1" fork with disc brakes

[cribbit]

700c road, of course.

Anyone found some on the cheaper side? For 1 1/8th I've gotten so used to Chinese carbon off ebay, especially for finding less common things (eg thru axle straight steer tube). But they don't seem to even have this one.

If I have to go expensive, what are the options?

[Mark McM]

I'm going to have to guess that you want to build a Mullet (disc brake front, rim brake rear). Disc brake road bikes are a relatively modern innovation, so any road frame built for a (rear) disc brake will almost certainly use a steerer that is larger than the effectively obsolete 1" standard.

Given the very niche application for a 1" disc road fork, I suspect you may have to go with a custom fork. The cost of custom forks can vary widely, depend on the myriad of options (and builders).

[DuddyJ]

Wound up makes 1" forks with disc brakes. Those will run you a pretty penny and dont come up used very often.

[ColonelJLloyd]

I have one of these very lightly used in a box and ready to ship if you're interested in one on the cheap. The canti bosses are removable (threaded).

Maybe Crust will have more of these made so you can go full-on weird with high offset, 1", mondo clearance AND threaded steerer.

[josephr]

nashbar offers one...but it has dual brake capability as it has canti-mounts as well as disc mounts...so it won't have that clean look.

[Ruimteaapje]

When I planned my Vetta road bike I discussed the option of a the straight 1" steel fork with disk brakes with Antonio. He questioned the long-term reliability of the 1" tube with the stress caused by the disk brake and rules against it so I went for conventional rim brakes instead.

[Mark McM]

Originally Posted by Ruimteaapje

When I planned my Vetta road bike I discussed the option of a the straight 1" steel fork with disk brakes with Antonio. He questioned the long-term reliability of the 1" tube with the stress caused by the disk brake and rules against it so I went for conventional rim brakes instead.

The steerer tube experiences exactly the same loads, regardless of the type of brake. Disc brakes shift (and amplify) loads between the crown and the fork tips, but the loads above the crown are the same.

[Ruimteaapje]

No, leverage is bigger when the brake is further from the crown. A rim brake is typically fixed on the crown whereas a disk brake is typically at the end of the fork leg. Hence a bigger load on the joint between the head tube and the crown in which case a 1 1/8" joint is stronger than a 1" one. At least that's what Antonio was worried about

[Mark McM]

Originally Posted by Ruimteaapje

No, leverage is bigger when the brake is further from the crown. A rim brake is typically fixed on the crown whereas a disk brake is typically at the end of the fork leg. Hence a bigger load on the joint between the head tube and the crown in which case a 1 1/8" joint is stronger than a 1" one. At least that's what Antonio was worried about

If you draw a free body diagram, you'll find this is not the case. Here's a simple example:

Say a wheel has a diameter of 330mm and a fork has a length of 370mm, or a total of 700mm from the ground to the top of the fork crown. If a brake is applied that generates a braking force of 100N, then there is a force of 100 N at the ground contact point, and this force will result in a equal and opposite force of 100 N at the crown, plus a bending moment at the crown of 100N x 700mm = 70000Nmm (or 70NM). It doesn't matter what type of brake is used to generate the brake force, the resultant forces at the crown (and on the steerer) are the same.

Of course, there are various forces between the brake components (rim, caliper and fork crown for the rim brake, and rotor, caliper and caliper mount for the disc brake). But all those forces are completely internal to the braking components an that portion of the fork that is between them, and all completely balance out. The external loads will depend only on the resultant brake force.

[TimD]

Originally Posted by josephr

nashbar offers one...but it has dual brake capability as it has canti-mounts as well as disc mounts...so it won't have that clean look.

We have the Nashbar item on our made-over Trek 750. Works fine. I think it is possible to remove the cantilever brake studs, leaving a bit of a hole behind (which you could tape over, or plug, or leave as-is). I could post a pic tomorrow if you are still interested.

[cribbit]

Originally Posted by Mark McM

I'm going to have to guess that you want to build a Mullet (disc brake front, rim brake rear). Disc brake road bikes are a relatively modern innovation, so any road frame built for a (rear) disc brake will almost certainly use a steerer that is larger than the effectively obsolete 1" standard.

Indeed! But actually no brake rear. For now single speed, in the future maybe fixed. Or something really weird like coaster brake.

[cribbit]

Originally Posted by Mark McM

If you draw a free body diagram, you'll find this is not the case. Here's a simple example:

Say a wheel has a diameter of 330mm and a fork has a length of 370mm, or a total of 700mm from the ground to the top of the fork crown. If a brake is applied that generates a braking force of 100N, then there is a force of 100 N at the ground contact point, and this force will result in a equal and opposite force of 100 N at the crown, plus a bending moment at the crown of 100N x 700mm = 70000Nmm (or 70NM). It doesn't matter what type of brake is used to generate the brake force, the resultant forces at the crown (and on the steerer) are the same.

Of course, there are various forces between the brake components (rim, caliper and fork crown for the rim brake, and rotor, caliper and caliper mount for the disc brake). But all those forces are completely internal to the braking components an that portion of the fork that is between them, and all completely balance out. The external loads will depend only on the resultant brake force.

Furthermore the forces of you going over even a small pothole will put far more force on the fork/bike than any braking ever could.

[cribbit]

Originally Posted by ColonelJLloyd

I have one of these very lightly used in a box and ready to ship if you're interested in one on the cheap. The canti bosses are removable (threaded).

Maybe Crust will have more of these made so you can go full-on weird with high offset, 1", mondo clearance AND threaded steerer.

Thank you, PM'd to talk about that nashbar (aaaaand bought, thanks!). I had seen those before but I can't drop $150 on just a fork for this.

That crust is beautiful. Short of full custom that's probably what I would go for if I had unlimited funds for this.