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The Road Warrior
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622 Posts
Discussion Starter · #1 ·
So I got my rigid disc fork, and noticed that it has rear-facing dropouts. Isn't this a bad idea? The load that braking puts onto a fork puts pressure going in the direction of wheel rotation, which would make sense, but common sense would tell me that a rear-facing dropout would be more susceptible to letting the wheel slip out if there's enough pressure coming from ground interaction. Plus, there are threads like this out there about rear-facing dropouts:
http://www.cyclingcrowd.com/Uwe/Forum.aspx/technical/12851/Another-broken-neck

What do you guys think?
 

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transmitter~receiver
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9,333 Posts
it doesn't sound like a great idea.
the force that a disc brake imparts on the axle is parallel to the tangent to the disc brake rotor at the caliper mount, or most often pointing from the axle rearward and downward. i have a drawing at my office that i'll post on tuesday.
i'd think the disc braking forces are your primary concern with a set-up like that. in the picture in the thread you linked the dropout opening looks parallel to the force that would be applied by the disc brake, or the worst possible geometry, in other words.
 

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Premium Member
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48,238 Posts
LandSpeed said:
So I got my rigid disc fork, and noticed that it has rear-facing dropouts. Isn't this a bad idea? The load that braking puts onto a fork puts pressure going in the direction of wheel rotation, which would make sense, but common sense would tell me that a rear-facing dropout would be more susceptible to letting the wheel slip out if there's enough pressure coming from ground interaction. Plus, there are threads like this out there about rear-facing dropouts:
http://www.cyclingcrowd.com/Uwe/Forum.aspx/technical/12851/Another-broken-neck

What do you guys think?
They are actually downward facing.

With a disc brake axle can come out during braking. Use a good skewer and it is rarely and issue.

I do prefer forks with forward facing slots, though.
 

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I will say this much; I have and old salsa cm with the downward facing dropouts and on hard braking, the wheel shifts to the point of being visibly out of line and stays there until I stop and fix it. I have the newer version on a different bike and have no such issues.
 

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Jamis, Vicious Cycles, IRD, Origin8, Surly, Kona.... all of these companies produce steel, rigid forks for 29ers that do not have forward facing dropouts. I personally have run three of the above without issue w/ 160mm disc brakes... using a QR or binder.

My personal opinion is that, yes Salsa has a fine idea. However, I don't see how a nice, tight QR or binder isn't a valid solution. And I know no one who has ever had a problem like this. And I don't think this is a "29er-only" issue if it exists.

Cromoly Delta axelrods are $10. If you are worried, it sure beats buying a new fork.
 
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