Steerer Tube Threading/Compression Bolt Size and Fork Failure

[red_spectre]

In the past I have read that forks that are threaded for 25x1.5mm compression bolts (correct me if I am wrong) are more likely to fail.

Sam from Tree, for instance, writes on their website (when describing their Okan forks): "I have found that forks with a 25mm compression bolt have a higher risk of snapping off the headtube."

Why is this the case? Is this based purely on anecdotal evidence? Can 1mm really have such a difference (24x1.5mm vs 25x1.5mm) and if this is the case why not use 10x1.25mm (like S&M/FIT) or 18x1.5mm (Cult) etc...?

When I browse forks online, it seems that the majority of brands are manufacturing forks for 25x1.5mm (a quick browse on Dan's for instance, will confirm this).
If they are inferior why is this still the case?

[Stoked]

S&M uses a welded pc similar to a starnut and I think same goes for cult.  They don't thread their steerers

Whatever odyssey does (24?) is probably the best

[weedbix]

It''s because 25 doesn't leave enough wall thickness

It's still used purely out of ignorance/apathy

[Dr. Steve Brule]

1mm less wall thickness is a fair bit when it's on a steerer.

[red_spectre]

But then, I wonder, if there is such a huge difference between 25 and 24mm compression caps and wall thickness, is a welded star nut (like S&M, Fit, Cult) not superior? Would, for instance, an Odyssey fork (which I run) not be better if it didn't have any threading? Or is there more to it?

Also, you would think that if 25x1.5mm forks were failing constantly, switching to 24mm would be an easy fix. Yet, I see companies like Shadow (who has had forks that evidently failed miserably) opting to develop oversized fork crowns (38mm) and what not... Could these brands really be that ignorant?

[Stoked]

haha yes,  sparky's literally keeps 25mm alive

[14thStbikes]

Just a guess, but I would imagine Odyssey and their designers have decided against welding a nut in the steerer as to not add more heat/stress to the area when applying said nut.

[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, FBM, Fly, Kink, Macneil, Premium, Snafu, Stolen, Total, Volume, Verde... (as far as I can tell).

[red_spectre]

Just a guess, but I would imagine Odyssey and their designers have decided against welding a nut in the steerer as to not add more heat/stress to the area when applying said nut.

If I remember correctly, Odyssey and Sunday forks used to use M18 bolts and switched more recently to M24. I am curious if this was a result of issues from welding in the steerer (heat/stress, like you say) or if this was a cost saving technique (I imagine welding is more costly than threading?).

[sans.terre]

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

[14thStbikes]

Just a guess, but I would imagine Odyssey and their designers have decided against welding a nut in the steerer as to not add more heat/stress to the area when applying said nut.

If I remember correctly, Odyssey and Sunday forks used to use M18 bolts and switched more recently to M24. I am curious if this was a result of issues from welding in the steerer (heat/stress, like you say) or if this was a cost saving technique (I imagine welding is more costly than threading?).

I bet it is a good bit cheaper to not weld a nut in place. Also lighter if you just thread the steerer tube.
I think they have used threaded steerers since the classic race/dirt forks came out, but I could be mistaken.

[weedbix]

I'd wager that 25 is so prevalent due to so many forks being a quick tweak of something out of a catalogue

I think they have used threaded steerers since the classic race/dirt forks came out, but I could be mistaken.

They switched away from H18 (I think it was) for the 07 forks

[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

There are definitely people running forks from Colony, Demolition, FBM, Fly, Kink, and Volume (among the others that I listed which I personally would not touch with a ten foot pole) and all are 25mm.

FBM, for instance, would not be using a catalogue part - so why use 25mm? Seems strange.

[JFax]

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

[sans.terre]

i kinda purposely took FBM out of the list hoping noone would mention it lol

maybe they just dont have a tap that size laying around the shop?