25mm alive

Bonedeth, Mutiny, Shadow and Subrosa do all use 25mm...

But so do Colony, Deco, Demolition, Fly, Kink, Macneil, Premium, Snafu, Stolen, Total, Verde... (as far as I can tell).

statistics will be taken into account as soon as someone actually runs something from one of those brands

What kind of dirty Canadian are you, not running Macneil parts. For shame...

TBH, as a Canadian, I don't see anyone running Macneil products anymore (outside of those few who are sponsored/flowed product). I'm not sure how you go from the Ruben kit, guard sprocket, pivotal etc... to what they offer now. But, I guess that's a topic for another thread...

[barcodebilly]

haha yes,  sparky's literally keeps 25mm alive

Bonedeth, Mutiny, Shadow and Subrosa do all use 25mm...

But so do Colony, Deco, Demolition, Fly, Kink, Macneil, Premium, Snafu, Stolen, Total, Verde... (as far as I can tell).

statistics will be taken into account as soon as someone actually runs something from one of those brands

Green box. We are on the same page

[@ss4oLe]

this video work? I don't know how to embed this stuff.

http://instagram.com/p/wz6FaUA_zk/?modal=true

[dude...]

this video work? I don't know how to embed this stuff.

http://instagram.com/p/wz6FaUA_zk/?modal=true

yeah that worked and fuck that!

even though i never go big, fuck taking risks with the front end of the bike. ive ran odyssey forks from as soon as i could afford them

[Spev]

this video work? I don't know how to embed this stuff.

http://instagram.com/p/wz6FaUA_zk/?modal=true

Brutal, although it would appear that they snapped at the crown. I'd say it would be un-related to the compression bolt thread size, still you don't see Odyssey forks snapping there.